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Communications

Exclusive Generation of Single-Atom Sulfur for Ultrahigh Quality Monolayer MoS2 Growth
Yunhao Zhang - ,
Jingwei Wang - ,
Yumo Chen - ,
Xian Wu - ,
Junyang Tan - ,
Jiarong Liu - ,
Huiyu Nong - ,
Liqiong He - ,
Qinke Wu - ,
Guangmin Zhou - ,
Xiaolong Zou - , and
Bilu Liu *
Preparation of high-quality two-dimensional (2D) transition metal dichalcogenides (TMDCs) is the precondition for realizing their applications. However, the synthesized 2D TMDCs (e.g., MoS2) crystals suffer from low quality due to the massive defects formed during the growth. Here, we report single-atom sulfur (S1) as a highly reactive sulfur species to grow ultrahigh-quality monolayer MoS2. Derived from battery waste, sulfurized polyacrylonitrile (SPAN) is found to be exclusive and efficient in releasing S1. The monolayer MoS2 prepared by SPAN exhibits an ultralow defect density of ∼7 × 1012 cm–2 and the narrowest photoluminescence (PL) emission peak with full-width at half-maximum of ∼47.11 meV at room temperature. Moreover, the statistical resonance Raman and low-temperature PL results further verify the significantly lower defect density and higher optical quality of SPAN-grown MoS2 than those of the conventional S-powder-grown samples. This work provides an effective approach for preparing ultrahigh-quality 2D single crystals, facilitating their industrial applications.

Enantioselective Synthesis of vic-Aminoalcohol Derivatives by Nickel-Catalyzed Reductive Coupling of Aldehydes with Protected Amino-pentadienoates
Thilo Bender - and
Alois Fürstner *
This publication is Open Access under the license indicated. Learn More
A VAPOL-derived phosphoramidite ligand is uniquely effective at reverting the regiochemical course of nickel-catalyzed reactions of aldehydes with carbamate-protected 5-amino-2,4-pentadienoates as “push/pull” dienes; the ensuing carbonyl α-amino-homoallylation reaction affords anti-configured vic-aminoalcohol derivatives in good yields with high optical purity. The reductive coupling is conveniently performed with a bench-stable Ni(0) precatalyst and Et3B as the promoter.

Catalytic Enantioselective Hydrogen Atom Abstraction Enables the Asymmetric Oxidation of Meso Diols
Nelson Y. S. Lam - ,
Jyoti Dhankhar - ,
Antti S. K. Lahdenperä - , and
Robert J. Phipps *
This publication is Open Access under the license indicated. Learn More
Desymmetrization of meso diols is an important strategy for the synthesis of chiral oxygen-containing building blocks. Oxidative desymmetrization is an important subclass, but existing methods are often constrained by the need for activated alcohol substrates. We disclose a conceptually distinct strategy toward oxidative diol desymmetrization that is enabled by catalytic enantioselective hydrogen atom abstraction. Following single electron oxidation of a cinchona alkaloid-derived catalyst, enantiodetermining hydrogen atom abstraction generates a desymmetrized ketyl radical intermediate which reacts with either DIAD or O2 before in situ elimination to form valuable hydroxyketone products. A range of cyclic and acyclic meso diols are competent, defining the absolute configuration of up to four stereocenters in a single operation. As well as providing rapid access to complex hydroxyketones, this work emphasizes the broad synthetic potential of harnessing hydrogen atom abstraction in an enantioselective manner.

Site-Specific Histidine Aza-Michael Addition in Proteins Enabled by a Ferritin-Based Metalloenzyme
Jo-Chu Tsou - ,
Chun-Ju Tsou - ,
Chun-Hsiung Wang - ,
An-Li A. Ko - ,
Yi-Hui Wang - ,
Huan-Hsuan Liang - ,
Jia-Cheng Sun - ,
Kai-Fa Huang - ,
Tzu-Ping Ko - ,
Shu-Yu Lin - , and
Yane-Shih Wang *
This publication is Open Access under the license indicated. Learn More
Histidine modifications of proteins are broadly based on chemical methods triggering N-substitution reactions such as aza-Michael addition at histidine’s moderately nucleophilic imidazole side chain. While recent studies have demonstrated chemoselective, histidine-specific modifications by further exploiting imidazole’s electrophilic reactivity to overcome interference from the more nucleophilic lysine and cysteine, achieving site-specific histidine modifications remains a major challenge due to the absence of spatial control over chemical processes. Herein, through X-ray crystallography and cryo-electron microscopy structural studies, we describe the rational design of a nature-inspired, noncanonical amino-acid-incorporated, human ferritin-based metalloenzyme that is capable of introducing site-specific post-translational modifications (PTMs) to histidine in peptides and proteins. Specifically, chemoenzymatic aza-Michael additions on single histidine residues were carried out on eight protein substrates ranging from 10 to 607 amino acids including the insulin peptide hormone. By introducing an insulin-targeting peptide into our metalloenzyme, we further directed modifications to be carried out site-specifically on insulin’s B-chain histidine 5. The success of this biocatalysis platform outlines a novel approach in introducing residue- and, moreover, site-specific post-translational modifications to peptides and proteins, which may further enable reactions to be carried out in vivo.

Stereoselective Glycosylation for 1,2-cis-Aminoglycoside Assembly by Cooperative Atom Transfer Catalysis
Hongze Li - ,
Dakang Zhang - ,
Chong Li - ,
Le Yin - ,
Zixiang Jiang - ,
Yunxuan Luo - , and
Hao Xu *
We report here a new catalytic method for exclusively 1,2-cis-α-selective glycosylation that assembles a wide variety of 1,2-cis-aminoglycosidic linkages in complex glycans and glycoconjugates. Mechanistic studies revealed a unique glycosylation mechanism in which the iron catalyst activates a glycosyl acceptor and an oxidant when it facilitates the cooperative atom transfer of both moieties to a glycosyl donor in an exclusively cis-selective manner. This catalytic approach is effective for a broad range of glycosyl donors and acceptors, and it can be operated in a reiterative fashion and scaled up to the multigram scale.
Articles

An Activity-Based Sensing Approach to Multiplex Mapping of Labile Copper Pools by Stimulated Raman Scattering
Yishu Jiang - ,
Elsy El Khoury - ,
Aidan T. Pezacki - ,
Naixin Qian - ,
Miku Oi - ,
Laura Torrente - ,
Sophia G. Miller - ,
Martina Ralle - ,
Gina M. DeNicola - ,
Wei Min *- , and
Christopher J. Chang *
Molecular imaging with analyte-responsive probes offers a powerful chemical approach to studying biological processes. Many reagents for bioimaging employ a fluorescence readout, but the relatively broad emission bands of this modality and the need to alter the chemical structure of the fluorophore for different signal colors can potentially limit multiplex imaging. Here, we report a generalizable approach to multiplex analyte imaging by leveraging the comparably narrow spectral signatures of stimulated Raman scattering (SRS) in activity-based sensing (ABS) mode. We illustrate this concept with two copper Raman probes (CRPs), CRP2181 and CRP2153.2, that react selectively with loosely bound Cu(I/II) and Cu(II) ions, respectively, termed the labile copper pool, through copper-directed acyl imidazole (CDAI) chemistry. These reagents label proximal proteins in a copper-dependent manner using a dye scaffold bearing a 13C≡N or 13C≡15N isotopic SRS tag with nearly identical physiochemical properties in terms of shape and size. SRS imaging with the CRP reagents enables duplex monitoring of changes in intracellular labile Cu(I) and Cu(II) pools upon exogenous copper supplementation or copper depletion or genetic perturbations to copper transport proteins. Moreover, CRP imaging reveals reciprocal increases in labile Cu(II) pools upon decreases in activity of the antioxidant response nuclear factor-erythroid 2-related factor 2 (NRF2) in cellular models of lung adenocarcinoma. By showcasing the use of narrow-bandwidth ABS probes for multiplex imaging of copper pools in different oxidation states and identifying alterations in labile metal nutrient pools in cancer, this work establishes a foundation for broader SRS applications in analyte-responsive imaging in biological systems.

Synthesis of Multisubstituted Cyclopentadiene Derivatives from 3,3-Disubstituted Cyclopropenes and Internal Alkynes Catalyzed by Low-Valent Niobium Complexes
Takuya Akiyama - ,
Tetsuro Kusamoto - ,
Kazushi Mashima - , and
Hayato Tsurugi *
A low-valent niobium species generated from NbCl5 and 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (Si-Me-CHD) in combination with PPh3 catalyzed a [2+2+1]-cycloaddition reaction of 3,3-disubstituted cyclopropenes and 2 equiv of diaryl/dialkylalkynes, leading to isomeric mixtures of multisubstituted cyclopentadienes 3–5. The initial catalyst activation process was a one-electron reduction of NbCl5 with Si-Me-CHD to provide [NbCl3(μ-Cl) (L)]2 (L = PMe2Ph (6), L = PPh3 (7)) in the presence of phosphine ligands. An NMR spectroscopic time course experiment using complex 7 as the catalyst revealed an induction period for the product formation, corresponding to an additional one-electron reduction of 7 by the substrates to give catalytically active η2-alkyne complexes of NbCl3. A combined computational and experimental study clarified the mechanism of this unprecedented [2+2+1]-cyclopentadiene synthesis; a rate-determining 1,2-insertion of cyclopropene into η2-alkyne niobium species to form cyclopropane-fused metallacyclopentene followed by ring-opening β-C elimination provides a dienylalkylidene intermediate prior to incorporation of the second alkyne through carbene/alkyne metathesis. We also demonstrated the synthetic utility of the multisubstituted cyclopentadienes as the cyclopentadienyl ligands by derivatizing to the corresponding lithium cyclopentadienide, which is applicable for the synthesis of ferrocene 10.

Borane-Catalyzed Intermolecular Aryl Transfer between Hydrosilanes: Shifting the Equilibrium by Removal of a Gaseous Hydrosilane
Jiong Zhang - ,
Ximei Tian - ,
Yaqiong Wang - ,
Yin Zhang - ,
Fang Wang *- , and
Lipeng Wu *
The preparation of organosilanes is indeed far from trivial, despite their vast application. Herein, we report a straightforward and general hydrosilane iterative evolution system for the on-demand synthesis of heteroleptic-substituted hydrosilanes. A series of previously difficult-to-prepare hydrosilanes with two or three diverse substituents were readily obtained. Our process is achieved just by using a catalytic amount of BH3 to initiate a selective hydrosilane redistribution process via aryl group migration. Thus, our work represents sporadic examples of the application of hydrosilane redistribution procedures for synthetic applications, whereas hydrosilane redistribution is often found as an unwanted side reaction; its synthetic value has rarely been explored. Furthermore, an unprecedented and challenging cross-redistribution of aryl hydrosilanes with alkyl hydrosilanes is achieved. Mechanistic studies and density functional theory (DFT) calculations revealed that this process was attained via a BH3-catalyzed C–Si bond cleavage and selective intermolecular aryl group migration from aryl hydrosilanes to alkyl hydrosilanes.

Chemically Driven Division of Protocells by Membrane Budding
Pablo Zambrano - ,
Xiaoyao Chen - ,
Christine M. E. Kriebisch - ,
Brigitte A. K. Kriebisch - ,
Oleksii Zozulia - , and
Job Boekhoven *
This publication is Open Access under the license indicated. Learn More
Division is crucial for replicating biological compartments and, by extension, a fundamental aspect of life. Current studies highlight the importance of simple vesicular structures in prebiotic conditions, yet the mechanisms behind their self-division remain poorly understood. Recent research suggests that environmental factors can induce phase transitions in fatty acid-based protocells, leading to vesicle fission. However, using chemical energy to induce vesicle division, similar to the extant of life, has been less explored. This study investigates a mechanism of vesicle division by membrane budding driven by chemical energy without complex molecular machinery. We demonstrate that, in response to chemical fuel, simple fatty acid-based vesicles can bud off smaller daughter vesicles. The division mechanism is finely controlled by adjusting fuel concentration, offering valuable insights into primitive cellular dynamics. We showcase the robustness of self-division across different fatty acids, retaining encapsulated materials during division and suggesting protocell-like behavior. These results underscore the potential for chemical energy to drive autonomous replication in protocell models, highlighting a plausible pathway for the emergence of life. Furthermore, this study contributes to the development of synthetic cells, enhancing our understanding of the minimal requirements for cellular life and providing a foundation for future research in synthetic biology and the origins of life.

Correlating Halide Segregation with Photolysis in Mixed-Halide Perovskites via In situ Opto-gravimetric Analysis
Zhaojian Xu - ,
Xinjue Zhong - ,
Tuo Hu - ,
Junnan Hu - ,
Antoine Kahn - , and
Barry P. Rand *
Halide oxidation plays a fundamental role in halide segregation and the degradation of halide perovskites, yet quantitative measurement of halide oxidation in solid-state perovskite samples remains challenging. Herein, we demonstrate that in situ opto-gravimetric measurements based on a quartz crystal microbalance can quantify the photolysis kinetics of solid-state perovskites. By investigating a series of mixed bromide/iodide perovskites with varying halide ratios, we demonstrate identical compositional thresholds (x ∼ 0.4 in the CsPb(BrxI1–x)3 system) for iodide oxidation, light-induced halide segregation, and photolysis. Our findings reveal the correlation between these light-induced instabilities and unambiguously explain the photolysis mechanism of mixed-halide perovskites. We also show that photolysis renders the perovskite film more n-type without involving lead reduction. This study introduces a powerful methodology for quantitatively analyzing the mass loss kinetics of halide perovskites under both practical operational and accelerated aging conditions, offering deeper insights into the mechanisms of perovskite degradation.

Nanoscale Evolution of Charge Transport Through C–H···π Interactions
Yu Zhou - ,
Shurui Ji - ,
Yixuan Zhu - ,
Huanhuan Liu - ,
Juejun Wang - ,
Yanxi Zhang - ,
Jie Bai - ,
Xiaohui Li - ,
Jia Shi - ,
Wenqiu Su - ,
Ruiyun Huang - ,
Junyang Liu - , and
Wenjing Hong *
C–H···π interactions, a prevalent intermolecular force, play a pivotal role in chemistry, materials science, and life sciences. Despite extensive studies of their influence on intermolecular binding configurations and energetics, their impact on intermolecular coupling and charge transport remains unexplored. Here, we investigate the charge transport within supramolecular junctions connected by C–H···π and π–π interactions, respectively, and find that C–H···π interactions exhibit conductances that are 3.5 times those of π–π interactions. Angstrom-scale distance-dependent experiments indicate that the conductance of C–H···π supramolecular junctions experiences initial decay under stretching, followed by gradual convergence, in contrast with the periodic fluctuations in π–π stacked supramolecular junctions. Theoretical calculations show that charge transport within C–H···π interactions transitions from destructive to constructive quantum interference under stretching, with a larger range of constructive quantum interference compared with π–π stacking. This study establishes that C–H···π interactions facilitate efficient intermolecular charge transport and elucidates the evolution of quantum interference effects with assembly configuration, offering critical insights for the design of supramolecular materials and devices.

Simultaneous Formation of a Foldamer and a Self-Replicator by Out-of-Equilibrium Dynamic Covalent Chemistry
Ankush Sood - ,
Pradeep K. Mandal - ,
Jim Ottelé - ,
Juntian Wu - ,
Marcel Eleveld - ,
Joydev Hatai - ,
Charalampos G. Pappas - ,
Ivan Huc *- , and
Sijbren Otto *
This publication is Open Access under the license indicated. Learn More
Systems chemistry has emerged as a useful paradigm to access structures and phenomena typically exhibited by living systems, including complex molecular systems such as self-replicators and foldamers. As we progress further toward the noncovalent synthesis of life-like systems, and eventually life itself, it is necessary to gain control over assembly pathways. Dissipative chemical fueling has enabled access to stable populations of (self-assembled) structures that would normally form only transiently. Here, we report a synthetic dynamic combinatorial library, made from a single structurally simple building block, from which a self-replicator and a foldamer can emerge along two distinct and competing pathways through an inter- or intramolecular assembly process, respectively. A fueled chemical reaction cycle is then set up to generate the foldamer transiently, in the presence of the self-replicator. The partitioning of the building block between the folding and self-replication pathways and the duration of the fueled reaction cycles are controlled by adjusting the amount of the chemical fuel. An out-of-equilibrium steady state involving the two assemblies could also be achieved by using a continuous stirred tank reactor with inflow and outflow of material. This work connects the domains of folding and self-replication in synthetic systems through dissipative out-of-equilibrium chemistry. It demonstrates that foldamers and self-replicators, formed from the same building block, can stably coexist if the system is continuously supplied with energy, while at equilibrium, the Gibbs phase rule prohibits such coexistence.

