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Silica Nanoparticle/Fluorescent Dye Assembly Capable of Ultrasensitively Detecting Airborne Triacetone Triperoxide: Proof-of-Concept Detection of Improvised Explosive Devices in the Workroom

  • Andrea Revilla-Cuesta
    Andrea Revilla-Cuesta
    Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
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  • Irene Abajo-Cuadrado
    Irene Abajo-Cuadrado
    Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
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  • María Medrano
    María Medrano
    Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
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  • Mateo M. Salgado
    Mateo M. Salgado
    Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
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  • Manuel Avella
    Manuel Avella
    Electron Microscopy Lab, IMDEA Materials Institute, Eric Kandel, 2, Tecnogetafe, 28906 Getafe, Madrid, Spain
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  • María Teresa Rodríguez
    María Teresa Rodríguez
    Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
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  • José García-Calvo
    José García-Calvo
    Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
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  • , and 
  • Tomás Torroba*
    Tomás Torroba
    Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
    *Email: [email protected]
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    Orcidhttps://orcid.org/0000-0002-5018-4173
Cite this: ACS Appl. Mater. Interfaces 2023, 15, 26, 32024–32036
Publication Date (Web):June 20, 2023
https://doi.org/10.1021/acsami.3c05931

Copyright © 2023 The Authors. Published by American Chemical Society. This publication is licensed under

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Abstract

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We describe the proof of concept of a portable testing setup for the detection of triacetone triperoxide (TATP), a common component in improvised explosive devices. The system allows for field testing and generation of real-time results to test for TATP vapor traces in air by simply using circulation of the air samples through the sensing mechanism under the air conditioning system of an ordinary room. In this way, the controlled trapping of the analyte in the chemical sensor gives reliable results at extremely low concentrations of TATP in air under real-life conditions, suitable for daily use in luggage storage for airlines or a locker room for a major sporting event. The reported fluorescent methodology is very sensitive and selective, allowing for the trapping of triacetone triperoxide in the chemical sensor to give reliable results at very low concentrations in air under ambient conditions, by comparing the fluorescence of the material before and after exposition to TATP traces in air.

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Introduction

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A major threat in modern society is constituted by the so-called improvised explosive devices (IEDs). (1−6) The explosives contained in IEDs were commonly used in war scenarios but some years ago they were also used in situations of everyday life, therefore constituting a threat to the lives of countless people. Methods for the quick detection of explosive devices are needed before they cause damage, but there are very few methods for the detection of some explosives used in IEDs. (7−11) Indeed, the most advanced spectroscopy devices are very sensitive and selective to identify the chemicals used in IEDs, but they are typically too heavy for portable devices and too much expensive for widespread use. (12) The cheap technology of the cotton swab (13) requires physical access to the substance that might be hidden or not easily accessible. There is a long tradition of the use of animals in the detection of explosives, particularly trained dogs, (14) but some explosives without a characteristic smell go undetected by animals. Electronic noses, made up of artificial sensor arrays, constitute a significant solution to replace the natural senses (15,16) for reliable monitorization of diverse environments. Appropriate portable devices should alert the presence of explosives within minutes. Triacetone triperoxide (TATP) is synthesized directly from readily available starting materials; (17) for this reason, it has been frequently used in the preparation of IEDs. TATP sublimes easily at room temperature, but, because of the lack of aromatic nitro groups, its presence in the vapor phase is not detected by using common methods for explosives. (18) Common explosives containing nitro groups, such as trinitrotoluene (TNT), have a large variety of fluorescent methods for their detection, including our contribution to the field (19) and from other groups. (20−23) Another explosive employed in IEDs which is also important, hexamethylene triperoxide diamine (HMTD), has a much lower vapor pressure than TATP. Unfortunately, the detection of HMTD in the vapor phase is not possible. (24) For the detection of TATP, the most common methods are mass spectrometry, (25) ion mobility spectrometry or related technologies, (26−28) and multiphoton spectroscopy. (29) Optional complementary methods are chemically modified nanosensor arrays, (30) or portable optical methods based on colorimetric sensor arrays, in this case to detect the hydrogen peroxide (H2O2) produced by decomposition of the TATP. (31−33) Alternative indirect detection methods, by detection of H2O2 from TATP, and the oxidative processes linked to them, are frequently used for fluorometric sensing, (34−46) as well as detection of acetone from decomposition of TATP. (37,38) The direct detection of TATP has also been achieved by fluorescence quenching. (39) Analytical methods for the detection of TATP (or HMTD) in different scenarios must be selective for peroxides, appropriate for immediate analysis, and safe sampling by a qualified operator. (40) They are expected to have very low limits of detection and high selectivity, in this way, they can detect peroxides in confined public places to prevent explosions and further damage. (41) An extremely low limit of detection is easier to achieve with the highly volatile TATP than with the much less volatile HMTD. (42) Most physicochemical analytical methods for peroxide-based explosives are designed in this way. (43,44) Trace detection of TATP in the vapor phase by colorimetric or fluorometric methods, taking into account its volatility, continues to be an attractive approach for the development of chemical sensors for peroxide explosives. Some characteristics such as sensitivity and selectivity are still not well addressed. Our previous approaches consisted of solid fluorogenic sensors for the sensitive and selective detection of pristine TATP (45,46) or the microwave detection of wet-TATP, (47) both in the vapor phase, and the detection of TATP gas in an air microfluidic device. (48) After that, we have been looking for more selective and sensitive materials specifically tailored for the unambiguous detection of TATP traces in air. (49) For that purpose, we searched among solid-supported fluorescent dyes in which an oxidation event could modulate the aggregation-induced emission (AIE) characteristics of the dyes for the detection of oxidizing species. Naphthalimides are known to have AIE effects. (50) We selected a collection of new naphthalimide structures with donor and accepting groups in the structure and amino-protecting substituents in which the variation of substituents permitted the control of the AIE characteristics; in this way, we arrived at a new naphthalimide dye supported on the surface of silica nanoparticles with optimum features for the selective and ultrasensitive detection of traces of TATP in air. In this material, the AIE-gen fluorescent emission mechanism could be triggered with optimum performance via oxidation by only hydrophobic oxygen-containing oxidants. The system worked within a typical office room by simply placing the sensor in the room’s air stream. In this way, the material functioned as an IED-directed chemical tracking system. The results of the study are presented here.

Results and Discussion

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Preparation of Materials

We synthesized a number of fluorogenic probes that were tested for several types of analytes. The synthesis was performed by using Suzuki reactions, following previous experiences in developing fluorogenic probes by carbon–carbon coupling chemistry. (51−59) The new fluorogenic probes are shown in Figure 1. The amino-protected naphthalimides showed an increase of fluorescence in mixtures of organic solvents with increasing amounts of water (AIE) that disappeared when the structures contained unprotected amino groups. Previous examples have shown some of these characteristics. (60,61) The selectivity of each fluorogenic probe against the most important oxygen-based oxidizing reagents was addressed in organic–aqueous solvents, with the aim to select the best candidates for an array of fluorogenic probes for oxygen-based explosives. With the new fluorogenic probes, we performed a complete characterization and a battery of preliminary tests about selectivity and sensitivity with target explosives and several expected interferents. The sensitivity of the collection of fluorogenic probes was checked in the presence of TATP and HMTD. We prepared an experimental design for this part of the work that was applied to all fluorescent probes. Then, the sensitivity of solid-supported naphthalimides was studied in the presence of gaseous traces of home-made explosive triacetone triperoxide, so the fluorogenic materials were capable of discriminate the presence and the nature of the most important oxygen-based home-made explosive, TATP. Having a previous experience in modified materials, (45,46,48,55,62−64) we performed initial experiments by supporting the fluorescent probes on poly(dimethylsiloxane) (PDMS), but the detection limits were not good enough. Instead, silica nanoparticles afforded much better results. Next, the best fluorogenic probes developed in the previous sections were studied by quantitative sensing experiments to measure the performance of the best probes in terms of sensitivity and selectivity to trace amounts of TATP. Probes AR82s and AR82d, from the first naphthalimide series (Figure 1), both bearing the same structure and different number of protective groups in the periphery, resulted sufficiently sensitive to the presence of TATP. Furthermore, we checked the stability of both probes and found that AR82s were much more stable than AR82d; therefore, we used only AR82s for the preparation of the sensing material. AR82s-supported silica nanoparticles (AR82s@SiO2) were prepared by stirring under nitrogen, in the dark, 1 mg of AR82s and 100 mg of silica nanopowder, 10–20 nm particle size, in 5 mL chloroform for 30 min until there was no trace of dye in the solvent, then the solvent was evaporated, the solid was washed for three times with hexane (3 mL each), and then subjected to centrifugation and drying under a nitrogen stream to get the material (Figure 1). The unique sensitivity manifested by the AR82s/d series was not attained by the other two series of compounds (AR83s/d and AR90s/d), despite the large number of tests performed for all of the synthesized compounds under study (see the Supporting Information).

Figure 1

Figure 1. (a) Structure of chemical probes used for the study. (b) Model of the chemical probe AR82s on silica. (c, e) Structural and (d) elemental TEM images of the AR82s@SiO2 nanoparticles. (f) Elemental composition of the AR82s@SiO2 nanoparticles and high-resolution TEM images.

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Titration under Increasing Concentration of TATP Using a Recirculation System for TATP Vapors

The titration of AR82s@SiO2 nanoparticles was carried out by placing 15 mg of nanoparticles in an Eppendorf, covered with tin foil to avoid degradation of the nanoparticles by the action of light, and increasing amounts of TATP (from 0.025 to 2 mg) in another Eppendorf (Figure 2). Both were connected to each other and to an air stream provided by a compressor, and the microfluidic system maintained under airflow, 100 cm3/min, was gently warmed below 50 °C until consumption of TATP in every case. The lowest amounts of TATP took only seconds to evaporate (plus 10 min for recirculation), and the highest amounts took up to 20 min; therefore, the experiments were performed within 10 and 30 min until consumption of TATP. Then, the sensor material was subjected to fluorescence measurements in every case in an Edinburg Instrument FLS-980 fluorometer at an excitation wavelength of 370 nm at 25 °C. The results are displayed in Figure 2 as qualitative and quantitative fluorescent emission measurements. The titration plot showed an initial decrease of fluorescence in the presence of very low amounts of TATP, then an increase in fluorescence at low concentrations of TATP, and a decrease at higher concentrations. We calculated the limit of detection, LOD, from the initial titration plot values by IUPAC-consistent methods. (65) In this case, we calculated the LOD within the values measured (different than 0) by adjusting the initial values to a mean square linear regression and using the R program. (66,67) In this way, linear regression at low concentrations of TATP led to a LOD = 13.03 ng of TATP in absolute value or, taking into account the time of measurement and air efflux, LOD = 13.3 ng/L (57 pM). Assuming that the best LOD reported values are found in the ppb–ppm range for TATP sensing in the gas phase, (68) this new method competes favorably in terms of sensitivity and simplicity with the best-known methods, with a LOD value of 1.4 ppb in air, the lowest found so far by artificial olfaction. (8)

Figure 2

Figure 2. (a) Microfluidic device dimensions: Eppendorf: outer top diameter: 11 mm, inner top diameter: 9 mm, outer bottom diameter: 5 mm, inner bottom diameter: 3 mm, volume: 1.5 mL, height (with lid): 40 mm, height (without lid): 38 mm; tubing: outer diameter: 3 mm, inner diameter: 1.5 mm, length (flow tube): 25 mm, length (return tube:): 35 mm. (b) The actual aspect of the system; reproduced from ref (48) with permission from the Chinese Chemical Society (CCS), Institute of Chemistry of Chinese Academy of Sciences (IC), and the Royal Society of Chemistry. (c) Fluorescence changes with TATP gas. (d) Titration curves of AR82s@SiO2 and TATP vapor. (e) Fluorescent profile at 535 nm and (f) calibration for the limit of detection of AR82s@SiO2 nanoparticles under increasing concentrations of TATP vapor. λexc = 370 nm, λem = 535 nm.

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Validation in Real-Life Scenarios

We looked for the validation of the fluorescent device to detect TATP explosive in real-life scenarios. We tested under close to realistic conditions the TATP sensor material by placing in a small room, at different temperatures, a few milligrams of solid TATP and some samples of the AR82s@SiO2 nanoparticles at different distances, leaving it for some time. In every case, we previously performed the experiment without TATP to have a set of comparison values. In all tests, there was a neat change of the fluorescence between the signal obtained with the nanomaterial in the presence of TATP at a certain distance, in comparison to the nanomaterial without the presence of TATP under the same ambient conditions. Subsequently, we looked for tests performed under the mildest conditions of the system to have a positive signal, under typical ambient temperatures and at increasingly longer distances from the TATP vapor source. The experiments were carried out in an office with dimensions 3.07 × 3.54 × 2.15 m3 (height × length × width). Inside the room, we placed appropriate air heaters to maintain constant temperature and an air compressor, which generated a gentle stream of clean air that passed over the TATP sample in the direction of the locations where the nanoparticles were positioned (Figure 3). The office had also its own central heating and ventilation system, so the airflow was not steady but subjected to the inherent small turbulences of every working office. A fixed amount of TATP (25 mg) was placed at a distance of 30 cm from the source of the airflow (100 cm3/min, 0.8 cm internal diameter) (Figure 3). A fixed amount of AR82s@SiO2 nanoparticles (0.75 mg) was placed on the surface of a cover glass, adhered to it with the help of a small amount of adhesive tape (Figure 3). This process was repeated 6 times, and the cover glasses were placed at increasing distances from the point where the TATP was located (10, 25, 50, 100, 150, and 200 cm) (Figure 3). We performed the experiments at different room temperatures between 20 and 30 °C. In order to find the best working conditions, the fluorescence changes of all experiments were normalized to the highest value and compared with the nonexposed nanomaterial samples subjected to the same room conditions, in turn normalized to the lowest fluorescence value, and the differences were represented together for comparison purposes. To compare the effect of TATP on time, we adjusted the values to 30 min in all cases. In a representative experiment, 0.2523 g of TATP was weighed and placed in the room at 26 °C for 30 min: Of the 0.2523 g of TATP initially weighed, only 0.0386 g evaporated under the temperature and time conditions used in this experiment, and the remaining 0.2167 g of TATP remained as solid in the original sample; this gave a maximum concentration of 1.65 mg/m3 in the air of the room, supposing that all TATP evaporated during the experiment remained in the room, which is not a sealed system. Comparative photographs of selected experiments taken under UV light (366 nm) before and after exposure to TATP vapors are shown in Figures S71 and S72 and the normalized emission intensities of all individual experiments are shown in Figures S73 and S74. Figure 3 shows a 3D histogram plotting the differences in intensity emission in all cases, before and after exposure to TATP vapors, as a function of distance from the TATP source and temperature of the room, normalized to the top and reference signals. Generally speaking, there was a clear increase in fluorescence from the solid sensor samples, with several variations related to the inherent turbulence of the air stream, combined to the air heating system, and the specific sensitivity of the nanoparticles to the amounts of TATP detected. The detection of TATP in air was well assured in quantities of around one milligram per cubic meter of air in an ordinary room where there was air exchange, central heating, and consequently inherent air turbulence; this means that not all samples received proportional amounts of TATP in the gas phase. Positive detection was therefore guaranteed by at least three neat increases in the fluorescence within 10 cm and 2 m from the TATP source (Figure 3). Hence, the detection system is suitable for practical measurements in standard real-life scenarios.

Figure 3

Figure 3. (a) Distribution of TATP sample (yellow arrow) and sensor samples (red arrows) in the room. (b) Close view of the arrangement of the TATP sample (yellow arrow) in front of the airflow outlet and the sensing material samples (red arrows). (c) Histogram plotting the differences in intensity emission in all cases before and after exposure to TATP vapors as a function of distance from the TATP source and temperature of the room, normalized to the top and reference signals. (d) A sample of sensing material showing the modified nanoparticles.

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From the results of the previous series of experiments, we observed that the best temperature to perform the experiment was around 26 °C. Therefore, a series of 6 additional experiments were performed at an average temperature of 26 °C for all experiments. The experiments were carried out in an office of dimensions 3.07 × 3.54 × 2.15 m3 (height × length × width) and had a duration of 30 min. Figures S76 and S77 illustrate both the dimensions and the arrangement of the different elements in the room as the experiments were performed. Inside the office, an air compressor was placed, which generated a continuous stream of clean air that passed through the TATP in the direction of the points where the particles were arranged. Initially, the temperature inside the room was regulated with a fan-forced convection air heater. When the temperature reached near 30 °C, the heater was turned off and the temperature was left to reach an average temperature of 26 °C for the performance of the experiments. Then, 0.75 mg of AR82s@SiO2 nanoparticles was placed on the surface of a cover glass and adhered to it with the help of a small amount of adhesive tape, as in previous experiments. This process was repeated six times, and the cover glasses were placed at increasing distances from the point where the TATP should be located (10, 25, 50, 100, 150, and 200 cm). To conduct every experiment, blank measurements of pristine nanoparticles left for 30 min in the room, with no presence of TATP, were performed and used as reference in every case. Then, 250 mg of TATP was placed at a 30 cm distance from the source of the airflow. Once TATP and nanoparticles were placed, the system was left in the presence of TATP for a period of 30 min so the measurements were made for each group of nanoparticles before and after the exposure to TATP vapors. After each experiment, the remaining amount of TATP was weighed and the fluorescence of nanoparticles was measured. To carry out the measurements in the fluorometer, each sample was covered with a quartz sheet to ensure that the nanoparticles remained in a fixed position (see Supporting Videos). This sheet was removed to leave the particles exposed to TATP vapors during the experiment. Pictures of the nanoparticles were taken under identical conditions in every case. The excitation wavelength was 370 nm. From the initial 250 mg samples of TATP, only a small amount evaporated in every case: 23, 23, 36, 36, 32, and 32 mg, an average of 30.3 mg of TATP involved in all of the experiments, 1.30 mg/m3 average, in a range of 0.98–1.54 mg/m3. Complete experimental data of all experiments are shown in Figures S78–S101. For easier visualization of the whole data, we graphically represented the normalized emission intensity variation before and after exposure to TATP vapors with respect to distance to the TATP source (Figure S102); this time the tendency of the data showed a clear decrease of the fluorescence intensity or the proportionality factor of fluorescence variation in each case from short to long distances from the TATP source, but again the number of fluctuations from the similarly performed experiments was high. For the representation of the data, the maximum emission intensity data from the experiments were organized according to the distance to the TATP source, representing in bars one next to the other, the emission values before and after contact with TATP vapors. These data were also normalized with respect to the maximum of emission from each experiment. After this, a common initial emission level was established using the lowest value measured for the nanoparticles prior to the exposure to TATP vapors. And finally, the subtraction was made between the final and initial emission values. Figure S104 shows the 2D representation, and Figure 4 shows the summary of experiments as a 3D representation of the variation of the normalized emission intensity as a function of the distance to the TATP source.

Figure 4

Figure 4. Summary of experiments 7–12. (a) Arrangement of the TATP in front of the airflow outlet. (b) Distribution of sensing nanoparticles in the room. (c) 3D representation of the variation of the normalized emission intensity as a function of the distance to the TATP source. (d) Assembly of the nanoparticles for measurements. (e) Details of one sample of AR82@SiO2.

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With the aim to extract the tendency of the described experiments, a selection of the measurements was made, discarding outliers and selecting only 3 measurements for every one of the distances to the TATP source. Using these measurements, the average and standard deviation of the normalized variation of the emission intensity for each point were calculated and represented. Figure 5 shows the average and standard deviation of normalized emission variation as a function of the distance to the TATP source. Albeit the large fluctuations, represented by the large deviations from the normalized emission variations, it is clear that there is a marked tendency to stronger variations of the fluorescence as the detecting material is closer to the source of TATP vapor and the system is strong enough to work under close to real conditions appropriate to any environment where TATP vapor with a concentration of at least 1 mg/m3 is suspected to be found, in a nonsealed environment suitable for life scenarios that could be sensitive to terrorism attack.

Figure 5

Figure 5. Average and standard deviation of normalized emission variation as a function of the distance to the TATP source.

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Mobile Phone Application

A dedicated mobile phone to the application was used to detect the presence of TATP in the vapor flow. The purpose of the application was to detect the amount of TATP from an image of AR82s@SiO2 sample exposed to TATP vapors. The user had to configure the system correctly in order to obtain a suitable result. The application has two systems for determining the amount of TATP by RGB: (1) Interval search: each sample exposed to a known amount of TATP was configured with several colors, in which the target could be included. To detect the amount of TATP to which the nanoparticles were exposed, a color was selected and an interval search was carried out. Example: suppose we have a target color 50, 240, 70 and we have the following intervals [40, 130, 60], [10, 250, 60], and [55, 244, 71]. The comparison algorithm will detect that the target 50, 240, 70 is in the interval [40, 230, 60] 50, 240, 70 [55, 244, 71]. (2) Radio search: suppose we have a target color 50, 240, 70 and we work with a radius of 10. The intervals we have are [40, 230, 60], [10, 250, 60], and [85, 244, 41]. Then, the compare algorithm will detect that the target 50, 240, 70 is in the radius of the interval [40, 230, 60] since if we add the radius ±10, we would have this radius [40, 230, 60] or [60, 250, 80]. The system of the application was composed of the following components: (1) Mobile application: it was developed with IONIC technology with which we have the possibility of generating an APK for Android or IPA for IOS. (2) Laravel api: communication with the backend where queries were made from the mobile application to the database. (3) Database: system of tables designed to be able to store colors dynamically and to meet the needs of the application. System configuration: The application is made up of different configurable sections, (1) Login: to be able to enter the system, access credentials are required. (2) Menu: allows the user to view and access the different options of the application. (3) Users: the list of users authorized to access the application is displayed, as well as the option to delete them. (4) User settings: personal data (name, email, password, etc.) can be changed from this screen. (5) New user: it allows the user to create new users by filling in the required information. The data will be verified before granting access to the application. (6) Color list: list of the different nanoparticle colors for each amount of TATP in vapor phase, accessed from “menu” and then “my colors”. In this screen, colors can be deleted and the data updated at any time as well as to watch the rest of the stored colors. (7) New color: to add a new color to a TATP measurement, we click on “add color” and select the TATP quantity and add an RGB color, manually or by selecting it on an image. The latter is the fastest method as it allows the user to save and continue adding colors. (8) Color detection: once the system is configured with the different TATP measurements, in the “analysis” screen, the user can take a picture or select an image from the gallery and choose the point where the user wants to detect how much TATP it has been exposed to. The images are very important because the higher the quality, the higher the accuracy in detecting RGB color (see Figures S64–S66 for detailed images of the app). The application for the mobile phone was based on: Ionic https://ionicframework.com. Laravel, https://laravel.com/docs/8.x/eloquent-resources. Database, https://www.mysql.com. The application was part of an autonomous system for capturing and quantitative evaluation of fluorescent probe images based on mobile telephony composed of: (1) customized display box, (2) 360° metal bracket, (3) customized APP, and (4) OPPO Find X3 Pro 5G. The system allows taking photographs with a mobile phone camera from very short distances of a sensor material previously exposed to an explosive atmosphere. For this, the sensing material was placed in a dark box with a metal holder and a UV lamp (366 nm) to illuminate the material (Figure S68). The application to compare the photo with a database of images of the material exposed to different amounts of TATP in vapor phase is loaded on the mobile phone, consequently, from the comparison and the calculated calibration curve, the amount of the explosive that was in contact with the AR82s@SiO2 can be extracted. Initially, the system was trained and tested by using the experiments described in Figure 2. In this way, the system worked as a quick test for detecting TATP in air (see Figures S65 and S67 for detailed images of a selection of positive and negative detection cases) from samples with quantitative TATP treatment under controlled conditions, in those cases giving accurate results. Then, the system was validated under close to real conditions from samples obtained in experiments 7–12 (Figure 4). Details of experiments and the corresponding pictures are given in the Supporting Information (2-app measurements file). The selected images corresponded to nondiscarded measurements used for Figure 5, to allow the measurements to be compared with previous results obtained in those experiments. For maximal randomization, one sample from each experiment from the 7 to 12 series was measured. Positive results gave a value in mg, taken from experiments in Figure 2, that are converted to TATP concentrations by using the table of evaporation times from Figure S60 under the air stream flow (100 cm3/min). Therefore, exp. 8@10 cm and exp. 7@25 cm (Figure 6) distances, exposed to TATP vapor in the room, gave a value of 0.70 mg/m3 of TATP concentration in the air, exp. 10@50 cm, exp. 9@100 cm, and exp. 12@150 cm distances, exposed to TATP vapor in the room, gave a value of 0.24 mg/m3 of TATP concentration in the air, and exp. 11@200 cm distance, exposed to TATP vapor in the room, gave a value of 0.06 mg/m3 of TATP concentration in the air. On the other hand, nonexposed sample references from exp. 7@10 cm and exp. 10@100 cm gave in both cases a negative result, thus providing roughly approximate values of existence, or confirming inexistence, of TATP in the room, with the only assistance of the sensing material, a black box with a UV lamp, and a customized app installed in a mobile phone.

