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Communications

Two-Photon and Three-Photon Circular Dichroism of Au38 Gold Nanoclusters Enantiomers
Patryk Obstarczyk - ,
Rania Kazan - ,
Thomas Bürgi - ,
Marek Samoć - , and
Joanna Olesiak-Bańska *
While circular dichroism (CD) and optical activity (OA) are well established as optical effects used in characterization of chiral media, harmonic generation and multiphoton circular dichroism are increasingly seen as new, convenient ways of exploring chirality thanks to their operation in the near-infrared range of wavelengths. However, quantitative data about two-photon circular dichroism (2PCD) of organic and inorganic materials are scarce, and even less can be found about three-photon circular dichroism (3PCD). Here, we show that both 2PCD and 3PCD can be readily detected in chiral atomically precise gold nanoclusters via polarimetric Z-scan technique. We provide quantitative data on 2PCD and 3PCD of both enantiomers of Au38(PET)24 nanoclusters, which exhibit extraordinary chiroptical properties arising from the interplay of several levels of molecular organization. Interestingly, the corresponding two- and three-photon dissymmetry factors of Au38(PET)24 enantiomers are significantly enhanced in comparison to the one-photon CD by factors of 178 and 217, respectively.

A Record-High Cryogenic Magnetocaloric Effect Discovered in EuCl2 Compound
Bingjie Wang - ,
Xinyang Liu - ,
Fengxia Hu *- ,
Jian-tao Wang - ,
Junsen Xiang - ,
Peijie Sun - ,
Jing Wang *- ,
Jirong Sun - ,
Tongyun Zhao - ,
Zhaojun Mo - ,
Jun Shen - ,
Yunzhong Chen - ,
Qingzhen Huang - , and
Baogen Shen *
Adiabatic demagnetization refrigeration (ADR) based on the magnetocaloric effect (MCE) is a promising technique to achieve cryogenic temperature. However, magnetic entropy change (ΔSM), the driving force of ADR, remains far below theoretical −ΔSM = nRln(2J + 1)/MW for most magnetic refrigerants. Here, we report giant MCE in orthorhombic EuCl2, where a ferromagnetic ground state with excellent single-ion behavior of Eu2+ and free spins has been demonstrated by combining ab initio calculations with Brillouin function analysis and magnetic measurements. Consequently, a record-high −ΔSM ∼ 74.6 J·kg–1·K–1 (1.8 K) at 5 T was experimentally achieved, approaching 96% of the theoretical limit (77.5 J·kg–1·K–1). At a lower field of 1 T, EuCl2 also achieves the highest-ever record of −ΔSM ∼ 36.8 J·kg–1·K–1. Further, direct quasi-adiabatic demagnetization measurements demonstrate that its large −ΔSM allows EuCl2 to maintain a long holding time at sub-Kelvin temperature (∼346 mK), surpassing all previously reported materials. These superior magnetocaloric performances position EuCl2 as an attractive cryogenic refrigerant.

Initiators for Continuous Activator Regeneration (ICAR) Depolymerization
Glen R. Jones - ,
Maria-Nefeli Antonopoulou - ,
Nghia P. Truong - , and
Athina Anastasaki *
This publication is Open Access under the license indicated. Learn More
Chemical recycling of polymers synthesized by atom transfer radical polymerization (ATRP) typically requires high temperatures (i.e., 170 °C) to operate effectively, not only consuming unnecessary energy but also compromising depolymerization yields due to unavoidable end-group deterioration. To overcome this, the concept of initiators for continuous activator regeneration (ICAR) depolymerization is introduced herein as a broadly applicable approach to significantly reduce reaction temperatures for ATRP depolymerizations. Addition of commercially available free radical initiators enables the on-demand increase of depolymerization efficiency from <1% to 96%, achieving monomer generation at 120 °C, with conversions on par with thermal reversible addition–fragmentation chain transfer (RAFT) depolymerizations. Incubation studies confirm the elimination of deleterious side reactions at the milder temperatures employed, while the methodology can be scaled up to 1 g. The robustness and versatility of ICAR depolymerization is further demonstrated by the possibility to effectively depolymerize both chlorine and bromine terminated polymers and its compatibility with both copper and iron catalysts.

Visible Light Triggerable CO Releasing Micelles
Mckenna G. Hanson - ,
Ram Ambre - ,
Riya Joshi - ,
Jeffrey D. Amidon - ,
Jackson B. Snow - ,
Vivian C. Lawless - , and
Brady T. Worrell *
Carbon monoxide (CO), along with nitric oxide and hydrogen sulfide, is one of a trinity of known gasotransmitters, or endogenously produced gaseous molecules that signal and regulate a panoply of physiological functions. CO releasing molecules (CORMs) are chemical tools that enable the study and application of this ephemeral gas, that, ideally, release CO on-demand when externally stimulated. Surveying the available triggers, photolysis is potentially advantageous: It is contactless and grants practitioners unparalleled spatial and temporal control. However, current phototriggered CORMs are capricious and do not meet current needs. Presented here is a highly efficient platform for the visible light triggered release of CO gas. This platform is built on a unique CO containing functionality, the cyclopropenone, which undergoes facile decarbonylation through visible light (470 nm) mediated photoredox catalysis. Due to the exothermic strain-release that occurs upon formation of CO, this photoreaction is rapid, quantitative, and has tunable release rates. To render this photo-CORM water-soluble, deliverable, and to keep reactants in proximity, necessary components were polymerized into block copolymers that self-assemble into CO releasing micelles (CORMIs). This platform was compared directly to other state-of-the-art CORMs, showing significantly improved CO production efficiency, lower toxicity, tunable release rates, and consistent efficacy in ex vivo and in vitro settings.

Alkene Carboxy-Alkylation via CO2•–
Y Dang - ,
Jimin Han - ,
Alyah F. Chmiel - ,
Sara N. Alektiar - ,
Myriam Mikhael - ,
Ilia A. Guzei - ,
Charles S. Yeung *- , and
Zachary K. Wickens *
Herein, we introduce a new platform for alkene carboxy-alkylation. This reaction is designed around CO2•– addition to alkenes followed by radical polar crossover, which enables alkylation through carbanion attack on carbonyl electrophiles. We discovered that CO2•– adds to alkenes faster than it reduces carbonyl electrophiles and that this reactivity can be exploited by accessing CO2•– via hydrogen atom transfer from formate. This photocatalytic system transforms vinylarenes and carbonyl compounds into a diverse array of substituted γ-lactone products. Furthermore, indoles can be engaged through dearomative carboxy-alkylation, delivering medicinally relevant C(sp3)-rich heterocyclic scaffolds. Mechanistic studies reveal that the active photocatalyst is generated in situ through a photochemically induced reaction between the precatalyst and DMSO. Overall, we have developed a three-component alkene carboxy-alkylation reaction enabled by the use of formate as the CO2•– precursor.
Articles

Ruthenium-Catalyzed Carbocycle-Selective Hydrogenation of Fused Heteroarenes
Chenguang Luo - ,
Chaozheng Wu - ,
Xiaoming Wang - ,
Zhaobin Han *- ,
Zheng Wang *- , and
Kuiling Ding *
This publication is Open Access under the license indicated. Learn More
The homogeneous catalytic hydrogenation of benzo-fused heteroarenes generally provides partially hydrogenated products wherein the heteroaryl ring is preferentially reduced, such as quinoline hydrogenation, leading to 1,2,3,4-tetrahydroquinoline. Herein, we report a carbocycle-selective hydrogenation of fused N-heteroarenes (quinoline, isoquinoline, quinoxaline, etc.) using the Ru complex of a chiral spiroketal-based diphosphine (SKP) as the catalyst, affording the corresponding 5,6,7,8-tetrahydro products in high chemoselectivities. This catalytic system is also effective for the asymmetric carbocycle hydrogenation of fused heteroarenes bearing a boryl or amino group. Experimental studies provided a strong support for the homogeneous nature of the catalysis, and an inner-sphere mechanism was proposed for the hydrogenation. DFT calculations indicated that the hydrogenation is initiated by η4-coordinative activation of quinoline carbocycle to Ru dihydride complex of SKP, followed by metal-to-ligand hydride transfer. Subsequent carbocycle reduction proceeds via consecutive steps of the H2 oxidative addition and C–H reductive elimination.

Unveiling Tetrafluoromethane Decomposition over Alumina Catalysts
Tao Luo - ,
Hang Zhang - ,
Yingkang Chen - ,
Shanyong Chen - ,
Yang Pan - ,
Kang Liu - ,
Junwei Fu - ,
Liyuan Chai - ,
Zhang Lin - ,
Michelle L. Coote *- , and
Min Liu *
Tetrafluoromethane (CF4), the simplest perfluorocompound known as a “forever chemical”, presents substantial environmental challenges due to its health risks and contribution to the greenhouse effect. Designing efficient catalysts for CF4 decomposition remains difficult, compounded by limited understanding of the mechanisms. Here, we use constrained ab initio molecular dynamics (cAIMD) simulations and in situ experiments to elucidate the mechanism of alumina-catalyzed CF4 decomposition, highlighting the pivotal role of surface hydroxyl groups. The initial C–F bond breaking is the rate-determining step, with surface hydroxyl groups reducing the reaction free energy from 1.69 to 1.34 eV. These hydroxyl groups also facilitate the self-healing of oxygen vacancies generated during the decomposition. Contrary to the belief that CF4 decomposes directly into CO2, our cAIMD simulations, supported by synchrotron vacuum ultraviolet photoionization mass spectrometry data, reveal significant CF2O and CO byproducts. Experimental data in an anhydrous environment indicate that water primarily replenishes surface hydroxyl groups rather than directly participating in decomposition. We conclude that the relatively high efficiency of Al2O3 catalysts stems from three key properties: (1) the presence of active sites with a specific affinity for CF4 adsorption, ensuring efficient substrate interaction; (2) appropriate metal–oxygen bond strength, enabling the participation of lattice oxygen in the reaction; and (3) a high density of surface hydroxyl groups that facilitate the initial C–F bond cleavage and the self-healing of oxygen vacancies.