Light-Mediated Interconversion between a Foldamer and a Self-Replicator
Yulong Jin *- ,
Pradeep K. Mandal - ,
Juntian Wu - ,
Armin Kiani - ,
Rui Zhao - ,
Ivan Huc *- , and
Sijbren Otto *
This publication is Open Access under the license indicated. Learn More
Self-replicating molecules and well-defined folded macromolecules are of great significance in the emergence and evolution of life. How they may interconnect and affect each other remains largely elusive. Here, we demonstrate an abiotic system where a single building block can oligomerize to yield either a self-replicating molecule or a foldamer. Specifically, agitation of a disulfide-based dynamic combinatorial library at moderately elevated pH channels it selectively into a self-replicating hexamer assembled into fibers, after passing through a period where a 15-subunit macrocyclic foldamer existed transiently. Without mechanoagitation or at lower pH, the formation of hexamer fiber is suppressed, resulting in the accumulation of the 15mer foldamer. Foldamer and self-replicator can be interconverted in response to external stimuli, including agitation and a change in pH. Furthermore, upon the addition of a photoacid, the pH of the medium can be controlled by irradiation, driving the switching between replicator and foldamer and allowing a dissipative out-of-equilibrium state to be accessed, using light as a source of energy.

Precisely Constructing Superlattices of Soft Giant Molecules via Regulating Volume Asymmetry
Huanyu Lei - ,
Xian-You Liu - ,
Yicong Wang - ,
Xing-Han Li - ,
Xiao-Yun Yan - ,
Tong Liu - ,
Jiahao Huang - ,
Weiyi Li - ,
Lichun Wang - ,
Xiaoyi Kuang - ,
Xiaran Miao - ,
Fenggang Bian - ,
Mingjun Huang - ,
Yuchu Liu *- , and
Stephen Z.D. Cheng *
Soft matters, particularly giant molecular self-assembly, have successfully replicated complex structures previously exclusive to metal alloys. These superlattices are constructed from mesoatoms─supramolecular spherical motifs of aggregated molecules, and the formation of superlattices critically depends on the volume distributions of these mesoatoms. Herein, we introduce two general methods to control volume asymmetry (i.e., the volumes’ ratio of the largest to smallest mesoatoms, VL/VS) within giant molecular self-assembly. Leveraging the spontaneous increase in the mesoatomic volume ratio in unary systems and self-sorted binary blends, we systematically adjust the volume asymmetry from 1.0 to 9.0 across 24 unary systems and 56 binary blends of giant molecules, uncovering the formation of various superlattices, including BCC, Frank-Kasper A15, σ, Laves C14, C15, NaZn13, AlB2, and notably, the first NaCl like superlattice in homogeneous soft matter self-assembly. A geometric-based analysis, combined with experimental results, further establishes a quantitative relationship between volume asymmetry and the corresponding superlattice formations, thus laying a solid foundation for superlattice engineering within giant molecular systems to mimic and even beyond metal alloys. The lattice parameters of various unit cells range from approximately 5 to 20 nm. Our investigation in giant molecules could guide the advancement of mesoscopic, periodic soft matter materials.

Two-Dimensional Superconductivity and Anomalous Vortex Dissipation in Newly Discovered Transition Metal Dichalcogenide-Based Superlattices
Mengzhu Shi - ,
Kaibao Fan - ,
Houpu Li - ,
Senyang Pan - ,
Jiaqiang Cai - ,
Nan Zhang - ,
Hongyu Li - ,
Tao Wu - ,
Jinglei Zhang - ,
Chuanying Xi - ,
Ziji Xiang *- , and
Xianhui Chen *
Properties of layered superconductors can vary drastically when thinned down from bulk to monolayer owing to the reduced dimensionality and weakened interlayer coupling. In transition metal dichalcogenides (TMDs), the inherent symmetry breaking effect in atomically thin crystals prompts novel states of matter such as Ising superconductivity with an extraordinary in-plane upper critical field. Here, we demonstrate that two-dimensional (2D) superconductivity resembling those in atomic layers but with more fascinating behaviors can be realized in the bulk crystals of two new TMD-based superconductors Ba0.75ClTaS2 and Ba0.75ClTaSe2 with superconducting transition temperatures 2.75 and 1.75 K, respectively. They comprise an alternating stack of H-type TMD layers and Ba–Cl layers. In both materials, intrinsic 2D superconductivity develops below a Berezinskii–Kosterlitz–Thouless transition. The upper critical field along the ab plane (Hc2||ab) exceeds the Pauli limit (μ0Hp); in particular, Ba0.75ClTaSe2 exhibits an extremely high μ0Hc2||ab≈ 14 μ0Hp and a colossal superconducting anisotropy (Hc2||ab/Hc2⊥ab) of ∼150. Moreover, the temperature-field phase diagram of Ba0.75ClTaSe2 under an in-plane magnetic field contains a large phase regime of vortex dissipation, which can be ascribed to the Josephson vortex motion, signifying an unprecedentedly strong fluctuation effect in TMD-based superconductors. Our results provide a new path toward the establishment of 2D superconductivity and novel exotic quantum phases in bulk crystals of TMD-based superconductors.

Directional Transport in Hierarchically Aligned ZSM-5 Zeolites with High Catalytic Activity
Bojun Zeng - ,
Siming Wu *- ,
Mingbin Gao - ,
Ge Tian *- ,
Liying Wang - ,
Zhiwen Yin - ,
Zhiyi Hu - ,
Wen Zhang - ,
Ganggang Chang - ,
Mao Ye - ,
Christoph Janiak - ,
Osamu Terasaki - , and
Xiaoyu Yang *
Zeolites, the most technically important crystalline microporous materials, are indispensable cornerstones of chemical engineering because of their remarkable catalytic properties and adsorption capabilities. Numerous studies have demonstrated that the hierarchical engineering of zeolites can maximize accessible active sites and improve mass transport, which significantly decreases the internal diffusion limits to achieve the desired performance. However, the construction of hierarchical zeolites with ordered alignments and size-controlled substructures in a convenient way is highly challenging. Herein, we develop a facile procedure using two common structure-directing agents, tetrapropylammonium hydroxide (TPAOH) and tetraethylammonium hydroxide (TEAOH), to synthesize hierarchically aligned ZSM-5 (Hie-ZSM-5) crystals with a-axis alignment substructures of controllable size. The control of the substructure size (α) in the range of 10–60 nm and the corresponding similarity (r = α/β, where β is the size of Hie-ZSM-5) ranging from 0.004 to 0.033 can be tuned by varying the Si/Al ratios (40–120). A systematic investigation of the overall crystallization process, using time-dependent XRD, SEM, TEM, and solid-state magic-angle spinning NMR (13C, 27Al, 29Si) methods, enable us to construct a solid mechanism for the generation of Hie-ZSM-5. Most importantly, directional transport in the unique structures of Hie-ZSM-5 efficiently enhances mass diffusion, as well as catalytic activity and stability. These findings improve our understanding of the zeolite crystallization process and inspire novel methods for the rational design of hierarchical zeolites.

Mathematical Expression and Prediction of VOCs Adsorption Capacity and Isotherm
Zhongshen Zhang - ,
Wenqing Wu - ,
Gang Wang - ,
Yuan Wang - ,
Xinxin Wang - ,
Wenpeng Li - ,
Zeyu Zhao - ,
Xiaoxiao Duan - ,
Zhihao Zhang - ,
Chunli Wang - ,
Ganggang Li - ,
Guoxia Jiang - ,
Fenglian Zhang - ,
Jie Cheng - ,
Jinjun Li - ,
Chi He - , and
Zhengping Hao *
This publication is Open Access under the license indicated. Learn More
Adsorption capacity prediction, which needs to be based on the precise structure–capacity relationship, is important for better adsorbent design. However, the precise adsorption contribution coefficients of pores of different sizes for volatile organic compound (VOC) adsorption remain unclear. Herein, a control variable method is employed as a generative model to realize the numerization of the precise structure–capacity relationship. For the first time, a concise equation is proposed that can predict the adsorption capacities/isotherms of unknown adsorbents through their pore structure parameters. Interestingly, practical VOC adsorption amounts aligned with predicted values obtained by simultaneously considering pore volume (which undergoes volume-filling adsorption) and surface area (which undergoes surface-covering adsorption) as input variables. Derivation of the equation is based on classical adsorption theories and mathematical expression of the precise structure–capacity relationship obtained from actual experimental results. Each parameter in the equation has a specific physical meaning. This unprecedented VOC adsorption capacity/isotherm prediction method provides in-depth insight for accurate quantification of VOC adsorption, with great potential for gas adsorption prediction and guidance in the development of adsorption materials and technologies.

Ultracompact Electrical Double Layers at TiO2(110) Electrified Interfaces
Immad M. Nadeem - ,
Christopher Penschke - ,
Ji Chen - ,
Xavier Torrelles - ,
Axel Wilson - ,
Hadeel Hussain - ,
Gregory Cabailh - ,
Oier Bikondoa - ,
Jameel Imran - ,
Christopher Nicklin - ,
Robert Lindsay - ,
Jörg Zegenhagen - ,
Matthew O. Blunt - ,
Angelos Michaelides - , and
Geoff Thornton *
This publication is Open Access under the license indicated. Learn More
Metal-oxide aqueous interfaces are important in areas as varied as photocatalysis and mineral reforming. Crucial to the chemistry at these interfaces is the structure of the electrical double layer formed when anions or cations compensate for the charge arising from adsorbed H+ or OH–. This has proven extremely challenging to determine at the atomic level. In this work, we use a surface science approach, involving atomic level characterization, to determine the structure of pH-dependent model electrified interfaces of TiO2(110) with HCl and NaOH using surface X-ray diffraction (SXRD). A comparison with ab initio molecular dynamics calculations reveals the formation of surprisingly compact double layers. These involve inner-sphere bound Cl and Na ions, with respectively H+ and O–/OH– in the contact layer. Their exceptionally high electric fields will play a key role in determining the chemical reactivity.

Preprocessed Monomer Interfacial Polymerization for Scalable Fabrication of High-Valent Cluster-Based Metal–Organic Framework Membranes
Yang Feng - ,
Zixi Kang *- ,
Zhikun Wang - ,
Zhanning Liu - ,
Q. Jason Niu - ,
Weidong Fan - ,
Lu Qiao - ,
Jia Pang - ,
Hu Chang - ,
Xiaolei Cui - ,
Lili Fan - ,
Hailing Guo - ,
Rongming Wang - ,
Dan Zhao *- , and
Daofeng Sun *
Current research on emergent membrane materials with ordered and stable nanoporous structures often overlooks the vital facet of manufacturing scalability. We propose the preprocessed monomer interfacial polymerization (PMIP) strategy for the scalable fabrication of high-valent cluster-based metal–organic framework (MOF) membranes with robust structures. Using a roll-to-roll device on commercial polymer supports, Zr-fum-MOF membranes are continuously processed at room temperature through the PMIP approach. These large-area membranes demonstrate the preeminent hydrogen separation capabilities, boasting an order of magnitude of permeance and a thrice-enhanced selectivity when juxtaposed with conventional polymeric membranes. The obtained PMIP-Zr-fum-MOF membranes possess superior stability in water compared with interfacial polymerization (IP)-processed low-valent metal-ion-based ZIF-8 membranes. Moreover, we have implemented the PMIP strategy’s universality to process the other four diverse MOF membranes. The proposal of PMIP significantly advances the scalable fabrication of water-stable high-valent cluster MOF membranes.

Molecular Design of Phthalocyanine-Based Drug Coassembly with Tailored Function
Dong Li - ,
Siyong Huang - ,
Jianlin Ge - ,
Ziqi Zhuang - ,
Longyi Zheng - ,
Lai Jiang - ,
Yulun Chen - ,
Chengchao Chu - ,
Yang Zhang - ,
Jie Pan - ,
Bingwei Cheng - ,
Jian-Dong Huang *- ,
Huirong Lin *- ,
Wei Han *- , and
Gang Liu *
Coassemblies with tailored functions, such as drug loading, tissue targeting and releasing, therapeutic and/or imaging purposes, and so on, have been widely studied and applied in biomedicine. De novo design of these coassemblies hinges on an integrated approach involving synergy between various design strategies, ranging from structure screening of combinations of “phthalocyanine-chemotherapeutic drug” molecules for molecular scaffolds, exploration of related fabrication principles to verification of intended activity of specific designs. Here, we propose an integrated approach combining computation and experiments to design from scratch coassembled nanoparticles. This nanocoassembly, termed NanoPC here, consists of phthalocyanine-based scaffolds hosting chemotherapeutic drugs, aimed at hypersensitive chemotherapy guided by photoimaging for targeting tumors. Our design starts from the selection of phthalocyanine derivatives that are not aggregation-prone, followed by computational screening of coassembled molecules covering various categories of chemotherapy drugs. To facilitate an efficient and accurate assessment of coassembly capabilities, we utilize small systems as surrogates to enable free-energy calculations at all-atom levels facilitated with enhanced sampling and statistical mechanics for efficient and accurate evaluation of coassembly ability. The final top NanoPC candidate, comprised of phthalocyanine PcL and cytarabine (CYT), can greatly increase the fluorescence intensity ratio of tumor/liver by 21.5 times and achieve higher antitumor efficiency in a pH-dependent manner. Therefore, the designing approach proposed here has a potential pattern, which can provide ideas and references for the design and development of coassembled nanodrugs with tailored functions and applications in biomedicine.

Utilizing High X-ray Energy Photon-In Photon-Out Spectroscopies and X-ray Scattering to Experimentally Assess the Emergence of Electronic and Atomic Structure of ZnS Nanorods
Lars Klemeyer - ,
Tjark L. R. Gröne - ,
Cecilia de Almeida Zito - ,
Olga Vasylieva - ,
Melike Gumus Akcaalan - ,
Sani Y. Harouna-Mayer - ,
Francesco Caddeo - ,
Torben Steenbock - ,
Sarah-Alexandra Hussak - ,
Jagadesh Kopula Kesavan - ,
Ann-Christin Dippel - ,
Xiao Sun - ,
Andrea Köppen - ,
Viktoriia A. Saveleva - ,
Surender Kumar - ,
Gabriel Bester - ,
Pieter Glatzel - , and
Dorota Koziej *
This publication is Open Access under the license indicated. Learn More
The key to controlling the fabrication process of transition metal sulfide nanocrystals is to understand the reaction mechanism, especially the coordination of ligands and solvents during their synthesis. We utilize in situ high-energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS) as well as in situ valence-to-core X-ray emission spectroscopy (vtc-XES) combined with density functional theory (DFT) calculations to identify the formation of a tetrahedral [Zn(OA)4]2+ and an octahedral [Zn(OA)6]2+ complex, and the ligand exchange to a tetrahedral [Zn(SOA)4]2+ complex (OA = oleylamine, OAS = oleylthioamide), during the synthesis of ZnS nanorods in oleylamine. We observe in situ the transition of the electronic structure of [Zn(SOA)4]2+ with a HOMO/LUMO gap of 5.0 eV toward an electronic band gap of 4.3 and 3.8 eV for 1.9 nm large ZnS wurtzite nanospheres and 2 × 7 nm sphalerite nanorods, respectively. Thus, we demonstrate how in situ multimodal X-ray spectroscopy and scattering studies can not only resolve structure, size, and shape during the growth and synthesis of NPs in organic solvents and at high temperature but also give direct information about their electronic structure, which is not readily accessible through other techniques.

Electrochemically Determined and Structurally Justified Thermochemistry of H atom Transfer on Ti-Oxo Nodes of the Colloidal Metal–Organic Framework Ti-MIL-125
Nazmiye Gökçe Altınçekiç - ,
Chance W. Lander - ,
Ayman Roslend - ,
Jiaqi Yu - ,
Yihan Shao - , and
Hyunho Noh *
Titanium dioxide (TiO2) has long been employed as a (photo)electrode for reactions relevant to energy storage and renewable energy synthesis. Proton-coupled electron transfer (PCET) reactions with equimolar amounts of protons and electrons at the TiO2 surface or within the bulk structure lie at the center of these reactions. Because a proton and an electron are thermochemically equivalent to an H atom, these reactions are essentially H atom transfer reactions. Thermodynamics of H atom transfer has a complex dependence on the synthetic protocol and chemical history of the electrode, the reaction medium, and many others; together, these complications preclude the understanding of the H atom transfer thermochemistry with atomic-level structural knowledge. Herein, we report our success in employing open-circuit potential (EOCP) measurements to quantitatively determine the H atom transfer thermochemistry at structurally well-defined Ti-oxo clusters within a colloidally stabilized metal–organic framework (MOF), Ti-MIL-125. The free energy to transfer H atom, Ti3+O–H bond dissociation free energy (BDFE), was measured to be 68(2) kcal mol–1. To the best of our understanding, this is the first report on using EOCP measurements to quantify thermochemistry on any MOFs. The proton topology, the structural change upon the redox reaction, and BDFE values were further quantitatively corroborated using computational simulations. Furthermore, comparisons of the EOCP-derived BDFEs of Ti-MIL-125 to similar parameters in the literature suggest that EOCP should be the preferred method for quantitatively accurate BDFE calculations. The reported success in employing EOCP for nanosized Ti-MIL-125 should lay the ground for thermochemical measurements of other colloidal systems, which are otherwise challenging. Implications of these measurements on Ti-MIL-125 as an H atom acceptor in chemical reactions and comparisons with other MOFs/metal oxides are discussed.