Figure 6

Figure 6. (a) View of the room for the experiment, (b) the TATP sample and the sensing material at different distances from the TATP, (c) picture of the sensing material placed at 25 cm from the TATP source, under a UV lamp, before (up) and after (down) being exposed to TATP, (d) picture (down) captured by the mobile phone app, and (e) the app assigned a positive value after comparing the RGB values in the selected point with the customized database.

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Experimental Methods

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The selection of the appropriate dye for TATP detection consisted of an iterative process. First, the synthesized compounds were fully characterized by physical and spectral methods, IR, 1H/13C NMR, HRMS (MALDI/ESI), UV–vis, FL, Ø, τ. UV–vis and fluorescence measurements were performed in a series of 14 solvents from high to low polarity [1. H2O, 2. MeOH, 3. DMSO, 4. DMF, 5. MeCN, 6. Acetone, 7. EtOAc, 8. THF, 9. CHCl3, 10. CH2Cl2, 11. Toluene, 12. Et2O, 13. Hexane, 14. Methylcyclohexane (MCH)]. Then, compounds are tested in solution for the sensitivity to low to high amounts of water (0 to 90% water, usually in THF), pH values (3.4–10.4), anions (11 representative anions: 1. F–, 2. Cl–, 3. Br–, 4. I–, 5. BzO–, 6. NO3–, 7. H2PO4–, 8. HSO4–, 9. AcO–, 10. CN–, 11. SCN–), cations (18 representative cations: 1. Ag+, 2. Ni2+, 3. Sn2+, 4. Cd2+, 5. Zn2+, 6. Pb2+, 7. Cu2+, 8. Fe3+, 9. Sc3+, 10. Al3+, 11. Hg2+, 12. Au2+, 13. Co2+, 14. Pd2+, 15. Ir3+, 16. Cu+, 17. Ru3+, 18. Pt2+), oxidizing and reducing agents in different solvents [(addition in water, series A: 1. HCl, 2. HNO3, 3. Oxone, 4. Hydrazine, 5. H2O2) (addition in MeOH, series B: 1. Meta-chloroperbenzoic acid (m-CPBA), 2. Trinitrobenzene (TNB), 3. Trinitrotoluene (TNT)) (addition as solid, series C: 1. m-CPBA, 2. TATP, 3. HMTD)] on suitable diluted solutions of the dye in an organic solvent, usually miscible with water, and the physical changes were followed by fluorescence measurements. Those compounds showing the utmost performance in terms of sensitivity and selectivity to the presence of peroxide-carried oxidants (except hydrogen peroxide) are then subjected to TATP sensitivity in different solvents, and the changes are monitored by fluorescence measurements. Then, kinetic behavior and titration experiments were performed, first in different solvents, then by accurate titration in the best solvent, selected from previous experiments. When the detection limit was sufficiently low, the study of detection of TATP in the gas phase was subsequently performed with the colorant adsorbed on the surface of silica, anatase, or hybrid nanoparticles. The experiments of sensitivity to TATP in the gas phase by solid-supported dyes were performed by comparing the increase of the quantum yield of the samples in the presence or absence of TATP under controlled conditions. Compound AR82s showed the best performance in all tests; therefore, it was selected for the experiments of TATP detection in the gas phase under real conditions in the open air. The mechanism of detection of TATP was carefully studied in solution by comparison of the action of TATP and m-CPBA, under the hypothesis that TATP acts in the experiments as a mild oxidant. We performed a point-to-point titration of AR82s (2.5 μM in CH2Cl2) in the presence of increasing amounts of TATP by preparing 33 solutions of AR82s (2.5 μM in CH2Cl2). TATP was added as a solid to each of them, resulting in 33 solutions of concentrations between 0 μM and 23.72 mM. The fluorescence changes were registered immediately after the addition of TATP to AR82s (2.5 μM in CH2Cl2), λexc = 370 nm and λem (CH2Cl2) = 500 nm, at 25 °C (Figure 7). The TATP titration plot showed an increase in fluorescence at low concentrations of TATP and a decrease at higher concentrations. We calculated the limit of detection, LOD, from the initial titration plot values by IUPAC-consistent methods. (65) In this case, we calculated the LOD within the values measured (different than 0) by adjusting the initial values to a mean square linear regression and using the R program. (66,67) In this way, linear regression at low concentrations of TATP led to a LOD = 0.87 μM or 0.19 μg·mL–1 of TATP, which was suitable for practical purposes. Analogously, we performed a point-to-point titration of a 2.5 μM solution of AR82s in CH2Cl2 and increasing amounts of m-CPBA (the oxidant concentration maintained between 0 and 0.02 M), and measuring the variation of the fluorescence after each addition with an Edinburg Instrument FLS-980 fluorometer. Measurements were carried out immediately after every addition of m-CPBA. λexc = 370 nm and λem = 430 and 500 nm, at 25 °C. The m-CPBA titration plot showed a decrease in fluorescence of the green emission at 500 nm at low concentrations of m-CPBA and an increase at higher concentrations, followed by a further decrease. We calculated the limit of detection, LOD, from the initial titration plot values by IUPAC-consistent methods. (65) In this case, we calculated the LOD within the values measured (different than 0) by adjusting the initial values to a mean square linear regression and using the R program. (66,67) In this way, linear regression at low concentrations of m-CPBA led to a LOD = 2.1 nM or 0.3 ng·mL–1 of m-CPBA, which was only interesting for comparison purposes (Figure 7). The blue emission at 430 nm showed instead a slow increase in intensity. The ratios of fluorescence intensities at 500 and 430 nm (F500/F430) exhibited good linearity with increasing m-CPBA concentrations in the range from 0 to 20 μM (Figure 7). The linear regression equation was F500/430 = 0.1744x + 59.8340.

Figure 7

Figure 7. (a) Titration curves, TATP titration. (b) Fluorescence profile at 500 nm, TATP titration. (c) Calibration plot for the limit of detection of 2.5 μM GC2 solutions in DCM under increasing concentrations of TATP. (d) Image of solutions before and after TATP titration. (e) Titration curves, m-CPBA titration. (f) Fluorescence profile at 500 nm, m-CPBA titration. (g) Calibration plot for the limit of detection. (h) Fluorescence profile at the corresponding working curves of the ratiometric probe in the presence of m-CPBA.

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1H NMR Titration of AR82s with TATP in the Presence of Amberlite

We performed a 1H NMR titration of AR82s (3 mg in 0.5 mL in CDCl3) with increasing amounts of TATP in the presence of Amberlite (1.5 mg) to prevent accumulation of TATP in the NMR tube. Two selected regions gave clear NMR modifications (Figure 8).

Figure 8

Figure 8. 1H NMR (CDCl3, 500 MHz) titration of AR82s with increasing amounts of TATP in the presence of amberlite, 3 mg of AR82s in 0.5 mL of CDCl3, and TATP amounts: (1) 0 μg, (2) 5 μg, (3) 10 μg, (4) 15 μg, (5) 20 μg, (6) 30 μg, (7) 40 μg, (8) 60 μg, (9) 90 μg, (10) 150 μg, (11) 300 μg, (12) 500 μg, (13) 800 μg, (14) 1400 μg, (15) 3200 μg, (16) 6800 μg, (17) 10 400 μg, (18) 15 800 μg as total added TATP after each addition, (a) 2.8–4.0 ppm region, (b) 7.5–8.7 ppm region.

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The titrations showed chemical shift of the signals of protons in the vicinity of the unprotected secondary amino group, signals at 2.93 and 3.46 ppm, accompanied by splitting of the signal at 2.93 at high amounts of TATP. There are no changes in the piperazine proton signals at 3.58 and 3.93 ppm. On the aromatic region, there is a clear splitting of all aromatic signals with changes in the coupling patterns between the signals, indicating a desymmetrization of the molecule. Apparently, oxidation of the unprotected secondary amino group will trigger the chemical shift of the methylene groups of the oxidized piperidine group as well as the association between molecules in solution, with a concomitant change in fluorescence either by suppressing the charge transfer from the amine group or by modifying the aggregation-induced effect when in solution because of the modification of the structure, in relation to the variation in the AIE effect we have observed for the rest of synthesized examples. We then studied the mechanism of oxidation of AR82s by NMR titration in the presence of increasing amounts of m-CPBA, and the titrations showed only oxidation of the unprotected secondary amino group with progressive disappearance of the proton signal of the amine group and chemical shift of the methylene groups of the oxidized piperidine group (the signals between 1.8 and 3.7 ppm in Figure S112), therefore confirming the oxidation mechanism. There is also splitting of the aromatic signals but, in this case, the changes in the aromatic region are obscured by the presence of the signals of the m-CPBA protons.

Conclusions

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We have described the proof of concept of a portable testing setup for the detection of triacetone triperoxide (TATP), a common component in improvised explosive devices. The system allows for field testing and generation of real-time results to test for TATP vapor traces in air by simply using circulation of the gas samples through the sensing material under the air conditioning system of an ordinary room. In this way, the controlled trapping of the analyte in the chemical sensor gives reliable results at extremely low concentrations of TATP in air under real-life conditions. The system may have immediate applications in everyday use. Air samples at airports, government buildings, sports arenas, or concert halls, where many people gather, should be checked for IED-containing peroxide explosives to prevent terrorist acts. The system provides for an extremely low limit of detection of traces of TATP in air as it is required to be of practical use. Vapor detection as we have shown here is a useful and noninvasive method suitable for explosive detection among current explosive detection technologies. TATP still goes largely unnoticed in many densely populated places, where permanent monitorization is needed. The results now reported are ready to convert the current knowledge in everyday useful technology to be applied whenever it is necessary for the detection of traces of IEDs in luggage storage, sports depots, headquarters, locker rooms, or restricted public access, before they can cause any harm.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsami.3c05931.

  • Complete characterization for all compounds, additional experimental details, materials, and methods (PDF)

  • Fluorometer measurements with nanoparticles in a fixed position (MP4)

  • Fluorometer measurements with nanoparticles in a fixed position (MP4)

  • Photographs of experimental setup (PDF)

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Author Information

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  • Corresponding Author
  • Authors
    • Andrea Revilla-Cuesta - Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
    • Irene Abajo-Cuadrado - Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
    • María Medrano - Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
    • Mateo M. Salgado - Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
    • Manuel Avella - Electron Microscopy Lab, IMDEA Materials Institute, Eric Kandel, 2, Tecnogetafe, 28906 Getafe, Madrid, Spain
    • María Teresa Rodríguez - Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain
    • José García-Calvo - Department of Chemistry, Faculty of Science, University of Burgos, 09001 Burgos, Spain;  Present Address: IMDEA Nanociencia Institute, Faraday 9, 28049 Madrid, Spain
  • Author Contributions

    The manuscript was written through contributions of all authors. A.R.-C., M.M.S., and M.T.R. performed the synthesis and characterization of all compounds. I.A.-C. and M.M. performed the titration experiments. J.G.-C. designed the titration experiments. M.A. performed the characterization of solid materials. T.T. designed the synthesis and, in collaboration with A.R.-C. and I.A.-C., wrote the manuscript. All authors have given approval to the final version of the manuscript.

  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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This research was funded by the NATO Science for Peace and Security Programme (Grant SPS G5536) and the Ministerio de Ciencia e Innovación (Grants PID2019-111215RB-I00 and PDC2022-133955-I00). A.R.-C. thanks Secretaría General de Universidades for a FPU18/03225 Grant. The authors thank J. Rafael Santana-Tejada, from Movilmatica (www.movilmatica.com) for technical assistance with the preparation of the app.

Abbreviations

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TATP

triacetone triperoxide

IED

improvised explosive devices

TNT

trinitrotoluene

HMTD

hexamethylene triperoxide diamine

AIE

aggregation-induced emission

PDMS

poly(dimethylsiloxane)