Influence of Curvature on the Physical Properties and Reactivity of Triplet Corannulene Nitrene
Kelley S. McKissic - ,
Mrinal Chakraborty - ,
Dmitrii Govorov - ,
Mayukh Majumder - ,
DeAnte F. Judkins - ,
Rajkumar Merugu - ,
H. Dushanee M. Sriyarathne - ,
Anushree Das - ,
W. Dinindu Mendis - ,
Jan-Simon von Glasenapp - ,
Rainer Herges - ,
Christopher M. Hadad - ,
James Mack - ,
Manabu Abe - , and
Anna D. Gudmundsdottir *
Although nitrene chemistry is promising for the light-induced modification of organic compounds, the reactivity of large polycyclic aromatic compounds and the effects of their curvature remain unexplored. Irradiation of azidocorannulene (1) in methanol/acetonitrile followed by HCl addition produced diastereomers 5 and 5′. Azirine 2 is apparently trapped by methanol to form diastereomeric acetal derivatives that are hydrolyzed with HCl to yield 5 and 5’. ESR spectroscopy in a glassy matrix at 77 K showed that irradiation of 1 yields corannulene nitrene 31N, which has significant 1,3-biradical character. Irradiation of 1 in a glassy matrix resulted in a new absorption band in the region of 360–440 nm, with λmax at 360 and 410 nm, attributed to 31N, as supported by time-dependent density function theory calculations, which placed the major electronic transitions of 31N at 367 nm (f = 0.0407) and 440 nm (f = 0.0353). Laser flash photolysis of 1 revealed a similar absorption spectrum. Nitrene 31N had a lifetime of only a few hundred nanoseconds and was efficiently quenched by oxygen, because of its 1,3-biradical character. CASPT2(12,11)/6-311G** calculations revealed small energy gap (7.2 kcal/mol) between singlet and triplet configurations, suggesting that 31N is formed by intersystem crossing of 11N to 31N. Spin-density, nucleus-independent chemical shift, and anisotropy of the induced current density calculations verified that 31N is a triplet vinylnitrene with unpaired electrons localized on the C═C–N moiety; decaying by intersystem crossing to 2, which is more stable owing to its aromaticity, as supported by calculations (SA-CASSCF/QD-NEVPT2/CBS).

Unraveling the Cleavage Reaction of Hydroxylamines with Cyclopropenones Considering Biocompatibility
Tianying Zeng - ,
Quan Wu - ,
Yongjie Liu - ,
Qianqian Qi - ,
Wei Shen - ,
Wei Gu - ,
Yuanyuan Zhang - ,
Wei Xiong - ,
Zhongpao Xie - ,
Xiaotian Qi - ,
Tian Tian *- , and
Xiang Zhou
We develop a latent biocompatible cleavage reaction involving the hitherto unexplored interaction between hydroxylamines and cyclopropenones. Our study addresses the regioselectivity challenges commonly observed in asymmetric cyclopropenone transformations, substantiated by variations in substrate, Density Functional Theory calculations, and in situ NMR analysis. This reaction is characterized by high efficiency, broad substrate scope, stability, latent biocompatibility, and mild reaction conditions. Significantly, it facilitates fluorescence activation and functions as a controlled release mechanism for prodrugs, showing great promise in biological assays. Our success in achieving the controlled release of nitrogen mustard in HeLa cells underscores its potential application in cellular contexts. Additionally, we introduce a simple and highly efficient method for synthesizing α, β-substituted pentenolides, applicable to a variety of substrates. Moreover, we extend this cleavage reaction to the CRISPR-Cas9 system, achieving precise, on-demand regulation of guide RNA activity. The introduction of this cleavage reaction offers a promising tool for biochemical research and biotechnological applications.

Morphological Tuning of Covalent Organic Framework Single Crystals
Jie Zhang - ,
Zitao Wang - ,
Jinquan Suo - ,
Chao Tuo - ,
Fengqian Chen - ,
Jianhong Chang - ,
Haorui Zheng - ,
Hui Li *- ,
Daliang Zhang *- ,
Qianrong Fang *- , and
Shilun Qiu
The synthesis of high-quality single-crystal covalent organic frameworks (COFs) presents significant challenges, particularly in achieving precise control over their morphologies. Herein, we present a straightforward strategy to fine-tune the morphology of COF single crystals. Using rigid triptycene derivatives as the core building blocks and varying the amounts of aniline modulators, we successfully synthesized a series of high-quality COF single crystals with different aspect ratios and well-defined facets, JUC-663-X (X = 30 to 135, the equivalent of aniline). Their structures were characterized using PXRD, TEM, and N2 adsorption analyses to confirm the structural consistency. The study of the growth mechanism and DFT calculations elucidated the crucial role of aniline as a modulator in facilitating anisotropic competitive binding throughout the crystal growth process. Furthermore, our findings demonstrate that the aspect ratio of these single crystals significantly influences the adsorption properties of Rh B. This research not only paves new paths in the synthesis and morphological control of COF single-crystal materials but also provides profound insights into the relationship between COF morphology and functional performance.

Preserving High Porosity of Covalent Organic Frameworks via Functional Polymer Guest Introduction
Tianwei Xue - ,
Olga A. Syzgantseva - ,
Li Peng *- ,
Ruiqing Li - ,
Yuyu Guo - ,
Chengbin Liu - ,
Tongxin Qiao - ,
Wenli Hao - ,
Jiaran Li - ,
Lilin Zhu - ,
Shuliang Yang *- ,
Jun Li *- , and
Wendy L. Queen *
Due to their high structural tunability, remarkable internal surface areas, readily accessible pore space, and host of possible applications, covalent organic frameworks (COFs) remain at the forefront of materials science research. Unfortunately, many COFs suffer from structural distortions or pore collapse during activation, which can lead to a substantial loss of crystallinity and functionality. Thus, herein, we demonstrate a facile method to address this issue by introducing polymer guests. The polymer adheres to the COF internal pore wall, acting as a supporting pillar during activation and effectively preserving the COF porosity and crystallinity. In fact, the surface area of one COF/polymer composite, known as TAPB-TA/PDA, was boosted by a factor of 16 when compared to the parent COF, TAPB-TA. More importantly, the now robust COF structure was able to resist layer shifting and order loss during both solvent immersion and removal. The introduction of functional polymer guests not only solidifies the COF structure and preserves its high porosity but is also shown to enhance the transport and separation of photogenerated charge carriers, thereby facilitating hydrogen evolution during photocatalytic water splitting. Molecular dynamics simulations further support experimental observations that the incorporation of PDA within the COF pores reinforces the walls, preventing its collapse. The proposed mechanism is based on the adsorption of PDA oligomers along the c direction of the unit cell, fastening the COF layers in place via van der Waals interactions. This kind of interaction locks −N═CH–Ph–CH═N– units in a trans-configuration in the COF pores.

Investigation of Electron Transfer Properties on Silicalite-1 Zeolite for Potential Electrocatalytic Applications
Yingying Jin - ,
Xichen Yin - ,
Guanghua Yu - ,
Qiming Sun *- , and
Jiong Wang *
To develop high-performance electrocatalysts is critical to sustainable conversion and storage of renewable energy. Silicalite-1 (S-1) zeolite is considered promising for constructing electrocatalysts featuring uniform and precise porosity and a stable structural skeleton even at extreme potentials. However, its electrochemical properties remain poorly understood, particularly regarding the roles of internal pore channels. Herein, inner- and outer-sphere electron transfer (ISET/OSET) routes on the S-1 zeolite were investigated by classical redox probes. The results for the first time revealed that the ISET kinetics inside the pores of S-1 zeolite is more rapid than that on external surfaces, optimized by microporous scale channels and terminated hydroxyl groups. Conversely, the kinetics of the OSET did not closely depend on the porosity and surface properties of the S-1 zeolite. These electrochemical insights further initiated a lithium-ion-incorporated S-1 zeolite with rapid ISET kinetics for electrocatalysis of oxygen reduction. It demonstrated a high performance of 85% selectivity for H2O2 production in a neutral solution and a yield of 9.2 mol gcat–1 h–1 when configured in a flow cell.

High-Performance Chemigenetic Potassium Ion Indicator
Dazhou Cheng - ,
Zhenlin Ouyang - ,
Xiaoyu He - ,
Yusuke Nasu - ,
Yurong Wen - ,
Takuya Terai *- , and
Robert E. Campbell *
Potassium ion (K+) is the most abundant metal ion in cells and plays an indispensable role in practically all biological systems. Although there have been reports of both synthetic and genetically encoded fluorescent K+ indicators, there remains a need for an indicator that is genetically targetable, has high specificity for K+ versus Na+, and has a high fluorescent response in the red to far-red wavelength range. Here, we introduce a series of chemigenetic K+ indicators, designated as the HaloKbp1 series, based on the bacterial K+-binding protein (Kbp) inserted into HaloTag7 self-labeled with environmentally sensitive rhodamine derivatives. This series of high-performance indicators features high brightness in the red to far-red region, large intensiometric fluorescence changes, and a range of Kd values. We demonstrate that they are suitable for the detection of physiologically relevant K+ concentration changes such as those that result from the Ca2+-dependent activation of the BK potassium channel.

