ACS Editors’ Choice
Description:
Functionalization of Alkenes with Difluoromethyl Nitrile Oxide to Access the Difluoromethylated Derivatives
- Bohdan A. Chalyk
- ,
- Oleksandr Zginnyk
- ,
- Andrii V. Khutorianskyi
- , and
- Pavel K. Mykhailiuk*
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Electron-rich, electron-deficient, and non-activated alkenes can be rapidly functionalized by in situ-generated difluoromethyl nitrile oxide. The (3+2) cycloaddition proceeds at room temperature, has broad functional group tolerance, and can be used for the late-stage modification of bioactive molecules (finasteride and carbamazepine). The obtained CF2H-isoxazolines can be easily transformed into CF2H-containing building blocks for medicinal chemistry: amines, amino acids, amino alcohols, and spirocyclic scaffolds.
Wireless Hollow Miniaturized Objects for Electroassisted Chiral Resolution
- Sara Grecchi
- ,
- Filippo Malacarne
- ,
- Roberto Cirilli
- ,
- Massimo Dell’Edera
- ,
- Sara Ghirardi
- ,
- Tiziana Benincori
- , and
- Serena Arnaboldi*
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Chiral resolution plays a crucial role in the field of drug development, especially for a better understanding of biochemical processes. In such a context, classic separation methods have been used for decades due to their versatility and easy scale-up. Among the many attempts proposed for enantioselective separation, electroassisted methods are presented as an interesting alternative. Herein, we present the use of wirelessly activated hollow tubular systems for the effective, simple, and tunable separation of racemic and enantioenriched mixtures. These double-layered tubular objects consist of an external polypyrrole chassis, a polymer with good electromechanical properties, functionalized in its inner part with an inherently chiral oligomer. The synergy between the electromechanical pumping process of the outer layer and the enantioselective affinity of the inner part induces the system to behave as a miniaturized chiral column. These hybrid objects are able to separate racemic and enantioenriched solutions of chiral model analytes into the corresponding enantiomers in high enantiomeric purity. Finally, these electromechanical systems can resolve mixtures formed by chiral probes with completely uncorrelated molecular structures injected simultaneously into the single antipodes.
Evanescent Gels: Competition between Sticker Dynamics and Single-Chain Relaxation
- Dominic Robe
- ,
- Aritra Santra
- ,
- Gareth H. McKinley
- , and
- J. Ravi Prakash*
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Solutions of polymer chains are modeled using nonequilibrium Brownian dynamics simulations, with physically associative beads which form reversible cross-links to establish a system-spanning physical gel network. Rheological properties such as the zero-shear-rate viscosity and relaxation modulus are investigated systematically as functions of polymer concentration and the binding energy between associative sites. It is shown that a system-spanning network can form regardless of the binding energy at a sufficiently high concentration. However, the contribution to the stress sustained by this physical network can decay faster than other relaxation processes, even single-chain relaxations. If the polymer relaxation time scales overlap with short-lived associations, the mechanical response of a gel becomes “evanescent,” decaying before it can be rheologically observed, even though the network is instantaneously mechanically rigid. In our simulations, the concentration of elastically active chains and the dynamic moduli are computed independently. This makes it possible to combine structural and rheological information to identify the concentration at which the sol–gel transition occurs as a function of the binding energy. Furthermore, it is shown that the competition of scales between the sticker dissociation time and the single-polymer relaxation time determines whether the gel is in the evanescent regime.