GC2@SiO2

C2-supported silica nanoparticles

TEM

transmission electron microscopy

LOD

limit of detection

MCH

methylcyclohexane

m-CPBA

meta-chloroperbenzoic acid

TNB

trinitrobenzene

IR

infrared

NMR

nuclear magnetic resonance

HRMS

high-resolution mass spectrometry

MALDI

matrix-assisted laser desorption/ionization

ESI

electrospray ionization

UV–Vis

ultraviolet–visible

FL

fluorescence

Ø

quantum yield

τ

lifetime

References

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    Ong, Ta-Hsuan; Mendum, Ted; Geurtsen, Geoff; Kelley, Jude; Ostrinskaya, Alla; Kunz, Roderick
    Analytical Chemistry (Washington, DC, United States) (2017), 89 (12), 6482-6490CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
    Canines remain the gold std. for explosives detection in many situations, and there is an ongoing desire for them to perform at the highest level. This goal requires canine training to be approached similarly to scientific sensor design. Developing a canine training regimen is made challenging by a lack of understanding of the canine's odor environment, which is dynamic and typically contains multiple odorants. Existing methodol. assumes that the handler's intention is an adequate surrogate for actual knowledge of the odors cuing the canine, but canines are easily exposed to unintentional explosive odors through training material cross-contamination. A sensitive, real-time (∼1 s) vapor anal. mass spectrometer was developed to provide tools, techniques, and knowledge to better understand, train, and utilize canines. The instrument has a detection library of nine explosives and explosive-related materials consisting of 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 2,4,6-trinitrotoluene (TNT), nitroglycerin (NG), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), pentaerythritol tetranitrate (PETN), triacetone triperoxide (TATP), hexamethylene triperoxide diamine (HMTD), and cyclohexanone, with detection limits in the parts-per-trillion to parts-per-quadrillion range by vol. The instrument can illustrate aspects of vapor plume dynamics, such as detecting plume filaments at a distance. The instrument was deployed to support canine training in the field, detecting cross-contamination among training materials, and developing an evaluation method based on the odor environment. Support for training material prodn. and handling was provided by studying the dynamic headspace of a nonexplosive HMTD training aid that is in development. These results supported existing canine training and identified certain areas that may be improved.
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  15. 15
    Li, Z.; Askim, J. R.; Suslick, K. S. The Optoelectronic Nose: Colorimetric and Fluorometric Sensor Arrays. Chem. Rev. 2019, 119, 231– 292,  DOI: 10.1021/acs.chemrev.8b00226
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    15
    The Optoelectronic Nose: Colorimetric and Fluorometric Sensor Arrays
    Li, Zheng; Askim, Jon R.; Suslick, Kenneth S.
    Chemical Reviews (Washington, DC, United States) (2019), 119 (1), 231-292CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
    A review. A comprehensive review on the development and state of the art of colorimetric and fluorometric sensor arrays is presented. Chem. sensing aims to detect subtle changes in the chem. environment by transforming relevant chem. or phys. properties of mol. or ionic species (i.e., analytes) into an anal. useful output. Optical arrays based on chemoresponsive colorants (dyes and nanoporous pigments) probe the chem. reactivity of analytes, rather than their phys. properties (e.g., mass). The chem. specificity of the olfactory system does not come from specific receptors for specific analytes (e.g., the traditional lock-and-key model of substrate-enzyme interactions), but rather olfaction makes use of pattern recognition of the combined response of several hundred olfactory receptors. In a similar fashion, arrays of chemoresponsive colorants provide high-dimensional data from the color or fluorescence changes of the dyes in these arrays as they are exposed to analytes. This provides chem. sensing with high sensitivity (often down to ppb levels), impressive discrimination among very similar analytes, and exquisite fingerprinting of extremely similar mixts. over a wide range of analyte types, in both the gas and liq. phases. Design of both sensor arrays and instrumentation for their anal. are discussed. In addn., the various chemometric and statistical analyses of high-dimensional data (including hierarchical cluster anal. (HCA), principal component anal. (PCA), linear discriminant anal. (LDA), support vector machines (SVMs), and artificial neural networks (ANNs)) are presented and critiqued in ref. to their use in chem. sensing. A variety of applications are also discussed, including personal dosimetry of toxic industrial chem., detection of explosives or accelerants, quality control of foods and beverages, biosensing intracellularly, identification of bacteria and fungi, and detection of cancer and disease biomarkers.
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  16. 16
    Li, Z.; Suslick, K. S. The Optoelectronic Nose. Acc. Chem. Res. 2021, 54, 950– 960,  DOI: 10.1021/acs.accounts.0c00671
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    16
    The Optoelectronic Nose
    Li, Zheng; Suslick, Kenneth S.
    Accounts of Chemical Research (2021), 54 (4), 950-960CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)
    A review. Conspectus: How does one tell the difference between one mol. or mixt. of mols. from another. Chem. sensing seeks to probe phys. or chem. properties of mol. or ionic species (i.e., analytes) and transform that information into a useful and distinguishable output. The olfactory system of animals is the prototype of chem. sensing. Even for human beings (who are generally more visual than olfactory creatures), the sense of smell is one of our most basic capabilities, and we can discriminate among many thousands, and possibly even billions, of different odors. The chem. specificity of the olfactory system does not come from specific receptors for specific analytes (i.e., the traditional lock-and-key model of enzyme-substrate interactions), but rather olfaction uses pattern recognition of the combined responses of several hundred olfactory receptors. In analogy to olfaction, colorimetric sensor arrays provide high dimensional data from the color changes of chem. responsive colorants as they are exposed to analytes. These colorants include pH responsive dyes, Lewis acid/base indicators, redox dyes, vapochromics, and surface-modified silver nanoparticles. The color difference maps so created provide chem. sensing with high sensitivity (often down to ppb levels), impressive discrimination among very similar analytes, and exquisite fingerprinting of extremely similar mixts. over a wide range of analyte types, both in the gas and liq. phases. Such colorimetric arrays probe a wide range of the chem. reactivity of analytes, rather than the limited dimensionality of phys. properties (e.g., mass) or physisorption (e.g., traditional electronic noses). Our sensor arrays are disposable and simple to produce by either inkjet or robotic dip-pen printing onto the surface of porous polymer membranes or even paper. Design of both sensor arrays and optical readers for their anal. has advanced to a fully self-contained pocket-sized instrument, the optoelectronic nose. Quant. anal. requires appropriate chemometric methods for pattern recognition of data with inherently high dimensionality, e.g., hierarchical cluster anal. and support vector machines. A wide range of applications for the colorimetric sensor arrays has been developed, including personal dosimetry of toxic industrial chems., detection of explosives or fire accelerants, monitoring pollutants for artwork and cultural heritage preservation, quality control of foods and beverages, rapid identification of bacteria and fungi, and detection of disease biomarkers in breath or urine. The development of portable, high-accuracy instrumentation using std. imaging devices with the capability of onboard, real-time anal. has had substantial progress and increasingly meets the expectations for real-world use.
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  17. 17
    Härtel, M. A. C.; Klapötke, T. M.; Stiasny, B.; Stierstorfer, J. Gas-phase Concentration of Triacetone Triperoxide (TATP) and Diacetone Diperoxide (DADP). Propellants Explos. Pyrotech. 2017, 42, 623– 634,  DOI: 10.1002/prep.201700034
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    There is no corresponding record for this reference.
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    Dubnikova, F.; Kosloff, R.; Almog, J.; Zeiri, Y.; Boese, R.; Itzhaky, H.; Alt, A.; Keinan, E. Decomposition of Triacetone Triperoxide Is an Entropic Explosion. J. Am. Chem. Soc. 2005, 127, 1146– 1159,  DOI: 10.1021/ja0464903
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    18
    Decomposition of Triacetone Triperoxide Is an Entropic Explosion
    Dubnikova, Faina; Kosloff, Ronnie; Almog, Joseph; Zeiri, Yehuda; Boese, Roland; Itzhaky, Harel; Alt, Aaron; Keinan, Ehud
    Journal of the American Chemical Society (2005), 127 (4), 1146-1159CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    Both X-ray crystallog. and electronic structure calcns. using the cc-pVDZ basis set at the DFT B3LYP level were employed to study the explosive properties of triacetone triperoxide (TATP) and diacetone diperoxide (DADP). The thermal decompn. pathway of TATP was investigated by a series of calcns. that identified transition states, intermediates, and the final products. Counterintuitively, these calcns. predict that the explosion of TATP is not a thermochem. highly favored event. It rather involves entropy burst, which is the result of formation of one ozone and three acetone mols. from every mol. of TATP in the solid state.
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  19. 19
    Romero, D. C.; Calvo-Gredilla, P.; García-Calvo, J.; Diez-Varga, A.; Cuevas, J. V.; Revilla-Cuesta, A.; Busto, N.; Abajo, I.; Aullón, G.; Torroba, T. Self-Assembly Hydrosoluble Coronenes: A Rich Source of Supramolecular Turn-On Fluorogenic Sensing Materials in Aqueous Media. Org. Lett. 2021, 23, 8727– 8732,  DOI: 10.1021/acs.orglett.1c03175
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    19
    Self-Assembly Hydrosoluble Coronenes: A Rich Source of Supramolecular Turn-On Fluorogenic Sensing Materials in Aqueous Media
    Romero, Daisy C.; Calvo-Gredilla, Patricia; Garcia-Calvo, Jose; Diez-Varga, Alberto; Cuevas, Jose Vicente; Revilla-Cuesta, Andrea; Busto, Natalia; Abajo, Irene; Aullon, Gabriel; Torroba, Tomas
    Organic Letters (2021), 23 (22), 8727-8732CODEN: ORLEF7; ISSN:1523-7052. (American Chemical Society)
    Water-sol. coronenes, that form nanoparticles by self-assocn., work as new fluorescent materials by complexation with cucurbit[7]uril, as well as selective turn-on fluorogenic sensors for nitroarom. explosives with remarkable selectivity, by using only water as solvent.
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  20. 20
    Wan, W.-M.; Tian, D.; Jing, Y.-N.; Zhang, X.-Y.; Wu, W.; Ren, H.; Bao, H.-L. NBN-Doped Conjugated Polycyclic Aromatic Hydrocarbons as an AIEgen Class for Extremely Sensitive Detection of Explosives. Angew. Chem., Int. Ed. 2018, 57, 15510– 15516,  DOI: 10.1002/anie.201809844
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    20
    NBN-Doped Conjugated Polycyclic Aromatic Hydrocarbons as an AIEgen Class for Extremely Sensitive Detection of Explosives
    Wan, Wen-Ming; Tian, Di; Jing, Ya-Nan; Zhang, Xiao-Yun; Wu, Wei; Ren, Hao; Bao, Hong-Li
    Angewandte Chemie, International Edition (2018), 57 (47), 15510-15516CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
    A simple and efficient synthesis of NBN-doped conjugated polycyclic arom. hydrocarbons (such as diazaborinines) has been accomplished by a catalyst-free intermol. dehydration reaction at room temp. between boronic acid and diamine moieties with yields up to 99 %. Polycyclic arom. hydrocarbons with a six-membered NBN ring are a new class of aggregation-induced emissive luminogens. Extremely sensitive detection of ppb levels of TNT by Ph naphthodiazaborinine is straightforward. Visual detection of TNT is illustrated by fabrication of TNT test strips, which can detect as little as 100 ng of TNT powder. This simple and sensitive detection of TNT has potential applications in the area of public safety and security against terrorist activities.
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  21. 21
    Kim, S.; Kim, H.; Qiao, T.; Cha, C.; Lee, S. K.; Lee, K.; Ro, H. J.; Kim, Y.; Lee, W.; Lee, H. Fluorescence Enhancement from Nitro-Compound-Sensitive Bacteria within Spherical Hydrogel Scaffolds. ACS Appl. Mater. Interfaces 2019, 11, 14354– 14361,  DOI: 10.1021/acsami.9b02262
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    21
    Fluorescence Enhancement from Nitro-Compound-Sensitive Bacteria within Spherical Hydrogel Scaffolds
    Kim, Soohyun; Kim, Hyunji; Qiao, Tian; Cha, Chaenyung; Lee, Sung Kuk; Lee, Kangseok; Ro, Hyun Ji; Kim, Youngkyun; Lee, Wonmok; Lee, Hyunjung
    ACS Applied Materials & Interfaces (2019), 11 (15), 14354-14361CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    For the safety of both prodn. and life, it is a very significant issue to detect explosive nitro-compds. in a remote way or over a long distance. Here, we report that nitro-compds. were detected by the bacterial sensor based on hydrogel micro-beads as a platform. A green fluorescent protein(GFP)-producing Escherichia coli which was genetically engineered in order to be sensitive to nitro-compds. was loaded within poly(2-hydroxyethyl methacrylate) (poly(HEMA)) based hydrogel beads, in which fluorescent signals from bacteria were concd. and strong enough to be easily detected. For efficient loading of neg. charged bacteria, a surface charge of poly(HEMA) based beads was controlled by copolymn. with 2-(methacryloyloxy) Et trimethylammonium chloride (MAETC) as a cationic monomer. With the addn. of MAETC, the cell affinity was nine times enhanced by an interaction between the pos. charged poly(HEMA-co-MAETC) beads and neg. charged bacteria. These increased cell affinity resulted in an enhancement of a sensing signal. After exposure to 2,4,6-trinitrotoluene (TNT), typical explosive nitro-compds., the fluorescence intensity of bacteria sensors using poly(HEMA-co MAETC) bead having 80 wt% of MAETC was five times increased compared to those based on poly(HEMA) beads. This amplification of the fluorescent signal enables easier detection of explosives efficiently by a remote detection, even over a long distance.
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  22. 22
    Zhang, Z.; Chen, S.; Shi, R.; Ji, J.; Wang, D.; Jin, S.; Han, T.; Zhou, C.; Shu, Q. A Single Molecular Fluorescent Probe for Selective and Sensitive Detection of Nitroaromatic Explosives: A New Strategy for The Mask-Free Discrimination of TNT and TNP Within Same Sample. Talanta 2017, 166, 228– 233,  DOI: 10.1016/j.talanta.2017.01.046
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    22
    A single molecular fluorescent probe for selective and sensitive detection of nitroaromatic explosives: A new strategy for the mask-free discrimination of TNT and TNP within same sample
    Zhang, Zhe; Chen, Shusen; Shi, Rui; Ji, Jiawen; Wang, Dequan; Jin, Shaohua; Han, Tongyu; Zhou, Chenxiao; Shu, Qinghai
    Talanta (2017), 166 (), 228-233CODEN: TLNTA2; ISSN:0039-9140. (Elsevier B.V.)
    A simple naphthalene based fluorescent probe was first time reported as dual sensing of 2,4,6-trinitrotolune (TNT) and 2,4,6-trinitrophenol (TNP) by distinguishable changes in both soln. color change and fluorescence within same sample without any mask agent. Upon addn. of TNT and TNP, the strong emission quenching at 412 nm and a new emission band at 530 nm was obsd., resp. In addn., the sensing mechanism was evaluated by DFT calcns. by Gaussian 09 software.
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  23. 23
    Tripathi, N.; Kumar, R.; Singh, P.; Kumar, S. Ratiometric Fluorescence “Turn On” Probe for Fast and Selective Detection of TNT in Solution, Solid and Vapour. Sens. Actuators, B 2017, 246, 1001– 1010,  DOI: 10.1016/j.snb.2017.02.174
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    23
    Ratiometric fluorescence "Turn On" probe for fast and selective detection of TNT in solution, solid and vapour
    Tripathi, Neetu; Kumar, Rahul; Singh, Prabhpreet; Kumar, Subodh
    Sensors and Actuators, B: Chemical (2017), 246 (), 1001-1010CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)
    A review. Fluorescent probe UREA-TP undergoes nearly 600% increase in emission intensity at 310 nm on addn. of 1 equiv of TNT, but the emission band centered at 440 nm remains unchanged. UREA-TP acts as a ratiometric fluorescence "turn-on" probe and can detect TNT between 10-9 to 10-5 M with limit of detection as low as 100 pM. Paper strips coated with UREA-TP on interaction with TNT become fluorescent purple under 365 nm light and can det. both qual. and quant. as low as 10μl soln. of 10-13 M TNT, which accounts for 2.27 × 10-16 g cm-2 TNT, significantly lower than the TNT concn. allowed in drinking water by EPA. The common nitroarom. derivs. 2,4-DNT, 2,6-DNT, picric acid and 2,4-DNP, the pain killers, food supplements and inorg. anions show insignificant interference in the detn. of TNT using UREA-TP. The aggregate size detn. using dynamic light scattering anal. and morphol. studies using TEM investigations reveals that UREA-TP in H2O-DMSO (98:2) remains in aggregate state with av. size of 200 nm, which undergo further aggregation to larger size aggregates with increasing amts. of TNT.
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  24. 24
    Colizza, K.; Yevdokimov, A.; McLennan, L.; Smith, J. L.; Oxley, J. C. Using Gas Phase Reactions of Hexamethylene Triperoxide Diamine (HMTD) to Improve Detection in Mass Spectrometry. J. Am. Soc. Mass Spectrom. 2018, 29, 675– 684,  DOI: 10.1007/s13361-017-1879-5
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    24
    Using Gas Phase Reactions of Hexamethylene Triperoxide Diamine (HMTD) to Improve Detection in Mass Spectrometry
    Colizza, Kevin; Yevdokimov, Alexander; McLennan, Lindsay; Smith, James L.; Oxley, Jimmie C.
    Journal of the American Society for Mass Spectrometry (2018), 29 (4), 675-684CODEN: JAMSEF; ISSN:1044-0305. (Springer)
    The authors' efforts to lower the detection limits of hexamethylene triperoxide diamine (HMTD) have uncovered previously unreported gas-phase reactions of primary and secondary amines with one of the six methylene carbons. The reaction occurs primarily in the atm. pressure chem. ionization (APCI) source and is similar to the behavior of alcs. with HMTD [1]. However, unlike alcs., the amine reaction conserves the hydrogen peroxide on the intact product. Furthermore, with or without amines, HMTD is oxidized to tetramethylene diperoxide diamine dialdehyde (TMDDD) in a temp.-dependent fashion in the APCI source. Synthesized TMDDD forms very strong adducts (not products) to ammonium and amine ions in the electrospray ionization (ESI) source. Attempts to improve HMTD detection by generating TMDDD in the APCI source with post-column addn. of amines were not successful. Signal intensity of the solvent related HMTD product in methanol, [HMTD+MeOH2-H2O2]+ (m/z 207.0975), was understandably related to the amt. of methanol in the HMTD environment as it elutes into the source. With conditions optimized for this product, the detection of 100 pg on column was accomplished with a robust anal. of 300 pg (1.44 pmol) routinely performed on the Orbitrap mass spectrometers.
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  25. 25
    Mäkinen, M.; Nousiainen, M.; Sillanpaa, M. Ion Spectrometric Detection Technologies for Ultra-Traces of Explosives: A Review. Mass Spectrom. Rev. 2011, 30, 940– 973,  DOI: 10.1002/mas.20308
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    25
    Ion spectrometric detection technologies for ultra-traces of explosives: a review
    Makinen Marko; Nousiainen Marjaana; Sillanpaa Mika
    Mass spectrometry reviews (2011), 30 (5), 940-73 ISSN:.
    In recent years, explosive materials have been widely employed for various military applications and civilian conflicts; their use for hostile purposes has increased considerably. The detection of different kind of explosive agents has become crucially important for protection of human lives, infrastructures, and properties. Moreover, both the environmental aspects such as the risk of soil and water contamination and health risks related to the release of explosive particles need to be taken into account. For these reasons, there is a growing need to develop analyzing methods which are faster and more sensitive for detecting explosives. The detection techniques of the explosive materials should ideally serve fast real-time analysis in high accuracy and resolution from a minimal quantity of explosive without involving complicated sample preparation. The performance of the in-field analysis of extremely hazardous material has to be user-friendly and safe for operators. The two closely related ion spectrometric methods used in explosive analyses include mass spectrometry (MS) and ion mobility spectrometry (IMS). The four requirements-speed, selectivity, sensitivity, and sampling-are fulfilled with both of these methods.
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  26. 26
    Jiang, D.; Peng, L.; Wen, M.; Zhou, Q.; Chen, C.; Wang, X.; Chen, W.; Li, H. Dopant-Assisted Positive Photoionization Ion Mobility Spectrometry Coupled with Time-Resolved Thermal Desorption for On-Site Detection of Triacetone Triperoxide and Hexamethylene Trioxide Diamine in Complex Matrices. Anal. Chem. 2016, 88, 4391– 4399,  DOI: 10.1021/acs.analchem.5b04830
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    26
    Dopant-Assisted Positive Photoionization Ion Mobility Spectrometry Coupled with Time-Resolved Thermal Desorption for On-Site Detection of Triacetone Triperoxide and Hexamethylene Trioxide Diamine in Complex Matrices
    Jiang, Dandan; Peng, Liying; Wen, Meng; Zhou, Qinghua; Chen, Chuang; Wang, Xin; Chen, Wendong; Li, Haiyang
    Analytical Chemistry (Washington, DC, United States) (2016), 88 (8), 4391-4399CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
    Peroxide explosives, such as triacetone triperoxide (TATP) and hexamethylene trioxide diamine (HMTD), were often used in the terrorist attacks due to their easy synthesis from readily starting materials. Therefore, an on-site detection method for TATP and HMTD is urgently needed. Herein, we developed a stand-alone dopant-assisted pos. photoionization ion mobility spectrometry (DAPP-IMS) coupled with time-resolved thermal desorption introduction for rapid and sensitive detection of TATP and HMTD in complex matrixes, such as white solids, soft drinks, and cosmetics. Acetone was chosen as the optimal dopant for better sepn. between reactant ion peaks and product ion peaks as well as higher sensitivity, and the limits of detection (LODs) of TATP and HMTD std. samples were 23.3 and 0.2 ng, resp. Explosives on the sampling swab were thermally desorbed and carried into the ionization region dynamically within 10 s, and the max. released concn. of TATP or HMTD could be time-resolved from the matrix interference owing to the different volatility. Furthermore, with the combination of the fast response thermal desorber (within 0.8 s) and the quick data acquisition software to DAPP-IMS, two-dimensional data related to drift time (TATP: 6.98 ms, K0 = 2.05 cm2 V-1 s-1; HMTD: 9.36 ms, K0 = 1.53 cm2 V-1 s-1) and desorption time was obtained for TATP and HMTD, which is beneficial for their identification in complex matrixes.
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  27. 27
    Correa, D. N.; Melendez-Perez, J. J.; Zacca, J. J.; Borges, R.; Schmidt, E. M.; Eberlin, M. N.; Meurer, E. C. Direct Detection of Triacetone Triperoxide (TATP) in Real Banknotes from ATM Explosion by EASI-MS. Propellants Explos. Pyrotech. 2017, 42, 370– 375,  DOI: 10.1002/prep.201600046
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    Hagenhoff, S.; Franzke, J.; Hayen, H. Determination of Peroxide Explosive TATP and Related Compounds by Dielectric Barrier Discharge Ionization-Mass Spectrometry (DBDI-MS). Anal. Chem. 2017, 89, 4210– 4215,  DOI: 10.1021/acs.analchem.7b00233
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    28
    Determination of Peroxide Explosive TATP and Related Compounds by Dielectric Barrier Discharge Ionization-Mass Spectrometry (DBDI-MS)
    Hagenhoff, Sebastian; Franzke, Joachim; Hayen, Heiko
    Analytical Chemistry (Washington, DC, United States) (2017), 89 (7), 4210-4215CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
    Dielec. barrier discharge ionization-mass spectrometry (DBDI-MS), which is based on the use of a low temp. helium plasma as ionization source, is used for the detn. of trace amts. of triacetone triperoxide (TATP) and its homolog diacetone diperoxide (DADP) from surfaces. TATP is obsd. as [M+NH4]+ adduct, whereas DADP is obsd. as [M+O+NH4]+. Measurement of DADP with varying deuteration degrees (DADP, DADP-d6, and DADP-d12) indicates that DADP undergoes oxidn. when ionized by DBDI. If acetonitrile is used as deposition solvent, TATP tends to show fragmentation and is not only detected as [M+NH4]+ but as [M-CH4+NH4]+ and [M-C2H4+NH4]+ as well. Quantification of TATP solns. from glass surfaces by DBDI-MS, using TATP-3,6,9-13C as internal std., was done and validated using an LC/APCI-MS method. Achievable limits of detection (LOD) for TATP are equiv. to the deposition of 15 ng TATP and are comparable with other ambient desorption/ionization mass spectrometric techniques like desorption electrospray ionization (DESI).