Joining Natural and Synthetic DNA Using Biversal Nucleotides: Efficient Sequencing of Six-Nucleotide DNA
Bang Wang - ,
Hyo-Joong Kim - ,
Kevin M. Bradley - ,
Cen Chen - ,
Chris McLendon - ,
Zunyi Yang - , and
Steven A. Benner *
By rearranging hydrogen bond donor and acceptor groups within a standard Watson–Crick geometry, DNA can add eight independently replicable nucleotides forming four additional not found in standard Terran DNA. For many applications, the orthogonal pairing of standard and nonstandard pairs offers a key advantage. However, other applications require standard and nonstandard nucleotides to communicate with each other. This is especially true when seeking to recruit high-throughput instruments (e.g., Illumina), designed to sequence standard 4-nucleotide DNA, to sequence DNA that includes added nucleotides. For this purpose, PCR workflows are needed to replace nonstandard nucleotides in (for example) a 6-letter DNA sequence by defined mixtures of standard nucleotides built from 4 nucleotides. High-throughput sequencing can then report the sequences of those mixtures to bioinformatic alignment tools, which infer the original 6-nucleotide sequence by analysis of the mixtures. Unfortunately, the intrinsic orthogonality of standard and nonstandard nucleotides often demand polymerases that violate pairing biophysics to do this replacement, leading to inefficiencies in this “transliteration” process. Thus, laboratory in vitro evolution (LIVE) using “anthropogenic evolvable genetic information systems” (AEGIS), an important “consumer” of new sequencing tools, has been slow to be democratized; robust sequencing is needed to identify the AegisBodies and AegisZymes that AEGIS-LIVE delivers. This work introduces a new way to connect synthetic and standard molecular biology: biversal nucleotides. In an example presented here, a pyrimidine analogue (pyridine-2-one, y) pairs with Watson–Crick geometry to both a nonstandard base (2-amino-8-imidazo-[1,2a]-1,3,5-triazin-[8H]-4-one, P, the Watson–Crick partner of 6-amino-5-nitro-[1H]-pyridin-2-one, Z) and a base that completes the Watson–Crick hydrogen bond pattern (2-amino-2′-deoxyadenosine, amA). PCR amplification of GACTZP DNA with dyTP delivers products where Z:P pairs are cleanly transliterated to A:T pairs. In parallel, PCR of the same GACTZP sample at higher pH delivers products where Z:P pairs are cleanly transliterated to C:G pairs. By allowing robust sequencing of 6-letter GACTZP DNA, this workflow will help democratize AEGIS-LIVE. Further, other implementations of the biversal concept can enable communication across and between standard DNA and synthetic DNA more generally.

Experimental Definition of the S = 1 π vs S = 2 σ Reactivity and S = 2 Character in the Ground State of an S = 1 FeIVO Complex
Augustin Braun - ,
Leland B. Gee - ,
Max D. J. Waters - ,
Michael L. Baker - ,
Michael W. Mara - ,
Ang Zhou - ,
Thomas Kroll - ,
Dennis Nordlund - ,
Dimosthenis Sokaras - ,
Britt Hedman - ,
Keith O. Hodgson - ,
Lawrence Que Jr.- , and
Edward I. Solomon *
Iron(IV)-oxo intermediates found in iron enzymes and artificial catalysts are competent for H atom abstraction in catalytic cycles. For S = 2 intermediates, both axial and equatorial approaches are well-established. The mechanism for S = 1 sites is not as well understood: an equatorial approach is more energetically favorable, and an axial approach requires crossing from the S = 1 to the S = 2 surface. In this study, we use 1s2p resonant inelastic X-ray scattering (RIXS) and Fe L-edge X-ray absorption spectroscopy on the S = 1 [FeIVO(TMC)(CH3CN)]2+ and observe both S = 2 and S = 1 final states, which enables the experimental evaluation of the energetics of the axial and equatorial reactivity of an S = 1 FeIVO center on its S = 2 vs S = 1 surface. The observation of S = 2 final states in the RIXS spectrum demonstrates significant S = 2 character spin–orbit mixed into the S = 1 ground state.

Synchronized Photoluminescence and Electrical Mobility Enhancement in 2D WS2 through Sequence-Specific Chemical Passivation
Zhaojun Li *- ,
Henry Nameirakpam - ,
Elin Berggren - ,
Ulrich Noumbe - ,
Takashi Kimura - ,
Eito Asakura - ,
Victor Gray - ,
Deepa Thakur - ,
Tomas Edvinsson - ,
Andreas Lindblad - ,
Makoto Kohda - ,
Rafael B. Araujo *- ,
Akshay Rao *- , and
M. Venkata Kamalakar *
This publication is Open Access under the license indicated. Learn More
Two-dimensional (2D) semiconducting dichalcogenides hold exceptional promise for next-generation electronic and photonic devices. Despite this potential, the pervasive presence of defects in 2D dichalcogenides results in carrier mobility and photoluminescence (PL) that fall significantly short of theoretical predictions. Although defect passivation offers a potential solution, its effects have been inconsistent. This arises from the lack of chemical understanding of the surface chemistry of the 2D material. In this work, we uncover new binding chemistry using a sequence-specific chemical passivation (SSCP) protocol based on 2-furanmethanothiol (FSH) and bis(trifluoromethane) sulfonimide lithium salt (Li-TFSI), which demonstrates a synchronized 100-fold enhancement in both carrier mobility and PL in WS2 monolayers. We propose an atomic-level synergistic defect passivation mechanism of both neutral and charged sulfur vacancies (SVs), supported by ultrafast transient absorption spectroscopy (TA), Hard X-ray photoelectron spectroscopy (HAXPES), and density functional theory (DFT) calculations. Our results establish a new semiconductor quality benchmark for 2D WS2, paving the way for the development of sustainable 2D semiconductor technologies.

Random Sanitization in DNA Information Storage Using CRISPR-Cas12a
Hongyu Shen - ,
Zhi Weng - ,
Haipei Zhao - ,
Haitao Song - ,
Fei Wang - ,
Chunhai Fan - , and
Ping Song *
DNA information storage provides an excellent solution for metadata storage due to its high density, programmability, and long-term stability. However, current research primarily focuses on the processes of storing and reading data, lacking comprehensive solutions for secure metadata wiping. Herein, we present a method of random sanitization in DNA information storage using CRISPR-Cas12a (RSDISC) based on precise control of the thermodynamic energy of primer-template hybridization. We utilize the collateral cleavage (trans-activity) of single-stranded DNA (ssDNA) by CRISPR-Cas12a to achieve selective sanitization of files in metadata. This method enables ssDNA degradation with different GC contents, lengths, and secondary structures to achieve a sanitization efficiency up to 99.9% for 28,258 oligonucleotides in DNA storage within one round. We demonstrate that the number of erasable files could reach 1012 based on a model of primer-template hybridization efficiency. Overall, RSDISC provides a random sanitization approach to set the foundation of information encryption, file classification, memory deallocation, and accurate reading in DNA storage.

Performance Descriptor of Subsurface Metal-Promoted Boron Catalysts for Low-Temperature Propane Oxidative Dehydrogenation to Propylene
Xiaofeng Gao - ,
Cheng Cai - ,
Shuheng Tian - ,
Shiqiang Xu - ,
Lili Lin *- ,
Jinan Shi - ,
Chuqiao Song - ,
Tao Wang *- ,
Ding Ma *- , and
Siyu Yao *
Boron-based catalysts have exhibited excellent olefin selectivity in the oxidative dehydrogenation of propane (ODHP) reaction. The substrate material should be a potential platform for performance modulation of boron catalysts in this reaction since the introduction of subsurface Ni promoters significantly improves the activity. In this study, we deciphered the substrate effect and identified a performance descriptor to comprehend the roles of subsurface materials in BOx/metal/BN ODHP catalysts by evaluating different metal promoters. Performance evaluation and transient infrared spectroscopic experiments demonstrate that the intrinsic activity and kinetic behaviors of the O–H bond dissociation/regeneration on the metal-promoted BOx overlayer are metal substrate-dependent. Combining density functional theory (DFT) calculations, it is found that the dissociation/regeneration inclination of the O–H bond in BOx(OH)3–x active species is controlled by the affinity of H for boron oxide species. The metal-O binding energy, which has been demonstrated to be linearly correlated with H affinity, can serve as a straightforward performance descriptor for both low-temperature radical initialization and ODHP reaction, revealing this reaction is controlled by the Sabatier principle, and moderate metal-O binding energy is essential for achieving remarkable performance in the BOx/M/BN catalysts. Following the guidance of a potential descriptor, Ni–Rh alloy substrates are investigated and the substrate with a Ni/Rh molar ratio of 15:1 significantly enhances the low-temperature intrinsic activity of the metal-modified BOx to 9.26 μmol/(m2·s), which reaches 105.9 times that of h-BN and is 18.3% larger than the monometallic BOx/Ni/BN catalysts.

Enhancing Sensitivity of Nuclear Magnetic Resonance in Biomolecules: Parahydrogen-Induced Hyperpolarization in Synthetic Disulfide-Rich Miniproteins
Jonas Lins - ,
Yuliya A. Miloslavina - ,
Olga Avrutina - ,
Franziska Theiss - ,
Sarah Hofmann - ,
Harald Kolmar *- , and
Gerd Buntkowsky *
This publication is Open Access under the license indicated. Learn More
Hyperpolarization of small peptides by parahydrogen-induced polarization (PHIP) to increase the sensitivity of nuclear magnetic resonance (NMR) techniques is well established, while its application to larger biopolymers is still a mainly unexplored area. A particular challenge is the presence of folding-essential disulfide bridges. They tend to form metal complexes, thus hampering catalytic hydrogenation, a prerequisite for PHIP. We applied the PHIP technique to enhance NMR signal intensity in cystine-knot miniproteins─highly ordered peptide architectures covalently stabilized by three disulfides. To achieve PHIP, we introduced an l-propargyl tyrosine label at different positions in three synthetic open-chain variants of a natural trypsin inhibitor MCoTI-II. For the folded cystine knot, we observed NMR signal enhancements of up to 499 in methanol, 307 in a D2O–methanol mixture, and 964 for the cysteine-bearing reduced precursor. Trypsin inhibition assays elucidated that introducing a PHIP label into the terminal regions is preferable to alterations within the functional loop to preserve bioactivity. Substitution of the native tyrosine resulted in the highest bioactivity. A drastic reduction in PHIP enhancement was observed in the presence of trypsin due to slower hydrogenation, conditioned by the accessibility of the label within an enzyme–inhibitor complex.