Gas-Selective Catalytic Regulation by a Newly Identified Globin-Coupled Sensor Phosphodiesterase Containing an HD-GYP Domain from the Human Pathogen Vibrio fluvialis
- Kenichi Kitanishi*
- ,
- Nao Aoyama
- , and
- Motoyuki Shimonaka
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Globin-coupled sensors constitute an important family of heme-based gas sensors, an emerging class of heme proteins. In this study, we have identified and characterized a globin-coupled sensor phosphodiesterase containing an HD-GYP domain (GCS-HD-GYP) from the human pathogen Vibrio fluvialis, which is an emerging foodborne pathogen of increasing public health concern. The amino acid sequence encoded by the AL536_01530 gene from V. fluvialis indicated the presence of an N-terminal globin domain and a C-terminal HD-GYP domain, with HD-GYP domains shown previously to display phosphodiesterase activity toward bis(3′,5′)-cyclic dimeric guanosine monophosphate (c-di-GMP), a bacterial second messenger that regulates numerous important physiological functions in bacteria, including in bacterial pathogens. Optical absorption spectral properties of GCS-HD-GYP were found to be similar to those of myoglobin and hemoglobin and of other bacterial globin-coupled sensors. The binding of O2 to the Fe(II) heme iron complex of GCS-HD-GYP promoted the catalysis of the hydrolysis of c-di-GMP to its linearized product, 5′-phosphoguanylyl-(3′,5′)-guanosine (pGpG), whereas CO and NO binding did not enhance the catalysis, indicating a strict discrimination of these gaseous ligands. These results shed new light on the molecular mechanism of gas-selective catalytic regulation by globin-coupled sensors, with these advances apt to lead to a better understanding of the family of globin-coupled sensors, a still growing family of heme-based gas sensors. In addition, given the importance of c-di-GMP in infection and virulence, our results suggested that GCS-HD-GYP could play an important role in the ability of V. fluvialis to sense O2 and NO in the context of host–pathogen interactions.
Leveraging Aptamer-Based DNA Nanotechnology for Bioanalysis and Cancer Therapeutics
- Zhiyong Huang
- ,
- Dan Wang
- ,
- Qiang Zhang
- ,
- Yutong Zhang
- ,
- Ruizi Peng*
- , and
- Weihong Tan*
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Aptamers are single-stranded DNA or RNA molecules composed of 15–80 nucleotides, obtained from a random oligonucleotide library via the systematic evolution of ligands by exponential enrichment (SELEX) technology. They can bind to a wide range of targets with high binding affinity and high specificity including metal ions, small molecules, proteins, cells, and even tissues. When compared to the commonly used antibodies, aptamers show better thermal stability, a smaller molecular weight, easier modification, and little batch-to-batch variation by chemical synthesis. These unique merits position aptamers as promising molecular tools in biomedical applications, spanning biosensing, bioimaging, disease diagnosis, targeted chemotherapy, and cancer immunotherapy. However, as chemically synthesized oligonucleotides, aptamers would be degraded by nucleic acid degrading enzymes (e.g., endonucleases or exonucleases) presented in the blood circulation, thereby reducing the stability and activity. Another limitation is the rapid clearance by the liver and kidneys, reducing their circulation life and bioavailability. Recent progress in DNA nanotechnology has garnered global interest, with emerging interdisciplinary applications across chemistry, materials, biology, and medicine. The fundamental of DNA self-assemblies and DNA dynamic operation is Watson–Crick base pairing assisted by in silico programmable design. As functional building blocks, aptamers can inherently enable great potential with DNA nanotechnology including bioanalysis, targeted drug delivery, and cancer immunotherapy. Therefore, aptamer-based DNA nanotechnology would arouse important interests in future research.
As molecular medicine offered personalized and precise diagnostic and therapeutic solutions, in this Account, we focus on the research advancements of leveraging DNA aptamer with DNA nanotechnology for molecular medicine, particularly our recent research progress. Often referred to as chemical antibodies, aptamers enable DNA nanotechnology for bioanalysis and cancer therapeutics. Thus, two parts are discussed in this Account: initially, we discuss the molecular modifications of aptamers by cyclization and nucleotide backbone engineering. The aptamer-tethered DNA nanostructures then were constructed for cell identification and bioanalysis. To perform intelligent cancer diagnosis, we detailed three formulations of aptamer-involved molecular computation. In the last part, we focus on aptamer-based targeted chemotherapy and immunotherapy. Based on the covalent coupling strategy, we report a series of aptamer drug conjugates. Similarly, by employing cyclization strategy, the circular bivalent aptamer drug conjugates are discussed. Next, as small molecule drug delivery systems encounter challenges related to insufficient biological stability, particularly in terms of vulnerability to enzyme cleavage and short circulation time in vivo, aptamer-tethered nanomedicines are introduced for targeted chemotherapy. The immunotherapy section includes tumor vaccines, adoptive cell immunotherapy, and immune checkpoint blockade. Finally, we propose the challenges and opportunities in bioapplications of aptamer-based DNA nanotechnology.