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  29. 29
    Tang, S.; Vinerot, N.; Fisher, D.; Bulatov, V.; Yavetz-Chen, Y.; Schechter, I. Detection and Mapping of Trace Explosives on Surfaces Under Ambient Conditions Using Multiphoton Electron Extraction Spectroscopy (MEES). Talanta 2016, 155, 235– 244,  DOI: 10.1016/j.talanta.2016.04.027
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    29
    Detection and mapping of trace explosives on surfaces under ambient conditions using multiphoton electron extraction spectroscopy (MEES)
    Tang, Shisong; Vinerot, Nataly; Fisher, Danny; Bulatov, Valery; Yavetz-Chen, Yehuda; Schechter, Israel
    Talanta (2016), 155 (), 235-244CODEN: TLNTA2; ISSN:0039-9140. (Elsevier B.V.)
    Multiphoton electron extn. spectroscopy (MEES) is an anal. method in which UV laser pulses are utilized for extg. electrons from solid surfaces in multiphoton processes under ambient conditions. Counting the emitted electrons as a function of laser wavelength results in detailed spectral features, which can be used for material identification. The method has been applied to detection of trace explosives on a variety of surfaces. Detection was possible on dusty swabs spiked with explosives and also in the std. dry-transfer contamination procedure. Plastic explosives could also be detected. The anal. limits of detection (LODs) are in the sub pmole range, which indicates that MEES is one of the most sensitive detection methods for solid surface under ambient conditions. Scanning the surface with the laser allows for its imaging, such that explosives (as well as other materials) can be located. The imaging mode is also useful in forensic applications, such as detection of explosives in human fingerprints.
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  30. 30
    Lichtenstein, A.; Havivi, E.; Shacham, R.; Hahamy, E.; Leibovich, R.; Pevzner, A.; Krivitsky, V.; Davivi, G.; Presman, I.; Elnathan, R.; Engel, Y.; Flaxer, E.; Patolsky, F. Supersensitive Fingerprinting of Explosives by Chemically Modified Nanosensors Arrays. Nat. Commun. 2014, 5, 4195  DOI: 10.1038/ncomms5195
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    30
    Supersensitive fingerprinting of explosives by chemically modified nanosensors arrays
    Lichtenstein, Amir; Havivi, Ehud; Shacham, Ronen; Hahamy, Ehud; Leibovich, Ronit; Pevzner, Alexander; Krivitsky, Vadim; Davivi, Guy; Presman, Igor; Elnathan, Roey; Engel, Yoni; Flaxer, Eli; Patolsky, Fernando
    Nature Communications (2014), 5 (), 4195CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)
    The capability to detect traces of explosives sensitively, selectively and rapidly could be of great benefit for applications relating to civilian national security and military needs. Here, we show that, when chem. modified in a multiplexed mode, nanoelec. devices arrays enable the supersensitive discriminative detection of explosive species. The fingerprinting of explosives is achieved by pattern recognizing the inherent kinetics, and thermodn., of interaction between the chem. modified nanosensors array and the mol. analytes under test. This platform allows for the rapid detection of explosives, from air collected samples, down to the parts-per-quadrillion concn. range, and represents the first nanotechnol.-inspired demonstration on the selective supersensitive detection of explosives, including the nitro- and peroxide-derivs., on a single electronic platform. Furthermore, the ultrahigh sensitivity displayed by our platform may allow the remote detection of various explosives, a task unachieved by existing detection technologies.
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  31. 31
    Lin, H.; Suslick, K. S. A Colorimetric Sensor Array for Detection of Triacetone Triperoxide Vapor. J. Am. Chem. Soc. 2010, 132, 15519– 15521,  DOI: 10.1021/ja107419t
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    A Colorimetric Sensor Array for Detection of Triacetone Triperoxide Vapor
    Lin, Hengwei; Suslick, Kenneth S.
    Journal of the American Chemical Society (2010), 132 (44), 15519-15521CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    Triacetone triperoxide (TATP), one of the most dangerous primary explosives, has emerged as an explosive of choice for terrorists in recent years. Owing to the lack of UV absorbance, fluorescence, or facile ionization, TATP is extremely difficult to detect directly. Techniques that are able to detect generally require expensive instrumentation, need extensive sample prepn., or cannot detect TATP in the gas phase. Here we report a simple and highly sensitive colorimetric sensor for the detection of TATP vapor with semiquant. anal. from 50 ppb to 10 ppm. By using a solid acid catalyst to pretreat a gas stream, we have discovered that a colorimetric sensor array of redox sensitive dyes can detect even very low levels of TATP vapor from its acid decompn. products (e.g., H2O2) with limits of detection (LOD) below 2 ppb (i.e., <0.02% of its satn. vapor pressure). Common potential interferences (e.g., humidity, personal hygiene products, perfume, laundry supplies, volatile org. compds., etc.) do not generate an array response, and the array can also differentiate TATP from other chem. oxidants (e.g., hydrogen peroxide, bleach, tert-butylhydroperoxide, peracetic acid).
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  32. 32
    Li, Z.; Bassett, W. P.; Askim, J. R.; Suslick, K. S. Differentiation Among Peroxide Explosives with an Optoelectronic Nose. Chem. Commun. 2015, 51, 15312– 15315,  DOI: 10.1039/C5CC06221G
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    Differentiation among peroxide explosives with an optoelectronic nose
    Li, Zheng; Bassett, Will P.; Askim, Jon R.; Suslick, Kenneth S.
    Chemical Communications (Cambridge, United Kingdom) (2015), 51 (83), 15312-15315CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
    Forensic identification of batches of homemade explosives (HME) poses a difficult anal. challenge. Differentiation among peroxide explosives is reported herein using a colorimetric sensor array and handheld scanner with a field-appropriate sampling protocol. Clear discrimination was demonstrated among twelve peroxide samples prepd. from different reagents, with a classification accuracy > 98%.
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  33. 33
    Askim, J. R.; Li, Z.; LaGasse, M. K.; Rankin, J. M.; Suslick, K. S. An Optoelectronic Nose for Identification of Explosives. Chem. Sci. 2016, 7, 199– 206,  DOI: 10.1039/C5SC02632F
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    An optoelectronic nose for identification of explosives
    Askim, Jon R.; Li, Zheng; La Gasse, Maria K.; Rankin, Jaqueline M.; Suslick, Kenneth S.
    Chemical Science (2016), 7 (1), 199-206CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)
    Compact and portable methods for identification of explosives are increasingly needed for both civilian and military applications. A portable optoelectronic nose for the gas-phase identification of explosive materials is described that uses a highly cross-reactive colorimetric sensor array and a handheld scanner. The array probes a wide range of chem. reactivities using 40 chem. responsive colorimetric indicators, including pH sensors, metal-dye salts, redox-sensitive chromogenic compds., solvatochromic dyes, and other chromogenic indicators. Sixteen sep. analytes including common explosives, homemade explosives, and characteristic explosive components were differentiated into fourteen sep. classes with a classification error rate of <1%. Portable colorimetric array sensing could represent an important, complementary part of the toolbox used in practical applications of explosives detection and identification.
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  34. 34
    Xu, M.; Han, J.-M.; Wang, C.; Yang, X.; Pei, J.; Zang, L. Fluorescence Ratiometric Sensor for Trace Vapor Detection of Hydrogen Peroxide. ACS Appl. Mater. Interfaces 2014, 6, 8708– 8714,  DOI: 10.1021/am501502v
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    Fluorescence Ratiometric Sensor for Trace Vapor Detection of Hydrogen Peroxide
    Xu, Miao; Han, Ji-Min; Wang, Chen; Yang, Xiaomei; Pei, Jian; Zang, Ling
    ACS Applied Materials & Interfaces (2014), 6 (11), 8708-8714CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    Trace vapor detection of hydrogen peroxide (H2O2) represents a practical approach to nondestructive detection of peroxide-based explosives, including liq. mixts. of H2O2 and fuels and energetic peroxide derivs., such as triacetone triperoxide (TATP), diacetone diperoxide (DADP), and hexamethylene triperoxide diamine (HMTD). Development of a simple chem. sensor system that responds to H2O2 vapor with high reliability and sufficient sensitivity (reactivity) remains a challenge. We report a fluorescence ratiometric sensor mol., di-Et 2,5-bis((((4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)oxy)carbonyl)amino)terephthalate (DAT-B), for H2O2 that can be fabricated into an expedient, reliable, and sensitive sensor system suitable for trace vapor detection of H2O2. DAT-B is fluorescent in the blue region, with an emission max. at 500 nm in the solid state. Upon reaction with H2O2, DAT-B is converted to an electronic "push-pull" structure, di-Et 2,5-diaminoterephthalate (DAT-N), which has an emission peak at a longer wavelength centered at 574 nm. Such H2O2-mediated oxidn. of aryl boronates can be accelerated through the addn. of an org. base such as tetrabutylammonium hydroxide (TBAH), resulting in a response time of less than 0.5 s under 1 ppm of H2O2 vapor. The strong overlap between the absorption band of DAT-N and the emission band of DAT-B enables efficient Forster resonance energy transfer (FRET), thus allowing further enhancement of the sensing efficiency of H2O2 vapor. The detection limit of a drop-cast DAT-B/TBAH film was projected to be 7.7 ppb. By combining high sensitivity and selectivity, the reported sensor system may find broad application in vapor detection of peroxide-based explosives and relevant chem. reagents through its fabrication into easy-to-use, cost-effective kits.
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  35. 35
    Zhu, Q.-H.; Zhang, G.-H.; Yuan, W.-L.; Wang, S.-L.; He, L.; Yong, F.; Tao, G.-H. Handy Fluorescent Paper Device Based on a Curcumin Derivative for Ultrafast Detection of Peroxide-Based Explosives. Chem. Commun. 2019, 55, 13661– 13664,  DOI: 10.1039/C9CC06737J
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    Handy fluorescent paper device based on a curcumin derivative for ultrafast detection of peroxide-based explosives
    Zhu, Qiu-Hong; Zhang, Guo-Hao; Yuan, Wen-Li; Wang, Shuang-Long; He, Ling; Yong, Fang; Tao, Guo-Hong
    Chemical Communications (Cambridge, United Kingdom) (2019), 55 (91), 13661-13664CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
    A handy, simple and inexpensive paper device is reported for extremely sensitive detection of peroxide-based explosives. The sensing device fabricated using a curcumin deriv. was capable of ultrafast sensing of triacetone triperoxide. The detection time was < 5 s. Moreover, the sensor retained full function under storage at ambient temp. for at least 120 days.
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  36. 36
    Yu, X.; Gong, Y.; Xiong, W.; Li, M.; Zhao, J.; Che, Y. Turn-on Fluorescent Detection of Hydrogen Peroxide and Triacetone Triperoxide via Enhancing Interfacial Interactions of a Blended System. Anal. Chem. 2019, 91, 6967– 6970,  DOI: 10.1021/acs.analchem.9b01255
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    36
    Turn-on Fluorescent Detection of Hydrogen Peroxide and Triacetone Triperoxide via Enhancing Interfacial Interactions of a Blended System
    Yu, Xinting; Gong, Yanjun; Xiong, Wei; Li, Mei; Zhao, Jincai; Che, Yanke
    Analytical Chemistry (Washington, DC, United States) (2019), 91 (11), 6967-6970CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
    In this work, we report the fabrication of a blend consisting of fluorescent 1 nanofibers and amberlyst-15 particles as a turn-on fluorescence sensor for trace TATP vapors. Fluorescence imaging and lifetime anal. reveal that the interface between 1 nanofibers and amberlyst-15 particles exhibits stronger photoluminescence than the unblended areas because of the formed strong hydrogen bonding between. Furthermore, the interfacial adhesion between 1 nanofibers and amberlyst-15 particles can be amplified by H2O2, which in turn gives rise to rapid and remarkable fluorescence enhancement. When exposed to TATP vapors, the amberlyst-15 component can rapidly decomp. TATP into H2O2 that gives sensitive fluorescence enhancement responses of the blend. On the basis of this detection mechanism, fluorescence detection of TATP with rapid response (ca. 5 s) and high sensitivity (ca. 0.1 ppm) is achieved. Here, the resulting blend combines the pretreatment of TATP and detection responses and thereby simplifies the sensor fabrication for the practical application.
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  37. 37
    Qi, Y.; Xu, W.; Ding, N.; Chang, X.; Shang, C.; Peng, H.; Liu, T.; Fang, Y. A Film-Based Fluorescent Device for Vapor Phase Detection of Acetone and Related Peroxide Explosives. Mater. Chem. Front. 2019, 3, 1218– 1224,  DOI: 10.1039/C9QM00095J
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    37
    A film-based fluorescent device for vapor phase detection of acetone and related peroxide explosives
    Qi, Yanyu; Xu, Wenjun; Ding, Nannan; Chang, Xingmao; Shang, Congdi; Peng, Haonan; Liu, Taihong; Fang, Yu
    Materials Chemistry Frontiers (2019), 3 (6), 1218-1224CODEN: MCFAC5; ISSN:2052-1537. (Royal Society of Chemistry)
    On site, sensitive and selective detection of acetone vapor at room temp. is of great importance for health, and in particular for in air detection of triacetone triperoxide (TATP) and diacetone diperoxide (DADP), two improvised explosives commonly used by terrorists in suicide attacks. This paper reports a relevant high-performance film-based fluorescent device, where a newly synthesized perylene monoimide modified non-planar organoboron deriv. (PMI-BQ) was adopted as the sensing fluorophore. The performance of the device is excellent as evidenced by less than 2 s response time, no more than 10 s recovery time, nearly perfect reversibility, and lower than 50 ppm exptl. detection limit (DL) for acetone. In addn., the presence of potential interferences showed little effect upon the sensing. Notably, more than 30 days sensing tests showed no observable degrdn. in the performance of the film device. Further tests revealed that the film-based device can be further used for the detection of TATP and DADP. The exptl. DLs for the two explosives are lower than 30 and 50 μg, resp. The superior performance of the device was ascribed to the non-planar structure of the sensing fluorophore as it may produce micro-channels in the film. Meanwhile, solvation may also play a crucial role in the process. We believe our contribution not only realizes reversible fluorescence sensing of acetone vapor and the related explosives, but also demonstrates that the combination of solvent effect and non-planar structure could be an effective way to develop high performance fluorescent sensing films.
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  38. 38
    An, Y.; Xu, X.; Liu, K.; An, X.; Shang, C.; Wang, G.; Liu, T.; Li, H.; Peng, H.; Fang, Y. Fast, Sensitive, Selective and Reversible Fluorescence Monitoring of TATP in a Vapor Phase. Chem. Commun. 2019, 55, 941– 944,  DOI: 10.1039/C8CC08399A
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    Fast, sensitive, selective and reversible fluorescence monitoring of TATP in a vapor phase
    An, Yanqin; Xu, Xiaojie; Liu, Ke; An, Xuan; Shang, Congdi; Wang, Gang; Liu, Taihong; Li, Hong; Peng, Haonan; Fang, Yu
    Chemical Communications (Cambridge, United Kingdom) (2019), 55 (7), 941-944CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
    The development of sensors for the detection of triacetone triperoxide (TATP) has attracted great attention. Here, we constructed a low-cost, portable, reusable, visible paper-based fluorescent sensor for the sensitive detection of TATP via vapor sampling. Under optimized conditions, the fluorescent film showed a high sensitivity to TATP with a detection limit of lower than 0.5μg mL-1 in air. The linear range of the response is from 0.5 to 8.0μg mL-1. In addn., the paper-based sensor exhibited high selectivity to TATP. The presence of potential interferents showed little effect on sensing. Moreover, sensing is fully reversible. Fortunately, the test can also be conducted in a visualized way.
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    Rao, M. R.; Fang, Y.; De Feyter, S.; Perepichka, D. F. Conjugated Covalent Organic Frameworks via Michael Addition–Elimination. J. Am. Chem. Soc. 2017, 139, 2421– 2427,  DOI: 10.1021/jacs.6b12005
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    Conjugated Covalent Organic Frameworks via Michael Addition-Elimination
    Rao, M. Rajeswara; Fang, Yuan; De Feyter, Steven; Perepichka, Dmitrii F.
    Journal of the American Chemical Society (2017), 139 (6), 2421-2427CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    Dynamic covalent chem. enables self-assembly of reactive building blocks into structurally complex yet robust materials, such as Covalent Org. Frameworks (COFs). However, the synthetic toolbox used to prep. such materials, and thus the spectrum of attainable properties, is limited. For π-conjugated COFs, the Schiff base condensation of aldehydes and amines is the only general dynamic reaction, but the resulting imine-linked COFs display only a moderate electron delocalization and are susceptible to hydrolysis, particularly in acidic conditions. Here we report a new dynamic polymn. based on Michael addn.-elimination reaction of structurally diverse β-ketoenols with amines, and use it to prep. novel two dimensional (2D) π-conjugated COFs, as cryst. powders and exfoliated micron-size sheets. π-Conjugation is manifested in these COFs in significantly reduced band gap (1.8-2.2 eV), solid state luminescence and reversible electrochem. doping creating mid-gap (NIR absorbing) polaronic states. The β-ketoenamine moiety enables protonation control of electron delocalization through the 2D COF sheets. It also gives rise to direct sensing of triacetone triperoxide (TATP) explosive through fluorescence quenching.
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    Liu, K.; Wang, Z.; Shang, C.; Li, X.; Peng, H.; Miao, R.; Ding, L.; Liu, J.; Liu, T.; Fang, Y. Unambiguous Discrimination and Detection of Controlled Chemical Vapors by a Film-Based Fluorescent Sensor Array. Adv. Mater. Technol. 2019, 4, 1800644  DOI: 10.1002/admt.201800644
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    Unambiguous Discrimination and Detection of Controlled Chemical Vapors by a Film-Based Fluorescent Sensor Array
    Liu, Ke; Wang, Zhaolong; Shang, Congdi; Li, Xiao; Peng, Haonan; Miao, Rong; Ding, Liping; Liu, Jing; Liu, Taihong; Fang, Yu
    Advanced Materials Technologies (Weinheim, Germany) (2019), 4 (7), 1800644CODEN: AMTDCM; ISSN:2365-709X. (Wiley-VCH Verlag GmbH & Co. KGaA)
    In situ, online, fast, and sensitive detection and discrimination of explosives, illicit drugs, and volatile org. compds. via vapor sampling is a challenge for many years. The highly efficient and noncontact detection of 15 types of chems. mentioned above using a film-based fluorescent sensor array is reported herein. Importantly, the presence of water, toiletries, fruit, dirty clothes, and other interferences has little effect upon detection. Discrimination of the controlled chems. is realized using a pattern recognition strategy. Meanwhile, a conceptual detector based on a sensor array is constructed and successfully used for simulated field tests. It is strongly believed that the present work not only provides a powerful fluorescent technique for efficient detection and discrimination of controlled chems. with remarkably different properties but also demonstrates that arraying a single sensor is a promising strategy to mitigate the limitations of conventional film-based fluorescent sensors.
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    OSAC. Analysis of Explosives Reference List, 2020. https://www.nist.gov/topics/organization-scientific-area-committees-forensic-science/fire-debris-explosives-subcommittee (accessed May 20, 2022).
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    EU-SENSE. Characteristics of Improvised Explosive Devices Containing Chemical Substances in the Context of the International Airports Protection, 2021. https://eu-sense.eu/characteristics-of-improvised-explosive-devices-containing-chemical-substances-in-the-context-of-the-international-airports-protection/ (accessed May 20, 2022).
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    González-Calabuig, A.; Cetó, X.; del Valle, M. Electronic Tongue for Nitro and Peroxide Explosive Sensing. Talanta 2016, 153, 340– 346,  DOI: 10.1016/j.talanta.2016.03.009
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    Electronic tongue for nitro and peroxide explosive sensing
    Gonzalez-Calabuig, Andreu; Ceto, Xavier; del Valle, Manel
    Talanta (2016), 153 (), 340-346CODEN: TLNTA2; ISSN:0039-9140. (Elsevier B.V.)
    This work reports the application of a voltammetric electronic tongue (ET) towards the simultaneous detn. of both nitro-contg. and peroxide-based explosive compds., two families that represent the vast majority of compds. employed either in com. mixts. or in improvised explosive devices. The multielectrode array was formed by graphite, gold and platinum electrodes, which exhibited marked mix-responses towards the compds. examd.; namely, 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), pentaerythritol tetranitrate (PETN), 2,4,6-trinitrotoluene (TNT), N-methyl-N,2,4,6-tetranitroaniline (Tetryl) and triacetone triperoxide (TATP). Departure information was the set of voltammograms, which were first analyzed by principal component anal. (PCA) allowing the discrimination of the different individual compds., while artificial neural networks (ANNs) were used for the resoln. and individual quantification of some of their mixts. (total normalized root mean square error for the external test set of 0.108 and correlation of the obtained vs. expected concns. comparison graphs r>0.929).
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    Krivitsky, V.; Filanovsky, B.; Naddaka, V.; Patolsky, F. Direct and Selective Electrochemical Vapor Trace Detection of Organic Peroxide Explosives via Surface Decoration. Anal. Chem. 2019, 91, 5323– 5330,  DOI: 10.1021/acs.analchem.9b00257
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    Direct and Selective Electrochemical Vapor Trace Detection of Organic Peroxide Explosives via Surface Decoration
    Krivitsky, Vadim; Filanovsky, Boris; Naddaka, Vladimir; Patolsky, Fernando
    Analytical Chemistry (Washington, DC, United States) (2019), 91 (8), 5323-5330CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
    The ability to detect traces of highly energetic explosive materials sensitively, selectively, accurately, and rapidly could be of enormous benefit to civilian national security, military applications, and environmental monitoring. Unfortunately, the detection of explosives still poses a largely unmet arduous anal. problem, making their detection an issue of burning immediacy and a massive current challenge in terms of research and development. Although numerous explosive detection approaches have been developed, these methods are usually time-consuming, require bulky equipment, tedious sample prepn., a trained operator, cannot be miniaturized, and lack the ability to perform automated real-time high-throughput anal., strongly handicapping their mass deployment. Here, we present the first demonstration of the "direct" electrochem. approach for the sensitive, selective, and rapid vapor trace detection of TATP and HMTD, under ambient conditions, unaffected by the presence of oxygen and hydrogen peroxide species, down to concns. lower than 10 ppb. The method is based on the use of Ag-nanoparticles-decorated carbon microfibers air-collecting electrodes (μCF), which allow for the selective direct detection of the org. peroxide explosives, through opening multiple redox routes, not existent in the undecorated carbon electrodes. Finally, we demonstrate the direct and rapid detection of TATP and HMTD explosive species from real-world air samples.
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    Calvo-Gredilla, P.; García-Calvo, J.; Cuevas, J. V.; Torroba, T.; Pablos, J.-L.; García, F. C.; García, J.-M.; Zink-Lorre, N.; Font-Sanchis, E.; Sastre-Santos, A.; Fernández-Lázaro, F. Solvent-Free Off–On Detection of the Improvised Explosive Triacetone Triperoxide (TATP) with Fluorogenic Materials. Chem. – Eur. J. 2017, 23, 13973– 13979,  DOI: 10.1002/chem.201702412
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    Solvent-Free Off-On Detection of the Improvised Explosive Triacetone Triperoxide (TATP) with Fluorogenic Materials
    Calvo-Gredilla, Patricia; Garcia-Calvo, Jose; Cuevas, Jose V.; Torroba, Tomas; Pablos, Jesus-Luis; Garcia, Felix C.; Garcia, Jose-Miguel; Zink-Lorre, Nathalie; Font-Sanchis, Enrique; Sastre-Santos, Angela; Fernandez-Lazaro, Fernando
    Chemistry - A European Journal (2017), 23 (56), 13973-13979CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
    A fluorogenic perylenediimide-functionalized polyacrylate capable of generating color and fluorescence changes in the presence of triacetone triperoxide (TATP), an improvised explosive used in terrorist attacks, under solvent-free, solid-state conditions has been developed. The material works by accumulating volatile TATP until it reaches a threshold; therefore, triggering colorimetric and fluorescent responses.