Acid Catalysis Mediated by Aqueous Hydronium Ions Formed by Contacting Zeolite Crystals with Liquid Water
Yue Liu - ,
Chen Luo - ,
Shuai Wang - ,
Enrique Iglesia *- , and
Haichao Liu *
Zeolites are crystalline microporous aluminosilicates widely used as solid acids in catalytic routes to clean and sustainable energy carriers and chemicals from biogenic and fossil feedstocks. This study addresses how zeolites act as weak polyprotic acids and dissociate to form extra-crystalline hydronium (H3O+) ions in liquid water. The extent of their dissociation depends on the energy required to form the conjugate framework anions, which becomes unfavorable as the extent of dissociation increases intracrystalline charge densities because repulsive interactions ultimately preclude the detachment of all protons as catalytically relevant H3O+(aq) ions. The extent of dissociation is accurately described using electrostatic repulsion formalisms that account for aqueous H3O+ concentrations for all zeolite concentrations, Al densities, and frameworks. Probed by hydrolysis of cellulose, the most abundant biogenic polymer, this study demonstrates that zeolites catalyze this reaction exclusively through the formation of the extra-crystalline H3O+ ions at rates strictly proportional to their concentrations in the aqueous phase, irrespective of their provenance from zeolites differing in framework structure or Al content, without the purported involvement of acid sites at extracrystalline surfaces or intervening formation of smaller cellulose oligomers. The results and mechanistic interpretations seamlessly and rigorously bridge the chemistry of solid and liquid acids in aqueous media, while resolving the enduring puzzle of solid acids that catalyze transformations of substrates that cannot enter the voids where acid sites reside.

Tunable Thiazolium Carbenes for Enantioselective Radical Three-Component Dicarbofunctionalizations
Sripati Jana - and
Nicolai Cramer *
This publication is Open Access under the license indicated. Learn More
Asymmetric N-heterocyclic carbene (NHC) organocatalysis is a cornerstone of synthetic organic chemistry. The emerging concept of single-electron NHC catalysis broadened the scope of C–C bond-forming reactions, facilitating the synthesis of a variety of attractive racemic compounds. However, the development of effective and selective chiral NHC catalysts for asymmetric radical-mediated reactions has been challenging. In this report, we introduce a family of highly tunable chiral thiazolium carbenes with three distinct positions for broad electronic and steric modulation featuring bulky chiral flanking groups. We demonstrate the catalytic efficacy of these chiral carbenes in an enantioselective SET-type three-component acyl-difluoroalkylation of olefins using a broad range of aldehydes and difluoroalkyl bromides. This method provides straightforward access to a diverse set of β-difluoroalkylated α-chiral ketones (65 examples) with an up to 87% yield and excellent enantioselectivities of up to >99:1 er. The utility of this methodology is further outlined by enantio- and diastereoselective late-stage modifications of pharmaceutically relevant compounds and selective twofold orthogonal acyl-difluoroalkylations of linchpin reagents.

A Crystalline NiX6 Complex
Josef T. Boronski *- ,
Agamemnon E. Crumpton - , and
Simon Aldridge *
This publication is Open Access under the license indicated. Learn More
High-valent nickel species are implicated as intermediates in industrially relevant chemical transformations and in the catalytic cycles of metalloenzymes. Although a small number of tetravalent NiX4 complexes have been crystallographically characterized, higher nickel valence states have not been identified. Here we report a stable, crystalline NiX6 complex, Ni(BeCp)6 (1; cyclopentadienyl anion (Cp)), formed by the insertion of zerovalent nickel into three Be–Be bonds. This 16-electron species features an inverted ligand field, is diamagnetic, and exhibits C3v symmetry, on account of the lifting of Ni 4p-orbital degeneracy in this molecular geometry. Single-crystal X-ray diffraction and quantum chemical calculations both reveal a toroidal band of electron density perpendicular to the C3 axis of the complex, which may be attributed to delocalized, multicenter aromatic NiBe6 bonding.

Deviation between the Structural Chemistry of Barium and Radium Halides: Synthesis and Characterization of RaX2·H2O and RaX2·2H2O (X– = Cl– and Br–)
Jacob P. Brannon - ,
Zhuanling Bai - ,
Nicholas B. Beck - ,
Daniela Gomez Martinez - ,
Tyler W. Hines - ,
Hannah B. Wineinger - ,
Megan A. Whitefoot - ,
Noah C. McKinnon - ,
Robert W. Merinsky - ,
Ben J. Valley - ,
Thomas E. Albrecht *- , and
Joseph M. Sperling *
To develop the structural chemistry of radium, the halide compounds RaX2·H2O and RaX2·2H2O (X– = Cl– and Br–) have been synthesized and characterized and serve as benchmarks for comparisons with more complex compounds in the future. In contrast with historic reports on the structural chemistry of radium, the Ra2+ chlorides differ from their Ba2+ analogues. For MCl2·H2O (M2+ = Ba2+, Ra2+), the variance between the metal coordination environments manifests as a small, local distortion that becomes more apparent in the extended structure. However, differences between RaCl2·2H2O and BaCl2·2H2O are more pronounced with a 10-coordinate Ra2+ cation being observed instead of a nine-coordinate Ba2+ in BaCl2·2H2O. RaBr2·nH2O (n = 1 or 2) are isomorphous with the Ba2+ analogues. Raman spectroscopy was used as an additional probe of these compounds and reveals substantial shifts and different vibrational modes between RaX2·H2O and RaX2·2H2O compared to BaX2·2H2O.

Weakly Solvating Electrolytes for Safe and Fast-Charging Sodium Metal Batteries
Mingzhu Wu - ,
Mingchen Yang - ,
Jiangtao Yu - ,
Xinyu Ma - ,
Shipeng Sun - ,
Yupo She - ,
Jinhua Yang - ,
Xiuyang Zou *- ,
Yin Hu *- , and
Feng Yan *
Electrolytes for high-performance sodium metal batteries (SMBs) are expected to have high electrode compatibility, low solvation energy, and nonflammability. However, conventional flammable carbonate ester electrolytes show high Na+ desolvation energy and poor compatibility with sodium metal anodes, leading to slow Faradaic reactions and significant degradation of SMBs. Herein, we report a weakly solvating electrolytes (WSEs) design developed by an ionized ether-induced solvent molecule polarization strategy. The steric hindrance and electron-withdrawing effect of the pyrrolidine cation weaken the solvation ability of the ionized ether and enable carbonate ester with low solvation energy through intermolecular polarization interactions. It enables WSEs with fast Na+ migration kinetics and electric-field-reinforced cationic electrode/electrolyte interface, thereby promoting the stability and reversibility of SMBs even under high-charge-rate conditions. The Na||Na3V2(PO4)3 battery with ionized ether-based WSEs exhibits a capacity retention of 83.5% with an average Coulombic efficiency (CE) of 99.69% after 500 cycles at 10C. Furthermore, the Na||Na2Fe2(SO4)3 cells maintained 92.8% capacity retention after 1000 cycles at 5C with an average CE of 99.77% at a cutoff voltage of 4.5 V. The ionized ether also eliminates the fire and safety risks associated with WSEs. This work offers valuable insights into the design of WSEs for safe and high-performance sodium metal batteries.

Electric Field-Induced Sequential Prototropic Tautomerism in Enzyme-like Nanopocket Created by Single Molecular Break Junction
PA Sreelakshmi - ,
Rahul Mahashaya - ,
Susanne Leitherer *- ,
Umar Rashid - ,
Joseph M. Hamill - ,
Manivarna Nair - ,
Pachaiyappan Rajamalli *- , and
Veerabhadrarao Kaliginedi *
This publication is Open Access under the license indicated. Learn More
Mastering the control of external stimuli-induced chemical transformations with detailed insights into the mechanistic pathway is the key for developing efficient synthetic strategies and designing functional molecular systems. Enzymes, the most potent biological catalysts, efficiently utilize their built-in electric field to catalyze and control complex chemical reactions within the active site. Herein, we have demonstrated the interfacial electric field-induced prototropic tautomerization reaction in acylhydrazone entities by creating an enzymatic-like nanopocket within the atomically sharp gold electrodes using a mechanically controlled break junction (MCBJ) technique. In addition to that, the molecular system used here contains two coupled acylhydrazone reaction centers, hence demonstrating a cooperative stepwise electric field-induced reaction realized at the single molecular level. Furthermore, the mechanistic studies revealed a proton relay-assisted tautomerization showing the importance of external factors such as solvent in such electric field-driven reactions. Finally, single-molecule charge transport and energetics calculations of different molecular species at various applied electric fields using a polarizable continuum solvent model confirm and support our experimental findings. Thus, this study demonstrates that mimicking an enzymatic pocket using a single molecular junction’s interfacial electric field as a trigger for chemical reactions can open new avenues to the field of synthetic chemistry.