A National Snapshot of Introductory Chemistry Instructors and Their Instructional Practices
- Ying Wang
- ,
- Naneh Apkarian
- ,
- Melissa H. Dancy
- ,
- Charles Henderson
- ,
- Estrella Johnson
- ,
- Jeffrey R. Raker
- , and
- Marilyne Stains*
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The effectiveness of active learning on promoting students’ academic outcomes and persistence has been established in the literature. However, despite the effort of purposeful change agents, the uptake of active learning in science, technology, engineering, and mathematics (STEM) is slow. While previous research from the chemistry education community has provided insights into the implementation of specific active learning strategies across the United States, the extent to which chemistry instructors leverage these strategies in general remains unknown. This article presents the results of a national survey aimed at exploring introductory chemistry instructors’ knowledge and implementation of active learning, variations on this knowledge, and use across tenure statuses and institution types. This paper also aims to address the gap in the literature in our understanding of the characteristics of instructors of these courses. We thus provide a description of instructors’ demographics, training, teaching experience, and teaching responsibilities. Our findings reveal that instructors in these courses are prominently males of European descent. Additionally, instructors come into their teaching position with minimal pedagogical training and participate mainly in short training once in their position. While the majority of instructors have knowledge of specific active learning strategies, their consistent implementation remains limited, with lecturing still being the instructional practice of choice. Variations were found between institution types and across tenure statuses within institutions in terms of pedagogical training, use of specific active learning strategies, and proportion of class time spent lecturing. The findings provide a baseline for future studies that aim to assess the effectiveness of interventions fostering the implementation of active learning in introductory chemistry courses and highlight the critical need for improved communication about teaching practices across institutions and tenure statuses.
Anisotropic Growth of Covalent Inorganic Complexes to Nanoplatelets
- Xinke Kong
- ,
- Yajun Wu
- ,
- Huan Li
- ,
- Yuelin Yang
- ,
- Lin Ru
- ,
- Yang Zhou*
- , and
- Yuanyuan Wang*
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Colloidal II–VI semiconductor nanoplatelets (NPLs) provide a new platform in material science due to their unique growth mode and advanced optical properties. However, in contrast to the rapid development of zinc blend structured NPLs, studies on the formation of wurtzite (WZ) NPLs have been limited to the lamellar assembly of specific magic-sized nanoclusters (MSCs). Therefore, the study of new precursors is important for enriching the synthesis strategy, improving the study of two-dimensional (2D) nanocrystal growth mechanisms, and constructing complex nanostructures. Here, we demonstrated that covalent inorganic complexes (CICs), as novel functional intermediates, can be directly used to form NPLs without involving MSCs. Using in situ absorption spectra, we demonstrated that the evolution followed a pseudo-first-order kinetics (kobs = 0.02 min−1 (t1/2 = 34.7 min)). Several types of binary WZ NPLs, including CdSe, CdS, CdTe, and ZnS, have been directly prepared based on this mechanism through the anisotropic growth of CICs. In addition, CICs can also be used to prepare Mn-doped CdSe NPLs. The present study not only affords new precursors for the synthesis of WZ NPLs but also advances our understanding of the synthesis mechanism of nanocrystals.