Structure–Function Insights into Thermoresponsive Copolymers as Lanthanide Precipitants
Supraja S. Chittari - ,
Peter A. Dykeman-Bermingham - ,
Matthew P. Bogen - , and
Abigail S. Knight *
The synthetic toolbox for stimuli-responsive polymers has broadened to include many tunable variables, making these materials applicable in diverse technologies. However, unraveling the key composition–structure–function relationships to facilitate ground-up design remains a challenge due to the inherent dispersity in sequence and conformations for synthetic polymers. We here present a systematic study of these relationships using a model system of copolymers with a thermoresponsive (N-isopropylacrylamide) backbone in addition to metal-chelating (acrylic acid) and hydrophobic structural comonomers and evaluate their efficiency at isolating technologically critical lanthanide ions. The efficiency of lanthanide ion extraction by precipitation was quantitated with a metallochromic dye to reveal trends relating copolymer hydrophobicity to improved separations. Further, we examined the role of different hydrophobic comonomers in dictating the solution-phase conformation of the polymer in the presence and absence of lanthanide ions, and we correlated key features of the hydrophobic comonomer to extraction efficiency. Finally, we identified how the local proximity of thermoresponsive, chelating, and hydrophobic subunits facilitates metal extraction by manipulating the copolymer sequence with multiblock polymerization. Through mechanistic analysis, we propose a binding-then-assembly process through which metal ions are coprecipitated with macromolecular chelators.

Scalable Melt Polymerization Synthesis of Covalent Organic Framework Films for Room Temperature Low-Concentration SO2 Detection
Sa Wang - ,
Yu Fu - ,
Fengdong Wang - ,
Xiyuan Wang - ,
Yi Yang - ,
Mengjin Wang - ,
Jian Wang - ,
En Lin - ,
Heping Ma - ,
Yao Chen - ,
Peng Cheng - , and
Zhenjie Zhang *
The development of highly efficient sensors for low-concentration SO2 at room temperature is important for human health and fine chemistry, but it still faces critical challenges. Herein, a scalable olefin-linked covalent organic framework (COF) with an ultramicroporous structure and abundant binding sites is first developed as the SO2 sensing material. The COF can adsorb SO2 of 220 cm3/g at 1 bar and 40 cm3/g at 0.01 bar and 298 K, surpassing all reported COFs. The computational and kinetic adsorption studies deeply unveil the selective adsorption mechanism for low-concentration SO2. Furthermore, the multicomponent gas mixture breakthrough experiments confirm that the COF can specifically capture low-concentration (2000 ppm) SO2. We innovated a melt polymerization technology to fabricate COF films with adjustable substrates and film thicknesses. COF films are directly grown on the interdigital electrodes to prepare the SO2 sensor device, which possesses a low detection limit (86 ppb) and excellent selectivity for SO2 in the presence of 10 other potentially interfering gases. Compared to other reported SO2 sensors, its overall performance is among the top. Prominently, the sensor maintains a stable output signal for more than two months, and recovery can be easily achieved by simply purifying nitrogen at room temperature without heating. This study marks the first use of COFs for SO2 sensing, opening new possibilities for COFs in the detection of low-concentration toxic gases and manufacturing gas sensor devices.

Copper-Mediated Cross-Coupling Selective for Pyroglutamate Post-Translational Modifications
Yuxuan Ding - ,
Yuecheng Jiang - ,
Nicolas Lorenzo Serrat - ,
Kangbao Zhong *- ,
Yu Lan *- , and
Zachary T. Ball *
Pyroglutamate is a cyclic N-terminal post-translational modification that occurs in both proteins and peptide hormones. The prevalence and biological roles of pyroglutamate are little understood, in part due to limited tools to identify, quantify, and manipulate its pyrrolidinone structure. Selective modification of pyroglutamate residues in complex polypeptides may provide unique tools to better understand its biological roles and to allow late-stage diversification of biologically active pyroglutamate-containing sequences. This work describes a copper-catalyzed N–H cross-coupling of unprotected peptides that is selective for N-terminal pyroglutamate residues. The reaction is operationally simple under mild conditions and tolerates all canonical residues. Mechanistic studies point to a key role for a multidentate copper-binding mode of the extended polypeptide structure in delivering the observed reactivity. The reaction allows for direct labeling and identification of a pyroglutamate hormone present in porcine intestinal extracts.

Ultrafast Cycloreversion of Thymine-Toluene [2 + 2] Cycloadducts by DNA Photolyase
Debanjana Chakraborty - ,
Chao Yang - ,
Jialong Jie - ,
Lijuan Wang - , and
Dongping Zhong *
DNA photolyases use blue light and fully reduced flavin cofactor to repair UV-induced cyclobutane pyrimidine dimers (CPD) formed between two adjacent thymine bases in DNA. Thymine can form [2 + 2] cyclobutane adducts with its biological isosteres like toluene upon UV irradiation, resulting in chemically different analogues of CPD. Here, we investigated the cycloreversion reactions of two such adducts formed between thymine and toluene, T<>Tol, catalyzed by a class-I CPD photolyase. The photolyase can bind to the T<>Tol adducts efficiently and restore the constituent bases upon excitation. Using femtosecond spectroscopy, we systematically characterized all the elementary steps involved in the enzymatic cycloreversion of the T<>Tol adducts and comprehensively analyzed the key intermolecular electron-transfer (ET) reactions and cyclobutane bond splitting steps. The initial electron injection to the bound adducts happens primarily through a two-step electron hopping mechanism, unlike in CPD repair where direct electron tunneling is dominant. After electron injection and ultrafast first-bond splitting, the delicate competition between the second bond splitting and a futile back ET dictates the overall reaction quantum yields of the adducts, influenced by the stability of adduct intermediates and steric crowding around the constituent bases. The final electron return for the cycloreversion reactions adopts a different pathway compared to CPD repair. The photolyase utilizes its conserved photorepair mechanism and allows ET pathway flexibility to reverse the [2 + 2] cycloaddition reaction of non-natural analogues of CPD.

A Discrete Trialane with a Near-Linear Al3 Axis
Debabrata Dhara - ,
Lukas Endres - ,
Aritra Roy - ,
Rian D. Dewhurst - ,
Rüdiger Bertermann - ,
Felipe Fantuzzi *- , and
Holger Braunschweig *
This publication is Open Access under the license indicated. Learn More
The presence of inherent electronic unsaturation in aluminum predominantly results in the formation of aluminum clusters, with very few examples of compounds containing discrete chains of aluminum atoms in existence. In this work, we present the successful synthesis and structural authentication of a highly unusual trialane species with a near-linear chain of three Al atoms, alongside a carbene-stabilized aluminyl anion ([LAlR2]−), an alternative product produced by varying the reaction conditions. Quantum-chemical calculations have been applied to elucidate the electronic structure and bonding of these novel compounds. Additionally, we successfully trapped a reaction intermediate using an alkyne, suggesting the intermediacy of a base-stabilized monomeric alumylene (LRAl:), which is also investigated through computational methods.

Catalytic Asymmetric Transfer Hydrogenation of β,γ-Unsaturated α-Diketones
Zhifei Zhao - ,
Wennan Dong - ,
Jinggong Liu - ,
Shuang Yang - ,
Andrej Emanuel Cotman - ,
Qi Zhang *- , and
Xinqiang Fang *
This publication is Open Access under the license indicated. Learn More
Asymmetric transfer hydrogenation (ATH) has been recognized as a highly valuable strategy that allows access to enantioenriched substances and has been widely applied in the industrial production of drug molecules. However, despite the great success in ATH of ketones, highly efficient, regio- and stereoselective ATH on enones remains underdeveloped. Moreover, optically pure acyloins and 1,2-diols are both extremely useful building blocks in organic synthesis, medicinal chemistry, and materials science, but concise asymmetric approaches allowing access to different types of acyloins and 1,2-diols have scarcely been discovered. We report in this paper the first highly efficient ATH of readily accessible β,γ-unsaturated α-diketones. The protocol affords four types of enantioenriched acyloins and four types of optically pure 1,2-diols in highly regio- and stereoselective fashion. The synthetic value of this work has been showcased by the divergent synthesis of four related natural products. Moreover, systematic mechanistic studies and density functional theory (DFT) calculations have illustrated the origin of the reactivity divergence, revealed the different roles of aromatic and aliphatic substituents in the substrates, and provided a range of unique mechanistic rationales that have not been disclosed in ATH-related studies.

Vibrational and Magnetic States of Point Defects in Bilayer MoSe2
Kai Fan - ,
Huimin Wang - ,
Ziwei Ma - ,
Wen-Ao Liao - ,
Wen-Hao Zhang - ,
Chao-Fei Liu - ,
Sheng Meng - ,
Guangjun Tian *- , and
Ying-Shuang Fu *
Defects in two-dimensional materials profoundly impact the physicochemical properties of the systems, whose characterization is highly desirable at the atomic scale. Here, using spectroscopic imaging scanning tunneling microscopy, we elucidate the vibrational and magnetic states of MoSe antisite and VMo vacancy with different charge states embedded in ultrathin MoSe2 bilayers supported on graphene substrate. Stringent vibronic states with multimode coupling are resolved on the defects. The spectral intensities are tunable with the electron tunneling rates and well-reproduced by theoretical modeling. Moreover, first-principles calculations suggest that the defects host a local magnetic moment of 2 μB in their neutral state, which is directly confirmed by our spin-flip inelastic electron tunneling spectroscopy. Our study deepens the understanding of defect properties and paves the way of defect-engineering material functionalities and spin-catalytic applications.

Cooperative Atomically Dispersed Fe–N4 and Sn–Nx Moieties for Durable and More Active Oxygen Electroreduction in Fuel Cells
Fan Xia - ,
Bomin Li - ,
Bowen An - ,
Michael J. Zachman - ,
Xiaohong Xie - ,
Yiqi Liu - ,
Shicheng Xu - ,
Sulay Saha - ,
Qin Wu *- ,
Siyuan Gao - ,
Iddrisu B. Abdul Razak - ,
Dennis E. Brown - ,
Vijay Ramani - ,
Rongyue Wang - ,
Tobin J. Marks - ,
Yuyan Shao *- , and
Yingwen Cheng *
One grand challenge for deploying porous carbons with embedded metal–nitrogen–carbon (M–N–C) moieties as platinum group metal (PGM)-free electrocatalysts in proton-exchange membrane fuel cells is their fast degradation and inferior activity. Here, we report the modulation of the local environment at Fe–N4 sites via the application of atomic Sn–Nx sites for simultaneously improved durability and activity. We discovered that Sn–Nx sites not only promote the formation of the more stable D2 FeN4C10 sites but also invoke a unique D3 SnNx–FeIIN4 site that is characterized by having atomically dispersed bridged Sn–Nx and Fe–N4. This new D3 site exhibits significantly improved stability against demetalation and several times higher turnover frequency for the oxygen reduction reaction (ORR) due to the shift of the reaction pathway from a single-site associative mechanism to a dual-site dissociative mechanism with the adjacent Sn site facilitating a lower overpotential cleavage of the O–O bond. This mechanism bypasses the formation of the otherwise inevitable intermediate that is responsible for demetalation, where two hydroxyl intermediates bind to one Fe site. As a result, a mesoporous Fe/Sn-PNC catalyst exhibits a positively shifted ORR half-wave potential and more than 50% lower peroxide formation. This, in combination with the stable D3 site and enriched D2 Fe sites, significantly enhanced the catalyst’s durability as demonstrated in membrane electrode assemblies using complementary accelerated durability testing protocols.

Activationless Charge Transfer Drives Photocurrent Generation in Organic Photovoltaic Blends Independent of Energetic Offset
Yifan Dong - ,
Rui Zheng - ,
Deping Qian - ,
Tack Ho Lee - ,
Helen L. Bristow - ,
Pabitra Shakya Tuladhar - ,
Hyojung Cha *- , and
James R. Durrant *
This publication is Open Access under the license indicated. Learn More
Organic photovoltaics (OPVs) have recently shown substantial progress in enhancing device efficiency, driven in particular by advances in the design of nonfullerene acceptors and the reduction of the energy offset driving exciton separation at the donor/acceptor interface. Herein, we employ temperature-dependent transient absorption spectroscopy to investigate the activation energy for charge generation and recombination in a range of bulk heterojunction blends with nonfullerene acceptors. Remarkably, we find that in all cases charge generation is almost activationless, in the range of 11–21 meV, independent of energetic offset. Geminate recombination is also observed to be almost activationless, with only the kinetics of bimolecular charge recombination being strongly temperature-dependent, with an activation energy >400 meV. Our observation of essentially activationless charge generation, independent of energy offset, strongly indicates that charge generation in such blends does not follow Marcus theory but can rather be considered an adiabatic process associated with the motion of thermally unrelaxed carriers.

Origin of Performance Decline in Carbonated Anion Exchange Membrane Fuel Cells
Qihao Li - ,
Mihail R. Krumov - ,
Meixue Hu - ,
Colin R. Bundschu - ,
Li Xiao - ,
Lin Zhuang *- , and
Héctor D. Abruña *
Anion exchange membrane fuel cells (AEMFCs) have successfully eliminated anode carbonate precipitation through cation immobilization with the incorporation of alkaline polymer electrolytes (APEs). However, carbonation by CO2 in ambient air continues to induce significant AEMFC performance losses via mechanisms that remain unclear/elusive. In this multimodal investigation of AEMFC carbonation, we find that the increase in ionic resistance after carbonation accounts for only a small fraction of the cell voltage drop, especially at high current densities. Controlled anode and cathode carbonation tests indicated that the anode hydrogen oxidation reaction (HOR) was significantly impeded by carbonation. Hydrogen pump tests showed that the HOR kinetics were more than an order of magnitude lower after carbonation, thus accounting for the large decrease in the cell voltage. Further studies using the electrochemical quartz crystal microbalance (EQCM) revealed that there exists a large barrier to the rearrangement of the double layer at the Pt/ionomer interface in the hydrogen underpotential deposition (HUPD) region, which may explain the slower HOR kinetics after carbonation. These results provide fundamental insight into the unique properties of the catalyst/APE interface and suggest new directions for energy materials and technology developments.

Isocyanide Ligation Enables Electrochemical Ammonia Formation in a Synthetic Cycle for N2 Fixation
Jeremy E. Weber - ,
Noah D. McMillion - ,
Alexander S. Hegg - ,
Ashlee E. Wertz - ,
Mehrnaz Aliahmadi - ,
Brandon Q. Mercado - ,
Robert H. Crabtree - ,
Hannah S. Shafaat *- ,
Alexander J. M. Miller *- , and
Patrick L. Holland *
Transition-metal-mediated splitting of N2 to form metal nitride complexes could constitute a key step in electrocatalytic nitrogen fixation, if these nitrides can be electrochemically reduced to ammonia under mild conditions. The envisioned nitrogen fixation cycle involves several steps: N2 binding to form a dinuclear end-on bridging complex with appropriate electronic structure to cleave the N2 bridge followed by proton/electron transfer to release ammonia and bind another molecule of N2. The nitride reduction and N2 splitting steps in this cycle have differing electronic demands that a catalyst must satisfy. Rhenium systems have had limited success in meeting these demands, and studying them offers an opportunity to learn strategies for modulating reactivity. Here, we report a rhenium system in which the pincer supporting ligand is supplemented by an isocyanide ligand that can accept electron density, facilitating reduction and enabling the protonation/reduction of the nitride to ammonia under mild electrochemical conditions. The incorporation of isocyanide raises the N–H bond dissociation free energy of the first N–H bond by 10 kcal/mol, breaking the usual compensation between pKa and redox potential; this is attributed to the separation of the protonation site (nitride) and the reduction site (delocalized between Re and isocyanide). Ammonia evolution is accompanied by formation of a terminal N2 complex, which can be oxidized to yield bridging N2 complexes including a rare mixed-valent complex. These rhenium species define the steps in a synthetic cycle that converts N2 to NH3 through an electrochemical N2 splitting pathway, and show the utility of a second, tunable supporting ligand for enhancing nitride reactivity.