Elemene Hydrogel Modulates the Tumor Immune Microenvironment for Enhanced Treatment of Postoperative Cancer Recurrence and Metastases
Jing Xian - ,
Fan Xiao - ,
Jianhua Zou - ,
Wei Luo - ,
Shiqi Han - ,
Ziwei Liu - ,
Yiquan Chen - ,
Qianru Zhu - ,
Meng Li - ,
Chuao Yu - ,
Qimanguli Saiding - ,
Wei Tao *- ,
Na Kong *- , and
Tian Xie *
As a representative active ingredient of traditional Chinese medicine (TCM) and a clinically approved anticancer drug, elemene (ELE) exhibits exciting potential in the antitumor field; however, appropriate drug formulations still need to be explored for specific diseases such as postoperative cancer recurrence and metastasis. Herein, we report an ELE hydrogel with controlled drug release kinetics that can allow ELE to maintain effective concentrations at local lesion sites for extended periods to enhance the bioavailability of ELE. Concretely, dopamine-conjugated hyaluronic acid is synthesized and utilized to prepare ELE nanodrug-embedded hydrogels. In a model of postoperative breast cancer recurrence and metastasis, the ELE hydrogel demonstrates a 96% inhibition rate of recurrence; in contrast, the free ELE nanodrug shows only a 65.5% inhibition rate of recurrence. Importantly, the ELE hydrogel markedly stimulates a potent antitumor immune response in the microenvironment of cancer lesions, increasing antitumor immune cells such as CD8+ T cells, CD4+ T cells, and M1-type macrophages, as well as elevating antitumor cytokines including TNF-α, IFN-γ, and IL-6. Overall, this study not only advances the field of TCM but also highlights the transformative impact of controlled-release hydrogels in improving antitumor therapy.

Interfacial Reactivity-Triggered Oscillatory Lattice Strains of Nanoalloys
Zhi-Peng Wu - ,
Dong Dinh - ,
Yazan Maswadeh - ,
Dominic T. Caracciolo - ,
Hui Zhang - ,
Tianyi Li - ,
Jorge A. Vargas - ,
Merry Madiou - ,
Cailing Chen - ,
Zhijie Kong - ,
Zeqi Li - ,
Huabin Zhang - ,
Javier Ruiz Martínez - ,
Susan S. Lu - ,
Lichang Wang - ,
Yang Ren - ,
Valeri Petkov *- , and
Chuan-Jian Zhong *
Understanding the structure evolution of nanoalloys under reaction conditions is vital to the design of active and durable catalysts. Herein, we report an operando measurement of the dynamic lattice strains of dual-noble-metal alloyed with an earth-abundant metal as a model electrocatalyst in a working proton-exchange membrane fuel cell using synchrotron high-energy X-ray diffraction coupled with pair distribution function analysis. The results reveal an interfacial reaction-triggered oscillatory lattice strain in the alloy nanoparticles upon surface dealloying. Analysis of the lattice strains with an apparent oscillatory irregularity in terms of frequency and amplitude using time-frequency domain transformation and theoretical calculation reveals its origin from a metal atom vacancy diffusion pathway to facilitate realloying upon dealloying. This process, coupled with surface metal partial oxidation, constitutes a key factor for the nanoalloy’s durability under the electrocatalytic oxygen reduction reaction condition, which serves as a new guiding principle for engineering durable or self-healable electrocatalysts for sustainable fuel cell energy conversion.

Selective Ni(I)/Ni(III) Process for Consecutive Geminal C(sp3)–C(sp2) Bond Formation
Xuejiao Li - ,
Yu Gan - ,
Yi-Yang Wang - , and
Baihua Ye *
This publication is Open Access under the license indicated. Learn More
Ni-catalyzed multicomponent cross-couplings have emerged as a powerful strategy for efficiently constructing complex molecular architectures from a diverse array of organic halides. Despite its potential, selectively forming multiple chemical bonds in a single operation, particularly in the realm of cross-electrophile coupling catalysis, remains a significant challenge. In this study, we have developed a consecutive open-shell reductive Ni catalysis, enabling the formation of two geminal C(sp3)–C(sp2) bonds from two stereoelectronically similar C(sp2)–I reactants in conjunction with a methylene electrophile. Using zirconaaziridine and elemental Mg0 as reductants, this protocol exhibits broad applicability across a wide range of (hetero)aromatic, alkenyl, and glycal halides, allowing for the rapid assembly of medicinally relevant scaffolds with excellent functional group tolerance. Further kinetic studies suggest a dual “sequential reduction” catalytic process facilitated by a zirconaaziridine-mediated redox-transmetalation process in Ni catalysis. Notably, the concerted oxidative addition of Ni(I)–I across a C(sp2)–I bond, as well as the halide atom abstraction among various C(sp3) electrophiles by an open-shell C(sp2)-Ni(I) species, can proceed with high selectivity. The use of an unsymmetrical methylene electrophile with exceptionally high reactivity in XEC resulted in the rapid accumulation of a benzylic or allylic electrophile intermediate at the outset of reaction, thereby finely controlling the coupling sequence.

Real-Time Quantification of Molecular-Level Dynamic Behaviors Underpinning Shear Thinning in End-Linked Associative Polymer Networks
Yu Zheng - ,
Devosmita Sen - ,
Weizhong Zou - ,
Kexin Dai - , and
Bradley D. Olsen *
Shear thinning of associative polymers is tied to bond breakage under deformation and retraction of dangling chains, as predicted by transient network theories. However, an in-depth understanding of the molecular mechanisms is limited by our ability to measure the molecular states of the polymers during deformation. Herein, utilizing a custom-built rheo-fluorescence setup, bond dissociation in model end-linked associative polymers is quantified in real time with nonlinear shear deformation based on a fluorescence quench transition when phenanthroline ligands bind with Ni2+. All of the networks exhibit shear thinning, and the dangling chain fraction increases with the shear rate. However, the number of broken bonds is smaller than that predicted by transient network theories, indicating additional relaxation modes or topological inhomogeneities in the networks. Through tuning counteranion chemistry, networks with similar relaxation times but varying dissociation and association rate constants (kd and ka) of Ni2+-phenanthroline cross-links are developed. Decreasing ka contributes to more dangling chain formation, while the effect of kd is less pronounced. Following force-accelerated bond dissociation of bridging chains, the dangling ends in networks with higher ka tend to reassociate to form elastically inactive loops, while the dangling chains are preserved in networks with lower ka. This indicates the critical role of bond reassociation kinetics in dictating shear-induced topological interchange of different chain configurations. Besides reaction kinetics, decreasing network junction functionality results in less shear thinning and broken bonds, originating from the lower amount of bond breakage required to flow and the higher tendency of the dissociated bonds to reform bridging chains.

Well-Defined Co2 Dual-Atom Catalyst Breaks Scaling Relations of Oxygen Reduction Reaction
Qidi Sun - ,
Xian Yue - ,
Linke Yu - ,
Fu-Zhi Li - ,
Yiwei Zheng - ,
Meng-Ting Liu - ,
Jian-Zhao Peng - ,
Xile Hu - ,
Hao Ming Chen - ,
Lei Li *- , and
Jun Gu *
The 4-electron oxygen reduction reaction (ORR) under alkaline conditions is central to the development of non-noble metal-based hydrogen fuel cell technologies. However, the kinetics of ORR are constrained by scaling relations, where the adsorption free energy of *OOH is intrinsically linked to that of *OH with a nearly constant difference larger than the optimal value. In this study, a well-defined binuclear Co2 complex was synthesized and adsorbed onto carbon black, serving as a model dual-atom catalyst. This catalyst achieved a record half-wave potential of 0.972 V versus the reversible hydrogen electrode in an alkaline electrolyte. Density functional theory simulations and in situ infrared spectroscopy revealed that the dual-atom site stabilizes the *OOH intermediate through bidentate coordination, thereby reducing the free energy gap between *OOH and *OH. By altering the adsorption configuration of *OOH on the dual-atom site, the scaling relations are effectively disrupted, leading to a significant enhancement in ORR activity.

Controlling the Reaction Pathways of Mixed NOxHy Reactants in Plasma-Electrochemical Ammonia Synthesis
Xiaoli Ge - ,
Chengyi Zhang - ,
Mayuresh Janpandit - ,
Shwetha Prakash - ,
Pratahdeep Gogoi - ,
Daoyang Zhang - ,
Timothy R. Cook - ,
Geoffrey I.N. Waterhouse - ,
Longwei Yin *- ,
Ziyun Wang *- , and
Yuguang C. Li *
Electrochemical activation of dinitrogen (N2) is notoriously challenging, typically yielding very low ammonia (NH3) production rates. In this study, we present a continuous flow plasma-electrochemical reactor system for the direct conversion of nitrogen from air into ammonia. In our system, nitrogen molecules are first converted into a mixture of NOx species in the plasma reactor, which are then fed into an electrochemical reactor. To selectively convert the generated NOx species into NH3, we employed a graph theory approach combined with first-principles calculations to comprehensively enumerate all possible pathways from N2-to-NH3, pinpointing key intermediates (NH2* and NO*). A series of bimetallic catalysts was then designed to target the optimal adsorption and conversion of the limiting intermediate in the NOx-to-NH3 pathway. Using an optimized CuPd foam catalyst, we demonstrated an ammonia production rate of 81.2 mg h–1 cm–2 with stability over 1000 h at an applied current of 2 A.

Photoinduced Electron–Nuclear Dynamics of Fullerene and Its Monolayer Networks in Solvated Environments
Qiang Xu *- ,
Daniel Weinberg - ,
Mahmut Sait Okyay - ,
Min Choi - ,
Mauro Del Ben - , and
Bryan M. Wong *
This publication is Open Access under the license indicated. Learn More
The recently synthesized monolayer fullerene network in a quasi-hexagonal phase (qHP-C60) exhibits superior electron mobility and optoelectronic properties compared to molecular fullerene (C60), making it highly promising for a variety of applications. However, the microscopic carrier dynamics of qHP-C60 remain unclear, particularly in realistic environments, which are of significant importance for applications in optoelectronic devices. Unfortunately, traditional ab initio methods are prohibitive for capturing the real-time carrier dynamics of such large systems due to their high computational cost. In this work, we present the first real-time electron–nuclear dynamics study of qHP-C60 using velocity-gauge density functional tight binding, which enables us to perform several picoseconds of excited-state electron–nuclear dynamics simulations for nanoscale systems with periodic boundary conditions. When applied to C60, qHP-C60, and their solvated counterparts, we demonstrate that water/moisture significantly increases the electron–hole recombination time in C60 but has little impact on qHP-C60. Our excited-state electron–nuclear dynamics calculations show that qHP-C60 is extremely unique and enable exploration of time-resolved dynamics for understanding excited-state processes of large systems in complex, solvated environments.