Iridium-Catalyzed Asymmetric Hydrogenation of Heteroaromatics with Multiple N Atoms via Substrate Activation: An Entry to 4,5,6,7-Tetrahydropyrazolo[1,5-a]pyrimidine-3-carbonitrile Core of a Potent BTK Inhibitor
- Mu-Wang Chen
- ,
- Hong-Wang Li
- ,
- Ying-Qi Wang
- ,
- Bo Wu
- ,
- Zheng Liu
- ,
- Xinzhong Lai
- ,
- Joerg Deerberg*
- , and
- Yong-Gui Zhou*
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The chiral 4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidine is the key core skeleton of potent Bruton’s tyrosine kinase (BTK) inhibitor Zanubrutinib, and the catalyst-controlled asymmetric hydrogenation of planar multinuclear pyrimidine heteroarenes with multiple N atoms could provide an efficient route toward its synthesis. Owing to the strong aromaticity and poisoning effect toward chiral transition metal catalyst, asymmetric hydrogenation of pyrazolo[1,5-a]pyrimidines with multiple nitrogen atoms is still a challenge for synthesizing the chiral 4,5,6,7-tetrahydropyrazolo[1,5-a]-pyrimidine. Herein, an efficient iridium-catalyzed asymmetric hydrogenation of pyrazolo[1,5-a]pyrimidines has been developed using substrate activation strategy, with up to 99% ee. The decagram scale synthesis further demonstrated the potential and promise of this procedure in the synthesis of Zanubrutinib. In addition, a mechanistic study indicated that the hydrogenation starts with 1,2-hydrogenation.
Sustainable Aviation Fuels for Clean Skies: Exploring the Potential and Perspectives of Strained Hydrocarbons
- Feng Wang*
- and
- Dilip Rijal
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Fuel is the lifeblood of the aviation industry. The pressing need to reduce carbon emissions calls for the adoption of sustainable aviation fuels (SAFs) as a feasible alternative, particularly in the absence of widespread hydrogen usage. SAFs with high energy density (HED) hold great promise due to their favorable weight and volume characteristics. This comprehensive review article delves into the history of aviation fuel, essential requirements for aviation fuels, and the imperative for SAF development, focusing on the power-to-liquid (PtL) pathway to produce SAFs. It particularly concentrates on recent advancements in the screening and design of new strained hydrocarbons as high-performance SAFs. By utilizing machine learning (ML) techniques, potential strained hydrocarbon or cycloalkane structures have been identified and optimized, revealing superior potentials for energy content and other critical properties that enhance the efficiency and performance of SAFs. The review also provides a perspective with a forward-looking approach and a route map in the development of new SAFs, including the exploration of strain energy in cycloalkanes through quantum mechanical calculations, the establishment of structure–property relationships for rational design, and the need for a technoeconomic assessment (TEA) of their production. It further highlights the potential new directions in SAF development.
Evaluating Strategies to Enhance Li Transference in Salt-in-Ionic Liquid Electrolytes: Mixed Anions, Coordinating Cations, and High Salt Concentration
- Martin Lorenz
- and
- Monika Schönhoff*
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The increased safety of salt-in-ionic liquid electrolytes compared with established carbonate-based systems has promoted intense research in this field, but low conductivities, slow lithium transport, and unfavorable lithium anion correlations still prevent a mass market application. In particular, strong Li-anion correlations lead to dominant vehicular Li transport with the same drift direction for anions and lithium in the electric field. Here, three different strategies and their mutual interplay are evaluated, which could reduce Li-anion coordination, i.e., high salt concentration, a mixed-anion composition, as well as an ether functionalization of the organic cation. To this end, two series of highly concentrated IL-based electrolytes, based on either ethylmethylimidazolium (EMIM) or the ether-functionalized 1-methoxyethyl-1-methylpyrrolidinium (Pyr12O1) organic cation, and employing mixed bis(fluorosulfonyl)imide/bis(trifluoromethylsulfonyl)imide (FSI/TFSI) anions are investigated. Measurements of conductivities, diffusion coefficients, and electrophoretic mobilities reveal no beneficial effect due to the increased heterogeneity of the FSI/TFSI-based electrolyte matrix, generally showing improved transport properties with increasing FSI share. However, a combination of both the ether-functionalized cation and high FSI content is proven successful, as lithium mobilities are positive, and vehicular transport is overcome by structural Li transport. Our study demonstrates the decisive role of synergy of the different approaches: While the single effect of a high salt concentration, weakly lithium-coordinating anions, or organic cations with lithium-affine functional groups is too weak to prevent vehicular transport, their joint effect can overcome vehicular Li transport, leading to improved Li conduction in ionic liquids.