Processable Coordination Polymer Inks for Highly Conductive and Robust Coatings
Patrick M. Crossland - ,
Chen-Yu Lien - ,
Liam O. de Jong - ,
Joseph L. Spellberg - ,
Maia E. Czaikowski - ,
Lei Wang - ,
Alexander S. Filatov - ,
Sarah B. King - , and
John S. Anderson *
The unique properties and processability of conducting and semiconducting organic materials have fascinated scientists since their discovery. Of this broad class of materials, conductive coordination polymers are of immense recent interest due to their innate modularity and tunability. However, these materials are typically generated as powders and, in some cases, single crystals which significantly limits possible processing and many applications. Herein, we report a method that enables solution-phase processing of a previously reported highly conductive coordination polymer, NiTTFtt (TTFtt = tetrathiafulvalenetetrathiolate), into thin films and conductive textiles. Thin films of NiTTFtt show record-breaking conductivity for a coordination polymer and unusual physical behavior that sheds light on the transport mechanisms in this glassy metallic material. Textiles coated with NiTTFtt are conductive and durable to air, water, washing, acid, base, and mechanical cycles. The properties and processability of NiTTFtt reported here make it notable among coordination polymers and conducting organic materials more broadly.

Interaction-Dependent Secondary Structure of Peptides in Biomolecular Condensates
Keegan A. Lorenz-Ochoa - ,
Moonyeon Cho - ,
Sapun H. Parekh - , and
Carlos R. Baiz *
Biomolecular condensates provide a mechanism for compartmentalization of biomolecules in eukaryotic cells. These liquid-like condensates are formed via liquid–liquid phase separation, by a plethora of interactions, and can mediate several biological processes in healthy cells. Expansions of dipeptide repeat proteins, DPRs, in which arginine rich DPRs like poly-proline-arginine (PR), and poly-glycine-arginine (GR), partition RNA into condensates can however induce cell toxicity. Here, we use (GR)20 as a model for biological poly-GR and condense it using either excluded volume interactions with polyethylene glycol (PEG) as a crowder or direct electrostatic interactions with RNA oligomers. Using two-dimensional infrared (2D IR) spectroscopy, we observe that (GR)20 condensed through an excluded volume forms β-sheet structures, whereas (GR)20 condensed with RNA forms loops. We also investigate local hydrogen-bond dynamics in the condensate and compare the measurements with molecular dynamics simulations. Hydrogen bond lifetimes undergo a marked slowdown compared to dynamics in the dilute phase. This is representative of confined water within the percolated networks inside the condensate due to the interaction present in the condensate disrupting H-bond networks. Overall, our results show that both protein structure and dynamics are inherently dependent on the type of interactions that stabilize the condensates.

Hydrogen–Deuterium Exchange Mass Spectrometry Reveals Mechanistic Insights into RNA Oligonucleotide-Mediated Inhibition of TDP-43 Aggregation
Thomas C. Minshull - ,
Emily J. Byrd - ,
Monika Olejnik - , and
Antonio N. Calabrese *
This publication is Open Access under the license indicated. Learn More
Deposits of aggregated TAR DNA-binding protein 43 (TDP-43) in the brain are associated with several neurodegenerative diseases. It is well established that binding of RNA/DNA to TDP-43 can prevent TDP-43 aggregation, but an understanding of the structure(s) and conformational dynamics of TDP-43, and TDP-43-RNA complexes, is lacking, including knowledge of how the solution environment modulates these properties. Here, we address this challenge using hydrogen–deuterium exchange-mass spectrometry. In the presence of RNA olignoucleotides, we observe protection from exchange in the RNA recognition motif (RRM) domains of TDP-43 and the linker region between the RRM domains, consistent with nucleic acid binding modulating interdomain interactions. Intriguingly, at elevated salt concentrations, the extent of protection from exchange is reduced in the RRM domains when bound to an RNA sequence derived from the 3′ UTR of the TDP-43 mRNA (CLIP34NT) compared to when bound to a (UG)6 repeat sequence. Under these conditions, CLIP34NT is no longer able to prevent TDP-43 aggregation. This suggests that a salt-induced structural rearrangement occurs when bound to this RNA, which may play a role in facilitating aggregation. Additionally, upon RNA binding, we identify differences in exchange within the short α-helical region located in the C-terminal domain (CTD) of TDP-43. These allosterically altered regions may influence the ability of TDP-43 to aggregate and fine-tune its RNA binding repertoire. Combined, these data provide additional insights into the intricate interplay between TDP-43 aggregation and RNA binding, an understanding of which is crucial for unraveling the molecular mechanisms underlying TDP-43-associated neurodegeneration.

Understanding Pt Active Sites on Nitrogen-Doped Carbon Nanocages for Industrial Hydrogen Evolution with Ultralow Pt Usage
Jingyi Tian - ,
Minqi Xia - ,
Xueyi Cheng - ,
Chenghui Mao - ,
Yiqun Chen - ,
Yan Zhang - ,
Changkai Zhou - ,
Fengfei Xu - ,
Lijun Yang - ,
Xi-Zhang Wang *- ,
Qiang Wu *- , and
Zheng Hu *
Engineering microstructures of Pt and understanding the related catalytic mechanism are critical to optimizing the performance for hydrogen evolution reaction (HER). Herein, Pt dispersion and coordination are precisely regulated on hierarchical nitrogen-doped carbon nanocages (hNCNCs) by a thermal-driven Pt migration, from edge-hosted Pt–N2Cl2 single sites in the initial Pt1/hNCNC-70 °C catalyst to Pt clusters/nanoparticles and back to in-plane Pt–NxC4–x single sites. Thereinto, Pt–N2Cl2 presents the optimal HER activity (6 mV@10 mA cm–2) while Pt–NxC4–x shows poor HER activity (321 mV@10 mA cm–2) due to their different Pt coordination. Operando characterizations demonstrate that the low-coordinated Pt–N2 intermediates derived from Pt–N2Cl2 under the working condition are the real active sites for HER, which enable the multi-H adsorption mechanism with an ideal H* adsorption energy of nearly 0 eV, thereby the high activity, as revealed by theoretical calculations. In contrast, the high-coordinated Pt–NxC4–x sites only allow the single-H adsorption with a positive adsorption energy and thereby the low HER activity. Accordingly, with an ultralow Pt loading of only 25 μgPt cm–2, the proton exchange membrane water electrolyzer assembled using Pt1/hNCNC-70 °C as the cathodic catalyst achieves an industrial-level current density of 1.0 A cm–2 at a low cell voltage of 1.66 V and high durability, showing great potential applications.

Water-Soluble Fluorescent Sensors for Quantification of Trace Cisplatin in Body Fluids from Clinical Cancer Patients
Zifeng Cao - ,
Rong Yan - ,
Jiao Chen - ,
Mengyao She - ,
Shanshan Jia - ,
Wei Sun - ,
Ping Liu *- ,
Shengyong Zhang - , and
Jian-Li Li *
This publication is free to access through this site. Learn More
ACS Editors' Choice® is a collection designed to feature scientific articles of broad public interest. Read the latest articles
Accurate quantification of cisplatin (cDDP) in body fluids (blood, urine, and ascites) is crucial in monitoring therapeutic processes, assessing drug metabolism, and optimizing treatment schedules for cancer patients. Nonetheless, due to the inherent fluorescence and complexity of the body fluid matrix, along with the low cDDP concentrations in these fluids during treatment, using fluorescent sensors for fluid detection remains a subject of ongoing research. Herein, a series of water-soluble cDDP-activatable fluorescent sensors was rationally constructed by introducing thioether groups to the xanthene skeleton based on the chalcogenophilicity of platinum. These sensors exhibit excellent sensitivity and certain anti-interference capabilities for sensing cDDP in living cells, rat tissues, and zebrafish. Especially, with a simplified sample pretreatment procedure, for the first time, Rh3 and Rh4 have enabled quantitative detection of cDDP levels in diversiform body fluids from clinical ovarian and bladder cancer patients. These results are highly consistent with those obtained by ICP-MS detection. This work paves the way for utilizing fluorescent sensors in clinical body fluid analysis, thus potentially revolutionizing the monitoring methods of cDDP in clinic settings.

A Complex Oxide Containing Inherent Peroxide Ions for Catalyzing Oxygen Evolution Reactions in Acid
Jie Dai - ,
Zihan Shen - ,
Yu Chen - ,
Mengran Li - ,
Vanessa K. Peterson - ,
Jiayi Tang - ,
Xixi Wang - ,
Yu Li - ,
Daqin Guan - ,
Chuan Zhou - ,
Hainan Sun - ,
Zhiwei Hu - ,
Wei-Hsiang Huang - ,
Chih-Wen Pao - ,
Chien-Te Chen - ,
Yinlong Zhu *- ,
Wei Zhou - , and
Zongping Shao *
Proton exchange membrane water electrolyzers powered by sustainable energy represent a cutting-edge technology for renewable hydrogen generation, while slow anodic oxygen evolution reaction (OER) kinetics still remains a formidable obstacle that necessitates basic comprehension for facilitating electrocatalysts’ design. Here, we report a low-iridium complex oxide La1.2Sr2.7IrO7.33 with a unique hexagonal structure consisting of isolated Ir(V)O6 octahedra and true peroxide O22– groups as a highly active and stable OER electrocatalyst under acidic conditions. Remarkably, La1.2Sr2.7IrO7.33, containing 59 wt % less iridium relative to the benchmark IrO2, shows about an order of magnitude higher mass activity, 6-folds higher intrinsic activity than the latter, and also surpasses the state-of-the-art Ir-based oxides ever reported. Combined electrochemical, spectroscopic, and density functional theory investigations reveal that La1.2Sr2.7IrO7.33 follows the peroxide-ion participation mechanism under the OER condition, where the inherent peroxide ions with accessible nonbonded oxygen states are responsible for the high OER activity. This discovery offers an innovative strategy for designing advanced catalysts for various catalytic applications.

Leveraging Dual-Ligase Recruitment to Enhance Protein Degradation via a Heterotrivalent Proteolysis Targeting Chimera
Adam G. Bond - ,
Miquel Muñoz i Ordoño - ,
Celia M. Bisbach - ,
Conner Craigon - ,
Nikolai Makukhin - ,
Elizabeth A. Caine - ,
Manjula Nagala - ,
Marjeta Urh - ,
Georg E. Winter *- ,
Kristin M. Riching *- , and
Alessio Ciulli *
This publication is Open Access under the license indicated. Learn More
Proteolysis targeting chimera (PROTAC) degraders are typically bifunctional with one E3 ligase ligand connected to one target protein ligand via a linker. While augmented valency has been shown with trivalent PROTACs targeting two binding sites within a given target protein, or used to recruit two different targets, the possibility of recruiting two different E3 ligases within the same compound has not been demonstrated. Here we present dual-ligase recruitment as a strategy to enhance targeted protein degradation. We designed heterotrivalent PROTACs composed of CRBN, VHL and BET targeting ligands, separately tethered via a branched trifunctional linker. Structure–activity relationships of 12 analogues qualifies AB3067 as the most potent and fastest degrader of BET proteins, with minimal E3 ligase cross-degradation. Comparative kinetic analyses in wild-type and ligase single and double knockout cell lines revealed that protein ubiquitination and degradation induced by AB3067 was contributed to by both CRBN and VHL in an additive fashion. We further expand the scope of the dual-ligase approach by developing a heterotrivalent CRBN/VHL-based BromoTag degrader and a tetravalent PROTAC comprising of two BET ligand moieties. In summary, we provide proof-of-concept for dual-E3 ligase recruitment as a strategy to boost degradation fitness by recruiting two E3 ligases with a single degrader molecule. This approach could potentially delay the outset of resistance mechanisms involving loss of E3 ligase functionality.

Generative Pretrained Transformer for Heterogeneous Catalysts
Dong Hyeon Mok - and
Seoin Back *
Discovery of novel and promising materials is a critical challenge in the field of chemistry and material science, traditionally approached through methodologies ranging from trial-and-error to machine-learning-driven inverse design. Recent studies suggest that transformer-based language models can be utilized as material generative models to expand the chemical space and explore materials with desired properties. In this work, we introduce the catalyst generative pretrained transformer (CatGPT), trained to generate string representations of inorganic catalyst structures from a vast chemical space. CatGPT not only demonstrates high performance in generating valid and accurate catalyst structures but also serves as a foundation model for generating the desired types of catalysts by text-conditioning and fine-tuning. As an example, we fine-tuned the pretrained CatGPT using a binary alloy catalyst data set designed for screening two-electron oxygen reduction reaction (2e-ORR) catalyst and generated catalyst structures specialized for 2e-ORR. Our work demonstrates the potential of generative language models as generative tools for catalyst discovery.

Rethinking Assumptions: Assessing the Impact of Strong Magnetic Fields on Luminescence Thermometry
Maxime Aragon-Alberti - ,
Mateusz Dyksik - ,
Carlos D. S. Brites - ,
Jérôme Rouquette - ,
Paulina Plochocka *- ,
Luís D. Carlos *- , and
Jérôme Long *
Luminescence (nano)thermometry has exploded in popularity, offering a remote detection way to measure temperature across diverse fields like nanomedicine, microelectronics, catalysis, and plasmonics. A key advantage is its supposed immunity to strong electromagnetic fields, a crucial feature in many environments. However, this assumption lacks comprehensive experimental verification as most of the proposed luminescent thermometers rely on magnetic ions, such as lanthanides. Here, we address this gap by critically examining the thermometric response of the luminescent molecular thermometer [Tb0.93Eu0.07(bpy)2(NO3)3] (bpy = 2,2′-bipyridine) under high magnetic fields (up to 58 T). Our findings reveal that the conventional intensity-based method for Tb/Eu luminescent thermometers fails even under weak magnetic fields. However, careful data analysis identified specific transitions with minimal magnetic correlation, enabling the thermometer to operate across the entire temperature range up to 20 T, and with larger fields for temperatures exceeding 120 K. This study highlights the strong dependence of thermometric performance on material properties, urging caution, but also offers a path forward for developing robust luminescent thermometers in such environments.

High-Throughput Search for Photostrictive Materials Based on a Thermodynamic Descriptor
Zeyu Xiang - ,
Yubi Chen - ,
Yujie Quan - , and
Bolin Liao *
Photostriction is a phenomenon that can potentially improve the precision of light-driven actuation, the sensitivity of photodetection, and the efficiency of optical energy harvesting. However, known materials with significant photostriction are limited, and effective guidelines to discover new photostrictive materials are lacking. In this study, we perform a high-throughput computational search for new photostrictive materials based on simple thermodynamic descriptors, namely, the band gap pressure and stress coefficients. Using the Δ-SCF method based on density functional theory, we establish that these descriptors can accurately predict intrinsic photostriction in a wide range of materials. Subsequently, we screened over 4770 stable semiconductors with a band gap below 2 eV from the Materials Project database to search for strongly photostrictive materials. This search identifies Te2I as the most promising candidate, with photostriction along out-of-plane direction exceeding 8 × 10–5 with a moderate photocarrier concentration of 1018 cm–3. Furthermore, we provide a detailed analysis of factors contributing to strong photostriction, including bulk moduli and band-edge orbital interactions. Our results provide physical insights into the photostriction of materials and demonstrate the effectiveness of using simple descriptors in high-throughput searches for new functional materials.

Early Folding Dynamics of i-Motif DNA Revealed by pH-Jump Time-Resolved X-ray Solution Scattering
Arnold M. Chan - ,
Sasha B. Ebrahimi - ,
Devleena Samanta - ,
Denis Leshchev - ,
Adam K. Nijhawan - ,
Darren J. Hsu - ,
Madeline B. Ho - ,
Namrata Ramani - ,
Irina Kosheleva - ,
Robert Henning - ,
Chad A. Mirkin - ,
Kevin L. Kohlstedt *- , and
Lin X. Chen *
The i-motif is a pH-responsive cytosine-rich oligonucleotide sequence that forms, under acidic conditions, a quadruplex structure. This tunable structural switching has made the i-motif a useful platform for designing pH-responsive nanomaterials. Despite the widespread application of i-motif DNA constructs as biomolecular switches, the mechanism of i-motif folding on the atomic scale has yet to be established. We investigate the early folding structural dynamics of i-motif oligonucleotides with laser-pulse-induced pH-jump time-resolved X-ray solution scattering. Following the pH-jump, we observe that the initial random coil ensemble converts into a contracted intermediate state within 113 ns followed by further folding on the 10 ms time scale. We reveal the representative structures of these transient species, hitherto unknown, with molecular dynamics simulations and ensemble fitting. These results pave the way for understanding metastable conformations of i-motif folding and for benchmarking emerging theoretical models for simulating noncanonical nucleic acid structures.