Chemistry of Street Art: Neural Network for the Spectral Analysis of Berlin Wall Colors
Francesco Armetta *- ,
Monika Baublytė - ,
Martina Lucia - ,
Rosina Celeste Ponterio *- ,
Dario Giuffrida - ,
Maria Luisa Saladino - , and
Santino Orecchio
This research starts with the analysis of some fragments of the Berlin Wall street art for the characterization of the painting materials. The spectroscopic results provide a general description of the paint executive technique but more importantly open the way to a new advantage of Raman application to the analytic analysis of acrylic colors. The study highlights the correlation between peak intensity and compound percentage and explores the powerful application of deep learning for the quantification of a pigment mixture in the acrylic commercial products from Raman spectra acquired with hand-held equipment (BRAVO by Bruker). The study reveals the ability of the convolutional neural network (CNN) algorithm to analyze the spectra and predict the ratio between the coloring compounds. The reference materials for calibration and training were obtained by the dilution of commercial acrylic colors commonly practiced by street artists, using Schmincke brand paints. For the first time, Raman investigation provides valuable insights into calibrations for determining dye dilution in mixtures of commercial products, offering a new opportunity for analytical quantification with Raman hand-held spectrometers and contributing to a comprehensive understanding of artists’ techniques and materials in street art.

Revealing Lithium Ion Transport Mechanisms and Solvation Structures in Carbonate Electrolytes
Junkun Pan - ,
Aaron P. Charnay - ,
Weizhong Zheng *- , and
Michael D. Fayer *
Optimizing lithium-ion battery (LIB) electrolytes is essential for high-current applications such as electric vehicles, yet experimental techniques to characterize the complex structural dynamics responsible for the lithium transport within these electrolytes are limited. In this study, we used ultrafast infrared spectroscopy to measure chemical exchange, spectral diffusion, and solvation structures across a wide range of lithium concentrations in propylene carbonate-based LiTFSI (lithium bis(trifluoromethanesulfonimide) electrolytes, with the CN stretch of phenyl selenocyanate as the long-lived vibrational probe. Phenyl selenocyanate is shown to be an excellent dynamical surrogate for propylene carbonate in Li+ solvation clusters. A strong correlation between exchange times and ionic conductivity was observed. This correlation and other observations suggest structural diffusion as the primary transport mechanism rather than vehicular diffusion. Additionally, spectral diffusion observables measured by the probe were directly linked to the desolvation dynamics of the Li+ clusters, as supported by density functional theory and molecular dynamics simulations. These findings provide detailed molecular-level insights into LIB electrolytes’ transport dynamics and solvation structures, offering rational design pathways to advanced electrolytes for next-generation LIBs.

Unraveling the Growth Mechanism of Chiral Inorganic Nanocrystals via High-Resolution Electron Microscopy
Chaoyang Chu - ,
Yao Wang - , and
Yanhang Ma *
This publication is Open Access under the license indicated. Learn More
Chiral inorganic nanomaterials have attracted broad interest due to their intriguing chirality-dependent performances. However, there is a lack of experimental studies and atomic-level evidence on their growth mechanism. Herein, high-crystalline chiral tellurium nanowires were synthesized in an alkali solution by using tellurium oxide as an inorganic source and hydrazine hydrate as a reductant. The evolution of the nucleus and crystalline domains was manifested using high-resolution electron microscopy and electron diffraction, demonstrating a nonclassical growth path, that is, from monomers to nanowires of clusters and then nanocrystals. Furthermore, chiral inducers, d/l-penicillamine, were used at different stages to study their effects on the bias of two enantiomorphic structures with different chiral space groups. A similar nonclassical growth mechanism was also found in the synthesis of chiral terbium phosphate nanowires, demonstrating a common growth phenomenon in chiral inorganic nanomaterials. This work provides novel insights into the formation of chiral nanomaterials, benefiting the further controllable synthesis of various chiral nanomaterials.

Gating the Rectifying Direction of Tunneling Current through Single-Molecule Junctions
Haoyu Wang - ,
Fenglu Hu - ,
Adila Adijiang - ,
Ramya Emusani - ,
Jieyi Zhang - ,
Qihong Hu - ,
Xuefeng Guo - ,
Takhee Lee - ,
Lichuan Chen *- , and
Dong Xiang *
In electronic functional chips, one of the most crucial components is the field-effect transistor (FET). To meet the urgent demands for further miniaturization of electronic devices, solid-state single-molecule transistors by molecular orbital gating have been extensively reported. However, under negative bias and positive bias, achieving a distinct gating effect is extremely challenging because molecular orbital gating is independent of the bias polarity. Here, we demonstrated that rectifiers can be realized in single-molecule junctions with a symmetric molecular structure and an electrode material by simply breaking the symmetry of the electrode’s chemical potential via ionic adsorption. We further demonstrated that the tunneling current can be gated with opposite change tendencies under negative and positive bias by applying an ionic gating voltage, which eventually results in a reversal of the rectifying direction. Our experiments elucidate that, unlike the classical mechanism for solid molecular FET, the modulation of the electrode's chemical potential, rather than the regulation of molecular orbitals, might dominate the electron transport in the ionic liquid environment upon a gating voltage. Our study gains deeper insights into the mechanism of ionic liquid gating and opens a window for designing high-performance electrochemical-based functional devices.

Semisynthetic Glycoconjugate Vaccine Lead against Klebsiella pneumoniae Serotype O2afg Induces Functional Antibodies and Reduces the Burden of Acute Pneumonia
Dacheng Shen - ,
Bruna M. S. Seco - ,
Luiz Gustavo Teixeira Alves - ,
Ling Yao - ,
Maria Bräutigam - ,
Bastian Opitz - ,
Martin Witzenrath - ,
Bettina C. Fries - , and
Peter H. Seeberger *
This publication is Open Access under the license indicated. Learn More
Carbapenem-resistant Klebsiella pneumoniae (CR-Kp) bacteria are a serious global health concern due to their drug-resistance to nearly all available antibiotics, fast spread, and high mortality rate. O2afg is a major CR-Kp serotype in the sequence type 258 group (KPST258) that is weakly immunogenic in humans. Here, we describe the creation and evaluation of semisynthetic O2afg glycoconjugate vaccine leads containing one and two repeating units of the polysaccharide epitope that covers the surface of the bacteria conjugated to the carrier protein CRM197. The semisynthetic glycoconjugate containing two repeating units induced functional IgG antibodies in rabbits with opsonophagocytic killing activity and enhanced complement activation and complement-mediated killing of CR-Kp. Passive immunization reduced the burden of acute pneumonia in mice and may represent an alternative to antimicrobial therapy. The semisynthetic glycoconjugate vaccine lead against CR-Kp expressing O2afg antigen is awaiting preclinical development.

Diamagnetic Carrier-Doping-Induced Continuous Electronic and Magnetic Crossover in One-Dimensional Coordination Polymers
Yongbing Shen *- ,
Mengxing Cui - ,
Guanping Li - ,
Olaf Stefanczyk - ,
Nobuto Funakoshi - ,
Tomu Otake - ,
Shinya Takaishi - ,
Masahiro Yamashita *- , and
Shin-ichi Ohkoshi *
The potential to introduce tunable electrical conductivity and molecular magnetism through carrier doping in metal–organic coordination polymers is particularly promising for nanoelectronics applications. Precise control of the doping level is essential for determining the electronic and magnetic properties. In this study, we present a series of one-dimensional coordination polymers, {(HNEt3)0.5[CuxCo(1–x)(L)]}n (HNEt3 = triethylammonium, L = 1,2,4,5-tetrakis(methanesulfonamido)benzene), doped with diamagnetic Cu1+ carriers. Through comprehensive characterization of the structural, optical, and magnetic properties, we observed continuous electronic and magnetic crossover as the doping level was gradually increased. When x < 0.5, the doped compounds exhibit ferromagnetic insulating behavior with very high energy barriers (Ueff up to 560 K) and excellent slow relaxation of magnetization. At x = 0.5, {(HNEt3)0.5[Cu0.5Co0.5(L)]}n functions as a paramagnetic semiconductor at high temperatures and a single-molecule magnet at low temperatures. When x > 0.5, the doped compounds act as diluted antiferromagnetic semiconductors with narrow band gaps (Ea = 0.2 eV). The emergence of such rich electronic and magnetic crossovers is ascribed to the cooperation of the strong electron-donating ability of the ligand and the pronounced crystal-field effects. Our findings indicate that one-dimensional (1D) coordination polymers are promising for the design of novel low-dimensional magnetic semiconductors.

Harnessing Oxetane and Azetidine Sulfonyl Fluorides for Opportunities in Drug Discovery
Oliver L. Symes - ,
Hikaru Ishikura - ,
Callum S. Begg - ,
Juan J. Rojas - ,
Harry A. Speller - ,
Anson M. Cherk - ,
Marco Fang - ,
Domingo Leung - ,
Rosemary A. Croft - ,
Joe I. Higham - ,
Kaiyun Huang - ,
Anna Barnard - ,
Peter Haycock - ,
Andrew J. P. White - ,
Chulho Choi - , and
James A. Bull *
This publication is Open Access under the license indicated. Learn More
Four-membered heterocycles such as oxetanes and azetidines represent attractive and emergent design options in medicinal chemistry due to their small and polar nature and potential to significantly impact the physiochemical properties of drug molecules. The challenging preparation of these derivatives, especially in a divergent manner, has severely limited their combination with other medicinally and biologically important groups. Consequently, there is a substantial demand for mild and effective synthetic strategies to access new oxetane and azetidine derivatives and molecular scaffolds. Here, we report the development and use of oxetane sulfonyl fluorides (OSFs) and azetidine sulfonyl fluorides (ASFs), which behave as precursors to carbocations in an unusual defluorosulfonylation reaction pathway (deFS). The small-ring sulfonyl fluorides are activated under mild thermal conditions (60 °C), and the generated reactive intermediates couple with a broad range of nucleophiles. Oxetane and azetidine heterocyclic, -sulfoximine, and -phosphonate derivatives are prepared, several of which do not have comparable carbonyl analogs, providing new chemical motifs and design elements for drug discovery. Alternatively, a SuFEx pathway under anionic conditions accesses oxetane-sulfur(VI) derivatives. We demonstrate the synthetic utility of novel OSF and ASF reagents through the synthesis of 11 drug analogs, showcasing their potential for subsequent diversification and facile inclusion into medicinal chemistry programs. Moreover, we propose the application of the OSF and ASF reagents as linker motifs and demonstrate the incorporation of pendant groups suitable for common conjugation reactions. Productive deFS reactions with E3 ligase recruiters such as pomalidomide and related derivatives provide new degrader motifs and potential PROTAC linkers.