Passivating the Background of Living Microbes with a Zwitterionic Peptide for Therapies
- Liang Fang
- ,
- Simian Cai
- ,
- Patrick McMullen
- ,
- Yi-Chen Hsu
- ,
- Michelle Yi Qin Chen
- , and
- Shaoyi Jiang*
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Living microbial therapies have been proposed as a course of action for a variety of diseases. However, problematic interactions between the host immune system and the microbial organism present significant clinical concerns. Previously, we developed a genetically encoded superhydrophilic zwitterionic peptide, termed EKP, to mimic low-immunogenic zwitterionic materials, which have been used for the chemical modification of biologics such as protein and nucleic acid drugs to increase their in vivo circulation time and reduce their immunogenicity. Herein, we demonstrate the protective effects of the EKP polypeptide genetically cloaking the surface of Saccharomyces cerevisiae as a model microbe in both in vitro and in vivo systems. First, we show that EKP peptide cloaking suppresses the interactions between yeast cells and their specific antibodies, thereby illustrating its cloaking behavior. Then, we examine the in vitro interactions between EKP peptide surface cloaked yeast cells and murine macrophage cells, which exhibit phagocytotic behavior in the presence of foreign microbes. Our results indicate that EKP cloaking suppresses macrophage interactions and thus reduces phagocytosis. Furthermore, EKP cloaked yeast cells demonstrate a prolonged circulation time in mice in vivo.
Electrocatalytic CO2 Reduction with Atomically Precise Au13 Nanoclusters: Effect of Ligand Shell on Catalytic Performance
- Tetyana I. Levchenko
- ,
- Hong Yi
- ,
- Mark D. Aloisio
- ,
- Ngoc Kim Dang
- ,
- Guorui Gao
- ,
- Shriya Sharma
- ,
- Cao-Thang Dinh*
- , and
- Cathleen M. Crudden*
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Supported gold nanoclusters of the formula [Au13(L)5Cl2]3+ where L = N-heterocyclic carbene (NHC) or phosphine ligands are examined in the electrocatalytic CO2 reduction reaction (eCO2RR) in a membrane electrode assembly cell configuration. Gold nanoclusters bearing bisNHC ligands are shown to exhibit improved catalytic performance compared with diphosphine-stabilized nanoclusters after activation at the optimum treatment temperatures. The thermal properties of the nanoclusters are shown to have a significant impact on their catalytic activity. Thermogravimetric analysis, UV–vis absorption spectroscopy, and X-ray photoelectron spectroscopy revealed that thermal treatment of [Au13(diphosphine)5Cl2]3+ nanoclusters results in complete loss of diphosphine ligands while [Au13(bisNHC)5Cl2]3+ nanoclusters show stepwise and partial removal of bisNHC ligands. We propose that the partial removal of bisNHC ligands enables efficient activation of [Au13(bisNHC)5Cl2]3+ clusters while conserving the core structure. This leads to the implication that intact clusters retaining at least some ligands in their coordination environment are more active than ligand-free clusters.