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  46. 46
    García-Calvo, J.; Calvo-Gredilla, P.; Ibáñez-Llorente, M.; Romero, D. C.; Cuevas, J. V.; García-Herbosa, G.; Avella, M.; Torroba, T. Surface Functionalized Silica Nanoparticles for the Off–On Fluorogenic Detection of an Improvised Explosive, TATP, in a Vapour Flow. J. Mater. Chem. A 2018, 6, 4416– 4423,  DOI: 10.1039/C7TA10792G
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    Surface functionalized silica nanoparticles for the off-on fluorogenic detection of an improvised explosive, TATP, in a vapor flow
    Garcia-Calvo, Jose; Calvo-Gredilla, Patricia; Ibanez-Llorente, Marcos; Romero, Daisy C.; Cuevas, Jose V.; Garcia-Herbosa, Gabriel; Avella, Manuel; Torroba, Tomas
    Journal of Materials Chemistry A: Materials for Energy and Sustainability (2018), 6 (10), 4416-4423CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)
    The development is reported of new fluorogenic silica nanomaterials that were able to generate fluorescence in the presence of vapors of triacetone triperoxide, TATP, an improvised explosive used in terrorist attacks. The materials worked in a vapor flow of TATP, giving a permanent and strongly fluorescent response.
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  47. 47
    Blanco, S.; Macario, A.; García-Calvo, J.; Revilla-Cuesta, A.; Torroba, T.; López, J. C. Microwave Detection of Wet Triacetone Triperoxide (TATP): Non-Covalent Forces and Water Dynamics. Chem. – Eur. J. 2021, 27, 1680– 1687,  DOI: 10.1002/chem.202003499
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    47
    Microwave Detection of Wet Triacetone Triperoxide (TATP): Non-Covalent Forces and Water Dynamics
    Blanco, Susana; Macario, Alberto; Garcia-Calvo, Jose; Revilla-Cuesta, Andrea; Torroba, Tomas; Lopez, Juan Carlos
    Chemistry - A European Journal (2021), 27 (5), 1680-1687CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
    The water adducts of triacetone triperoxide (TATP) have been obsd. by using broadband rotational spectroscopy. This work opens a new way for the gas-phase detection of this improvised explosive. The obsd. clusters exhibit unusual water dynamics and rarely obsd. multicenter interactions. TATP-H2O is formed from the D3 symmetry conformer of TATP with water lying close to the C3 axis. Water rotation around this axis with a very low barrier gives rise to the rotational spectrum of a sym. top. The main interaction of the monohydrate is a four-center trifurcated donor Ow-H···O hydrogen bond, not obsd. previously in the gas phase, reinforced by a weak four-center trifurcated acceptor C-H···Ow interaction. Surprisingly, all structural signatures show the weakness of these interactions. The complex TATP-(H2O)2 is formed from the monohydrated TATP by the self-assocn. of water.
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  48. 48
    Lapcinska, S.; Revilla-Cuesta, A.; Abajo-Cuadrado, I.; Cuevas, J. V.; Avella, M.; Arsenyan, P.; Torroba, T. Dye-Modified Silica-Anatase Nanoparticles for the Ultrasensitive Fluorogenic Detection of the Improvised Explosive TATP in an Air Microfluidic Device. Mater. Chem. Front. 2021, 5, 8097– 8107,  DOI: 10.1039/D1QM01041G
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    48
    Dye-modified silica-anatase nanoparticles for the ultrasensitive fluorogenic detection of the improvised explosive TATP in an air microfluidic device
    Lapcinska, Sindija; Revilla-Cuesta, Andrea; Abajo-Cuadrado, Irene; Cuevas, Jose V.; Avella, Manuel; Arsenyan, Pavel; Torroba, Tomas
    Materials Chemistry Frontiers (2021), 5 (23), 8097-8107CODEN: MCFAC5; ISSN:2052-1537. (Royal Society of Chemistry)
    We describe the proof of concept of a portable testing setup for the detection of triacetone triperoxide (TATP), a common component in improvised explosive devices. The system will allow field-testing and generation of real-time results to test for TATP vapor traces in a no. of different environments. It will work by recirculating the gas samples in connection to the sensing mechanism in a suitable microfluidic portable device. In this way, the system will allow controlled trapping of the analyte in the chem. sensor to afford reliable results at very low concns. in air.
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  49. 49
    Torroba, T.; Schechter, I.; Calvo, J. G.; Revilla-Cuesta, A. Explosives Detection, Sensors, Electronic Systems and Data Processing; Capineri, L.; Turmus, E. K., Eds.; Springer: The Netherlands, 2019; pp 208– 247.
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    Gopikrishna, P.; Meher, N.; Iyer, P. K. Functional 1,8-Naphthalimide AIE/AIEEgens: Recent Advances and Prospects. ACS Appl. Mater. Interfaces 2018, 10, 12081– 12111,  DOI: 10.1021/acsami.7b14473
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    50
    Functional 1,8-Naphthalimide AIE/AIEEgens: Recent Advances and Prospects
    Gopikrishna, Peddaboodi; Meher, Niranjan; Iyer, Parameswar Krishnan
    ACS Applied Materials & Interfaces (2018), 10 (15), 12081-12111CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    A review. A survey is given of the up-to-date development of aggregation-induced emission/aggregation-induced emission enhancement (AIE/AIEE) active naphthalimide (NI)-based smart materials with potential for wide and real-world applications and that serves as a highly versatile building block with tunable absorption and emission in the complete visible region. The review article commences with a precise description of the importance of NI moiety and its several restricted area of applications owing to its aggregation caused quenching (ACQ) properties, followed by the discovery and importance of AIE/AIEE-active NIs. The introduction section tracked an overview of the state of the art in NI luminogens in multiple applications. It also includes a few mechanistic studies on the structure-property correlation of NIs and provides more insights into the condensed-state photophys. properties of small aggregation-prone systems. The review aims to ultimately accomplish current and forthcoming views comprising the use of the NIs for the detection of biol. active mols., such as amino acids and proteins, recognition of toxic analytes, fabrication of light emitting diodes, and their potential in therapeutics and diagnostics.
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  51. 51
    de Greñu, B. D.; Moreno, D.; Torroba, T.; Berg, A.; Gunnars, J.; Nilsson, T.; Nyman, R.; Persson, M.; Pettersson, J.; Eklind, I.; Wästerby, P. Fluorescent Discrimination between Traces of Chemical Warfare Agents and Their Mimics. J. Am. Chem. Soc. 2014, 136, 4125– 4128,  DOI: 10.1021/ja500710m
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    There is no corresponding record for this reference.
  52. 52
    de Greñu, B. D.; García-Calvo, J.; Cuevas, J.; García-Herbosa, G.; García, B.; Busto, N.; Ibeas, S.; Torroba, T.; Torroba, B.; Herrera, A.; Pons, S. Chemical Speciation of MeHg+ and Hg2+ in Aqueous Solution and HEK Cells Nuclei by means of DNA Interacting Fluorogenic Probes. Chem. Sci. 2015, 6, 3757– 3764,  DOI: 10.1039/C5SC00718F
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    There is no corresponding record for this reference.
  53. 53
    García-Calvo, J.; Vallejos, S.; García, F. C.; Rojo, J.; García, J. M.; Torroba, T. A Smart Material for the in Situ Detection of Mercury in Fish. Chem. Commun. 2016, 52, 11915– 11918,  DOI: 10.1039/C6CC05977E
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    53
    A smart material for the in situ detection of mercury in fish
    Garcia-Calvo, Jose; Vallejos, Saul; Garcia, Felix C.; Rojo, Josefa; Garcia, Jose M.; Torroba, Tomas
    Chemical Communications (Cambridge, United Kingdom) (2016), 52 (80), 11915-11918CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
    We have developed a new fluorogenic polymer capable of detecting the presence of mercury contamination in fish samples. The modified polymer emits blue light when irradiated with UV light proportional to the quantity of mercury, as MeHg+ or Hg2+, present in fish. The quant. relation between the concn. of mercury in fish and the increase of fluorescence in the polymer in contact with fish samples was confirmed, giving rise to quick and reliable results in the measurements of the presence of mercury in fish using a portable fluorogenic polymeric probe.
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  54. 54
    García-Calvo, J.; Calvo-Gredilla, P.; Ibáñez-Llorente, M.; Rodríguez, T.; Torroba, T. Detection of Contaminants of High Environmental Impact by Means of Fluorogenic Probes. Chem. Rec. 2016, 16, 810– 824,  DOI: 10.1002/tcr.201500253
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    54
    Detection of Contaminants of High Environmental Impact by Means of Fluorogenic Probes
    Garcia-Calvo, Jose; Calvo-Gredilla, Patricia; Ibanez-Llorente, Marcos; Rodriguez, Teresa; Torroba, Tomas
    Chemical Record (2016), 16 (2), 810-824CODEN: CRHEAK; ISSN:1528-0691. (Wiley-VCH Verlag GmbH & Co. KGaA)
    This personal account describes our contribution to the design of selective fluorogenic probes for contaminants of high environmental impact. For this purpose, we have developed a new family of highly versatile fluorogenic reagents that were able to show large differences in their fluorescence in the presence of selected analytes. They were used in the prepn. of fluorogenic probes for the detection of contaminants of high environmental impact which currently have no good solns.: phosphorylating agents, such as chem. weapons; Me mercury(II); the cyanide anion; amino-acid metabolites, such as doping substances; and biogenic amine mimics, such as drugs of abuse and recreational drugs. The development of new materials for specific sensing was achieved by anchoring selected probes to silica nanomaterials, suitable for the selective detection of org. analytes in water for immediate application to toxicol. or environmental purposes.
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  55. 55
    García-Calvo, J.; Robson, J. A.; Torroba, T.; Wilton-Ely, J. D. E. T. Synthesis and Application of Ruthenium(II) Alkenyl Complexes with Perylene Fluorophores for the Detection of Toxic Vapours and Gases. Chem. – Eur. J. 2019, 25, 14214– 14222,  DOI: 10.1002/chem.201903303
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    55
    Synthesis and Application of Ruthenium(II) Alkenyl Complexes with Perylene Fluorophores for the Detection of Toxic Vapours and Gases
    Garcia-Calvo, Jose; Robson, Jonathan A.; Torroba, Tomas; Wilton-Ely, James D. E. T.
    Chemistry - A European Journal (2019), 25 (62), 14214-14222CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
    A series of new ruthenium(II) vinyl complexes has been prepd. incorporating perylenemonoimide (PMI) units. This fluorogenic moiety was functionalized with terminal alkyne or pyridyl groups, allowing attachment to the metal either as a vinyl ligand or through the pyridyl nitrogen. The inherent low soly. of the perylene compds. was improved through the design of poly-PEGylated (PEG = polyethylene glycol) units bearing a terminal alkyne or a pyridyl group. By absorbing the compds. on silica, vapors and gases could be detected in the solid state. The reaction of the complexes [Ru(CH:CH-PerIm)Cl(CO)(py-3PEG)(PPh3)2] and [Ru(CH:CH-3PEG)Cl(CO)(py-PerIm)(PPh3)2] with carbon monoxide, isonitrile or cyanide was found to result in modulation of the fluorescence behavior. The complexes were obsd. to display solvatochromic effects and the interaction of the complexes with a wide range of other species was also studied. The study suggests that such complexes have potential for the detection of gases or vapors that are toxic to humans.
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  56. 56
    García-Calvo, V.; Cuevas, J. V.; Barbero, H.; Ferrero, S.; Álvarez, C. M.; González, J. A.; Díaz de Greñu, B.; García-Calvo, J.; Torroba, T. Synthesis of a Tetracorannulene-perylenediimide That Acts as a Selective Receptor for C60 over C70. Org. Lett. 2019, 21, 5803– 5807,  DOI: 10.1021/acs.orglett.9b01729
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    56
    Synthesis of a Tetracorannulene-perylenediimide That Acts as a Selective Receptor for C60 over C70
    Garcia-Calvo, Victor; Cuevas, Jose V.; Barbero, Hector; Ferrero, Sergio; Alvarez, Celedonio M.; Gonzalez, Jesus A.; Diaz de Grenu, Borja; Garcia-Calvo, Jose; Torroba, Tomas
    Organic Letters (2019), 21 (15), 5803-5807CODEN: ORLEF7; ISSN:1523-7052. (American Chemical Society)
    The authors report the use of a tetraborylated perylenediimide as starting material for the prepn. of a tetracorannulene-perylenediimide that is able to bind up to two fullerene-C60 mols. by host-guest mol. recognition with preference over C70. Titrn. with fullerene-C60 is followed by a dramatic shift of the arom. signals in 1H NMR and an initial increase in the fluorescence of the system. By this simple mechanism, fluorogenic sensing of fullerene-C60 is easily accomplished by an unprecedented fluorescent turn-on mechanism.
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  57. 57
    Busto, N.; Calvo, P.; Santolaya, J.; Leal, J. M.; Guédin, A.; Barone, G.; Torroba, T.; Mergny, J.-L.; García, B. Fishing for G-Quadruplexes in Solution with a Perylene Diimide Derivative Labeled with Biotins. Chem. – Eur. J. 2018, 24, 11292– 11296,  DOI: 10.1002/chem.201802365
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    57
    Fishing for G-Quadruplexes in Solution with a Perylene Diimide Derivative Labeled with Biotins
    Busto, Natalia; Calvo, Patricia; Santolaya, Javier; Leal, Jose M.; Guedin, Aurore; Barone, Giampaolo; Torroba, Tomas; Mergny, Jean-Louis; Garcia, Begona
    Chemistry - A European Journal (2018), 24 (44), 11292-11296CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
    A new fluorescent, noncytotoxic perylene diimide deriv. with two biotins at the peri position, PDI2B, has been synthesized. This mol. is able to interact selectively with G-quadruplexes with scarce or no affinity towards single- or double-stranded DNA. These features have made it possible to design a simple, effective, safe, cheap, and selective method for fishing G-quadruplex structures in soln. by use of PDI2B and streptavidin coated magnetic beads. The new cyclic method reported leads to the recovery of more than 80% of G-quadruplex structures from soln., even in the presence of an excess of single-stranded or duplex DNA as competitors. Moreover, PDI2B is a G4 ligand that can display higher thermal stabilization and greater affinity for 2- over 3-tetrad quadruplexes, which constitutes a novel type of behavior.
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  58. 58
    García-Calvo, J.; Torroba, T.; Brañas-Fresnillo, V.; Perdomo, G.; Cózar-Castellano, I.; Li, Y.-H.; Legrand, Y.-M.; Barboiu, M. Manipulation of Transmembrane Transport by Synthetic K+ Ionophore Depsipeptides and Its Implications in Glucose-Stimulated Insulin Secretion in β-Cells. Chem. – Eur. J. 2019, 25, 9287– 9294,  DOI: 10.1002/chem.201901372
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    58
    Manipulation of transmembrane transport by synthetic K+ ionophore depsipeptides and its implications in glucose-stimulated insulin secretion in β-cells
    Garcia-Calvo, Jose; Torroba, Tomas; Branas-Fresnillo, Virginia; Perdomo, German; Cozar-Castellano, Irene; Li, Yu-Hao; Legrand, Yves-Marie; Barboiu, Mihail
    Chemistry - A European Journal (2019), 25 (39), 9287-9294CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
    The cyclic depsipeptide cereulide toxin it is a very well-known potassium electrogenic ionophore particularly sensitive to pancreatic beta cells. The mechanistic details of its specific activity are unknown. Here, we describe a series of synthetic substituted cereulide potassium ionophores that cause impressive selective activation of glucose-induced insulin secretion in a constitutive manner in rat insulinoma INS1E cells. Our study demonstrates that the different electroneutral K+ transport mechanism exhibited by the anionic mutant depsipeptides when compared with classical electrogenic cereulides can have an important impact of pharmacol. value on glucose-stimulated insulin secretion.
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  59. 59
    Busto, N.; García-Calvo, J.; Cuevas, J. V.; Herrera, A.; Mergny, J.-L.; Pons, S.; Torroba, T.; García, B. Influence of Core Extension and Side Chain Nature in Targeting G-Quadruplex Structures with Perylene Monoimide Derivatives. Bioorg. Chem. 2021, 108, 104660  DOI: 10.1016/j.bioorg.2021.104660
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    59
    Influence of core extension and side chain nature in targeting G-quadruplex structures with perylene monoimide derivatives
    Busto, Natalia; Garcia-Calvo, Jose; Cuevas, Jose Vicente; Herrera, Antonio; Mergny, Jean-Louis; Pons, Sebastian; Torroba, Tomas; Garcia, Begona
    Bioorganic Chemistry (2021), 108 (), 104660CODEN: BOCMBM; ISSN:0045-2068. (Elsevier B.V.)
    A structure-activity relationship (SAR) study in terms of G-quadruplex binding ability and antiproliferative activity of six fluorescent perylenemonoimide (PMIs) derivs. is reported. A pos. charge seems to be the key to target G4. This study also reveals the importance of the element substitution in the potential biol. activity of PMIs, being the polyethylene glycol (PEG) chains in the peri position responsible for their antiproliferative activity. Among them, the cationic PMI6 with two PEG chains is the most promising compd. since its fluorescence is enhanced in the presence of G-quadruplex structures. Moreover, PMI6 binds to the human telomeric G-quadruplex hTelo with high affinity and displays a high antiproliferative potential towards HeLa (cervical adenocarcinoma), A549 (lung adenocarcinoma) and A2780 (ovarian adenocarcinoma) cells. Its fate can be followed inside cells thanks to its fluorescent properties: the compd. is found to accumulate in the mitochondria.
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  60. 60
    Tajima, K.; Fukui, N.; Shinokubo, H. Aggregation-Induced Emission of Nitrogen-Bridged Naphthalene Monoimide Dimers. Org. Lett. 2019, 21, 9516– 9520,  DOI: 10.1021/acs.orglett.9b03699
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    60
    Aggregation-Induced Emission of Nitrogen-Bridged Naphthalene Monoimide Dimers
    Tajima, Keita; Fukui, Norihito; Shinokubo, Hiroshi
    Organic Letters (2019), 21 (23), 9516-9520CODEN: ORLEF7; ISSN:1523-7052. (American Chemical Society)
    We have prepd. four 4-aminonaphthalene monoimide derivs. and examd. the aggregation-induced emission (AIE) properties. A nitrogen-bridged dimer is AIE-active and exhibits bright green emission with a high quantum yield in the solid state. The X-ray diffraction anal. suggests that key to the bright luminescence is the favorable crystal packing dominated by CH/π interaction. The late-stage cyanation of the dimer tuned its AIE color from green to orange.
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  61. 61
    Wang, Y.; Teng, Y.; Yang, H.; Li, X.; Yin, D.; Tian, Y. Bioorthogonally Applicable Multicolor Fluorogenic Naphthalimide–Tetrazine Probes with Aggregation-Induced Emission Characters. Chem. Commun. 2022, 58, 949– 952,  DOI: 10.1039/D1CC05204G
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    61
    Bioorthogonally applicable multicolor fluorogenic naphthalimide-tetrazine probes with aggregation-induced emission characters
    Wang, Yongcheng; Teng, Yu; Yang, Hong; Li, Xiang; Yin, Dali; Tian, Yulin
    Chemical Communications (Cambridge, United Kingdom) (2022), 58 (7), 949-952CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
    A series of naphthalimide-tetrazines were developed as bioorthogonal fluorogenic probes, which could produce significant fluorescence enhancement, notable aggregation-induced emission (AIE) characters and multicolor emissions after bioorthogonal reaction with strained dienophiles. Manipulating the π-bridge in the fluorophore skeleton allows fine-tuning of the emission wavelength and influences the AIE-active properties. With these probes, we succeeded in no-wash fluorogenic protein labeling and mitochondria-selective bioorthogonal imaging in live cells.
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  62. 62
    García-Calvo, J.; Calvo-Gredilla, P.; Vallejos, S.; García, J. M.; Cuevas-Vicario, J. V.; García-Herbosa, G.; Avella, M.; Torroba, T. Palladium Nanodendrites Uniformly Deposited on the Surface of Polymers as an Efficient and Recyclable Catalyst for Direct Drug Modification Via Z-Selective Semihydrogenation of Alkynes. Green Chem. 2018, 20, 3875– 3883,  DOI: 10.1039/C8GC01522H
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    62
    Palladium nanodendrites uniformly deposited on the surface of polymers as an efficient and recyclable catalyst for direct drug modification via Z-selective semihydrogenation of alkynes
    Garcia-Calvo, Jose; Calvo-Gredilla, Patricia; Vallejos, Saul; Garcia, Jose Miguel; Cuevas-Vicario, Jose Vicente; Garcia-Herbosa, Gabriel; Avella, Manuel; Torroba, Tomas
    Green Chemistry (2018), 20 (16), 3875-3883CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)
    The prepn. of new monodisperse polycryst. palladium nanoparticles uniformly distributed on the surface of polymers, by simply adding a palladium(II) soln. in water to the polymers, is described. The polymer supported palladium nanoparticles material was used as an efficient portable and reusable catalyst for the stereoselective semihydrogenation reaction of internal alkynes to (Z)-alkenes in green solvents.
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  63. 63
    García-Calvo, J.; García-Calvo, V.; Vallejos, S.; García, F. C.; Avella, M.; García, J.-M.; Torroba, T. Surface Coating by Gold Nanoparticles on Functional Polymers: On-Demand Portable Catalysts for Suzuki Reactions. ACS Appl. Mater. Interfaces 2016, 8, 24999– 25004,  DOI: 10.1021/acsami.6b07746
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    63
    Surface Coating by Gold Nanoparticles on Functional Polymers: On-Demand Portable Catalysts for Suzuki Reactions
    Garcia-Calvo, Jose; Garcia-Calvo, Victor; Vallejos, Saul; Garcia, Felix C.; Avella, Manuel; Garcia, Jose-Miguel; Torroba, Tomas
    ACS Applied Materials & Interfaces (2016), 8 (38), 24999-25004CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    We have developed new functionalized polymers capable of being easily coated by gold nanoparticles, uniformly distributed on the surface of the polymers, by simply adding a gold(III) soln. in water to the polymers. The polymer-supported gold nanoparticle material was used as an efficient portable and reusable catalyst for Suzuki reactions in mixed org.-aq. solvents.
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  64. 64
    Sanluis-Verdes, A.; Colomer-Vidal, P.; Rodriguez-Ventura, F.; Bello-Villarino, M.; Spinola-Amilibia, M.; Ruiz-Lopez, E.; Illanes-Vicioso, R.; Castroviejo, P.; Aiese Cigliano, R.; Montoya, M.; Falabella, P.; Pesquera, C.; Gonzalez-Legarreta, L.; Arias-Palomo, E.; Solà, M.; Torroba, T.; Arias, C. F.; Bertocchini, F. Wax Worm Saliva and the Enzymes therein Are the Key to Polyethylene Degradation by Galleria mellonella. Nat. Commun. 2022, 13, 5568  DOI: 10.1038/s41467-022-33127-w
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    64
    Wax worm saliva and the enzymes therein are the key to polyethylene degradation by Galleria mellonella
    Sanluis-Verdes, A.; Colomer-Vidal, P.; Rodriguez-Ventura, F.; Bello-Villarino, M.; Spinola-Amilibia, M.; Ruiz-Lopez, E.; Illanes-Vicioso, R.; Castroviejo, P.; Aiese Cigliano, R.; Montoya, M.; Falabella, P.; Pesquera, C.; Gonzalez-Legarreta, L.; Arias-Palomo, E.; Sola, M.; Torroba, T.; Arias, C. F.; Bertocchini, F.
    Nature Communications (2022), 13 (1), 5568CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)
    Plastic degrdn. by biol. systems with re-utilization of the byproducts could be a future soln. to the global threat of plastic waste accumulation. Here, we report that the saliva of Galleria mellonella larvae (wax worms) is capable of oxidizing and depolymg. polyethylene (PE), one of the most produced and sturdy polyolefin-derived plastics. This effect is achieved after a few hours' exposure at room temp. under physiol. conditions (neutral pH). The wax worm saliva can overcome the bottleneck step in PE biodegrdn., namely the initial oxidn. step. Within the saliva, we identify two enzymes, belonging to the phenol oxidase family, that can reproduce the same effect. To the best of our knowledge, these enzymes are the first animal enzymes with this capability, opening the way to potential solns. for plastic waste management through bio-recycling/up-cycling.
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    A new pre-concn./sepn. system coupled to a micro-hollow glow discharge plasma detector is demonstrated for the anal. of explosives. The detector and spectrometer are miniaturized and field-portable. Sepn. eliminated air interferences while pre-concn. improved detection limits for TATP (triacetone triperoxide) and DNT (dinitrotoluene). In the anal. step, a temp. ramp desorbed the 2 explosives into an entraining Ar flow. Optical emission spectroscopy was applied to detect the plasma generated at. and diat. radicals using a spectrometer at atm. pressure. For both test species, the detection limits reached values <5 ppb. The effect of an at-sea environment was also evaluated. Such a detector system is very promising for the detection of explosives due its small size, high sensitivity, and selectivity.
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  • Abstract