Luminescent Fe(III) Complex Sensitizes Aerobic Photon Upconversion and Initiates Photocatalytic Radical Polymerization
Pengyue Jin - ,
Xinhuan Xu - ,
Yongli Yan - ,
Heinrich Hammecke - , and
Cui Wang *
This publication is Open Access under the license indicated. Learn More
Light energy conversion often relies on photosensitizers with long-lived excited states, which are mostly made of precious metals such as ruthenium or iridium. Photoactive complexes based on highly abundant iron seem attractive for sustainable energy conversion, but this remains very challenging due to the short excited state lifetimes of the current iron complexes. This study shows that a luminescent Fe(III) complex sensitizes triplet–triplet annihilation upconversion with anthracene derivatives via underexplored doublet-triplet energy transfer, which is assisted by preassociation between the photosensitizer and the annihilator. In the presence of an organic mediator, the green-to-blue upconversion efficiency ΦUC with 9,10-diphenylanthracene (DPA) as the annihilator achieves a 6-fold enhancement to ∼0.2% in aerated solution at room temperature. The singlet excited state of DPA, accessed via photon upconversion in the Fe(III)/DPA pair, allows efficient photoredox catalytic radical polymerization of acrylate monomers in a spatially controlled manner, whereas this process is kinetically hindered with the prompt DPA. Our study provides a new strategy of using low-cost iron and low-energy visible light for efficient polymer synthesis, which is a significant step for both fundamental research and future applications.

Supramolecular Switching-Enabled Quorum Sensing Trap for Pathogen-Specific Recognition and Eradication to Treat Enteritis
Xiaojie Wu - ,
Qinggele Borjihan - ,
Yueying Su - ,
Haoran Bai - ,
Xinshang Hu - ,
Xin Wang - ,
Jing Kang *- ,
Alideertu Dong *- , and
Ying-Wei Yang *
Intestinal bacterial infections have become a significant threat to human health. However, the current typical antibiotic-based therapies not only contribute to drug resistance but also disrupt gut microbiota balance, resulting in additional adverse effects on life activities. There is an urgent need to develop new antibacterial materials that selectively eliminate pathogenic bacteria without disrupting beneficial bacterial communities or promoting drug resistance. Herein, we utilize bacterial quorum sensing (QS), a universal mechanism for regulating community behavior, to develop a supramolecular QS trap by encapsulating cucurbit[7]uril (CB[7]) on 1-vinyl-3-pentylimidazolium bromide ([VPIM]Br) to form a supramolecular switch ([VPIM]Br⊂CB[7]) through host–guest interactions followed by grafting it onto bacterial cell surfaces using atom transfer radical polymerization. Subsequently, the matched pathogens are recognized and aggregated through interbacterial QS signals. Furthermore, the addition of amantadine (AD) facilitates the release of [VPIM]Br by competitive binding of CB[7] on [VPIM]Br⊂CB[7] for sterilization. This QS trap specifically triggers the self-aggregation and efficient elimination of matched bacteria. The [VPIM]Br⊂CB[7]-based trap can increase the diversity and abundance of intestinal microorganisms in mice, effectively treating Escherichia coli K88-induced intestinal damage without perturbing gut microbiota balance. This supramolecular-switched QS trap opens up a promising avenue to specifically recognize and eradicate pathogens for the antibiotic-free treatment of intestinal bacterial infections and other inflammatory diseases.

Do Rh-Hydride Phases Contribute to the Catalytic Activity of Rh Catalysts under Reductive Conditions?
Ke-Xiang Zhang - ,
Lin Chen *- , and
Zhi-Pan Liu *
Rh-hydride phases were believed to be key causes of the exceptional catalytic ability of Rh catalysts under H2 reductive conditions. Here, we utilize the large-scale machine-learning-based global optimization to explore millions of Rh bulk, surface, and nanoparticle structures in contact with H2, which rules out the presence of subsurface/interstitial H in Rh and Rh-hydride phases as thermodynamically stable phases under ambient conditions. Instead, an exceptional Rh–H affinity is identified for surface Rh atoms in Rh nanoparticles that can accommodate a high concentration of adsorbed H, with the surface Rh to H ratio reaching ∼2.5, featuring stable six-H-coordinated Rh, [RhH6]. Such [RhH6] species forming at edged Rh sites are found to be the key intermediates in the electrochemical hydrogen evolution reaction (HER) on Rh. Guided by theory, our synthesized Rh concave nanocubes with a high density of edged Rh sites achieve a Tafel slope of 28.4 mV dec–1 and a low overpotential of 36.1 mV at jECSA = 1 mA cm–2, which outperforms commercial Pt/C and other morphologies of Rh catalysts. Our results clarify the active phase in Rh–H nanosystems and guide the catalyst design by precise morphology control of nanocatalysts

Synthesis of Single-Crystal Two-Dimensional Covalent Organic Frameworks and Uncovering Their Hidden Structural Features by Three-Dimensional Electron Diffraction
Lejian Deng - ,
Wantao Chen - ,
Guojun Zhou - ,
Ying Liu - ,
Lingmei Liu - ,
Yu Han - ,
Zhehao Huang *- , and
Donglin Jiang *
Two-dimensional covalent organic frameworks (2D COFs) are formed by the polycondensation of geometrically specific monomers to grow covalently connected 2D polygonal polymers over the a–b plane and supramolecular polymerization and/or crystallization of 2D sheets along the c direction to constitute layer architectures. Despite various efforts, the synthesis of single-crystal 2D COFs remains a challenging goal. Here, we report the synthesis of single-crystal 2D COFs, by taking the representative imine-linked TPB-DMTP-COF as an example, to reveal the key synthetic parameters that control the crystallization of 2D COFs. We systematically tune the synthetic conditions including the glassware setup, the degas method, the solvent, the temperature, the modulator, and the reaction time and observed that all these parameters greatly affect the polymerization and crystallization processes, controlling the crystal quality. We found that a homogeneous system with all components dissolved and the presence of a suitable modulator at a temperature of 50–70 °C allows the growth of TPB-DMTP-COF single crystals as isolated individual rods, with tunable diameters of 200 nm to 3 μm and a length of 1–20 μm. The single-crystal structure was characterized by three-dimensional electron diffraction (3DED), which revealed two conformations of trans and cis for the linker in the 2D polymer sheets, which stack in an antiparallel mode to shape the frameworks with double-sized unit cells. These results uncover these hidden structural features which have been overlooked in polycrystalline and single-crystal studies and provide new insights into the synthesis of high-quality single crystals of 2D COFs.

Lewis Acid-Mediated Interfacial Water Supply for Sustainable Proton Exchange Membrane Water Electrolysis
Liming Deng - ,
Hongjun Chen - ,
Sung-Fu Hung - ,
Ying Zhang - ,
Hanzhi Yu - ,
Han-Yi Chen - ,
Linlin Li - , and
Shengjie Peng *
The catalyst–electrolyte interface plays a crucial role in proton exchange membrane water electrolysis (PEMWE). However, optimizing the interfacial hydrogen bonding to enhance both catalytic activity and stability remains a significant challenge. Here, a novel catalyst design strategy is proposed based on the hard–soft acid–base principle, employing hard Lewis acids (LAs = ZrO2, TiO2, HfO2) to mediate the reconfiguration of interfacial hydrogen bonding, thereby enhancing the acidic oxygen evolution reaction (OER) performance of RuO2. Mechanistic analysis indicates that LAs prompt a directional evolution from a rigid hydrogen bonding network to free water, enhancing the trapping of interfacial water on the RuO2 surface, which continuously supplies reactants to the catalytic sites. Moreover, the interconnected hydrogen bonding network facilitates rapid proton transfer, reducing local acidity on the catalyst surface and preventing structural corrosion, thus significantly improving long-term stability. The tandem pathway of water supply and deprotonation transforms the dissolution mechanism of traditional Ru-based catalysts, emphasizing the widespread applicability. Consequently, ZrO2–RuO2 displays a significantly reduced overpotential of 170 mV and exhibits high durability, sustaining 1800 h at 10 mA cm–2 under acidic OER, and maintains robust activity for 100 h at 2 A cm–2 in PEMWE, outperforming most Ru/Ir-based catalysts.