Biosynthesis-Encoded Lipogenic Acetyl-CoA Measurement Using NMR Reveals Glucose-Driven Lipogenesis and Glutamine’s Alternative Roles in Kidney Cancer
Sihyang Jo - ,
Munjun Seo - ,
Thi Ha Nguyen - ,
Jin Wook Cha - ,
Yong Jin An *- , and
Sunghyouk Park *
Fatty acid de novo synthesis (FADNS) is a critical process in lipogenesis that is characteristically altered in clear cell renal cell carcinoma (ccRCC), which is the major type of kidney cancer. An important challenge in studying the FADNS process has been the accurate measurement of cytosolic lipogenic acetyl-CoA (AcCoA), the precursor in FADNS, due to its compartmentalization within cells. Here, we describe a novel NMR-based method to decode the isotopic enrichment of lipogenic AcCoA, which, as we demonstrated, is encoded in the simple signal ratios of the geminal methyl groups of lanosterol during its biosynthesis. The approach was validated based on the independence of the tracer enrichment and species along with the expected FADNS modulation using differentially enriched tracers and a well-studied drug. Application of this technique to 786-O ccRCC cells showed that glucose may serve as a major carbon source for lipogenic AcCoA in FADNS at physiological nutrient concentrations, at odds with previous studies that indicated glutamine’s dominant role through reductive carboxylation under higher nutrient conditions. Further investigation into glutamine’s alternative roles in ccRCC cells suggested its major involvement in the bioenergetic TCA cycle, pyrimidine synthesis, and glutathione synthesis, which is also critical in ccRCC growth. The glutamine-dependent glutathione synthesis was also suggested as a possible metabolic vulnerability compared to normal kidney cells using a glutathione synthesis inhibitor. The current study provides a simple tool for studying an important aspect of lipid metabolism and suggests translational implications for targeting glucose-driven lipogenesis and glutamine-supported glutathione synthesis in ccRCC.

Synthesis of P(V)-Stereogenic Phosphorus Compounds via Organocatalytic Asymmetric Condensation
Fengrui Che - ,
Junyuan Hu - ,
Minghong Liao - ,
Zhongfu Luo - ,
Hongyan Long - ,
Benpeng Li - ,
Yonggui Robin Chi - , and
Xingxing Wu *
Enantioenriched phosphorus(V)-stereogenic compounds, featuring a pentavalent phosphorus atom as the stereogenic center, are crucial in various natural products, drugs, bioactive molecules, and catalysts/ligands. While a handful of stereoselective synthetic approaches have been developed, achieving direct stereocontrol at the phosphorus atom through catalytic generation of phosphorus(V)-heteroatom bonds continues to be a formidable challenge. Here, we disclose an organocatalytic asymmetric condensation strategy that employs a novel activation mode of stable feedstock phosphinic acids by the formation of mixed phosphinic anhydride as the reactive species to facilitate further catalyst-controlled asymmetric P–O bond formations, involving a dynamic kinetic asymmetric transformation (DYKAT) process with alcohol nucleophiles via a cinchonidine-derived bifunctional catalyst. The resulting H-phosphinate intermediates allow further stereospecific derivatizations, affording modular access to a diverse library of chiral phosphonates and phosphonamidates with notable antibacterial activity. Furthermore, this synthetic platform facilitates P–O/N coupling with various natural products and drugs, presenting a valuable tool for medicine and agrochemical discovery.

Plateau–Rayleigh Instability in Soft-Lattice Inorganic Solids
Zhen-Chao Shao - ,
Xianyun Jiang - ,
Chong Zhang - ,
Tianhao Wang - ,
Yan-Ru Wang - ,
Guo-Qiang Liu - ,
Zong-Ying Huang - ,
Yu-Zhuo Zhang - ,
Liang Wu - ,
Zhong-Huai Hou - ,
Huijun Jiang *- ,
Yi Li *- , and
Shu-Hong Yu *
Plateau–Rayleigh instability─a macroscopic phenomenon describing the volume-constant breakup of one-dimensional continuous fluids─has now been widely observed in adatoms, liquids, polymers, and liquid metals. This instability enables controlled wetting–dewetting behavior at fluid–solid interfaces and, thereby, the self-limited patterning into ordered structures. However, it has yet to be observed in conventional inorganic solids, as the rigid lattices restrict their “fluidity”. Here, we report the general fluid-like Plateau–Rayleigh instability of silver-based chalcogenide semiconductors featuring soft-lattice ionic crystals. It enables postsynthetic morphing from conformal core–shell nanowires to periodically coaxial ones. We reveal that such self-limited reconstruction is thermodynamically driven by the surface energy and interface energy and kinetically favored by the high ionic diffusion coefficients of subnanoscale soft-lattice shells. The resulting periodic heterostructures can be topotactically transformed for epitaxial combinations of functional semiconductors free from the lattice-matching rule. This fluid-like behavior in soft inorganic solids thus offers routes toward sophisticated nanostructures and controllable patterning at all-inorganic solid–solid interfaces.

Precisely Controlling the Activation of an Iron-Locked Drug Generator in the Liver Sinusoid to Enhance Barrier Penetration and Reduction of Liver Fibrosis
Quanwei Sun - ,
Wenshuo Yang - ,
Zhengwei Song - ,
Huiyu Lu - ,
Wencui Shang - ,
Huihui Li - ,
Zexin Yang - ,
Wenheng Gao - ,
Yunlong Li - ,
Yujing Xu - ,
Min Luo - ,
Kang Liu - ,
Qinghua Wu - ,
Zihua Xuan - ,
Wei Shen *- ,
Ye Yang *- , and
Dengke Yin *
Complex physical barriers and the nanomaterial’s clearance mechanism in the liver greatly hinder the feasibility of using a conventional liver-targeting nanoplatform to deliver antifibrotic drugs to pathological sites for the treatment of liver fibrosis. Here, a novel drug delivery strategy was designed to overcome drug penetration barriers in a fibrotic liver and cooperated with oral nattokinase (NKase)-mediated antifibrosis therapy as a proof of concept, which relies on the coadministration of a nanosized iron-locked drug generator (named Pro-HAase) and orally absorbed iron chelator deferasirox (DFX). Such a strategy starts from the rapid accumulation of intravenously injected Pro-HAase in the microcapillaries of the fibrotic liver followed by disrupting the polyphenol-iron coordination inside Pro-HAase by DFX, liberating antifibrotic components, including procyanidine (PA) and hyaluronidase (HAase). Attractively, absorption of DFX requires the sequential processes of traversing the intestinal mucosa and targeting the liver, which enable DFX to preferentially disassemble Pro-HAase accumulated in the liver sinusoid rather than in systemic circulation or other organs, thus avoiding the off-target activation of Pro-HAase and depletion of the normal iron pool. The in situ disassembly process decreases the sequestration of Pro-HAase by cells of the mononuclear phagocyte system and promotes gradient-driven permeation of therapeutic components to surrounding liver tissues within 2 h, accompanied by biliary excretion of the inactive iron-DFX complex. As a result, the cooperation of Pro-HAase and DFX not only allows NKase-mediated therapy to completely reverse liver fibrosis but also suppresses the chronic hepatotoxicity of residual liver iron after multiple doses of Pro-HAase. The high spatiotemporal precision, unique barrier-penetration mechanism, and self-detoxification ability of this strategy will inspire the rational design of analogous iron-locked nanosystems to improve the therapeutic outcomes of liver fibrosis or other liver diseases.

Gold/HNTf2-Cocatalyzed Asymmetric Annulation of Diazo-Alkynes: Divergent Construction of Atropisomeric Biaryls and Arylquinones
Yi-Bo Wang - ,
Wei Liu - ,
Ting Li - ,
Yazhu Lu - ,
Yi-Tian Yu - ,
Hai-Tao Liu - ,
Meiwen Liu - ,
Pengfei Li - ,
Peng-Cheng Qian *- ,
Hao Tang *- ,
Jia Guan - ,
Long-Wu Ye - , and
Long Li *
Due to the inherent challenges posed by the linear coordination of gold(I) complexes, asymmetric gold-catalyzed processes remain challenging, particularly in the atroposelective synthesis of axially chiral skeletons. Except for extremely few examples of intramolecular annulations, the construction of axial chirality via asymmetric gold-catalyzed intermolecular alkyne transformation is still undeveloped. Herein, a gold/HNTf2-cocatalyzed asymmetric diazo-alkyne annulation is developed, allowing the atroposelective and divergent synthesis of chiral non-C2-symmetric biaryls and arylquinones in generally good to excellent yield (up to 93% yield) and enantioselectivity (up to 99% ee), with broad substrate scope. Notably, this work represents the first gold-catalyzed atroposelective construction in an intermolecular manner. More interestingly, this strategy is successfully extended to the first asymmetric construction of seven-membered-ring atropisomers bearing one carbon-centered chirality in excellent diastereoselectivity and high enantioselectivity (up to 93% ee and 50:1 dr). Remarkably, the utility of this methodology is further illustrated by the successful application of a representative axially chiral ligand in a series of enantioselective reactions. Importantly, the Brønsted acid as a proton-shuttle cocatalyst significantly promotes this asymmetric annulation. Additionally, the origin of enantioselectivity of this annulation and the role of HNTf2 are disclosed by density functional calculations and control experiments.

DNA Nanopatch-Specific Modification of Probiotics for Ultrasound-Triggered Inflammatory Bowel Disease Therapy
Xiangbowen Jin - ,
Hongyang Li - ,
Sheng Pan - ,
Bin Song - ,
Yanping Jiang - ,
Haoliang Shi - ,
Jiawei Zhang - ,
Binbin Chu *- ,
Houyu Wang *- , and
Yao He *
Probiotics offer promising results for treating inflammatory bowel disease, yet precision therapy remains challenging, particularly in manipulating probiotics spatially and temporally and shielding them from oxidative stress. To address these limitations, herein we synthesized bacteria-specific DNA nanopatches to modify ultrasound-triggered engineered Escherichia coli Nissle 1917. These probiotics produced the anti-inflammatory cytokine interleukin-10 when stimulated by ultrasound and were fortified with DNPs for oxidative stress resistance. The DNPs were composed of rectangular DNA origami nanosheets with reactive oxygen species’ scavenging ability and bacterial targeting ligands of maltodextrin molecules. We systematically demonstrated that the DNPs could selectively attach to bacterial surface but not mammalian cell surface via the maltodextrin transporter pathway. To further enhance the bioavailability of engineered probiotics in the gastrointestinal tract, we employed a self-assembly strategy to encapsulate them using chitosan and sodium alginate. In a murine model of ulcerative colitis, this system significantly improved the gut barrier integrity and reduced inflammation. Our results indicate that this DNA nanopatch-bacteria system holds substantial promise for mitigating oxidative stress, correcting microbiota dysbiosis, and enhancing the intestinal barrier function in colitis.

Reversible Circularly Polarized Luminescence Inversion and Emission Color Switching in Photo-Modulated Supramolecular Polymer for Multi-Modal Information Encryption
Kuo Fu - ,
Da-Hui Qu *- , and
Guofeng Liu *
Constructing circularly polarized luminescence (CPL) materials that exhibit dynamic handedness inversion and emissive color modulation for multimodal information encryption presents both a significant challenge and a compelling opportunity. Here, we have developed a pyridinethiazole acrylonitrile-cholesterol derivative (Z-PTC) that exhibits wavelength-dependent photoisomerization and photocyclization, enabling dynamic handedness inversion and emissive color modulation in supramolecular assemblies with decent CPL activity. Coordination with Ag+ ions form the Z-PTC Ag supramolecular polymer (SP1), which assembles into nanotubes displaying enhanced positive yellow-green CPL. Irradiation at 454 nm transforms SP1 into nanospheres of a mixture supramolecular polymer (SP2) of Z/E-PTC Ag, displaying inverted supramolecular chirality and emitting negative orange-yellow CPL. Reheating SP2 to 343 K restores the original nanotube structure via excellent reversible photoisomerization. Exposure to 365 nm light also induces CPL inversion from positive to negative and triggers morphological changes from SP1 to SP2. Prolonged irradiation causes further transformation into irregular supramolecular aggregate, shifting the emission color to blue and eliminating CPL. These dynamic properties of the multicolor CPL system, including reversible handedness inversion, can also be realized in the semisolid state, exhibiting promising potential for multimodal information encryption applications with enhanced security and complexity.

Structural Disorder of a Layered Lithium Manganese Oxide Cathode Paving a Reversible Phase Transition Route toward Its Theoretical Capacity
Suwon Lee - ,
Seongkoo Kang - ,
Youngju Choi - ,
Jihyun Kim - ,
Junghoon Yang - ,
Daseul Han - ,
Kyung-Wan Nam - ,
Olaf J. Borkiewicz - ,
Jiliang Zhang - , and
Yong-Mook Kang *
Layered lithium manganese oxides suffer from irreversible phase transitions induced by Mn migration and/or dissolution associated with the Jahn–Teller effect (JTE) of Mn3+, leading to inevitable capacity fading during cycling. The popular doping strategy of oxidizing Mn3+ to Mn4+ to relieve the JTE cannot completely eliminate the detrimental structural collapse from the cooperative JTE. Therefore, they are considered to be impractical for commercial use as cathode materials. Here, we demonstrate a layered lithium manganese oxide that can be charged and discharged without any serious structural collapse using metastable Li-birnessite with controlled structural disorder. Although Li-birnessite is thermodynamically unstable under ambient conditions, Li ion exchange into Na-birnessite followed by an optimal dehydration resulted in a disordered Li-birnessite. The control over crystal water in the interlayer provides intriguing short-range order therein, which can help to suppress parasitic Mn migration and dissolution, thereby ensuring a reversible electrochemical cycling. The Mn redox behavior and local structure change of the Li-birnessite were investigated by ex situ soft X-ray absorption spectroscopy (sXAS) and X-ray pair distribution function (PDF) analysis. The combined sXAS and PDF with electrochemical analyses disclosed that the reversible Mn redox and suppressed phase transitions in Dh Li-birnessite contribute to dramatically improving its electrochemical reversiblity during cycling. Our findings underscore the substantial effects of controlled static disorder on the structural stability and electrochemical reversibility of a layered lithium manganese oxide, Li-birnessite, which extends the practical capacity of layered oxides close to their theoretical limit.

Three-Dimensional Mesoporous Covalent Organic Framework for Photocatalytic Oxidative Dehydrogenation to Quinoline
Chou-Hung Hsueh - ,
Chang He - ,
Jiaqi Zhang - ,
Xin Tan - ,
Haojie Zhu - ,
Weng-Chon Max Cheong - ,
An-Zhen Li - ,
Xin Chen - ,
Haohong Duan - ,
Yingbo Zhao *- , and
Chen Chen *
Developing precious metal-free catalysts for organic reactions under mild conditions is urgent. Herein, we report a three-dimensional covalent organic framework (3D-COF) with high crystallinity and permanent pores, termed 3D-TABPA-COF, for the oxidation of tetrahydroquinoline to quinoline. The 3D-TABPA-COF assembled based on N4,N4-bis(4′-amino-[1,1′-biphenyl]-4-yl)-[1,1′-biphenyl]-4,4′-diamine (TABPA) is the catalytic active center for the conversion of tetrahydroquinoline. The triphenylamine in the structure is an effective photosensitizer, which not only enhances the light absorption capacity but also facilitates the rapid transfer of photogenerated electrons and ensures effective carrier separation. The obtained 3D-TABPA-COF has a high specific surface area (2745.06 m2 g–1) and mesopores of 3.57 nm. This is attributed to the fact that the bor topology is not easy to interpenetrate. It can oxidize tetrahydroquinoline to obtain quinoline efficiently under visible light irradiation. In addition, we also performed various photochemical characterizations combined with density functional theory calculations to elucidate the reaction mechanism from tetrahydroquinoline to quinoline. This work provides a feasible strategy for constructing 3D-COF to achieve efficient photocatalytic organic reactions.

Real-Space Spectral Determination of Short Single-Stranded DNA Sequence Structures
Yu Han - ,
Li Dong - ,
Lu-Yao Zhu - ,
Chun-Rui Hu - ,
Hang Li - ,
Yang Zhang - ,
Chao Zhang *- ,
Yao Zhang *- , and
Zhen-Chao Dong *
Resolving the sequence and structure of flexible biomolecules such as DNA is crucial to understanding their biological mechanisms and functions. Traditional structural biology methods remain challenging for the analysis of small and disordered biomolecules, especially those that are difficult to label or crystallize. Recent development of single-molecule tip-enhanced Raman spectroscopy (TERS) offers a label-free approach to identifying nucleobases in a single DNA chain. However, a clear demonstration of sequencing both spatially and spectrally at single-base resolution is still elusive due to the challenges caused by weak Raman signals and the flexibility of DNA molecules. Here, we report a proof-of-principle demonstration to this end, spectrally resolving in real space individual nucleobases and their sequence structures within a short, single-stranded DNA molecule artificially designed. This breakthrough is achieved through the development of subnanometer-resolved low-temperature TERS methodology for such thermally unstable flexible biomolecules. Further TERS mapping over individual nucleobases provides additional structural information about the molecular configurations and even the locations of functional groups, offering a way to track modification types and binding sites in biomolecules.