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    Figure 1

    Figure 1. (a) Structure of chemical probes used for the study. (b) Model of the chemical probe AR82s on silica. (c, e) Structural and (d) elemental TEM images of the AR82s@SiO2 nanoparticles. (f) Elemental composition of the AR82s@SiO2 nanoparticles and high-resolution TEM images.

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    Figure 2

    Figure 2. (a) Microfluidic device dimensions: Eppendorf: outer top diameter: 11 mm, inner top diameter: 9 mm, outer bottom diameter: 5 mm, inner bottom diameter: 3 mm, volume: 1.5 mL, height (with lid): 40 mm, height (without lid): 38 mm; tubing: outer diameter: 3 mm, inner diameter: 1.5 mm, length (flow tube): 25 mm, length (return tube:): 35 mm. (b) The actual aspect of the system; reproduced from ref (48) with permission from the Chinese Chemical Society (CCS), Institute of Chemistry of Chinese Academy of Sciences (IC), and the Royal Society of Chemistry. (c) Fluorescence changes with TATP gas. (d) Titration curves of AR82s@SiO2 and TATP vapor. (e) Fluorescent profile at 535 nm and (f) calibration for the limit of detection of AR82s@SiO2 nanoparticles under increasing concentrations of TATP vapor. λexc = 370 nm, λem = 535 nm.

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    Figure 3

    Figure 3. (a) Distribution of TATP sample (yellow arrow) and sensor samples (red arrows) in the room. (b) Close view of the arrangement of the TATP sample (yellow arrow) in front of the airflow outlet and the sensing material samples (red arrows). (c) Histogram plotting the differences in intensity emission in all cases before and after exposure to TATP vapors as a function of distance from the TATP source and temperature of the room, normalized to the top and reference signals. (d) A sample of sensing material showing the modified nanoparticles.

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    Figure 4

    Figure 4. Summary of experiments 7–12. (a) Arrangement of the TATP in front of the airflow outlet. (b) Distribution of sensing nanoparticles in the room. (c) 3D representation of the variation of the normalized emission intensity as a function of the distance to the TATP source. (d) Assembly of the nanoparticles for measurements. (e) Details of one sample of AR82@SiO2.

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    Figure 5

    Figure 5. Average and standard deviation of normalized emission variation as a function of the distance to the TATP source.

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    Figure 6

    Figure 6. (a) View of the room for the experiment, (b) the TATP sample and the sensing material at different distances from the TATP, (c) picture of the sensing material placed at 25 cm from the TATP source, under a UV lamp, before (up) and after (down) being exposed to TATP, (d) picture (down) captured by the mobile phone app, and (e) the app assigned a positive value after comparing the RGB values in the selected point with the customized database.

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    Figure 7

    Figure 7. (a) Titration curves, TATP titration. (b) Fluorescence profile at 500 nm, TATP titration. (c) Calibration plot for the limit of detection of 2.5 μM GC2 solutions in DCM under increasing concentrations of TATP. (d) Image of solutions before and after TATP titration. (e) Titration curves, m-CPBA titration. (f) Fluorescence profile at 500 nm, m-CPBA titration. (g) Calibration plot for the limit of detection. (h) Fluorescence profile at the corresponding working curves of the ratiometric probe in the presence of m-CPBA.

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    Figure 8

    Figure 8. 1H NMR (CDCl3, 500 MHz) titration of AR82s with increasing amounts of TATP in the presence of amberlite, 3 mg of AR82s in 0.5 mL of CDCl3, and TATP amounts: (1) 0 μg, (2) 5 μg, (3) 10 μg, (4) 15 μg, (5) 20 μg, (6) 30 μg, (7) 40 μg, (8) 60 μg, (9) 90 μg, (10) 150 μg, (11) 300 μg, (12) 500 μg, (13) 800 μg, (14) 1400 μg, (15) 3200 μg, (16) 6800 μg, (17) 10 400 μg, (18) 15 800 μg as total added TATP after each addition, (a) 2.8–4.0 ppm region, (b) 7.5–8.7 ppm region.