Unveiling Hidden Shake-Up Features in the Uranyl M4-Edge Spectrum
- Jordan N. Ehrman
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- Kirill Shumilov
- ,
- Andrew J. Jenkins
- ,
- Joseph M. Kasper
- ,
- Tonya Vitova
- ,
- Enrique R. Batista
- ,
- Ping Yang*
- , and
- Xiaosong Li*
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The M4,5-edge high energy resolution X-ray absorption near-edge structure (HR-XANES) spectra of actinyls offer valuable insights into the electronic structure and bonding properties of heavy-element complexes. To conduct a comprehensive spectral analysis, it is essential to employ computational methods that accurately account for relativistic effects and electron correlation. In this work, we utilize variational relativistic multireference configurational interaction methods to compute and analyze the X-ray M4-edge absorption spectrum of uranyl. By employing these advanced computational techniques, we achieve excellent agreement between the calculated spectral features and experimental observations. Moreover, the calculations unveil significant shake-up features, which arise from the intricate interplay between strongly correlated 3d core-electron and ligand excitations. This research provides important theoretical insights into the spectral characteristics of heavy-element complexes. Furthermore, it establishes the foundation for utilizing M4,5-edge spectroscopy as a means to investigate the chemical activities of such complexes. By leveraging this technique, we can gain a deeper understanding of the bonding behavior and reactivity of heavy-element compounds.
Microfluidic Detection and Analysis of Microplastics Using Surface Nanodroplets
- Paniz Faramarzi
- ,
- Wonik Jang
- ,
- Donghyeon Oh
- ,
- Byeunggon Kim
- ,
- Ju Hyeon Kim
- , and
- Jae Bem You*
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Detection of microplastics from water is crucial for various reasons, such as food safety monitoring, monitoring of the fate and transport of microplastics, and development of preventive measures for their occurrence. Currently, microplastics are detected by isolating them using filtration, separation by centrifugation, or membrane filtration, subsequently followed by analysis using well-established analytical methods, such as Raman spectroscopy. However, due to their variability in shape, color, size, and density, isolation using the conventional methods mentioned above is cumbersome and time-consuming. In this work, we show a surface-nanodroplet-decorated microfluidic device for isolation and analysis of small microplastics (diameter of 10 μm) from water. Surface nanodroplets are able to capture nearby microplastics as water flows through the microfluidic device. Using a model microplastic solution, we show that microplastics of various sizes and types can be captured and visualized by using optical and fluorescence microscopy. More importantly, as the surface nanodroplets are pinned on the microfluidic channel, the captured microplastics can also be analyzed using a Raman spectroscope, which enables both physical (i.e., size and shape) and chemical (i.e., type) characterization of microplastics at a single-particle level. The technique shown here can be used as a simple, fast, and economical detection method for small microplastics.
Ultramicroporous Tröger’s Base Framework Membranes for pH-Neutral Aqueous Organic Redox Flow Batteries
- Junmin Liu
- ,
- Wenyi Wu
- ,
- Peipei Zuo*
- ,
- Zhengjin Yang*
- , and
- Tongwen Xu*
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Processable polymers of intrinsic microporosity (PIMs) are emerging as promising candidates for next-generation ion exchange membranes (IEMs). However, especially with high ion exchange capacity (IEC), IEMs derived from PIMs suffer from severe swelling, thus, resulting in decreased selectivity. To solve this problem, we report ultramicroporous polymer framework membranes constructed with rigid Tröger’s Base network chains, which are fabricated via an organic sol–gel process. These membranes demonstrate excellent antiswelling, with swelling ratios below 4.5% at a high IEC of 2.09 mmol g–1, outperforming currently reported PIM membranes. The rigid ultramicropore confinement and charged modification of pore channels endow membranes with both very high size-exclusion selectivity and competitive ion conductivity. The membranes thus enable the efficient and stable operation of pH-neutral aqueous organic redox flow batteries (AORFBs). This work presents the advantages of polymer framework materials as IEMs and calls for increasing attention to extending their varieties and utilization in other applications.