Application of Voronoi Polyhedra for Analysis of Electronic Dimensionality in Emissive Halide Materials
Sergei A. Novikov - ,
Hope A. Long - ,
Aleksandra D. Valueva - , and
Vladislav V. Klepov *
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The synthesis of new hybrid halide materials is attracting increasing research interest due to their potential optoelectronic applications. However, general design principles that explain and predict their properties are still limited. In this work, we attempted to reveal the role of intermolecular interactions on the optical properties in a series of hybrid halides with an (EtnNH4–n)2Sn1–xTexCl6 (n = 1–4) composition. DFT calculations showed that the dispersions of the bands involving the Te 5s orbital character gradually decrease as the size of the organic cation increases, indicating a reducing orbital overlap between neighboring TeCl62– complexes. We characterized the photoluminescence (PL) of the Sn/Te solid solutions in (EtnNH4–n)2Sn1–xTexCl6 (n = 1–4) phases to correlate the electronic and optical properties. The PL response shows no concentration quenching effects in the (Et4N)2Sn1–xTexCl6 series, which demonstrated electronically isolated TeCl62– complexes. However, the series with smaller organic cations (n = 1–3) and higher electronic dimensionality show concentration quenching effects, which decrease as a function of the Te 5s band dispersions in these compounds. Similar trends can be revealed using a simple semiquantitative electronic dimensionality analysis method by means of Voronoi polyhedra. Since this approach relies only on structural data, it enables rapid characterization of orbital overlap between metal halide complexes in hybrid materials without DFT calculations. The present results allow us to conclude that electronic dimensionality plays an essential role in the photophysical properties of hybrid halide compounds and can be used to fine-tune their properties.

Engineering a Near-Infrared Spiro-Based Aggregation-Induced Emission Luminogen for DNAzyme-Sensitized Photothermal Therapy with High Efficiency and Accuracy
Yingying Chen - ,
Sheng-Yi Yang - ,
Xinwen Ou - ,
Hui Wang - ,
Fan-Cheng Kong - ,
Philip C. Y. Chow - ,
Yifei Wang - ,
Yuqian Jiang - ,
Wei Zhao - ,
Jianwei Sun - ,
Ryan T. K. Kwok - ,
Di-Wei Zheng - ,
Wenqian Yu *- ,
Fuan Wang *- ,
Jacky W. Y. Lam *- , and
Ben Zhong Tang *
Aggregation-induced emission luminogen (AIEgens)-based photothermal therapy (PTT) has grown into a sparkling frontier for tumor ablation. However, challenges remain due to the uncoordinated photoluminescence (PL) and photothermal properties of classical AIEgens, along with hyperthermia-induced antiapoptotic responses in tumor cells, hindering satisfactory therapeutic outcomes. Herein, a near-infrared (NIR) spiro-AIEgen TTQ-SA was designed for boosted PTT by auxiliary DNAzyme-regulated tumor cell sensitization. TTQ-SA with a unique molecular structure and packing mode was initially fabricated, endowing it with a strong AIE effect, favorable PL quantum yield, and good photothermal performance. DNAzyme, as a gene silencing tool, could alleviate antiapoptosis response during PTT. By integrating TTQ-SA and DNAzyme into folate-modified poly(lactic-co-glycolic acid) (PLGA) polymer, the as-fabricated nanosystem could promote cell apoptosis and sensitize tumor cells to PTT, thereby maximizing the therapeutic outcomes. With the combination of spiro-AIEgen-based PTT and DNAzyme-based gene silencing, the as-designed nanosystem showed promising NIR and photothermal imaging abilities for tumor targeting and demonstrated significant cell apoptotic, antitumor, and antimetastasis effects against orthotopic breast cancer. Furthermore, a synergistic antitumor effect was realized in spontaneous MMTV-PyMT transgenic mice. These findings offer new insights into AIEgen-based photothermal theranostics and DNAzyme-regulated tumor cell sensitization, paving the way for synergistic gene silencing-PTT nanoplatforms in clinical research.

Sequential Photocatalysis for Homologative Diversification of α-Amino Acids to β-Amino Acids Via Phosphonium Ylide Linchpin Strategy
Hui Qiu - ,
Akira Matsumoto *- , and
Keiji Maruoka *
β-Amino acids serve as crucial building blocks for a broad range of biologically active molecules and peptides with potential as peptidomimetics. While numerous methods have been developed for the synthesis of β-amino acids, most of them require multistep preparation of specific reagents and substrates, which limits their synthetic practicality. In this regard, a homologative transformation of abundant and readily available α-amino acids would be an attractive approach for β-amino acid synthesis. Herein, we disclose the development of a sequential process to provide diverse β-amino acids from α-amino acid derivatives and commercially available phosphonium ylides via visible light photoredox catalysis. In this two-step protocol, phosphonium ylides function as a bifunctional linchpin: they act as a carbon nucleophile to forge a C–C bond in the first step and as a carbon-centered radical source for diverse modifications of the β-amino acid scaffold in the second step. The orthogonal activation of these reactivities under mild photocatalytic conditions enables a modular three-component assembly to access β-amino acids and dipeptides with high structural diversity.

Bonding of Polyethylenimine in Covalent Organic Frameworks for CO2 Capture from Air
Haozhe Li - ,
Zihui Zhou - ,
Tianqiong Ma - ,
Kaiyu Wang - ,
Heyang Zhang - ,
Ali H. Alawadhi - , and
Omar M. Yaghi *
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We have developed a polyethylenimine-functionalized covalent organic framework (COF) for capturing CO2 from the air. It was synthesized by the crystallization of an imine-linked COF, termed imine-COF-709, followed by linkage oxidation and polyamine installation through aromatic nucleophilic substitution. The chemistry of linkage oxidation and amine installation was fully characterized through Fourier transform infrared spectroscopy, elemental analysis, and solid-state nuclear magnetic resonance (ssNMR) spectroscopy. Sorption isotherms and dynamic breakthrough were applied to study the sorption behavior of the resulting sorbent (COF-709). The COF exhibited a CO2 capacity of 0.48 mmol g–1 under dry conditions and 1.24 mmol g–1 under 75% relative humidity, both from simulated air containing 400 ppm of CO2 at 25 °C. The CO2 capacity and adsorption rate of COF-709 showed a strong relationship with the relative humidity in the environment, in accordance with the CO2 adsorption mechanism revealed by ssNMR. The chemical stability of C–S bonds utilized to covalently install the polyamine in COF pores prevented its amine loss and hydrolysis, giving COF-709 an excellent cycling stability, which was confirmed by applying 10 adsorption–desorption cycles under simulated direct air capture conditions, showing no uptake loss.

Ternary Heteronanocrystals with Dual-Heterojunction for Boosting Near-Infrared-Triggered Photo-Chemodynamic Therapy
Yufang Kou - ,
Minchao Liu - ,
Mengmeng Hou - ,
Tiancong Zhao - ,
Liang Chen - ,
Jia Jia - ,
Yating Zhan - ,
Kui Yan - ,
Boya Wang - ,
Fan Zhang - ,
Dongyuan Zhao - , and
Xiaomin Li *
Strongly coupled interfaces in the epitaxial growth heteronanocrystals (HNCs) provide advanced functionalities regarding interface connection, electron transfer, and carrier separation. However, the majority of current nanocomposites primarily focus on a single heterojunction involving only two subunits, which hinders the achievement of optimized synergy energy transfer among more than two components. Herein, ternary NaGdF4:Yb,Tm-TiO2:F-Fe3O4 HNCs with dual-heterojunction were synthesized based on the crystal plane epitaxial growth strategy for boosting near-infrared (NIR)-triggered photo-chemodynamic therapy (PCDT). Fluorine is doped into TiO2 (TiO2:F), which not only enhances the exposure of the (001) facet of TiO2 for Fe3O4 subunit growth but also promotes the growth of the NaGdF4:Yb,Tm upconversion nanocrystal (UCNC) subunit, enabling an epitaxial combination of all three components. Upon NIR irradiation, the UCNC subunit transfers the light energy of the absorbed NIR light to the TiO2:F subunit, thereby facilitating the generation of electron–hole pairs within TiO2:F. Due to different work functions between TiO2:F and Fe3O4 in the ternary HNCs, electrons tend to transfer from TiO2:F into Fe3O4, resulting in a reduction of inactive Fe3+ into active Fe2+ and further enhancing the Fenton-catalysis performance. Simultaneously, the efficient separation of electrons and holes improves the photocatalytic oxidation property induced by TiO2:F. Based on ternary UCNC-TiO2:F-Fe3O4 HNCs boosting Fenton catalysis and photocatalysis at the single particle level, as a proof of concept, we propose a NIR light-triggered PCDT (NIR-PCDT) synergistically enhanced tumor treatment strategy. In vitro and in vivo experiments demonstrate that this NIR-PCDT agent exhibits a pronounced ability to generate reactive oxygen species, effectively inducing apoptosis in tumor cells.

Investigating a Seemingly Simple Imine-Linked Covalent Organic Framework Structure
Cailing Chen - ,
Li Cao - ,
Yaozu Liu - ,
Zhihao Li - ,
Zhen-Hua Li - ,
Guojun Zhou - ,
Daliang Zhang *- ,
Xuehai Huang - ,
Yu Wang *- ,
Guanxing Li - ,
Lingmei Liu - ,
You-You Yuan - ,
Yaping Zhang - ,
Qingxiao Wang - ,
Yiqiang Chen - ,
Zhan Shi - ,
Qianrong Fang - ,
Zhehao Huang *- ,
Zhiping Lai *- , and
Yu Han *
The structures of covalent organic frameworks (COFs) are typically determined through modeling based on powder X-ray diffraction. However, the intrinsically limited crystallinity of COFs often results in structural determinations of low fidelity. Here, we present real-space imaging of an extensively studied two-dimensional imine-based COF. Contrary to the conventional understanding that this COF features uniform hexagonal pores, our observations reveal the presence of two distinct sets of pores with differences in shape and size. Motivated by this finding, we conducted reciprocal-space characterizations, complemented by solid-state nuclear magnetic resonance spectroscopy and density functional theory calculations, to reevaluate this seemingly simple structure. The collective results allow for the establishment of a new structural model for this landmark COF and its derivatives, differing from the conventional model in both intra- and interlayer configurations. Furthermore, we identified various previously unrecognized defective structures through real-space imaging, which have significant implications for COF applications in separation and catalysis. Our study demonstrates the complexity and heterogeneity of COF structures, while also highlighting the imperative for structural reevaluation using advanced characterization techniques.
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