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      Li, Z.; Askim, J. R.; Suslick, K. S. The Optoelectronic Nose: Colorimetric and Fluorometric Sensor Arrays. Chem. Rev. 2019, 119, 231– 292,  DOI: 10.1021/acs.chemrev.8b00226
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      15
      The Optoelectronic Nose: Colorimetric and Fluorometric Sensor Arrays
      Li, Zheng; Askim, Jon R.; Suslick, Kenneth S.
      Chemical Reviews (Washington, DC, United States) (2019), 119 (1), 231-292CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
      A review. A comprehensive review on the development and state of the art of colorimetric and fluorometric sensor arrays is presented. Chem. sensing aims to detect subtle changes in the chem. environment by transforming relevant chem. or phys. properties of mol. or ionic species (i.e., analytes) into an anal. useful output. Optical arrays based on chemoresponsive colorants (dyes and nanoporous pigments) probe the chem. reactivity of analytes, rather than their phys. properties (e.g., mass). The chem. specificity of the olfactory system does not come from specific receptors for specific analytes (e.g., the traditional lock-and-key model of substrate-enzyme interactions), but rather olfaction makes use of pattern recognition of the combined response of several hundred olfactory receptors. In a similar fashion, arrays of chemoresponsive colorants provide high-dimensional data from the color or fluorescence changes of the dyes in these arrays as they are exposed to analytes. This provides chem. sensing with high sensitivity (often down to ppb levels), impressive discrimination among very similar analytes, and exquisite fingerprinting of extremely similar mixts. over a wide range of analyte types, in both the gas and liq. phases. Design of both sensor arrays and instrumentation for their anal. are discussed. In addn., the various chemometric and statistical analyses of high-dimensional data (including hierarchical cluster anal. (HCA), principal component anal. (PCA), linear discriminant anal. (LDA), support vector machines (SVMs), and artificial neural networks (ANNs)) are presented and critiqued in ref. to their use in chem. sensing. A variety of applications are also discussed, including personal dosimetry of toxic industrial chem., detection of explosives or accelerants, quality control of foods and beverages, biosensing intracellularly, identification of bacteria and fungi, and detection of cancer and disease biomarkers.
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    16. 16
      Li, Z.; Suslick, K. S. The Optoelectronic Nose. Acc. Chem. Res. 2021, 54, 950– 960,  DOI: 10.1021/acs.accounts.0c00671
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      16
      The Optoelectronic Nose
      Li, Zheng; Suslick, Kenneth S.
      Accounts of Chemical Research (2021), 54 (4), 950-960CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)
      A review. Conspectus: How does one tell the difference between one mol. or mixt. of mols. from another. Chem. sensing seeks to probe phys. or chem. properties of mol. or ionic species (i.e., analytes) and transform that information into a useful and distinguishable output. The olfactory system of animals is the prototype of chem. sensing. Even for human beings (who are generally more visual than olfactory creatures), the sense of smell is one of our most basic capabilities, and we can discriminate among many thousands, and possibly even billions, of different odors. The chem. specificity of the olfactory system does not come from specific receptors for specific analytes (i.e., the traditional lock-and-key model of enzyme-substrate interactions), but rather olfaction uses pattern recognition of the combined responses of several hundred olfactory receptors. In analogy to olfaction, colorimetric sensor arrays provide high dimensional data from the color changes of chem. responsive colorants as they are exposed to analytes. These colorants include pH responsive dyes, Lewis acid/base indicators, redox dyes, vapochromics, and surface-modified silver nanoparticles. The color difference maps so created provide chem. sensing with high sensitivity (often down to ppb levels), impressive discrimination among very similar analytes, and exquisite fingerprinting of extremely similar mixts. over a wide range of analyte types, both in the gas and liq. phases. Such colorimetric arrays probe a wide range of the chem. reactivity of analytes, rather than the limited dimensionality of phys. properties (e.g., mass) or physisorption (e.g., traditional electronic noses). Our sensor arrays are disposable and simple to produce by either inkjet or robotic dip-pen printing onto the surface of porous polymer membranes or even paper. Design of both sensor arrays and optical readers for their anal. has advanced to a fully self-contained pocket-sized instrument, the optoelectronic nose. Quant. anal. requires appropriate chemometric methods for pattern recognition of data with inherently high dimensionality, e.g., hierarchical cluster anal. and support vector machines. A wide range of applications for the colorimetric sensor arrays has been developed, including personal dosimetry of toxic industrial chems., detection of explosives or fire accelerants, monitoring pollutants for artwork and cultural heritage preservation, quality control of foods and beverages, rapid identification of bacteria and fungi, and detection of disease biomarkers in breath or urine. The development of portable, high-accuracy instrumentation using std. imaging devices with the capability of onboard, real-time anal. has had substantial progress and increasingly meets the expectations for real-world use.
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    17. 17
      Härtel, M. A. C.; Klapötke, T. M.; Stiasny, B.; Stierstorfer, J. Gas-phase Concentration of Triacetone Triperoxide (TATP) and Diacetone Diperoxide (DADP). Propellants Explos. Pyrotech. 2017, 42, 623– 634,  DOI: 10.1002/prep.201700034
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      There is no corresponding record for this reference.
    18. 18
      Dubnikova, F.; Kosloff, R.; Almog, J.; Zeiri, Y.; Boese, R.; Itzhaky, H.; Alt, A.; Keinan, E. Decomposition of Triacetone Triperoxide Is an Entropic Explosion. J. Am. Chem. Soc. 2005, 127, 1146– 1159,  DOI: 10.1021/ja0464903
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      18
      Decomposition of Triacetone Triperoxide Is an Entropic Explosion
      Dubnikova, Faina; Kosloff, Ronnie; Almog, Joseph; Zeiri, Yehuda; Boese, Roland; Itzhaky, Harel; Alt, Aaron; Keinan, Ehud
      Journal of the American Chemical Society (2005), 127 (4), 1146-1159CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      Both X-ray crystallog. and electronic structure calcns. using the cc-pVDZ basis set at the DFT B3LYP level were employed to study the explosive properties of triacetone triperoxide (TATP) and diacetone diperoxide (DADP). The thermal decompn. pathway of TATP was investigated by a series of calcns. that identified transition states, intermediates, and the final products. Counterintuitively, these calcns. predict that the explosion of TATP is not a thermochem. highly favored event. It rather involves entropy burst, which is the result of formation of one ozone and three acetone mols. from every mol. of TATP in the solid state.
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    19. 19
      Romero, D. C.; Calvo-Gredilla, P.; García-Calvo, J.; Diez-Varga, A.; Cuevas, J. V.; Revilla-Cuesta, A.; Busto, N.; Abajo, I.; Aullón, G.; Torroba, T. Self-Assembly Hydrosoluble Coronenes: A Rich Source of Supramolecular Turn-On Fluorogenic Sensing Materials in Aqueous Media. Org. Lett. 2021, 23, 8727– 8732,  DOI: 10.1021/acs.orglett.1c03175
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      19
      Self-Assembly Hydrosoluble Coronenes: A Rich Source of Supramolecular Turn-On Fluorogenic Sensing Materials in Aqueous Media
      Romero, Daisy C.; Calvo-Gredilla, Patricia; Garcia-Calvo, Jose; Diez-Varga, Alberto; Cuevas, Jose Vicente; Revilla-Cuesta, Andrea; Busto, Natalia; Abajo, Irene; Aullon, Gabriel; Torroba, Tomas
      Organic Letters (2021), 23 (22), 8727-8732CODEN: ORLEF7; ISSN:1523-7052. (American Chemical Society)
      Water-sol. coronenes, that form nanoparticles by self-assocn., work as new fluorescent materials by complexation with cucurbit[7]uril, as well as selective turn-on fluorogenic sensors for nitroarom. explosives with remarkable selectivity, by using only water as solvent.
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    20. 20
      Wan, W.-M.; Tian, D.; Jing, Y.-N.; Zhang, X.-Y.; Wu, W.; Ren, H.; Bao, H.-L. NBN-Doped Conjugated Polycyclic Aromatic Hydrocarbons as an AIEgen Class for Extremely Sensitive Detection of Explosives. Angew. Chem., Int. Ed. 2018, 57, 15510– 15516,  DOI: 10.1002/anie.201809844
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      20
      NBN-Doped Conjugated Polycyclic Aromatic Hydrocarbons as an AIEgen Class for Extremely Sensitive Detection of Explosives
      Wan, Wen-Ming; Tian, Di; Jing, Ya-Nan; Zhang, Xiao-Yun; Wu, Wei; Ren, Hao; Bao, Hong-Li
      Angewandte Chemie, International Edition (2018), 57 (47), 15510-15516CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
      A simple and efficient synthesis of NBN-doped conjugated polycyclic arom. hydrocarbons (such as diazaborinines) has been accomplished by a catalyst-free intermol. dehydration reaction at room temp. between boronic acid and diamine moieties with yields up to 99 %. Polycyclic arom. hydrocarbons with a six-membered NBN ring are a new class of aggregation-induced emissive luminogens. Extremely sensitive detection of ppb levels of TNT by Ph naphthodiazaborinine is straightforward. Visual detection of TNT is illustrated by fabrication of TNT test strips, which can detect as little as 100 ng of TNT powder. This simple and sensitive detection of TNT has potential applications in the area of public safety and security against terrorist activities.
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    21. 21
      Kim, S.; Kim, H.; Qiao, T.; Cha, C.; Lee, S. K.; Lee, K.; Ro, H. J.; Kim, Y.; Lee, W.; Lee, H. Fluorescence Enhancement from Nitro-Compound-Sensitive Bacteria within Spherical Hydrogel Scaffolds. ACS Appl. Mater. Interfaces 2019, 11, 14354– 14361,  DOI: 10.1021/acsami.9b02262
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      21
      Fluorescence Enhancement from Nitro-Compound-Sensitive Bacteria within Spherical Hydrogel Scaffolds
      Kim, Soohyun; Kim, Hyunji; Qiao, Tian; Cha, Chaenyung; Lee, Sung Kuk; Lee, Kangseok; Ro, Hyun Ji; Kim, Youngkyun; Lee, Wonmok; Lee, Hyunjung
      ACS Applied Materials & Interfaces (2019), 11 (15), 14354-14361CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      For the safety of both prodn. and life, it is a very significant issue to detect explosive nitro-compds. in a remote way or over a long distance. Here, we report that nitro-compds. were detected by the bacterial sensor based on hydrogel micro-beads as a platform. A green fluorescent protein(GFP)-producing Escherichia coli which was genetically engineered in order to be sensitive to nitro-compds. was loaded within poly(2-hydroxyethyl methacrylate) (poly(HEMA)) based hydrogel beads, in which fluorescent signals from bacteria were concd. and strong enough to be easily detected. For efficient loading of neg. charged bacteria, a surface charge of poly(HEMA) based beads was controlled by copolymn. with 2-(methacryloyloxy) Et trimethylammonium chloride (MAETC) as a cationic monomer. With the addn. of MAETC, the cell affinity was nine times enhanced by an interaction between the pos. charged poly(HEMA-co-MAETC) beads and neg. charged bacteria. These increased cell affinity resulted in an enhancement of a sensing signal. After exposure to 2,4,6-trinitrotoluene (TNT), typical explosive nitro-compds., the fluorescence intensity of bacteria sensors using poly(HEMA-co MAETC) bead having 80 wt% of MAETC was five times increased compared to those based on poly(HEMA) beads. This amplification of the fluorescent signal enables easier detection of explosives efficiently by a remote detection, even over a long distance.
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    22. 22
      Zhang, Z.; Chen, S.; Shi, R.; Ji, J.; Wang, D.; Jin, S.; Han, T.; Zhou, C.; Shu, Q. A Single Molecular Fluorescent Probe for Selective and Sensitive Detection of Nitroaromatic Explosives: A New Strategy for The Mask-Free Discrimination of TNT and TNP Within Same Sample. Talanta 2017, 166, 228– 233,  DOI: 10.1016/j.talanta.2017.01.046
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      22
      A single molecular fluorescent probe for selective and sensitive detection of nitroaromatic explosives: A new strategy for the mask-free discrimination of TNT and TNP within same sample
      Zhang, Zhe; Chen, Shusen; Shi, Rui; Ji, Jiawen; Wang, Dequan; Jin, Shaohua; Han, Tongyu; Zhou, Chenxiao; Shu, Qinghai
      Talanta (2017), 166 (), 228-233CODEN: TLNTA2; ISSN:0039-9140. (Elsevier B.V.)
      A simple naphthalene based fluorescent probe was first time reported as dual sensing of 2,4,6-trinitrotolune (TNT) and 2,4,6-trinitrophenol (TNP) by distinguishable changes in both soln. color change and fluorescence within same sample without any mask agent. Upon addn. of TNT and TNP, the strong emission quenching at 412 nm and a new emission band at 530 nm was obsd., resp. In addn., the sensing mechanism was evaluated by DFT calcns. by Gaussian 09 software.
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    23. 23
      Tripathi, N.; Kumar, R.; Singh, P.; Kumar, S. Ratiometric Fluorescence “Turn On” Probe for Fast and Selective Detection of TNT in Solution, Solid and Vapour. Sens. Actuators, B 2017, 246, 1001– 1010,  DOI: 10.1016/j.snb.2017.02.174
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      23
      Ratiometric fluorescence "Turn On" probe for fast and selective detection of TNT in solution, solid and vapour
      Tripathi, Neetu; Kumar, Rahul; Singh, Prabhpreet; Kumar, Subodh
      Sensors and Actuators, B: Chemical (2017), 246 (), 1001-1010CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)
      A review. Fluorescent probe UREA-TP undergoes nearly 600% increase in emission intensity at 310 nm on addn. of 1 equiv of TNT, but the emission band centered at 440 nm remains unchanged. UREA-TP acts as a ratiometric fluorescence "turn-on" probe and can detect TNT between 10-9 to 10-5 M with limit of detection as low as 100 pM. Paper strips coated with UREA-TP on interaction with TNT become fluorescent purple under 365 nm light and can det. both qual. and quant. as low as 10μl soln. of 10-13 M TNT, which accounts for 2.27 × 10-16 g cm-2 TNT, significantly lower than the TNT concn. allowed in drinking water by EPA. The common nitroarom. derivs. 2,4-DNT, 2,6-DNT, picric acid and 2,4-DNP, the pain killers, food supplements and inorg. anions show insignificant interference in the detn. of TNT using UREA-TP. The aggregate size detn. using dynamic light scattering anal. and morphol. studies using TEM investigations reveals that UREA-TP in H2O-DMSO (98:2) remains in aggregate state with av. size of 200 nm, which undergo further aggregation to larger size aggregates with increasing amts. of TNT.
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    24. 24
      Colizza, K.; Yevdokimov, A.; McLennan, L.; Smith, J. L.; Oxley, J. C. Using Gas Phase Reactions of Hexamethylene Triperoxide Diamine (HMTD) to Improve Detection in Mass Spectrometry. J. Am. Soc. Mass Spectrom. 2018, 29, 675– 684,  DOI: 10.1007/s13361-017-1879-5
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      24
      Using Gas Phase Reactions of Hexamethylene Triperoxide Diamine (HMTD) to Improve Detection in Mass Spectrometry
      Colizza, Kevin; Yevdokimov, Alexander; McLennan, Lindsay; Smith, James L.; Oxley, Jimmie C.
      Journal of the American Society for Mass Spectrometry (2018), 29 (4), 675-684CODEN: JAMSEF; ISSN:1044-0305. (Springer)
      The authors' efforts to lower the detection limits of hexamethylene triperoxide diamine (HMTD) have uncovered previously unreported gas-phase reactions of primary and secondary amines with one of the six methylene carbons. The reaction occurs primarily in the atm. pressure chem. ionization (APCI) source and is similar to the behavior of alcs. with HMTD [1]. However, unlike alcs., the amine reaction conserves the hydrogen peroxide on the intact product. Furthermore, with or without amines, HMTD is oxidized to tetramethylene diperoxide diamine dialdehyde (TMDDD) in a temp.-dependent fashion in the APCI source. Synthesized TMDDD forms very strong adducts (not products) to ammonium and amine ions in the electrospray ionization (ESI) source. Attempts to improve HMTD detection by generating TMDDD in the APCI source with post-column addn. of amines were not successful. Signal intensity of the solvent related HMTD product in methanol, [HMTD+MeOH2-H2O2]+ (m/z 207.0975), was understandably related to the amt. of methanol in the HMTD environment as it elutes into the source. With conditions optimized for this product, the detection of 100 pg on column was accomplished with a robust anal. of 300 pg (1.44 pmol) routinely performed on the Orbitrap mass spectrometers.
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    25. 25
      Mäkinen, M.; Nousiainen, M.; Sillanpaa, M. Ion Spectrometric Detection Technologies for Ultra-Traces of Explosives: A Review. Mass Spectrom. Rev. 2011, 30, 940– 973,  DOI: 10.1002/mas.20308
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      25
      Ion spectrometric detection technologies for ultra-traces of explosives: a review
      Makinen Marko; Nousiainen Marjaana; Sillanpaa Mika
      Mass spectrometry reviews (2011), 30 (5), 940-73 ISSN:.
      In recent years, explosive materials have been widely employed for various military applications and civilian conflicts; their use for hostile purposes has increased considerably. The detection of different kind of explosive agents has become crucially important for protection of human lives, infrastructures, and properties. Moreover, both the environmental aspects such as the risk of soil and water contamination and health risks related to the release of explosive particles need to be taken into account. For these reasons, there is a growing need to develop analyzing methods which are faster and more sensitive for detecting explosives. The detection techniques of the explosive materials should ideally serve fast real-time analysis in high accuracy and resolution from a minimal quantity of explosive without involving complicated sample preparation. The performance of the in-field analysis of extremely hazardous material has to be user-friendly and safe for operators. The two closely related ion spectrometric methods used in explosive analyses include mass spectrometry (MS) and ion mobility spectrometry (IMS). The four requirements-speed, selectivity, sensitivity, and sampling-are fulfilled with both of these methods.
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    26. 26
      Jiang, D.; Peng, L.; Wen, M.; Zhou, Q.; Chen, C.; Wang, X.; Chen, W.; Li, H. Dopant-Assisted Positive Photoionization Ion Mobility Spectrometry Coupled with Time-Resolved Thermal Desorption for On-Site Detection of Triacetone Triperoxide and Hexamethylene Trioxide Diamine in Complex Matrices. Anal. Chem. 2016, 88, 4391– 4399,  DOI: 10.1021/acs.analchem.5b04830
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      26
      Dopant-Assisted Positive Photoionization Ion Mobility Spectrometry Coupled with Time-Resolved Thermal Desorption for On-Site Detection of Triacetone Triperoxide and Hexamethylene Trioxide Diamine in Complex Matrices
      Jiang, Dandan; Peng, Liying; Wen, Meng; Zhou, Qinghua; Chen, Chuang; Wang, Xin; Chen, Wendong; Li, Haiyang
      Analytical Chemistry (Washington, DC, United States) (2016), 88 (8), 4391-4399CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      Peroxide explosives, such as triacetone triperoxide (TATP) and hexamethylene trioxide diamine (HMTD), were often used in the terrorist attacks due to their easy synthesis from readily starting materials. Therefore, an on-site detection method for TATP and HMTD is urgently needed. Herein, we developed a stand-alone dopant-assisted pos. photoionization ion mobility spectrometry (DAPP-IMS) coupled with time-resolved thermal desorption introduction for rapid and sensitive detection of TATP and HMTD in complex matrixes, such as white solids, soft drinks, and cosmetics. Acetone was chosen as the optimal dopant for better sepn. between reactant ion peaks and product ion peaks as well as higher sensitivity, and the limits of detection (LODs) of TATP and HMTD std. samples were 23.3 and 0.2 ng, resp. Explosives on the sampling swab were thermally desorbed and carried into the ionization region dynamically within 10 s, and the max. released concn. of TATP or HMTD could be time-resolved from the matrix interference owing to the different volatility. Furthermore, with the combination of the fast response thermal desorber (within 0.8 s) and the quick data acquisition software to DAPP-IMS, two-dimensional data related to drift time (TATP: 6.98 ms, K0 = 2.05 cm2 V-1 s-1; HMTD: 9.36 ms, K0 = 1.53 cm2 V-1 s-1) and desorption time was obtained for TATP and HMTD, which is beneficial for their identification in complex matrixes.
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    27. 27
      Correa, D. N.; Melendez-Perez, J. J.; Zacca, J. J.; Borges, R.; Schmidt, E. M.; Eberlin, M. N.; Meurer, E. C. Direct Detection of Triacetone Triperoxide (TATP) in Real Banknotes from ATM Explosion by EASI-MS. Propellants Explos. Pyrotech. 2017, 42, 370– 375,  DOI: 10.1002/prep.201600046
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      There is no corresponding record for this reference.
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      Hagenhoff, S.; Franzke, J.; Hayen, H. Determination of Peroxide Explosive TATP and Related Compounds by Dielectric Barrier Discharge Ionization-Mass Spectrometry (DBDI-MS). Anal. Chem. 2017, 89, 4210– 4215,  DOI: 10.1021/acs.analchem.7b00233
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      28
      Determination of Peroxide Explosive TATP and Related Compounds by Dielectric Barrier Discharge Ionization-Mass Spectrometry (DBDI-MS)
      Hagenhoff, Sebastian; Franzke, Joachim; Hayen, Heiko
      Analytical Chemistry (Washington, DC, United States) (2017), 89 (7), 4210-4215CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      Dielec. barrier discharge ionization-mass spectrometry (DBDI-MS), which is based on the use of a low temp. helium plasma as ionization source, is used for the detn. of trace amts. of triacetone triperoxide (TATP) and its homolog diacetone diperoxide (DADP) from surfaces. TATP is obsd. as [M+NH4]+ adduct, whereas DADP is obsd. as [M+O+NH4]+. Measurement of DADP with varying deuteration degrees (DADP, DADP-d6, and DADP-d12) indicates that DADP undergoes oxidn. when ionized by DBDI. If acetonitrile is used as deposition solvent, TATP tends to show fragmentation and is not only detected as [M+NH4]+ but as [M-CH4+NH4]+ and [M-C2H4+NH4]+ as well. Quantification of TATP solns. from glass surfaces by DBDI-MS, using TATP-3,6,9-13C as internal std., was done and validated using an LC/APCI-MS method. Achievable limits of detection (LOD) for TATP are equiv. to the deposition of 15 ng TATP and are comparable with other ambient desorption/ionization mass spectrometric techniques like desorption electrospray ionization (DESI).
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    29. 29
      Tang, S.; Vinerot, N.; Fisher, D.; Bulatov, V.; Yavetz-Chen, Y.; Schechter, I. Detection and Mapping of Trace Explosives on Surfaces Under Ambient Conditions Using Multiphoton Electron Extraction Spectroscopy (MEES). Talanta 2016, 155, 235– 244,  DOI: 10.1016/j.talanta.2016.04.027
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      29
      Detection and mapping of trace explosives on surfaces under ambient conditions using multiphoton electron extraction spectroscopy (MEES)
      Tang, Shisong; Vinerot, Nataly; Fisher, Danny; Bulatov, Valery; Yavetz-Chen, Yehuda; Schechter, Israel
      Talanta (2016), 155 (), 235-244CODEN: TLNTA2; ISSN:0039-9140. (Elsevier B.V.)
      Multiphoton electron extn. spectroscopy (MEES) is an anal. method in which UV laser pulses are utilized for extg. electrons from solid surfaces in multiphoton processes under ambient conditions. Counting the emitted electrons as a function of laser wavelength results in detailed spectral features, which can be used for material identification. The method has been applied to detection of trace explosives on a variety of surfaces. Detection was possible on dusty swabs spiked with explosives and also in the std. dry-transfer contamination procedure. Plastic explosives could also be detected. The anal. limits of detection (LODs) are in the sub pmole range, which indicates that MEES is one of the most sensitive detection methods for solid surface under ambient conditions. Scanning the surface with the laser allows for its imaging, such that explosives (as well as other materials) can be located. The imaging mode is also useful in forensic applications, such as detection of explosives in human fingerprints.
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    30. 30
      Lichtenstein, A.; Havivi, E.; Shacham, R.; Hahamy, E.; Leibovich, R.; Pevzner, A.; Krivitsky, V.; Davivi, G.; Presman, I.; Elnathan, R.; Engel, Y.; Flaxer, E.; Patolsky, F. Supersensitive Fingerprinting of Explosives by Chemically Modified Nanosensors Arrays. Nat. Commun. 2014, 5, 4195  DOI: 10.1038/ncomms5195
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      Supersensitive fingerprinting of explosives by chemically modified nanosensors arrays
      Lichtenstein, Amir; Havivi, Ehud; Shacham, Ronen; Hahamy, Ehud; Leibovich, Ronit; Pevzner, Alexander; Krivitsky, Vadim; Davivi, Guy; Presman, Igor; Elnathan, Roey; Engel, Yoni; Flaxer, Eli; Patolsky, Fernando
      Nature Communications (2014), 5 (), 4195CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)
      The capability to detect traces of explosives sensitively, selectively and rapidly could be of great benefit for applications relating to civilian national security and military needs. Here, we show that, when chem. modified in a multiplexed mode, nanoelec. devices arrays enable the supersensitive discriminative detection of explosive species. The fingerprinting of explosives is achieved by pattern recognizing the inherent kinetics, and thermodn., of interaction between the chem. modified nanosensors array and the mol. analytes under test. This platform allows for the rapid detection of explosives, from air collected samples, down to the parts-per-quadrillion concn. range, and represents the first nanotechnol.-inspired demonstration on the selective supersensitive detection of explosives, including the nitro- and peroxide-derivs., on a single electronic platform. Furthermore, the ultrahigh sensitivity displayed by our platform may allow the remote detection of various explosives, a task unachieved by existing detection technologies.
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    31. 31
      Lin, H.; Suslick, K. S. A Colorimetric Sensor Array for Detection of Triacetone Triperoxide Vapor. J. Am. Chem. Soc. 2010, 132, 15519– 15521,  DOI: 10.1021/ja107419t
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      31
      A Colorimetric Sensor Array for Detection of Triacetone Triperoxide Vapor
      Lin, Hengwei; Suslick, Kenneth S.
      Journal of the American Chemical Society (2010), 132 (44), 15519-15521CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      Triacetone triperoxide (TATP), one of the most dangerous primary explosives, has emerged as an explosive of choice for terrorists in recent years. Owing to the lack of UV absorbance, fluorescence, or facile ionization, TATP is extremely difficult to detect directly. Techniques that are able to detect generally require expensive instrumentation, need extensive sample prepn., or cannot detect TATP in the gas phase. Here we report a simple and highly sensitive colorimetric sensor for the detection of TATP vapor with semiquant. anal. from 50 ppb to 10 ppm. By using a solid acid catalyst to pretreat a gas stream, we have discovered that a colorimetric sensor array of redox sensitive dyes can detect even very low levels of TATP vapor from its acid decompn. products (e.g., H2O2) with limits of detection (LOD) below 2 ppb (i.e., <0.02% of its satn. vapor pressure). Common potential interferences (e.g., humidity, personal hygiene products, perfume, laundry supplies, volatile org. compds., etc.) do not generate an array response, and the array can also differentiate TATP from other chem. oxidants (e.g., hydrogen peroxide, bleach, tert-butylhydroperoxide, peracetic acid).
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    32. 32
      Li, Z.; Bassett, W. P.; Askim, J. R.; Suslick, K. S. Differentiation Among Peroxide Explosives with an Optoelectronic Nose. Chem. Commun. 2015, 51, 15312– 15315,  DOI: 10.1039/C5CC06221G
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      32
      Differentiation among peroxide explosives with an optoelectronic nose
      Li, Zheng; Bassett, Will P.; Askim, Jon R.; Suslick, Kenneth S.
      Chemical Communications (Cambridge, United Kingdom) (2015), 51 (83), 15312-15315CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
      Forensic identification of batches of homemade explosives (HME) poses a difficult anal. challenge. Differentiation among peroxide explosives is reported herein using a colorimetric sensor array and handheld scanner with a field-appropriate sampling protocol. Clear discrimination was demonstrated among twelve peroxide samples prepd. from different reagents, with a classification accuracy > 98%.
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    33. 33
      Askim, J. R.; Li, Z.; LaGasse, M. K.; Rankin, J. M.; Suslick, K. S. An Optoelectronic Nose for Identification of Explosives. Chem. Sci. 2016, 7, 199– 206,  DOI: 10.1039/C5SC02632F
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      33
      An optoelectronic nose for identification of explosives
      Askim, Jon R.; Li, Zheng; La Gasse, Maria K.; Rankin, Jaqueline M.; Suslick, Kenneth S.
      Chemical Science (2016), 7 (1), 199-206CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)
      Compact and portable methods for identification of explosives are increasingly needed for both civilian and military applications. A portable optoelectronic nose for the gas-phase identification of explosive materials is described that uses a highly cross-reactive colorimetric sensor array and a handheld scanner. The array probes a wide range of chem. reactivities using 40 chem. responsive colorimetric indicators, including pH sensors, metal-dye salts, redox-sensitive chromogenic compds., solvatochromic dyes, and other chromogenic indicators. Sixteen sep. analytes including common explosives, homemade explosives, and characteristic explosive components were differentiated into fourteen sep. classes with a classification error rate of <1%. Portable colorimetric array sensing could represent an important, complementary part of the toolbox used in practical applications of explosives detection and identification.
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    34. 34
      Xu, M.; Han, J.-M.; Wang, C.; Yang, X.; Pei, J.; Zang, L. Fluorescence Ratiometric Sensor for Trace Vapor Detection of Hydrogen Peroxide. ACS Appl. Mater. Interfaces 2014, 6, 8708– 8714,  DOI: 10.1021/am501502v
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      Fluorescence Ratiometric Sensor for Trace Vapor Detection of Hydrogen Peroxide
      Xu, Miao; Han, Ji-Min; Wang, Chen; Yang, Xiaomei; Pei, Jian; Zang, Ling
      ACS Applied Materials & Interfaces (2014), 6 (11), 8708-8714CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      Trace vapor detection of hydrogen peroxide (H2O2) represents a practical approach to nondestructive detection of peroxide-based explosives, including liq. mixts. of H2O2 and fuels and energetic peroxide derivs., such as triacetone triperoxide (TATP), diacetone diperoxide (DADP), and hexamethylene triperoxide diamine (HMTD). Development of a simple chem. sensor system that responds to H2O2 vapor with high reliability and sufficient sensitivity (reactivity) remains a challenge. We report a fluorescence ratiometric sensor mol., di-Et 2,5-bis((((4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)oxy)carbonyl)amino)terephthalate (DAT-B), for H2O2 that can be fabricated into an expedient, reliable, and sensitive sensor system suitable for trace vapor detection of H2O2. DAT-B is fluorescent in the blue region, with an emission max. at 500 nm in the solid state. Upon reaction with H2O2, DAT-B is converted to an electronic "push-pull" structure, di-Et 2,5-diaminoterephthalate (DAT-N), which has an emission peak at a longer wavelength centered at 574 nm. Such H2O2-mediated oxidn. of aryl boronates can be accelerated through the addn. of an org. base such as tetrabutylammonium hydroxide (TBAH), resulting in a response time of less than 0.5 s under 1 ppm of H2O2 vapor. The strong overlap between the absorption band of DAT-N and the emission band of DAT-B enables efficient Forster resonance energy transfer (FRET), thus allowing further enhancement of the sensing efficiency of H2O2 vapor. The detection limit of a drop-cast DAT-B/TBAH film was projected to be 7.7 ppb. By combining high sensitivity and selectivity, the reported sensor system may find broad application in vapor detection of peroxide-based explosives and relevant chem. reagents through its fabrication into easy-to-use, cost-effective kits.
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    35. 35
      Zhu, Q.-H.; Zhang, G.-H.; Yuan, W.-L.; Wang, S.-L.; He, L.; Yong, F.; Tao, G.-H. Handy Fluorescent Paper Device Based on a Curcumin Derivative for Ultrafast Detection of Peroxide-Based Explosives. Chem. Commun. 2019, 55, 13661– 13664,  DOI: 10.1039/C9CC06737J
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      35
      Handy fluorescent paper device based on a curcumin derivative for ultrafast detection of peroxide-based explosives
      Zhu, Qiu-Hong; Zhang, Guo-Hao; Yuan, Wen-Li; Wang, Shuang-Long; He, Ling; Yong, Fang; Tao, Guo-Hong
      Chemical Communications (Cambridge, United Kingdom) (2019), 55 (91), 13661-13664CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
      A handy, simple and inexpensive paper device is reported for extremely sensitive detection of peroxide-based explosives. The sensing device fabricated using a curcumin deriv. was capable of ultrafast sensing of triacetone triperoxide. The detection time was < 5 s. Moreover, the sensor retained full function under storage at ambient temp. for at least 120 days.
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    36. 36
      Yu, X.; Gong, Y.; Xiong, W.; Li, M.; Zhao, J.; Che, Y. Turn-on Fluorescent Detection of Hydrogen Peroxide and Triacetone Triperoxide via Enhancing Interfacial Interactions of a Blended System. Anal. Chem. 2019, 91, 6967– 6970,  DOI: 10.1021/acs.analchem.9b01255
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      36
      Turn-on Fluorescent Detection of Hydrogen Peroxide and Triacetone Triperoxide via Enhancing Interfacial Interactions of a Blended System
      Yu, Xinting; Gong, Yanjun; Xiong, Wei; Li, Mei; Zhao, Jincai; Che, Yanke
      Analytical Chemistry (Washington, DC, United States) (2019), 91 (11), 6967-6970CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      In this work, we report the fabrication of a blend consisting of fluorescent 1 nanofibers and amberlyst-15 particles as a turn-on fluorescence sensor for trace TATP vapors. Fluorescence imaging and lifetime anal. reveal that the interface between 1 nanofibers and amberlyst-15 particles exhibits stronger photoluminescence than the unblended areas because of the formed strong hydrogen bonding between. Furthermore, the interfacial adhesion between 1 nanofibers and amberlyst-15 particles can be amplified by H2O2, which in turn gives rise to rapid and remarkable fluorescence enhancement. When exposed to TATP vapors, the amberlyst-15 component can rapidly decomp. TATP into H2O2 that gives sensitive fluorescence enhancement responses of the blend. On the basis of this detection mechanism, fluorescence detection of TATP with rapid response (ca. 5 s) and high sensitivity (ca. 0.1 ppm) is achieved. Here, the resulting blend combines the pretreatment of TATP and detection responses and thereby simplifies the sensor fabrication for the practical application.
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    37. 37
      Qi, Y.; Xu, W.; Ding, N.; Chang, X.; Shang, C.; Peng, H.; Liu, T.; Fang, Y. A Film-Based Fluorescent Device for Vapor Phase Detection of Acetone and Related Peroxide Explosives. Mater. Chem. Front. 2019, 3, 1218– 1224,  DOI: 10.1039/C9QM00095J
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      37
      A film-based fluorescent device for vapor phase detection of acetone and related peroxide explosives
      Qi, Yanyu; Xu, Wenjun; Ding, Nannan; Chang, Xingmao; Shang, Congdi; Peng, Haonan; Liu, Taihong; Fang, Yu
      Materials Chemistry Frontiers (2019), 3 (6), 1218-1224CODEN: MCFAC5; ISSN:2052-1537. (Royal Society of Chemistry)
      On site, sensitive and selective detection of acetone vapor at room temp. is of great importance for health, and in particular for in air detection of triacetone triperoxide (TATP) and diacetone diperoxide (DADP), two improvised explosives commonly used by terrorists in suicide attacks. This paper reports a relevant high-performance film-based fluorescent device, where a newly synthesized perylene monoimide modified non-planar organoboron deriv. (PMI-BQ) was adopted as the sensing fluorophore. The performance of the device is excellent as evidenced by less than 2 s response time, no more than 10 s recovery time, nearly perfect reversibility, and lower than 50 ppm exptl. detection limit (DL) for acetone. In addn., the presence of potential interferences showed little effect upon the sensing. Notably, more than 30 days sensing tests showed no observable degrdn. in the performance of the film device. Further tests revealed that the film-based device can be further used for the detection of TATP and DADP. The exptl. DLs for the two explosives are lower than 30 and 50 μg, resp. The superior performance of the device was ascribed to the non-planar structure of the sensing fluorophore as it may produce micro-channels in the film. Meanwhile, solvation may also play a crucial role in the process. We believe our contribution not only realizes reversible fluorescence sensing of acetone vapor and the related explosives, but also demonstrates that the combination of solvent effect and non-planar structure could be an effective way to develop high performance fluorescent sensing films.