Discovery of TRPA1 Antagonist GDC-6599: Derisking Preclinical Toxicity and Aldehyde Oxidase Metabolism with a Potential First-in-Class Therapy for Respiratory Disease
- Jack A. Terrett*
- ,
- Justin Q. Ly
- ,
- Paula Katavolos
- ,
- Catrin Hasselgren
- ,
- Steven Laing
- ,
- Fiona Zhong
- ,
- Elisia Villemure
- ,
- Martin Déry
- ,
- Robin Larouche-Gauthier
- ,
- Huifen Chen
- ,
- Daniel G. Shore
- ,
- Wyne P. Lee
- ,
- Eric Suto
- ,
- Kevin Johnson
- ,
- Marjory Brooks
- ,
- Alyssa Stablein
- ,
- Francis Beaumier
- ,
- Léa Constantineau-Forget
- ,
- Chantal Grand-Maître
- ,
- Luce Lépissier
- ,
- Stéphane Ciblat
- ,
- Claudio Sturino
- ,
- Yong Chen
- ,
- Baihua Hu
- ,
- Justin Elstrott
- ,
- Vineela Gandham
- ,
- Victory Joseph
- ,
- Helen Booler
- ,
- Gary Cain
- ,
- Carolina Chou
- ,
- Aaron Fullerton
- ,
- Michelle Lepherd
- ,
- Shannon Stainton
- ,
- Elizabeth Torres
- ,
- Konnie Urban
- ,
- Lanlan Yu
- ,
- Yu Zhong
- ,
- Linda Bao
- ,
- Kang-Jye Chou
- ,
- Jessica Lin
- ,
- Wei Zhang
- ,
- Hank La
- ,
- Liling Liu
- ,
- Teresa Mulder
- ,
- Jun Chen
- ,
- Tania Chernov-Rogan
- ,
- Adam R. Johnson
- ,
- David H. Hackos
- ,
- Rebecca Leahey
- ,
- Shannon D. Shields
- ,
- Alessia Balestrini
- ,
- Lorena Riol-Blanco
- ,
- Brian S. Safina
- ,
- Matthew Volgraf
- ,
- Steven Magnuson
- , and
- Satoko Kakiuchi-Kiyota*
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Transient receptor potential ankyrin 1 (TRPA1) is a nonselective calcium ion channel highly expressed in the primary sensory neurons, functioning as a polymodal sensor for exogenous and endogenous stimuli, and has been implicated in neuropathic pain and respiratory disease. Herein, we describe the optimization of potent, selective, and orally bioavailable TRPA1 small molecule antagonists with strong in vivo target engagement in rodent models. Several lead molecules in preclinical single- and short-term repeat-dose toxicity studies exhibited profound prolongation of coagulation parameters. Based on a thorough investigative toxicology and clinical pathology analysis, anticoagulation effects in vivo are hypothesized to be manifested by a metabolite─generated by aldehyde oxidase (AO)─possessing a similar pharmacophore to known anticoagulants (i.e., coumarins, indandiones). Further optimization to block AO-mediated metabolism yielded compounds that ameliorated coagulation effects in vivo, resulting in the discovery and advancement of clinical candidate GDC-6599, currently in Phase II clinical trials for respiratory indications.
Chemical Bonding Induces One-Dimensional Physics in Bulk Crystal BiIr4Se8
- Connor J. Pollak
- ,
- Grigorii Skorupskii
- ,
- Martin Gutierrez-Amigo
- ,
- Ratnadwip Singha
- ,
- Joseph W. Stiles
- ,
- Franziska Kamm
- ,
- Florian Pielnhofer
- ,
- N. P. Ong
- ,
- Ion Errea
- ,
- Maia G. Vergniory
- , and
- Leslie M. Schoop*
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One-dimensional (1D) systems persist as some of the most interesting because of the rich physics that emerges from constrained degrees of freedom. A desirable route to harness the properties therein is to grow bulk single crystals of a physically three-dimensional (3D) but electronically 1D compound. Most bulk compounds which approach the electronic 1D limit still field interactions across the other two crystallographic directions and, consequently, deviate from the 1D models. In this paper, we lay out chemical concepts to realize the physics of 1D models in 3D crystals. These are based on both structural and electronic arguments. We present BiIr4Se8, a bulk crystal consisting of linear Bi2+ chains within a scaffolding of IrSe6 octahedra, as a prime example. Through crystal structure analysis, density functional theory calculations, X-ray diffraction, and physical property measurements, we demonstrate the unique 1D electronic configuration in BiIr4Se8. This configuration at ambient temperature is a gapped Su-Schriefer-Heeger system, generated by way of a canonical Peierls distortion involving Bi dimerization that relieves instabilities in a 1D metallic state. At 190 K, an additional 1D charge density wave distortion emerges, which affects the Peierls distortion. The experimental evidence validates our design principles and distinguishes BiIr4Se8 among other quasi-1D bulk compounds. We thus show that it is possible to realize unique electronically 1D materials applying chemical concepts.