Why Does a Transition Metal Dichalcogenide Nanoribbon Narrow into a Nanowire under Electron Irradiation?
Yue Liu - ,
Tian Cui *- , and
Da Li *
Transition metal dichalcogenide (TMDC) nanowires have practical applications in 1D electron channels, spintronics, optoelectronics, and catalysis due to their authentic subnanometer width (<1 nm) and intrinsic metallicity. Although narrowing of a TMDC nanoribbon into a nanowire under electron irradiation has been frequently observed in the synthesis of TMDC nanowires, the mechanism underlying this unexpected structural transformation remains a mystery. Here, to reveal the underlying mechanism, we combine first-principles calculations with a global structure search of 1D nanowires and show that a nanoribbon of 1H-phase MoS2 with a width narrower than 6 rings is energetically unfavorable compared with its nanowire counterpart due to the edge–edge interaction. The bending effect induced by S defects under electron irradiation is the major driving force for the transition of MoS2 nanoribbon into a nanowire. We predict that the precursor of the Mo6S6 nanowire is a well-defined Mo11S11-i nanowire with an unexpected stoichiometry. The intrinsic local compressive strain triggers a phase transition from Mo11S11-i to its slightly modified sister nanowire, Mo11S11-ii, which is characterized by the configuration (Mo1S1)5&Mo6S6. Triggered by electron irradiation, the nanoribbon undergoes a step-by-step narrowing process with sequential peeling of a Mo1S1 fragment in each step to form a robust Mo6S6 nanowire. This unique narrowing mechanism is universal for the nanoribbon-to-nanowire transformation of other TMDCs under electron irradiation. Our study highlights a hitherto unexplored mechanism for creating individual M6X6 nanowires and contributes to an in-depth understanding of the narrowing of TMDC nanoribbons under electron irradiation.

Deriving Chiroptical Properties from Intrinsically Achiral Building Blocks of One-Dimensional CsPbBr3 Perovskite Nanowires
Shramana Guha - ,
Suman Bera - ,
Arghyadeep Garai - ,
D. D. Sarma - ,
Narayan Pradhan - , and
Somobrata Acharya *
Chirality is a ubiquitous feature in biological systems and occurs even in certain inorganic crystals. Interestingly, some inorganic nanocrystals have been shown to possess chirality, despite their achiral bulk forms. However, the mechanism of chirality formation and chiroptical responses in such nanocrystals is still ambiguous due to the presence of chiral organic ligands used to passivate such nanocrystals. Here, we recognize intrinsic chiroptical responses from lead halide perovskite nanowires with different length scales. Cube-connected nanowires with minimum interfacial contacts make their arrangement chiral for chiroptical responses even in the absence of chiral ligands. The chiral nanowires with varying lengths serve as a systematic platform for improving dissymmetric factors significantly with increasing lengths. The dissymmetric factor of the longest nanowires reaches 1.4 × 10–2, which is the highest among the intrinsic chiral perovskite nanocrystals at present. The nanowires generate circularly polarized luminescence, which has been seldom reported in halide perovskite nanocrystals in the absence of any chiral ligands. Furthermore, we find that chirality exists in the basic unit consisting of two corner-connected cubes in the form of a dimer. The intrinsic chirality of the nanowires is determined by the lattice rotation of connected cubes along the interfacial boundaries, which is different from the commonly observed chirality induced by chiral ligands. Such chiral lead halide perovskite nanocrystals with robust chiroptical properties provide an ideal platform for understanding the origin of intrinsic chirality and the rational design of anisotropic chiral nanostructures.

Oxygen Vacancy Boosts Nitrogen-Centered Radical Coupling Initiated by Primary Amine Electrooxidation
Mengwei Han - ,
Yongxiang Luo - ,
Leitao Xu - ,
Wei Chen *- ,
Chengmei Li - ,
Yu-Cheng Huang - ,
Yandong Wu - ,
Yimin Jiang - ,
Wenjie Wu - ,
Ruiqi Wang - ,
Ying-Rui Lu - ,
Yuqin Zou *- , and
Shuangyin Wang *
Synthesis of nitrogen-centered radicals (NCRs) for radical coupling reactions is a powerful and versatile tool in the arsenal of organic synthetic chemistry. However, there are few reports on the direct synthesis of NCRs based on aqueous electrocatalysis. Herein, we present a new electrochemical primary amine oxidation reaction (ePAOR) system with R1R2-CH-NH2 as the substrate for synthesizing NCRs and N–N coupling products. However, ePAOR on the model catalyst (NiO) suffers from low N–N coupling selectivity due to the weak adsorption energy of imine (R1R2-C═NH) intermediates. Guided by theoretical calculations, the oxygen vacancy gives NiO a strong adsorption capacity of R1R2-C═NH so that it boosts nitrogen-centered radical coupling initiated by the ePAOR on oxygen vacancy-rich NiO (VO-NiO), and the effective utilization rate of NCRs was increased from 36 to 75%. This approach is compatible with a wide range of primary amines and can be applied to N–N cross-coupling systems as well.

Cryo-EM Structures Reveal the Unique Binding Modes of Metyltetraprole in Yeast and Porcine Cytochrome bc1 Complex Enabling Rational Design of Inhibitors
Yu-Xia Wang - ,
Ying Ye - ,
Zhi-Wen Li - ,
Guang-Rui Cui - ,
Xing-Xing Shi - ,
Ying Dong - ,
Jia-Jia Jiang - ,
Jia-Yue Sun - ,
Ze-Wei Guan - ,
Nan Zhang - ,
Qiong-You Wu - ,
Fan Wang - ,
Xiao-Lei Zhu *- , and
Guang-Fu Yang *
Cytochrome bc1 (complex III) represents a significant target for the discovery of both drugs and fungicides. Metyltetraprole (MET) is commonly classified as a quinone site inhibitor (QoI) that combats the G143A mutated isolate, which confers high resistance to strobilurin fungicides such as pyraclostrobin (PYR). The binding mode and antiresistance mechanism of MET remain unclear. Here, we determined the high-resolution structures of inhibitor-bound S. cerevisiae complex III (MET, 2.52 Å; PYR, 2.42 Å) and inhibitor-bound porcine complex III (MET, 2.53 Å; PYR, 2,37 Å) by cryo-electron microscopy. The distinct binding modes of MET and PYR were observed for the first time. Notably, the MET exhibited different binding modes in the two species. In S. cerevisiae, the binding site of MET was the same as PYR, serving as a Pm-type inhibitor of the Qo site. However, in porcine, MET acted as a dual-target inhibitor of both Qo and Qi. Based on the structural insights, a novel inhibitor (YF23694) was discovered and demonstrated excellent fungicidal activity against downy mildew and powdery mildew fungi. This work provides a new starting point for the design of the next generation of inhibitors to overcome the resistance.

Circular Engineered Sortase for Interrogating Histone H3 in Chromatin
Samuel D. Whedon - ,
Kwangwoon Lee - ,
Zhipeng A. Wang - ,
Emily Zahn - ,
Congcong Lu - ,
Maheeshi Yapa Abeywardana - ,
Louise Fairall - ,
Eunju Nam - ,
Sarah DuBois-Coyne - ,
Pablo De Ioannes - ,
Xinlei Sheng - ,
Adelina Andrei - ,
Emily Lundberg - ,
Jennifer Jiang - ,
Karim-Jean Armache - ,
Yingming Zhao - ,
John W. R. Schwabe - ,
Mingxuan Wu *- ,
Benjamin A. Garcia *- , and
Philip A. Cole *
This publication is Open Access under the license indicated. Learn More
Reversible modification of the histone H3 N-terminal tail is critical in regulating the chromatin structure, gene expression, and cell states, while its dysregulation contributes to disease pathogenesis. Understanding the crosstalk between H3 tail modifications in nucleosomes constitutes a central challenge in epigenetics. Here, we describe an engineered sortase transpeptidase, cW11, that displays highly favorable properties for introducing scarless H3 tails onto nucleosomes. This approach significantly accelerates the production of both symmetrically and asymmetrically modified nucleosomes. We demonstrate the utility of asymmetrically modified nucleosomes produced in this way in dissecting the impact of multiple modifications on eraser enzyme processing and molecular recognition by a reader protein. Moreover, we show that cW11 sortase is very effective at cutting and tagging histone H3 tails from endogenous histones, facilitating multiplex “cut-and-paste” middle-down proteomics with tandem mass tags. This cut-and-paste proteomics approach permits the quantitative analysis of histone H3 modification crosstalk after treatment with different histone deacetylase inhibitors. We propose that these chemoenzymatic tail isolation and modification strategies made possible with cW11 sortase will broadly power epigenetic discovery and therapeutic development.

Slow Dephasing of Coherent Optical Phonons in Two-Dimensional Lead Organic Chalcogenides
Hanjun Yang *- ,
Sagarmoy Mandal - ,
Bowen Li - ,
Tushar Kanti Ghosh - ,
Jonas Mark Peterson - ,
Peijun Guo - ,
Letian Dou - ,
Ming Chen *- , and
Libai Huang *
Hybrid organic–inorganic semiconductors with strong electron–phonon interactions provide a programmable platform for developing a variety of electronic, optoelectronic, and quantum materials by controlling these interactions. However, in current hybrid semiconductors such as halide perovskites, anharmonic vibrations with rapid dephasing hinder the ability to coherently manipulate phonons. Here, we report the observation of long-lived coherent phonons in lead organic chalcogenides (LOCs), a new family of hybrid two-dimensional semiconductors. These materials feature harmonic phonon dynamics despite distorted lattices, combining long phonon dephasing times with tunable semiconducting properties. A dephasing time -up to 75 ps at 10 K, with up to ∼500 cycles of phonon oscillation between scattering events, was observed, corresponding to a dimensionless harmonicity parameter that is more than an order of magnitude larger than that of halide perovskites. The phonon dephasing time is significantly influenced by anharmonicity and centrosymmetry, both of which can be tuned through the design of the organic ligands enabled by the direct bonding between the organic and inorganic motifs. This research opens new opportunities for the manipulation of electronic properties with coherent phonons in hybrid semiconductors.

Strain-Enhanced Low-Temperature High Ionic Conductivity in Perovskite Nanopillar-Array Films
Chuanrui Huo - ,
Liyang Ma - ,
Yonghao Yao - ,
Xinyu Cui - ,
Shi Liu - ,
Shiqing Deng *- , and
Jun Chen *
Solid oxide ionic conductors with high ionic conductivity are highly desired for oxide-based electrochemical and energy devices, such as solid oxide fuel cells. However, achieving high ionic conductivity at low temperatures, particularly for practical out-of-plane transport applications, remains a challenge. In this study, leveraging the emergent interphase strain methodology, we achieve an exceptional low-temperature out-of-plane ionic conductivity in Na0.5Bi0.5TiO3 (NBT)-MgO nanopillar-array films. This ionic conductivity (0.003 S cm–1 at 400 °C) is over one order of magnitude higher than that of the pure NBT films and surpasses all conventional intermediate-temperature ionic conductors. Combining atomic-scale electron microscopy studies and first-principles calculations, we attribute this enhanced conductivity to the well-defined periodic alignment of NBT and MgO nanopillars, where the interphase tensile strain reaches as large as +2%. This strain expands the c-lattice and weakens the oxygen bonding, reducing oxygen vacancy formation and migration energy. Moreover, the interphase strain greatly enhances the stability of NBT up to 600 °C, well above the bulk transition temperature of 320 °C. On this basis, we clarify the oxygen migration path and establish an unambiguous strain–structure–ionic conductivity relationship. Our results demonstrate new possibilities for designing applicable high-performance ionic conductors through strain engineering.

Melt Alloying of Two-Dimensional Hybrid Perovskites: Composition-Dependence of Thermal and Optical Properties
Arad Lang *- ,
Celia Chen - ,
Chumei Ye - ,
Lauren N. McHugh - ,
Xian Wei Chua - ,
Samuel D. Stranks - ,
Siân E. Dutton - , and
Thomas D. Bennett
This publication is Open Access under the license indicated. Learn More
Melt alloying, the process of melting a physical powder blend to create a homogeneous alloy, is widely used in materials processing. By carefully selecting the materials and their proportions, the physical properties of the resulting alloy can be precisely controlled. In this study, we investigate the possibility of utilizing melt alloying principles for meltable two-dimensional hybrid organic–inorganic perovskites (2D-HOIPs). We blend and melt mixtures of two selected 2D-HOIPs: the glass-forming (S-NEA)2PbBr4 (S-NEA = (S)-(−)-1-(1-naphthyl)ethylammonium) and the liquid-forming (1-MHA)2PbI4 (1-MHA = 1-methylhexylammonium). Upon melting and cooling, 1-MHA-poor blends (X1-MHA ≤ 50% mol, where X1-MHA corresponds to the relative molar concentration of (1-MHA)2PbI4 in the blend) form a hybrid glass, while 1-MHA-rich blends (X1-MHA ≥ 70% mol) crystallize. The melting temperature of all blends, as well as the glass transition temperature of the glass-forming blends, change according to blend composition. In all cases, melting produces a homogeneous structure, either glassy or crystalline, which remains such after the glassy samples are recrystallized upon a second heat treatment. This method enables band gap tuning of the blends, given that it varies with composition and crystallinity. Overall, this work demonstrates the applicability of classical melt processing to binary-component functional hybrid systems, and paves the way to solvent-free perovskite-based device fabrication.

Single-Molecule Resolved Conformational and Orbital Symmetry Breaking in Tetraphenylethylene-Based Macrocycles
En Li - ,
Tao Lin - ,
Songshan Dai - ,
Chengyi Chen - ,
Cheng-Kun Lyu - ,
Huilin Xie - ,
Jianyu Zhang - ,
Jacky Wing Yip Lam - ,
Ben Zhong Tang - ,
Jun Zhu - , and
Nian Lin *
Tetraphenylethylene (TPE) is a prototype aggregate-induced emission molecule. TPE-based conjugated macrocycles exhibit unique optical properties due to their peculiar cyclic topology. Because the symmetry of macrocycles strongly affects their photophysical properties, here we report a single-molecule study of the structures and orbitals of two TPE-based macrocycles of (C26H18)4 and (C26H18)6. Using scanning tunneling microscopy and spectroscopy, we discover that both macrocycles undergo spontaneous symmetry breaking in their conformations and frontier orbitals. The computational analyses reveal that the symmetry breaking is driven by a subtle interplay of higher extended conjugation between phenyl and node carbon atoms and conformation flexibility of the macrocycles. The observed symmetry breaking in TPE-based macrocycles is expected to strongly alter their photophysical properties.

Ligand-Directed Valence Band Engineering in Pb2+ Hybrid Crystals: Achieving Dispersive Bands and Shallow Valence Band Maximum
Daiki Umeyama *- and
Soshi Iimura
While crystalline hybrid solids hold great potential as novel semiconductors, most semiconductive hybrids utilize transition metal ions, which inherently limit carrier mobility due to the small band dispersion derived from the d orbitals. The filled s orbitals of post-transition metal ions offer the potential to design dispersed valence bands, but a method to translate the local structure design of these metal ions to valence band engineering is still in development. This study focuses on Pb2+-containing hybrid crystals, developing a simple strategy to control the Pb2+ coordination geometry through the molecular design of azole ligands. By preprogramming the coordination number of Pb2+ with azolate ligands, we succeeded in obtaining an isotropic coordination environment at a higher coordination number, resulting in a dispersed valence band and shallow valence band maximum while having a wide band gap. Detailed analysis of the band structures reveals that the energy levels and symmetry of the molecular orbitals of the anions play important roles in realizing these antinomic properties. This ligand-directed approach achieves both isotropy and covalency in the coordination bond by exploiting the diversity of the molecular orbitals. Our findings provide a foundation for future design strategies to optimize electronic structures in hybrid materials, advancing their application in semiconductive devices.

Efficient Light-Driven Ion Pumping for Deep Desalination via the Vertical Gradient Protonation of Covalent Organic Framework Membranes
Weipeng Xian - ,
Xiaoyi Xu - ,
Yongxin Ge - ,
Zhiwei Xing - ,
Zhuozhi Lai - ,
Qing-Wei Meng - ,
Zhifeng Dai - ,
Sai Wang *- ,
Ruotian Chen - ,
Ning Huang - ,
Shengqian Ma - , and
Qi Sun *
Traditional desalination methods face criticism due to high energy requirements and inadequate trace ion removal, whereas natural light-driven ion pumps offer superior efficiency. Current synthetic systems are constrained by short exciton lifetimes, which limit their ability to generate sufficient electric fields for effective ion pumping. We introduce an innovative approach utilizing covalent-organic framework membranes that enhance light absorption and reduce charge recombination through vertical gradient protonation of imine linkages during acid-catalyzed liquid–liquid interfacial polymerization. This technique creates intralayer and interlayer heterojunctions, facilitating interlayer hybridization and establishing a robust built-in electric field under illumination. These improvements enable the membranes to achieve remarkable ion transport across extreme concentration gradients (2000:1), with a transport rate of approximately 3.2 × 1012 ions per second per square centimeter and reduce ion concentrations to parts per billion. This performance significantly surpasses that of conventional reverse osmosis systems, representing a major advancement in solar-powered desalination technology by substantially reducing energy consumption and secondary waste.