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    38. 38
      An, Y.; Xu, X.; Liu, K.; An, X.; Shang, C.; Wang, G.; Liu, T.; Li, H.; Peng, H.; Fang, Y. Fast, Sensitive, Selective and Reversible Fluorescence Monitoring of TATP in a Vapor Phase. Chem. Commun. 2019, 55, 941– 944,  DOI: 10.1039/C8CC08399A
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      Fast, sensitive, selective and reversible fluorescence monitoring of TATP in a vapor phase
      An, Yanqin; Xu, Xiaojie; Liu, Ke; An, Xuan; Shang, Congdi; Wang, Gang; Liu, Taihong; Li, Hong; Peng, Haonan; Fang, Yu
      Chemical Communications (Cambridge, United Kingdom) (2019), 55 (7), 941-944CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
      The development of sensors for the detection of triacetone triperoxide (TATP) has attracted great attention. Here, we constructed a low-cost, portable, reusable, visible paper-based fluorescent sensor for the sensitive detection of TATP via vapor sampling. Under optimized conditions, the fluorescent film showed a high sensitivity to TATP with a detection limit of lower than 0.5μg mL-1 in air. The linear range of the response is from 0.5 to 8.0μg mL-1. In addn., the paper-based sensor exhibited high selectivity to TATP. The presence of potential interferents showed little effect on sensing. Moreover, sensing is fully reversible. Fortunately, the test can also be conducted in a visualized way.
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      Rao, M. R.; Fang, Y.; De Feyter, S.; Perepichka, D. F. Conjugated Covalent Organic Frameworks via Michael Addition–Elimination. J. Am. Chem. Soc. 2017, 139, 2421– 2427,  DOI: 10.1021/jacs.6b12005
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      Conjugated Covalent Organic Frameworks via Michael Addition-Elimination
      Rao, M. Rajeswara; Fang, Yuan; De Feyter, Steven; Perepichka, Dmitrii F.
      Journal of the American Chemical Society (2017), 139 (6), 2421-2427CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      Dynamic covalent chem. enables self-assembly of reactive building blocks into structurally complex yet robust materials, such as Covalent Org. Frameworks (COFs). However, the synthetic toolbox used to prep. such materials, and thus the spectrum of attainable properties, is limited. For π-conjugated COFs, the Schiff base condensation of aldehydes and amines is the only general dynamic reaction, but the resulting imine-linked COFs display only a moderate electron delocalization and are susceptible to hydrolysis, particularly in acidic conditions. Here we report a new dynamic polymn. based on Michael addn.-elimination reaction of structurally diverse β-ketoenols with amines, and use it to prep. novel two dimensional (2D) π-conjugated COFs, as cryst. powders and exfoliated micron-size sheets. π-Conjugation is manifested in these COFs in significantly reduced band gap (1.8-2.2 eV), solid state luminescence and reversible electrochem. doping creating mid-gap (NIR absorbing) polaronic states. The β-ketoenamine moiety enables protonation control of electron delocalization through the 2D COF sheets. It also gives rise to direct sensing of triacetone triperoxide (TATP) explosive through fluorescence quenching.
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    40. 40
      Liu, K.; Wang, Z.; Shang, C.; Li, X.; Peng, H.; Miao, R.; Ding, L.; Liu, J.; Liu, T.; Fang, Y. Unambiguous Discrimination and Detection of Controlled Chemical Vapors by a Film-Based Fluorescent Sensor Array. Adv. Mater. Technol. 2019, 4, 1800644  DOI: 10.1002/admt.201800644
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      Unambiguous Discrimination and Detection of Controlled Chemical Vapors by a Film-Based Fluorescent Sensor Array
      Liu, Ke; Wang, Zhaolong; Shang, Congdi; Li, Xiao; Peng, Haonan; Miao, Rong; Ding, Liping; Liu, Jing; Liu, Taihong; Fang, Yu
      Advanced Materials Technologies (Weinheim, Germany) (2019), 4 (7), 1800644CODEN: AMTDCM; ISSN:2365-709X. (Wiley-VCH Verlag GmbH & Co. KGaA)
      In situ, online, fast, and sensitive detection and discrimination of explosives, illicit drugs, and volatile org. compds. via vapor sampling is a challenge for many years. The highly efficient and noncontact detection of 15 types of chems. mentioned above using a film-based fluorescent sensor array is reported herein. Importantly, the presence of water, toiletries, fruit, dirty clothes, and other interferences has little effect upon detection. Discrimination of the controlled chems. is realized using a pattern recognition strategy. Meanwhile, a conceptual detector based on a sensor array is constructed and successfully used for simulated field tests. It is strongly believed that the present work not only provides a powerful fluorescent technique for efficient detection and discrimination of controlled chems. with remarkably different properties but also demonstrates that arraying a single sensor is a promising strategy to mitigate the limitations of conventional film-based fluorescent sensors.
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    41. 41
      OSAC. Analysis of Explosives Reference List, 2020. https://www.nist.gov/topics/organization-scientific-area-committees-forensic-science/fire-debris-explosives-subcommittee (accessed May 20, 2022).
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      EU-SENSE. Characteristics of Improvised Explosive Devices Containing Chemical Substances in the Context of the International Airports Protection, 2021. https://eu-sense.eu/characteristics-of-improvised-explosive-devices-containing-chemical-substances-in-the-context-of-the-international-airports-protection/ (accessed May 20, 2022).
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      There is no corresponding record for this reference.
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      González-Calabuig, A.; Cetó, X.; del Valle, M. Electronic Tongue for Nitro and Peroxide Explosive Sensing. Talanta 2016, 153, 340– 346,  DOI: 10.1016/j.talanta.2016.03.009
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      Electronic tongue for nitro and peroxide explosive sensing
      Gonzalez-Calabuig, Andreu; Ceto, Xavier; del Valle, Manel
      Talanta (2016), 153 (), 340-346CODEN: TLNTA2; ISSN:0039-9140. (Elsevier B.V.)
      This work reports the application of a voltammetric electronic tongue (ET) towards the simultaneous detn. of both nitro-contg. and peroxide-based explosive compds., two families that represent the vast majority of compds. employed either in com. mixts. or in improvised explosive devices. The multielectrode array was formed by graphite, gold and platinum electrodes, which exhibited marked mix-responses towards the compds. examd.; namely, 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), pentaerythritol tetranitrate (PETN), 2,4,6-trinitrotoluene (TNT), N-methyl-N,2,4,6-tetranitroaniline (Tetryl) and triacetone triperoxide (TATP). Departure information was the set of voltammograms, which were first analyzed by principal component anal. (PCA) allowing the discrimination of the different individual compds., while artificial neural networks (ANNs) were used for the resoln. and individual quantification of some of their mixts. (total normalized root mean square error for the external test set of 0.108 and correlation of the obtained vs. expected concns. comparison graphs r>0.929).
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      Krivitsky, V.; Filanovsky, B.; Naddaka, V.; Patolsky, F. Direct and Selective Electrochemical Vapor Trace Detection of Organic Peroxide Explosives via Surface Decoration. Anal. Chem. 2019, 91, 5323– 5330,  DOI: 10.1021/acs.analchem.9b00257
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      Direct and Selective Electrochemical Vapor Trace Detection of Organic Peroxide Explosives via Surface Decoration
      Krivitsky, Vadim; Filanovsky, Boris; Naddaka, Vladimir; Patolsky, Fernando
      Analytical Chemistry (Washington, DC, United States) (2019), 91 (8), 5323-5330CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      The ability to detect traces of highly energetic explosive materials sensitively, selectively, accurately, and rapidly could be of enormous benefit to civilian national security, military applications, and environmental monitoring. Unfortunately, the detection of explosives still poses a largely unmet arduous anal. problem, making their detection an issue of burning immediacy and a massive current challenge in terms of research and development. Although numerous explosive detection approaches have been developed, these methods are usually time-consuming, require bulky equipment, tedious sample prepn., a trained operator, cannot be miniaturized, and lack the ability to perform automated real-time high-throughput anal., strongly handicapping their mass deployment. Here, we present the first demonstration of the "direct" electrochem. approach for the sensitive, selective, and rapid vapor trace detection of TATP and HMTD, under ambient conditions, unaffected by the presence of oxygen and hydrogen peroxide species, down to concns. lower than 10 ppb. The method is based on the use of Ag-nanoparticles-decorated carbon microfibers air-collecting electrodes (μCF), which allow for the selective direct detection of the org. peroxide explosives, through opening multiple redox routes, not existent in the undecorated carbon electrodes. Finally, we demonstrate the direct and rapid detection of TATP and HMTD explosive species from real-world air samples.
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    45. 45
      Calvo-Gredilla, P.; García-Calvo, J.; Cuevas, J. V.; Torroba, T.; Pablos, J.-L.; García, F. C.; García, J.-M.; Zink-Lorre, N.; Font-Sanchis, E.; Sastre-Santos, A.; Fernández-Lázaro, F. Solvent-Free Off–On Detection of the Improvised Explosive Triacetone Triperoxide (TATP) with Fluorogenic Materials. Chem. – Eur. J. 2017, 23, 13973– 13979,  DOI: 10.1002/chem.201702412
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      Solvent-Free Off-On Detection of the Improvised Explosive Triacetone Triperoxide (TATP) with Fluorogenic Materials
      Calvo-Gredilla, Patricia; Garcia-Calvo, Jose; Cuevas, Jose V.; Torroba, Tomas; Pablos, Jesus-Luis; Garcia, Felix C.; Garcia, Jose-Miguel; Zink-Lorre, Nathalie; Font-Sanchis, Enrique; Sastre-Santos, Angela; Fernandez-Lazaro, Fernando
      Chemistry - A European Journal (2017), 23 (56), 13973-13979CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
      A fluorogenic perylenediimide-functionalized polyacrylate capable of generating color and fluorescence changes in the presence of triacetone triperoxide (TATP), an improvised explosive used in terrorist attacks, under solvent-free, solid-state conditions has been developed. The material works by accumulating volatile TATP until it reaches a threshold; therefore, triggering colorimetric and fluorescent responses.
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    46. 46
      García-Calvo, J.; Calvo-Gredilla, P.; Ibáñez-Llorente, M.; Romero, D. C.; Cuevas, J. V.; García-Herbosa, G.; Avella, M.; Torroba, T. Surface Functionalized Silica Nanoparticles for the Off–On Fluorogenic Detection of an Improvised Explosive, TATP, in a Vapour Flow. J. Mater. Chem. A 2018, 6, 4416– 4423,  DOI: 10.1039/C7TA10792G
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      46
      Surface functionalized silica nanoparticles for the off-on fluorogenic detection of an improvised explosive, TATP, in a vapor flow
      Garcia-Calvo, Jose; Calvo-Gredilla, Patricia; Ibanez-Llorente, Marcos; Romero, Daisy C.; Cuevas, Jose V.; Garcia-Herbosa, Gabriel; Avella, Manuel; Torroba, Tomas
      Journal of Materials Chemistry A: Materials for Energy and Sustainability (2018), 6 (10), 4416-4423CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)
      The development is reported of new fluorogenic silica nanomaterials that were able to generate fluorescence in the presence of vapors of triacetone triperoxide, TATP, an improvised explosive used in terrorist attacks. The materials worked in a vapor flow of TATP, giving a permanent and strongly fluorescent response.
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    47. 47
      Blanco, S.; Macario, A.; García-Calvo, J.; Revilla-Cuesta, A.; Torroba, T.; López, J. C. Microwave Detection of Wet Triacetone Triperoxide (TATP): Non-Covalent Forces and Water Dynamics. Chem. – Eur. J. 2021, 27, 1680– 1687,  DOI: 10.1002/chem.202003499
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      Microwave Detection of Wet Triacetone Triperoxide (TATP): Non-Covalent Forces and Water Dynamics
      Blanco, Susana; Macario, Alberto; Garcia-Calvo, Jose; Revilla-Cuesta, Andrea; Torroba, Tomas; Lopez, Juan Carlos
      Chemistry - A European Journal (2021), 27 (5), 1680-1687CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
      The water adducts of triacetone triperoxide (TATP) have been obsd. by using broadband rotational spectroscopy. This work opens a new way for the gas-phase detection of this improvised explosive. The obsd. clusters exhibit unusual water dynamics and rarely obsd. multicenter interactions. TATP-H2O is formed from the D3 symmetry conformer of TATP with water lying close to the C3 axis. Water rotation around this axis with a very low barrier gives rise to the rotational spectrum of a sym. top. The main interaction of the monohydrate is a four-center trifurcated donor Ow-H···O hydrogen bond, not obsd. previously in the gas phase, reinforced by a weak four-center trifurcated acceptor C-H···Ow interaction. Surprisingly, all structural signatures show the weakness of these interactions. The complex TATP-(H2O)2 is formed from the monohydrated TATP by the self-assocn. of water.
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    48. 48
      Lapcinska, S.; Revilla-Cuesta, A.; Abajo-Cuadrado, I.; Cuevas, J. V.; Avella, M.; Arsenyan, P.; Torroba, T. Dye-Modified Silica-Anatase Nanoparticles for the Ultrasensitive Fluorogenic Detection of the Improvised Explosive TATP in an Air Microfluidic Device. Mater. Chem. Front. 2021, 5, 8097– 8107,  DOI: 10.1039/D1QM01041G
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      48
      Dye-modified silica-anatase nanoparticles for the ultrasensitive fluorogenic detection of the improvised explosive TATP in an air microfluidic device
      Lapcinska, Sindija; Revilla-Cuesta, Andrea; Abajo-Cuadrado, Irene; Cuevas, Jose V.; Avella, Manuel; Arsenyan, Pavel; Torroba, Tomas
      Materials Chemistry Frontiers (2021), 5 (23), 8097-8107CODEN: MCFAC5; ISSN:2052-1537. (Royal Society of Chemistry)
      We describe the proof of concept of a portable testing setup for the detection of triacetone triperoxide (TATP), a common component in improvised explosive devices. The system will allow field-testing and generation of real-time results to test for TATP vapor traces in a no. of different environments. It will work by recirculating the gas samples in connection to the sensing mechanism in a suitable microfluidic portable device. In this way, the system will allow controlled trapping of the analyte in the chem. sensor to afford reliable results at very low concns. in air.
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    49. 49
      Torroba, T.; Schechter, I.; Calvo, J. G.; Revilla-Cuesta, A. Explosives Detection, Sensors, Electronic Systems and Data Processing; Capineri, L.; Turmus, E. K., Eds.; Springer: The Netherlands, 2019; pp 208– 247.
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    50. 50
      Gopikrishna, P.; Meher, N.; Iyer, P. K. Functional 1,8-Naphthalimide AIE/AIEEgens: Recent Advances and Prospects. ACS Appl. Mater. Interfaces 2018, 10, 12081– 12111,  DOI: 10.1021/acsami.7b14473
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      50
      Functional 1,8-Naphthalimide AIE/AIEEgens: Recent Advances and Prospects
      Gopikrishna, Peddaboodi; Meher, Niranjan; Iyer, Parameswar Krishnan
      ACS Applied Materials & Interfaces (2018), 10 (15), 12081-12111CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      A review. A survey is given of the up-to-date development of aggregation-induced emission/aggregation-induced emission enhancement (AIE/AIEE) active naphthalimide (NI)-based smart materials with potential for wide and real-world applications and that serves as a highly versatile building block with tunable absorption and emission in the complete visible region. The review article commences with a precise description of the importance of NI moiety and its several restricted area of applications owing to its aggregation caused quenching (ACQ) properties, followed by the discovery and importance of AIE/AIEE-active NIs. The introduction section tracked an overview of the state of the art in NI luminogens in multiple applications. It also includes a few mechanistic studies on the structure-property correlation of NIs and provides more insights into the condensed-state photophys. properties of small aggregation-prone systems. The review aims to ultimately accomplish current and forthcoming views comprising the use of the NIs for the detection of biol. active mols., such as amino acids and proteins, recognition of toxic analytes, fabrication of light emitting diodes, and their potential in therapeutics and diagnostics.
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    51. 51
      de Greñu, B. D.; Moreno, D.; Torroba, T.; Berg, A.; Gunnars, J.; Nilsson, T.; Nyman, R.; Persson, M.; Pettersson, J.; Eklind, I.; Wästerby, P. Fluorescent Discrimination between Traces of Chemical Warfare Agents and Their Mimics. J. Am. Chem. Soc. 2014, 136, 4125– 4128,  DOI: 10.1021/ja500710m
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      There is no corresponding record for this reference.
    52. 52
      de Greñu, B. D.; García-Calvo, J.; Cuevas, J.; García-Herbosa, G.; García, B.; Busto, N.; Ibeas, S.; Torroba, T.; Torroba, B.; Herrera, A.; Pons, S. Chemical Speciation of MeHg+ and Hg2+ in Aqueous Solution and HEK Cells Nuclei by means of DNA Interacting Fluorogenic Probes. Chem. Sci. 2015, 6, 3757– 3764,  DOI: 10.1039/C5SC00718F
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      There is no corresponding record for this reference.
    53. 53
      García-Calvo, J.; Vallejos, S.; García, F. C.; Rojo, J.; García, J. M.; Torroba, T. A Smart Material for the in Situ Detection of Mercury in Fish. Chem. Commun. 2016, 52, 11915– 11918,  DOI: 10.1039/C6CC05977E
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      53
      A smart material for the in situ detection of mercury in fish
      Garcia-Calvo, Jose; Vallejos, Saul; Garcia, Felix C.; Rojo, Josefa; Garcia, Jose M.; Torroba, Tomas
      Chemical Communications (Cambridge, United Kingdom) (2016), 52 (80), 11915-11918CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
      We have developed a new fluorogenic polymer capable of detecting the presence of mercury contamination in fish samples. The modified polymer emits blue light when irradiated with UV light proportional to the quantity of mercury, as MeHg+ or Hg2+, present in fish. The quant. relation between the concn. of mercury in fish and the increase of fluorescence in the polymer in contact with fish samples was confirmed, giving rise to quick and reliable results in the measurements of the presence of mercury in fish using a portable fluorogenic polymeric probe.
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    54. 54
      García-Calvo, J.; Calvo-Gredilla, P.; Ibáñez-Llorente, M.; Rodríguez, T.; Torroba, T. Detection of Contaminants of High Environmental Impact by Means of Fluorogenic Probes. Chem. Rec. 2016, 16, 810– 824,  DOI: 10.1002/tcr.201500253
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      54
      Detection of Contaminants of High Environmental Impact by Means of Fluorogenic Probes
      Garcia-Calvo, Jose; Calvo-Gredilla, Patricia; Ibanez-Llorente, Marcos; Rodriguez, Teresa; Torroba, Tomas
      Chemical Record (2016), 16 (2), 810-824CODEN: CRHEAK; ISSN:1528-0691. (Wiley-VCH Verlag GmbH & Co. KGaA)
      This personal account describes our contribution to the design of selective fluorogenic probes for contaminants of high environmental impact. For this purpose, we have developed a new family of highly versatile fluorogenic reagents that were able to show large differences in their fluorescence in the presence of selected analytes. They were used in the prepn. of fluorogenic probes for the detection of contaminants of high environmental impact which currently have no good solns.: phosphorylating agents, such as chem. weapons; Me mercury(II); the cyanide anion; amino-acid metabolites, such as doping substances; and biogenic amine mimics, such as drugs of abuse and recreational drugs. The development of new materials for specific sensing was achieved by anchoring selected probes to silica nanomaterials, suitable for the selective detection of org. analytes in water for immediate application to toxicol. or environmental purposes.
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    55. 55
      García-Calvo, J.; Robson, J. A.; Torroba, T.; Wilton-Ely, J. D. E. T. Synthesis and Application of Ruthenium(II) Alkenyl Complexes with Perylene Fluorophores for the Detection of Toxic Vapours and Gases. Chem. – Eur. J. 2019, 25, 14214– 14222,  DOI: 10.1002/chem.201903303
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      55
      Synthesis and Application of Ruthenium(II) Alkenyl Complexes with Perylene Fluorophores for the Detection of Toxic Vapours and Gases
      Garcia-Calvo, Jose; Robson, Jonathan A.; Torroba, Tomas; Wilton-Ely, James D. E. T.
      Chemistry - A European Journal (2019), 25 (62), 14214-14222CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
      A series of new ruthenium(II) vinyl complexes has been prepd. incorporating perylenemonoimide (PMI) units. This fluorogenic moiety was functionalized with terminal alkyne or pyridyl groups, allowing attachment to the metal either as a vinyl ligand or through the pyridyl nitrogen. The inherent low soly. of the perylene compds. was improved through the design of poly-PEGylated (PEG = polyethylene glycol) units bearing a terminal alkyne or a pyridyl group. By absorbing the compds. on silica, vapors and gases could be detected in the solid state. The reaction of the complexes [Ru(CH:CH-PerIm)Cl(CO)(py-3PEG)(PPh3)2] and [Ru(CH:CH-3PEG)Cl(CO)(py-PerIm)(PPh3)2] with carbon monoxide, isonitrile or cyanide was found to result in modulation of the fluorescence behavior. The complexes were obsd. to display solvatochromic effects and the interaction of the complexes with a wide range of other species was also studied. The study suggests that such complexes have potential for the detection of gases or vapors that are toxic to humans.
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    56. 56
      García-Calvo, V.; Cuevas, J. V.; Barbero, H.; Ferrero, S.; Álvarez, C. M.; González, J. A.; Díaz de Greñu, B.; García-Calvo, J.; Torroba, T. Synthesis of a Tetracorannulene-perylenediimide That Acts as a Selective Receptor for C60 over C70. Org. Lett. 2019, 21, 5803– 5807,  DOI: 10.1021/acs.orglett.9b01729
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      56
      Synthesis of a Tetracorannulene-perylenediimide That Acts as a Selective Receptor for C60 over C70
      Garcia-Calvo, Victor; Cuevas, Jose V.; Barbero, Hector; Ferrero, Sergio; Alvarez, Celedonio M.; Gonzalez, Jesus A.; Diaz de Grenu, Borja; Garcia-Calvo, Jose; Torroba, Tomas
      Organic Letters (2019), 21 (15), 5803-5807CODEN: ORLEF7; ISSN:1523-7052. (American Chemical Society)
      The authors report the use of a tetraborylated perylenediimide as starting material for the prepn. of a tetracorannulene-perylenediimide that is able to bind up to two fullerene-C60 mols. by host-guest mol. recognition with preference over C70. Titrn. with fullerene-C60 is followed by a dramatic shift of the arom. signals in 1H NMR and an initial increase in the fluorescence of the system. By this simple mechanism, fluorogenic sensing of fullerene-C60 is easily accomplished by an unprecedented fluorescent turn-on mechanism.
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    57. 57
      Busto, N.; Calvo, P.; Santolaya, J.; Leal, J. M.; Guédin, A.; Barone, G.; Torroba, T.; Mergny, J.-L.; García, B. Fishing for G-Quadruplexes in Solution with a Perylene Diimide Derivative Labeled with Biotins. Chem. – Eur. J. 2018, 24, 11292– 11296,  DOI: 10.1002/chem.201802365
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      57
      Fishing for G-Quadruplexes in Solution with a Perylene Diimide Derivative Labeled with Biotins
      Busto, Natalia; Calvo, Patricia; Santolaya, Javier; Leal, Jose M.; Guedin, Aurore; Barone, Giampaolo; Torroba, Tomas; Mergny, Jean-Louis; Garcia, Begona
      Chemistry - A European Journal (2018), 24 (44), 11292-11296CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
      A new fluorescent, noncytotoxic perylene diimide deriv. with two biotins at the peri position, PDI2B, has been synthesized. This mol. is able to interact selectively with G-quadruplexes with scarce or no affinity towards single- or double-stranded DNA. These features have made it possible to design a simple, effective, safe, cheap, and selective method for fishing G-quadruplex structures in soln. by use of PDI2B and streptavidin coated magnetic beads. The new cyclic method reported leads to the recovery of more than 80% of G-quadruplex structures from soln., even in the presence of an excess of single-stranded or duplex DNA as competitors. Moreover, PDI2B is a G4 ligand that can display higher thermal stabilization and greater affinity for 2- over 3-tetrad quadruplexes, which constitutes a novel type of behavior.
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    58. 58
      García-Calvo, J.; Torroba, T.; Brañas-Fresnillo, V.; Perdomo, G.; Cózar-Castellano, I.; Li, Y.-H.; Legrand, Y.-M.; Barboiu, M. Manipulation of Transmembrane Transport by Synthetic K+ Ionophore Depsipeptides and Its Implications in Glucose-Stimulated Insulin Secretion in β-Cells. Chem. – Eur. J. 2019, 25, 9287– 9294,  DOI: 10.1002/chem.201901372
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      58
      Manipulation of transmembrane transport by synthetic K+ ionophore depsipeptides and its implications in glucose-stimulated insulin secretion in β-cells
      Garcia-Calvo, Jose; Torroba, Tomas; Branas-Fresnillo, Virginia; Perdomo, German; Cozar-Castellano, Irene; Li, Yu-Hao; Legrand, Yves-Marie; Barboiu, Mihail
      Chemistry - A European Journal (2019), 25 (39), 9287-9294CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
      The cyclic depsipeptide cereulide toxin it is a very well-known potassium electrogenic ionophore particularly sensitive to pancreatic beta cells. The mechanistic details of its specific activity are unknown. Here, we describe a series of synthetic substituted cereulide potassium ionophores that cause impressive selective activation of glucose-induced insulin secretion in a constitutive manner in rat insulinoma INS1E cells. Our study demonstrates that the different electroneutral K+ transport mechanism exhibited by the anionic mutant depsipeptides when compared with classical electrogenic cereulides can have an important impact of pharmacol. value on glucose-stimulated insulin secretion.
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    59. 59
      Busto, N.; García-Calvo, J.; Cuevas, J. V.; Herrera, A.; Mergny, J.-L.; Pons, S.; Torroba, T.; García, B. Influence of Core Extension and Side Chain Nature in Targeting G-Quadruplex Structures with Perylene Monoimide Derivatives. Bioorg. Chem. 2021, 108, 104660  DOI: 10.1016/j.bioorg.2021.104660
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      59
      Influence of core extension and side chain nature in targeting G-quadruplex structures with perylene monoimide derivatives
      Busto, Natalia; Garcia-Calvo, Jose; Cuevas, Jose Vicente; Herrera, Antonio; Mergny, Jean-Louis; Pons, Sebastian; Torroba, Tomas; Garcia, Begona
      Bioorganic Chemistry (2021), 108 (), 104660CODEN: BOCMBM; ISSN:0045-2068. (Elsevier B.V.)
      A structure-activity relationship (SAR) study in terms of G-quadruplex binding ability and antiproliferative activity of six fluorescent perylenemonoimide (PMIs) derivs. is reported. A pos. charge seems to be the key to target G4. This study also reveals the importance of the element substitution in the potential biol. activity of PMIs, being the polyethylene glycol (PEG) chains in the peri position responsible for their antiproliferative activity. Among them, the cationic PMI6 with two PEG chains is the most promising compd. since its fluorescence is enhanced in the presence of G-quadruplex structures. Moreover, PMI6 binds to the human telomeric G-quadruplex hTelo with high affinity and displays a high antiproliferative potential towards HeLa (cervical adenocarcinoma), A549 (lung adenocarcinoma) and A2780 (ovarian adenocarcinoma) cells. Its fate can be followed inside cells thanks to its fluorescent properties: the compd. is found to accumulate in the mitochondria.
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    60. 60
      Tajima, K.; Fukui, N.; Shinokubo, H. Aggregation-Induced Emission of Nitrogen-Bridged Naphthalene Monoimide Dimers. Org. Lett. 2019, 21, 9516– 9520,  DOI: 10.1021/acs.orglett.9b03699
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      60
      Aggregation-Induced Emission of Nitrogen-Bridged Naphthalene Monoimide Dimers
      Tajima, Keita; Fukui, Norihito; Shinokubo, Hiroshi
      Organic Letters (2019), 21 (23), 9516-9520CODEN: ORLEF7; ISSN:1523-7052. (American Chemical Society)
      We have prepd. four 4-aminonaphthalene monoimide derivs. and examd. the aggregation-induced emission (AIE) properties. A nitrogen-bridged dimer is AIE-active and exhibits bright green emission with a high quantum yield in the solid state. The X-ray diffraction anal. suggests that key to the bright luminescence is the favorable crystal packing dominated by CH/π interaction. The late-stage cyanation of the dimer tuned its AIE color from green to orange.
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    61. 61
      Wang, Y.; Teng, Y.; Yang, H.; Li, X.; Yin, D.; Tian, Y. Bioorthogonally Applicable Multicolor Fluorogenic Naphthalimide–Tetrazine Probes with Aggregation-Induced Emission Characters. Chem. Commun. 2022, 58, 949– 952,  DOI: 10.1039/D1CC05204G
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      61
      Bioorthogonally applicable multicolor fluorogenic naphthalimide-tetrazine probes with aggregation-induced emission characters
      Wang, Yongcheng; Teng, Yu; Yang, Hong; Li, Xiang; Yin, Dali; Tian, Yulin
      Chemical Communications (Cambridge, United Kingdom) (2022), 58 (7), 949-952CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
      A series of naphthalimide-tetrazines were developed as bioorthogonal fluorogenic probes, which could produce significant fluorescence enhancement, notable aggregation-induced emission (AIE) characters and multicolor emissions after bioorthogonal reaction with strained dienophiles. Manipulating the π-bridge in the fluorophore skeleton allows fine-tuning of the emission wavelength and influences the AIE-active properties. With these probes, we succeeded in no-wash fluorogenic protein labeling and mitochondria-selective bioorthogonal imaging in live cells.
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    62. 62
      García-Calvo, J.; Calvo-Gredilla, P.; Vallejos, S.; García, J. M.; Cuevas-Vicario, J. V.; García-Herbosa, G.; Avella, M.; Torroba, T. Palladium Nanodendrites Uniformly Deposited on the Surface of Polymers as an Efficient and Recyclable Catalyst for Direct Drug Modification Via Z-Selective Semihydrogenation of Alkynes. Green Chem. 2018, 20, 3875– 3883,  DOI: 10.1039/C8GC01522H
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      62
      Palladium nanodendrites uniformly deposited on the surface of polymers as an efficient and recyclable catalyst for direct drug modification via Z-selective semihydrogenation of alkynes
      Garcia-Calvo, Jose; Calvo-Gredilla, Patricia; Vallejos, Saul; Garcia, Jose Miguel; Cuevas-Vicario, Jose Vicente; Garcia-Herbosa, Gabriel; Avella, Manuel; Torroba, Tomas
      Green Chemistry (2018), 20 (16), 3875-3883CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)
      The prepn. of new monodisperse polycryst. palladium nanoparticles uniformly distributed on the surface of polymers, by simply adding a palladium(II) soln. in water to the polymers, is described. The polymer supported palladium nanoparticles material was used as an efficient portable and reusable catalyst for the stereoselective semihydrogenation reaction of internal alkynes to (Z)-alkenes in green solvents.
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    63. 63
      García-Calvo, J.; García-Calvo, V.; Vallejos, S.; García, F. C.; Avella, M.; García, J.-M.; Torroba, T. Surface Coating by Gold Nanoparticles on Functional Polymers: On-Demand Portable Catalysts for Suzuki Reactions. ACS Appl. Mater. Interfaces 2016, 8, 24999– 25004,  DOI: 10.1021/acsami.6b07746
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      63
      Surface Coating by Gold Nanoparticles on Functional Polymers: On-Demand Portable Catalysts for Suzuki Reactions
      Garcia-Calvo, Jose; Garcia-Calvo, Victor; Vallejos, Saul; Garcia, Felix C.; Avella, Manuel; Garcia, Jose-Miguel; Torroba, Tomas
      ACS Applied Materials & Interfaces (2016), 8 (38), 24999-25004CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      We have developed new functionalized polymers capable of being easily coated by gold nanoparticles, uniformly distributed on the surface of the polymers, by simply adding a gold(III) soln. in water to the polymers. The polymer-supported gold nanoparticle material was used as an efficient portable and reusable catalyst for Suzuki reactions in mixed org.-aq. solvents.
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    64. 64
      Sanluis-Verdes, A.; Colomer-Vidal, P.; Rodriguez-Ventura, F.; Bello-Villarino, M.; Spinola-Amilibia, M.; Ruiz-Lopez, E.; Illanes-Vicioso, R.; Castroviejo, P.; Aiese Cigliano, R.; Montoya, M.; Falabella, P.; Pesquera, C.; Gonzalez-Legarreta, L.; Arias-Palomo, E.; Solà, M.; Torroba, T.; Arias, C. F.; Bertocchini, F. Wax Worm Saliva and the Enzymes therein Are the Key to Polyethylene Degradation by Galleria mellonella. Nat. Commun. 2022, 13, 5568  DOI: 10.1038/s41467-022-33127-w
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      Wax worm saliva and the enzymes therein are the key to polyethylene degradation by Galleria mellonella
      Sanluis-Verdes, A.; Colomer-Vidal, P.; Rodriguez-Ventura, F.; Bello-Villarino, M.; Spinola-Amilibia, M.; Ruiz-Lopez, E.; Illanes-Vicioso, R.; Castroviejo, P.; Aiese Cigliano, R.; Montoya, M.; Falabella, P.; Pesquera, C.; Gonzalez-Legarreta, L.; Arias-Palomo, E.; Sola, M.; Torroba, T.; Arias, C. F.; Bertocchini, F.
      Nature Communications (2022), 13 (1), 5568CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)
      Plastic degrdn. by biol. systems with re-utilization of the byproducts could be a future soln. to the global threat of plastic waste accumulation. Here, we report that the saliva of Galleria mellonella larvae (wax worms) is capable of oxidizing and depolymg. polyethylene (PE), one of the most produced and sturdy polyolefin-derived plastics. This effect is achieved after a few hours' exposure at room temp. under physiol. conditions (neutral pH). The wax worm saliva can overcome the bottleneck step in PE biodegrdn., namely the initial oxidn. step. Within the saliva, we identify two enzymes, belonging to the phenol oxidase family, that can reproduce the same effect. To the best of our knowledge, these enzymes are the first animal enzymes with this capability, opening the way to potential solns. for plastic waste management through bio-recycling/up-cycling.
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    65. 65
      Allegrini, F.; Olivieri, A. C. IUPAC-Consistent Approach to the Limit of Detection in Partial Least-Squares Calibration. Anal. Chem. 2014, 86, 7858– 7866,  DOI: 10.1021/ac501786u
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      65
      IUPAC-Consistent Approach to the Limit of Detection in Partial Least-Squares Calibration
      Allegrini, Franco; Olivieri, Alejandro C.
      Analytical Chemistry (Washington, DC, United States) (2014), 86 (15), 7858-7866CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      There is currently no well-defined procedure for providing the limit of detection (LOD) in multivariate calibration. Defining an estimator for the LOD in this scenario showed to be more complex than intuitively extending the traditional univariate definition. For these reasons, although many attempts were made to arrive at a reasonable convention, addnl. effort is required to achieve full agreement between the univariate and multivariate LOD definitions. A novel approach is presented to est. the LOD in partial least-squares (PLS) calibration. Instead of a single LOD value, an interval of LODs is provided, which depends on the variation of the background compn. in the calibration space. This is in contrast with previously proposed univariate extensions of the LOD concept. With the present definition, the LOD interval becomes a parameter characterizing the overall PLS calibration model, and not each test sample in particular, as was proposed in the past. The new approach takes into account IUPAC official recommendations, and also the latest developments in error-in-variables theory for PLS calibration. Both simulated and real anal. systems were studied for illustrating the properties of the new LOD concept.
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