Sharp-to-Broad Band Energy Transfer in Lithium Aluminate and Gallate Phosphors for SWIR LED
- Yi-Ting Tsai
- ,
- Pei-Xuan Chen
- ,
- Mikołaj Kamiński
- ,
- Natalia Majewska
- ,
- Sebastian Mahlik*
- , and
- Mu-Huai Fang*
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Short-wave infrared (SWIR) phosphor-converted light-emitting diode (LED) technology holds promise for advancing broadband light sources. Despite the potential, limited research has delved into the energy transfer mechanism from sharp-line to broadband emission in SWIR phosphors, which remains underexplored. Herein, we demonstrate bright SWIR phosphors achieved through Cr3+/Ni2+ energy transfer in LiGa5(1–x)Al5xO8. High-resolution X-ray diffraction revealed the typical solid solution and distortion occurring in Al3+ octahedral sites. In addition, the X-ray absorption spectrum illustrates that Cr3+ and Ni2+ have different coordination environments, showing the possibility that they occupy different positions or that the coordinated environment of Ni2+ is distorted due to charge imbalance. Temperature-dependent studies provide insights into the energy transfer dynamics between Cr3+/Ni2+, from the 2E level of Cr3+ (sharp band) to the 3T1 level of Ni2+ (broadband). The increased emission intensity at lower temperatures in the x = 0.6 and x = 1.0 samples can be explained by the positioning of the 3T1 level above the 2E level of Cr3+ ions. Finally, we established a mechanism involving a sharp line to broadband energy transfer showcasing a high-power SWIR LED with a radiant power of 21.45 mW.
Controlling Phase in Colloidal Synthesis
- Emma J. Endres
- ,
- Jeremy R. Bairan Espano
- ,
- Alexandra Koziel
- ,
- Antony R. Peng
- ,
- Andrey A. Shults
- , and
- Janet E. Macdonald*
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A fundamental precept of chemistry is that properties are manifestations of the elements present and their arrangement in space. Controlling the arrangement of atoms in nanocrystals is not well understood in nanocrystal synthesis, especially in the transition metal chalcogenides and pnictides, which have rich phase spaces. This Perspective will cover some of the recent advances and current challenges. The perspective includes introductions to challenges particular to chalcogenide and pnictide chemistry, the often-convoluted roles of bond dissociation energies and mechanisms by which precursors break down, using very organized methods to map the synthetic phase space, a discussion of polytype control, and challenges in characterization, especially for solving novel structures on the nanoscale and time-resolved studies.
Similarity of Polymer Packing in Melts Is Dictated by N̅
- Jian Qin*
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ACS Editors' Choice® is a collection designed to feature scientific articles of broad public interest. Read the latest articles
The literature usage of the invariant degree of polymerization N̅ is surveyed and categorized according to the physical arguments involved. By providing rationales based on the universal packing geometry and the structure of the free energy in polymer melts, it is argued that the packing similarity of flexible polymers is controlled by the value of N̅. The historical introduction of N̅ and the connection of N̅ with the other dimensional properties are reviewed, followed by discussion of factors constraining the application of N̅.