Covalent DNA-Encoded Library Workflow Drives Discovery of SARS-CoV-2 Nonstructural Protein Inhibitors
Xudong Wang - ,
Liwei Xiong - ,
Ying Zhu - ,
Sixiu Liu - ,
Wenfeng Zhao - ,
Xinyuan Wu - ,
Mengnisa Seydimemet - ,
Linjie Li - ,
Peiqi Ding - ,
Xian Lin - ,
Jiaxiang Liu - ,
Xuan Wang - ,
Zhiqiang Duan - ,
Weiwei Lu - ,
Yanrui Suo - ,
Mengqing Cui - ,
Jinfeng Yue - ,
Rui Jin - ,
Mingyue Zheng - ,
Yechun Xu - ,
Lianghe Mei *- ,
Hangchen Hu *- , and
Xiaojie Lu *
This publication is Open Access under the license indicated. Learn More
The COVID-19 pandemic, exacerbated by persistent viral mutations, underscored the urgent need for diverse inhibitors targeting multiple viral proteins. In this study, we utilized covalent DNA-encoded libraries to discover innovative triazine-based covalent inhibitors for the 3-chymotrypsin-like protease (3CLpro, Nsp5) and the papain-like protease (PLpro) domains of Nsp3, as well as novel non-nucleoside covalent inhibitors for the nonstructural protein 12 (Nsp12, RdRp). Optimization through molecular docking and medicinal chemistry led to the development of LU9, a nonpeptide 3CLpro inhibitor with an IC50 of 0.34 μM, and LU10, whose crystal structure showed a distinct binding mode within the 3CLpro active site. The X-ray cocrystal structure of SARS-CoV-2 PLpro in complex with XD5 uncovered a previously unexplored binding site adjacent to the catalytic pocket. Additionally, a non-nucleoside covalent Nsp12 inhibitor XJ5 achieved a potency of 0.12 μM following comprehensive structure–activity relationship analysis and optimization. Molecular dynamics revealed a potential binding mode. These compounds offer valuable chemical probes for target validation and represent promising candidates for the development of SARS-CoV-2 antiviral therapies.

Irreversible Lattice Expansion Effects in Nanoscale Indium Oxide for CO2 Hydrogenation Catalysis
Chenyue Qiu - ,
Junchuan Sun - ,
Mengsha Li - ,
Chengliang Mao - ,
Rui Song - ,
Zeshu Zhang - ,
Doug D. Perovic - ,
Jane Y. Howe *- ,
Lu Wang *- , and
Geoffrey A. Ozin *
Thermal energy has been considered the exclusive driving force in thermochemical catalysis, yet associated lattice expansion effects have been overlooked. To shed new light on this issue, variable temperature in situ high-resolution (scanning) transmission electron microscopy (HR-(S)TEM) and electron energy-loss spectroscopy (EELS) were employed to provide detailed information on the structural changes of an archetype nanoscale indium oxide materials and how these effects are manifest in reverse water gas shift heterogeneous catalytic reactivity. It is found that with increasing temperature and vacuum conditions, an irreversible surface lattice expansion is traced to the formation and migration of oxygen vacancies. Together, these changes are believed to be responsible for the decreased activation energy and improved reaction rate observed for the reverse water gas shift reaction. Studies of this kind provide new insight into how thermal energy affects thermochemical heterogeneous catalysis.

Stenhouse Salts: Visible Light Photoswitches for Protic Environments
Derek Puthoff - ,
Hrishikesh Kuttiyil - , and
Julie A. Peterson *
Designing photoswitches that have large structural changes, are visible-light responsive, and are compatible with water is a major challenge for moving toward applications in biological systems. Despite the potential for Stenhouse salts to be a water-compatible counterpart to the popular DASA photoswitches, there has not yet been any major investigation into their properties as a photoswitch. Here, we report a series of aniline-based Stenhouse salt (AnSten) photoswitches with electron donating and withdrawing groups. AnSten photoswitches reversibly switch from a visible light absorbing isomer to a visible light transparent isomer upon irradiation with green light. The dark equilibrium and switching kinetics are dependent on the electronics of the aniline. These molecules switch reversibly in common protic solvents including water and hydrogels. Stenhouse salts show significant potential as a visible light active, water compatible, negative photochromic, T-type photoswitch with a large structural change.

Alkanes C1–C6 C–H Bond Activation via a Barrierless Potential Energy Path: Trifluoromethyl Carbenes Enhance Primary C–H Bond Functionalization
Jonathan Martínez-Laguna - ,
Julia Altarejos - ,
M. Ángeles Fuentes - ,
Giuseppe Sciortino - ,
Feliu Maseras *- ,
Javier Carreras *- ,
Ana Caballero *- , and
Pedro J. Pérez *
This publication is Open Access under the license indicated. Learn More
In this mixed computational and experimental study, we report a catalytic system for alkane C1–C6 functionalization in which the responsible step for C–H bond activation shows no barrier in the potential energy path. DFT modeling of three silver-based catalysts and four diazo compounds led to the conclusion that the TpFAg═C(H)CF3 (TpF = fluorinated trispyrazolylborate ligand) carbene intermediates interact with methane without a barrier in the potential energy surface, a prediction validated by experimentation using N2═C(H)CF3 as the carbene source. The array of alkanes from propane to n-hexane led to the preferential functionalization of the primary sites with unprecedented values of selectivity for an acceptor diazo compound. The lack of those barriers implies that selectivity can no longer be controlled by differences in the energy barriers. Molecular dynamics calculations (with propane as the model alkane) are consistent with the preferential functionalization of the primary sites due to a higher concentration of such C–H bonds in the vicinity of the carbenic carbon atom.

In Situ Welding Ionic Conductive Breakpoints for Highly Reversible All-Solid-State Lithium–Sulfur Batteries
Zhonghao Hu - ,
Chuannan Geng - ,
Jiwei Shi - ,
Qiang Li - ,
Haotian Yang - ,
Mingyang Jiang - ,
Li Wang - ,
Quan-Hong Yang *- , and
Wei Lv *
Poly(ethylene oxide) (PEO)-based solid-state lithium–sulfur batteries (SSLSBs) have garnered considerable interest owing to their impressive energy density and high safety. However, the dissolved lithium polysulfide (LiPS) together with sluggish reaction kinetics disrupts the electrolyte network, bringing about ionic conductive breakpoints and severely limiting battery performance. To cure this, we propose an in situ welding strategy by introducing phosphorus pentasulfide (P2S5) as the welding filler into PEO-based solid cathodes. P2S5 can react with LiPS to form ion-conducting lithium polysulfidophosphate (LSPS), which suppresses the interaction with PEO and in situ weld breakpoints within the ionic conductive network. Of interest, LSPS also shows another function, that is, to catalyze sulfur redox reactions by decreasing the activation energy of sulfur reduction reaction from 0.87 to 0.75 eV, mitigating the shuttle effect. The in situ welding strategy helps the assembled SSLSB to feature exceptional cycling stability and a high energy density of up to 358 Wh·kg–1 due to the high sulfur utilization. Our findings pave an avenue for practical high-performance SSLSBs with a novel welding filler for in situ welding of ionic conductive network.

Activating the Mn Single Atomic Center for an Efficient Actual Active Site of the Oxygen Reduction Reaction by Spin-State Regulation
Kiwon Kim - ,
Gyuchan Kim - ,
Taeyoung Jeong - ,
Wonyoung Lee - ,
Yunho Yang - ,
Byung-Hyun Kim - ,
Bubryur Kim - ,
Byeongyong Lee - ,
Joonhee Kang *- , and
Myeongjin Kim *
The ligand engineering for single-atom catalysts (SACs) is considered a cutting-edge strategy to tailor their electrocatalytic activity. However, the fundamental reasons underlying the reaction mechanism and the contemplation for which the actual active site for the catalytic reaction depends on the pyrrolic and pyridinic N ligand structure remain to be fully understood. Herein, we first reveal the relationship between the oxygen reduction reaction (ORR) activity and the N ligand structure for the manganese (Mn) single atomic site by the precisely regulated pyrrolic and pyridinic N4 coordination environment. Experimental and theoretical analyses reveal that the long Mn–N distance in Mn–pyrrolic N4 enables a high spin state of the Mn center, which is beneficial to reduce the adsorption strength of oxygen intermediates by the high filling state in antibond orbitals, thereby activating the Mn single atomic site to achieve a half-wave potential of 0.896 V vs RHE with outstanding stability in acidic media. This work provides a new fundamental insight into understanding the ORR catalytic origin of Mn SACs and the rational design strategy of SACs for various electrocatalytic reactions.

Enantioselective Nickel-Electrocatalyzed Cross-Dehydrogenative α- and γ-Nitroalkylation
Juan Li - ,
Minghao Liu - ,
Boyuan Wei - ,
Lingzi Peng - ,
Jin Song *- , and
Chang Guo *
Asymmetric catalytic versions of electricity-driven processes hold immense potential for the sustainable preparation of chiral compounds. However, the involvement of anodic oxidative cross-dehydrogenative coupling events between two distinct nucleophiles makes it challenging for a chiral catalyst to regulate the stereochemistry of the products. Our current electrocatalytic strategy for enantioconvergent cross-dehydrogenative α- and γ-nitroalkylation via radical-based pathways produces an array of enantioenriched nitroesters without supplementary stoichiometric oxidants. Mechanistic investigations reveal that the nickel catalyst plays a key role in both the electrochemical activation of the substrates and the stereoselectivity-defining events, affording the electrochemically generated Lewis acid-bound α-carbonyl radicals to interact with in situ-generated nitronate anions in a stereoselective manner. This electrocatalytic approach enables transformations that are highly challenging under thermal conditions, such as umpolung reactivity with readily available substrates, all-carbon quaternary stereocenter creation, and the control of remote stereochemistry.

Single-Crystal Dynamic Covalent Organic Frameworks for Adaptive Guest Alignments
Shan Liu - ,
Lei Wei - ,
Tengwu Zeng - ,
Wentao Jiang - ,
Yu Qiu - ,
Xuan Yao - ,
Qisheng Wang - ,
Yingbo Zhao - , and
Yue-Biao Zhang *
This publication is Open Access under the license indicated. Learn More
Dynamic 3D covalent organic frameworks (COFs) have shown a concerted structural transformation upon adaptive guest inclusion. However, the origin of the conformational mobility and the host–guest adaptivity remain conjecture of the pedal motions of revolving imine linkages, often without considering the steric hindrance from the interwoven frameworks. Here, we present atomic-level observation of the rotational and translational dynamics in single-crystal COF-300 upon adaptive guest inclusion of various organic molecules, featuring multiple rotamers of covalent linkages and switchable interframework noncovalent interactions. Specifically, we developed a diffusion gradient transimination protocol to facilitate the growth of COF single crystals, enabling a high-resolution X-ray diffraction structural analysis. We uncovered metastable and low-symmetry intermediate phases from contracted to expanded phases during structural evolution. We identified torsion angles in the terephthalaldehyde diimine motifs that switch from anti-periplanar to syn-periplanar/anticlinal conformations. Moreover, the rotational dynamics of the imine linkage were concurrent with the translational dynamics of tetraphenylmethane units, which tend to form the translational quadruple phenyl embrace. Such conformational mobility allows the frameworks to adapt to various guest molecules, such as alcohols, esters, phenols, and diols, featuring double linear, herringbone, zigzag chains, triple helix, and tubular alignments. Quantitative energy analyses revealed that such dynamic structure transformations are not arbitrary but follow specific pathways that resemble protein folding. The work is paving the way to developing robust, dynamic, and crystalline molecular sponges for studying the condensed structure of liquids without the need for further crystallization.

Conformational Chirality of Single-Crystal Covalent Organic Frameworks
Zhipeng Zhou - ,
Guohong Cai - ,
Zeyue Zhang - ,
Guobao Li - ,
Dongyang Lou - ,
Shangqing Qu - ,
Yuyao Li - ,
Meiying Huang - ,
Wei Liu - ,
Zhikun Zheng - , and
Junliang Sun *
The crystallization of organic polymers is often hindered by chiral units, hence resulting in chiral organic polymers typically existing as amorphous or partially crystalline phases such as natural rubber and cellulose. Similarly, as an emerging crystalline chiral polymer, chiral covalent organic frameworks (COFs) also inevitably face a delicate balance between chiral units and crystallization, limiting their production and applications in separation, catalysis, and optics. Here, we present a general strategy for producing a series of conformational chiral COFs with high crystallinity through breaking the meso conformation of achiral COFs. Conformational chirality of COF-300 was constructed by involving chiral amino-acid derivative templates during synthesis and was proven to have excellent thermodynamic (200 °C annealing in air) and dynamic stability (61% cell volume change). The stereochemistry of the conformational chiral crystals can be controllably tuned by chiral templates, resulting in wide-range circular dichroism signals from ultraviolet to infrared wavelengths and absorption dissymmetry factors (gabs) varying by up to 300%, with a maximum of gabs = 0.012. This strategy paves the way for stereochemistry modification, property enhancement, and exploration of new applications of crystalline chiral materials.

Above-Room-Temperature Ferromagnetism Regulation in Two-Dimensional Heterostructures by van der Waals Interfacial Magnetochemistry
Gaojie Zhang - ,
Hao Wu - ,
Li Yang - ,
Zheng Chen - ,
Wen Jin - ,
Bichen Xiao - ,
Wenfeng Zhang - ,
Changsheng Song *- , and
Haixin Chang *
Most methods for regulating physical and chemical properties of materials involve the breaking and formation of chemical bonds, which inevitably change local structures. Two-dimensional (2D) ferromagnets are critical for spintronic memory and quantum devices, but most of them maintain ferromagnetism at low temperature, and multiaspect control of 2D ferromagnetism at room temperature or above is still missing. Here, we report a nondestructive, van der Waals (vdW) interfacial magnetochemistry strategy for above-room-temperature, multiaspect 2D ferromagnetism regulation. By vdW coupling nonmagnetic MoS2, WSe2, or Bi1.5Sb0.5Te1.7Se1.3 with 2D vdW ferromagnet Fe3GaTe2, the Curie temperature is enhanced up to 400 K, best for 2D ferromagnets, with 26.8% tuning of room-temperature perpendicular magnetic anisotropy and an unconventional anomalous Hall effect up to 340 K. These phenomena originate from changes in magnetic exchange interactions and magnetic anisotropy energy by interfacial charge transfer and spin–orbit coupling. This work opens a pathway for engineering multifunctional 2D heterostructures by vdW interfacial magnetochemistry.

Activation of Strong π–Acids at [Fe4S4]+ Clusters Enabled by a Noncanonical Electronic Structure
Alexandra C. Brown - ,
Niklas B. Thompson - , and
Daniel L. M. Suess *
Although Fe–S clusters are privileged metallocofactors for the reduction of N2, CO, and other π-acidic substrates, their constituent metal ions─high-spin Fe2+ and Fe3+─are typically not amenable to binding and activating strong π-acids. Here, we demonstrate that [Fe4S4]+ clusters can overcome this limitation by adopting a noncanonical electronic structure. Specifically, we report the synthesis and characterization of a series of 3:1 site-differentiated [Fe4S4]+ clusters in which the unique Fe site is bound by one of 10 electronically variable arylisocyanide ligands. Rather than being continuously tuned as a function of the arylisocyanides’ electronic properties (e.g., as quantified by linear free energy relationships), the structures of the clusters are divided into two groups: (i) those with moderately π-acidic isocyanides, which adopt a “typical” structure characterized by standard bond metrics and geometric distortions from tetrahedral symmetry, and (ii) those with more strongly π-acidic isocyanides, which adopt a “contracted” structure with an unusually symmetric geometry and a compressed cluster core. Computational studies revealed that although the “typical” structure has a canonical electronic structure, the “contracted” structure has a noncanonical arrangement of spin density, with a full complement of π-backbonding electrons and more substantial Fe–Fe delocalization. These features of the “contracted” structure enable substantial C≡N bond weakening of the strongest π-acceptors in the series. More generally, the experimental characterization of the “contracted” electronic isomer suggests that other noncanonical electronic structures of Fe–S clusters remain to be discovered.

Boosting Enzyme-like Activities via Atomization of Cerium for Tumor Microenvironment-Responsive Cascade Therapy
Mengdie Jin - ,
Zhong Liang - ,
Yongkang Huang - ,
Mengzhen Zhang - ,
Hao Fu - ,
Biao Wang - ,
Jialiang Guo - ,
Qiang Yang - ,
Huayi Fang - ,
Jin-Cheng Liu - ,
Xinyun Zhai *- ,
Chun-Hua Yan - , and
Yaping Du *
Nanozyme catalytic therapeutic efficacy is limited by the finite enzyme activity and specificity. In this work, nitrogen-doped carbon loaded with a cerium single-atom nanozyme (Ce SAs@NC) is synthesized, exhibiting tumor specificity and excellent multiple enzyme-like activities. Compared with nitrogen-doped carbon loaded with CeO2 nanoparticles, Ce SAs@NC shows excellent peroxidase-like and catalase-like activity. Ce SAs@NC can convert intracellular hydrogen peroxide into cytotoxic hydroxyl radical and O2, which can be further transferred to superoxide radicals. Cascade enzyme reactions not only alleviate the hypoxic microenvironment of tumors but also induce lipid peroxidation and apoptosis or necrosis of tumor cells. The mild photothermal action will enhance the enzyme-like activities of Ce SAs@NC rather than induce the production of heat shock proteins to protect tumor cells. In addition, Ce SAs@NC can regulate the immune environment, stimulate M1 macrophages to trigger immune responses, and inhibit tumor proliferation. Thanks to the combination of the size effect of the single atoms, photothermal influence, multiple enzyme-like activities, and immunological effect, the Ce SAs@NC platform appears to have tumor specificity, less toxic side effects, and a high curative effect both in vitro and in vivo.

Highly Efficient and Enantioselective Iridium-Catalyzed Asymmetric Reductive Cycloetherification
Yan Zong *- ,
Xiaomei Zou - ,
Hongqi Tao - ,
Qiuchen Huang - ,
Gen-Qiang Chen *- , and
Xumu Zhang *
A catalytic protocol for the iridium-catalyzed asymmetric hydrogenation (AH) of γ- or δ-hydroxy ketones to rapidly assemble various aliphatic enantioenriched tetrahydrofurans (THFs) or tetrahydropyrans (THPs) is disclosed. A wide range of enantioenriched THFs or THPs were obtained in high yields and excellent enantioselectivities (up to 99% and up to 96.5:3.5 er). The dynamic kinetic resolution asymmetric hydrogenation (DKR-AH) process was also achieved, simultaneously constructing enantioenriched THP scaffolds with two contiguous stereogenic centers with high yields and stereoselectivities (up to 92% yield, up to 98.5:1.5 er and >20:1 dr). Mechanistic investigation indicates that the key step of the reaction involves the AH of the challenging cyclic, aliphatic oxocarbenium ions. Furthermore, this catalytic enantioselective approach could be carried out on a gram scale, and various enantioenriched cyclic ethers were further transformed into an array of useful building blocks for enantioenriched natural products and bioactive molecules.

Ligand Effects on the Emission Characteristics of Molecular Eu(II) Luminescence Thermometers
Roberto M. Diaz-Rodriguez - ,
Diogo A. Gálico - ,
Daniel Chartrand - , and
Muralee Murugesu *
Discrete molecular organometallic europium(II) complexes are promising functional materials due to their ability to behave as highly sensitive band-shift luminescence thermometers. Furthering our understanding of the design principles salient to the emission behavior of such systems is important for developing them in this emerging application. To this end, a series of pseudo-C4v-symmetric organometallic europium(II) complexes bearing systematically varying ligand sets were synthesized and characterized to probe the influence of subtle structural modification on their optical properties. Opto-structural correlation analyses via variable-temperature single-crystal X-ray diffraction and photoluminescence spectroscopy reveal a remarkable variability in properties among structurally similar complexes and a convoluted dependence of the emission characteristics on the stereoelectronic properties of the ligands. A few factors of particular influence are nevertheless identified, including the distance between the europium(II) ion and the basal plane of the square-pyramidal coordination polyhedron, the presence of pendant electron density that might further interact with the excited-state 5d orbitals, and, qualitatively, the metal–ligand flexibility of the construct. These results help to elucidate principles that govern the luminescence properties of organometallic europium(II) complexes with an eye to enabling the rational design of high-performance luminescence thermometers of this genre.

Charge Transfer Dynamics in Supramolecular Tessellations Composed of Aromatic Donors and Chiral Tris(naphthalenediimide) Triangular Acceptors
Malik L. Williams - ,
Jonathan R. Palmer - ,
Ryan M. Young - , and
Michael R. Wasielewski *
Understanding charge transfer (CT) dynamics in donor–acceptor (D–A) cocrystals is important for the development of efficient organic photovoltaic and electronic materials. This study explores the photogenerated CT states of supramolecular tessellations formed by cocrystallizing a chiral tris(naphthalenediimide) triangular prism (−)-NDI-Δ with pyrene, perylene, and peri-xanthenoxanthene electron donors. By manipulating crystallization conditions, one-dimensional (1D) and two-dimensional (2D) cocrystals with distinct structural motifs and morphologies are achieved. Femtosecond and nanosecond transient absorption microscopies and time-resolved electron paramagnetic resonance spectroscopy were employed to elucidate the CT state dynamics. Our findings reveal that the CT state lifetimes are lengthened in the 2D cocrystals relative to the 1D cocrystals, which is attributable to the symmetry and molecular packing differences between them that modulate the CT interactions. This work highlights the potential of using preorganized covalent multisite charge carriers as donors or acceptors in cocrystals as a strategy for engineering structures for advanced multifunctional materials with tunable CT properties.

Hydrogen Isotope Labeling of Pharmaceuticals Via Dual Hydrogen Isotope Exchange Pathways Using CdS Quantum Dot Photocatalyst
Rajendra Maity - ,
Otto Dungan - ,
Frédéric A. Perras - ,
Jingwei Li *- ,
Daohua Liu - ,
Sumei Ren - ,
Dan Lehnherr - ,
Zheng Huang - ,
Eric M. Phillips - ,
Moses Adeyemo - ,
Joseph Frimpong - ,
Timothy Quainoo - ,
Zhen-Fei Liu - , and
Long Luo *
Isotopic labeling is a powerful technique extensively used in the pharmaceutical industry. By tracking isotope-labeled molecules, researchers gain unique and invaluable insights into the pharmacokinetics and pharmacodynamics of new drug candidates. Hydrogen isotope labeling is particularly important as hydrogen is ubiquitous in organic molecules in biological systems, and it can be introduced effectively through late-stage hydrogen isotope exchange (HIE). However, hydrogen isotope methods that simultaneously label multiple sites with varying types of C–H bonds in the different types of molecules are still lacking. Herein, we demonstrate a heterogeneous photocatalytic system using a CdS quantum dot catalyst that proceeds via a unique dual HIE pathway mechanism─one occurs in the reaction solution and the other on the catalytic surface─to address it. This unique mechanism unlocked several unique labeling capabilities, including simultaneous labeling of multiple and challenging sites such as secondary α-amino, α-ethereal, allyl, and vinyl sites, providing great versatility in practical uses for pharmaceutical labeling.

Wavelength-Dependent Dynamic Behavior in Thiol–Ene Networks Based on Disulfide Exchange
Bernhard Sölle - ,
Max Schmallegger - ,
Sandra Schlögl *- , and
Elisabeth Rossegger *
While latent catalysts have become a well-established strategy for locally and temporally controlling bond exchange reactions in dynamic polymer networks, there is a lack of inherently tailorable systems. Herein, we introduce a thiol–ene network based on disulfide exchange that alters its dynamic properties as a function of the color of light used during the curing reaction. For this purpose, selected allyl-bearing disulfides are synthesized, which are transparent at 450 nm but undergo disulfide scission upon 365 nm light irradiation, as confirmed by UV–vis and EPR measurements. Incorporated into a thiol–ene resin, the wavelength used in the curing reaction defines the dynamic properties of the obtained photopolymer. At 450 nm, photocuring yields a dynamic network with disulfide bonds, which relaxes to 63% of its original stress within 112 s at 160 °C (without the requirement of an external catalyst). In contrast, curing with 365 nm light induces disulfide scission yielding photopolymers, which contain predominately monosulfidic links. The permanent nature of the links effectively prevents relaxation of the polymer within a reasonable period of time, confirming the successful alteration of its dynamic properties simply by the color of the light source used.

Charting Regions of Cobalt’s Chemical Space with Maximally Large Magnetic Anisotropy: A Computational High-Throughput Study
Lorenzo A. Mariano - ,
Vu Ha Anh Nguyen - ,
Valerio Briganti - , and
Alessandro Lunghi *
This publication is Open Access under the license indicated. Learn More
Magnetic anisotropy slows down magnetic relaxation and plays a prominent role in the design of permanent magnets. Coordination compounds of Co(II) in particular exhibit large magnetic anisotropy in the presence of low-coordination environments and have been used as single-molecule magnet prototypes. However, only a limited sampling of cobalt’s vast chemical space has been performed, potentially obscuring alternative chemical routes toward large magnetic anisotropy. Here we perform a computational high-throughput exploration of Co(II)’s chemical space in search of new single-molecule magnets. We automatically assemble a diverse set of ∼15,000 novel complexes of Co(II) and fully characterize them with multireference ab initio methods. More than 100 compounds exhibit magnetic anisotropy comparable to or larger than leading known compounds. The analysis of these results shows that compounds with record-breaking magnetic anisotropy can also be achieved with coordination four or higher, going beyond the established paradigm of two-coordinated linear complexes.

Multistep Growth Pathway of Covalent Organic Framework Onion Nanostructures
Qi Zheng - ,
Amy Ren - ,
Alexandra Zagalskaya - ,
Haiyan Mao - ,
Daewon Lee - ,
Chongqing Yang - ,
Karen C. Bustillo - ,
Liwen F. Wan - ,
Tuan Anh Pham - ,
Jeffrey A. Reimer - ,
Jian Zhang - ,
Yi Liu - , and
Haimei Zheng *
The growth of complex organic macromolecular materials in solution is a pervasive phenomenon in both natural and synthetic systems, yet the underlying growth mechanisms remain largely unresolved. Using liquid-phase transmission electron microscopy (TEM), we elucidate the real-time growth pathways of covalent organic framework (COF) onion nanostructures, which involve graphitic layer formation, subsequent layer attachment, onion ring closure, and structural relaxation. This process is marked by variations in orientation and curvature, driven by the dynamic formation of the COF structure, which further regulates order–disorder transition and defect generation within the framework. Our in situ TEM characterizations provide valuable insights into how molecular arrangement drives the formation of complex nanostructures. We anticipate that direct imaging of COF nanostructure growth in liquids will open new opportunities for controlling COF crystal morphology, composition, and hierarchical structure development.

Engineering Supramolecular [c2]Daisy Chains for Structural Hierarchy-Dependent Emission and Photoreactivity
Jiahui Xu - ,
Shengyong Deng - , and
Peifa Wei *
Organic photofunctional materials exhibit properties that are highly dependent on their structural hierarchy. The variability in intermolecular interactions and molecular packing in both monomeric and aggregated states complicates the controllability and predictability of their photophysical and photochemical properties. To address this challenge, we developed three luminescent supramolecular [c2]daisy chains as simplified models. The rigid and mutually embedded linkers between the host and guests facilitate the formation of [c2]daisy chains with balanced stability and dynamics. Additionally, the close and tunable π–π interactions between the luminescent units provide a structural basis for fluorescence modulation and topochemical photoreactions. We performed two sets of comparisons to assess luminescence and photoreactivity: one comparison involves molecules with and without crown ethers, and the other contrasting their behavior under UV excitation in solution (diluted and concentrated) versus in the aggregated and crystalline states. Specifically, in the crystalline state, [c2]daisy chains effectively stabilize molecular packing, leading to highly efficient dimer-dependent emission. This unique structure remains in both solution (c > 1 mM) and aggregated states, which can direct the reaction pathway toward rapid and efficient intermolecular photocycloaddition upon UV irradiation. However, in highly diluted solution (10 μM), [c2]daisy chains dissociate into monomers, which further undergo intramolecular photocyclization. This study provides new insights into employing supramolecular strategies for controllable molecular aggregation and the fine-tuning of photoreaction pathways and kinetics.

Degradable and Piezoelectric Hollow ZnO Heterostructures for Sonodynamic Therapy and Pro-Death Autophagy
Lihan Cai - ,
Tao Sun - ,
Fuping Han - ,
Han Zhang - ,
Jiyu Zhao - ,
Qiao Hu - ,
Tiancong Shi - ,
Xiao Zhou - ,
Fang Cheng - ,
Chong Peng - ,
Ye Zhou - ,
Saran Long - ,
Wen Sun - ,
Jiangli Fan *- ,
Jianjun Du *- , and
Xiaojun Peng
Piezoelectric materials can generate charges and reactive oxygen species (ROS) under external force stimulation for ultrasound-induced sonodynamic therapy (SDT). However, their poor piezoelectricity, fast electron–hole pair recombination rate, and biological toxicity of piezoelectric materials limit the therapeutic effects of piezoelectric SDT. In this study, hollow ZnO (HZnO) nanospheres were synthesized by using a one-step method. The hollow structure facilitated the deformation of HZnO under stimulation by ultrasound mechanical force and increased the piezoelectric constant. Subsequently, black phosphorus quantum dots (BPQDs) and arginine-glycine-aspartic acid peptide (RGD)-poly(ethylene glycol) (PEG) were combined with HZnO to further enhance the piezoelectric effect by constructing heterojunctions and enable tumor-targeting ability. During treatment, HZnO-BPQDs-PEG could degrade in an acidic tumor microenvironment and release Zn2+ and PO43– ions to induce pro-death autophagy. The ROS produced by SDT also accelerated autophagy and promoted ferroptosis in cancer cells. This study demonstrates that HZnO-BPQDs-PEG has a strong piezoelectric SDT effect and can effectively induce autophagy in cancer cells, providing a new idea for the design and application of piezoelectric materials for tumor therapy.

Copper-Iodide Hybrid Clusters with Partial Distortion Enable High-Performance Full-Visible-Spectrum White-Light-Emitting Diodes
Kuang-Hui Song - ,
Min Peng - ,
Jing-Jing Wang - ,
Li-Zhe Feng - ,
Yi-Chen Yin - ,
Yong-Hui Song - ,
Xue-Chen Ru - ,
Ya-Ping Xie - ,
Guozhen Zhang *- ,
Zhengtao Deng *- , and
Hong-Bin Yao *
Phosphor-converted white-light-emitting diodes (pc-WLEDs) have become increasingly prevalent artificial light sources. Currently, multicomponent phosphors are commonly used for pc-WLEDs, but they often suffer from issues of undesirable reabsorption and unstable emission colors. The potential alternative for pc-WLEDs is a single-component white phosphor that covers the broad visible spectrum with desirable low thermal quenching and efficient luminescence, which is still scarce. To address this challenge, we design a unique single-component white phosphor based on Cu4I4(4-(tert-butyl)-2-(diphenylphosphaneyl)pyridine)2 (Cu4I4(NP-tBu)2) hybrid clusters, which exhibits ultrabroad dual emission from 400 to 800 nm and a high photoluminescence quantum yield of 97% under 320 nm light excitation. Based on time-resolved fluorescence spectroscopy and theoretical model analysis of our Cu4I4 series clusters, we hypothesize that the dual emission comes from the coexistence of two triplet states caused by partial cluster distortion under light excitation. The Cu4I4(NP-tBu)2 cluster’s high structural stability also endows consistent spectral performance and low thermal quenching up to 240 °C. Thus, the fabricated pc-WLED using Cu4I4(NP-tBu)2 white phosphor exhibits a maximum efficiency of 63.4 lm/W and maintains a high color rendering index of ∼88 during 1000 h of continuous operation. Our results highlight a new strategy of low-cost and high-performance copper-iodide cluster-based single-component white phosphors for high-quality pc-WLEDs.

Crown-like Biodegradable Lipids Enable Lung-Selective mRNA Delivery and Dual-Modal Tumor Imaging In Vivo
Zhaoming Chen - ,
Yuexia Yang - ,
Xinyu Qiu - ,
Hao Zhou - ,
Rui Wang - , and
Hu Xiong *
Systemic mRNA delivery to specific cell types remains a great challenge. We herein report a new class of crown-like biodegradable ionizable lipids (CBILs) for predictable lung-selective mRNA delivery by leveraging the metal coordination chemistry. Each CBIL contains an impressive crown-like amino core that coordinates with various metal ions such as Zn2+ and further regulates the in vivo organ-targeting behavior of lipid nanoparticles (LNPs). The representative CBIL (Zn-9C-SCC-10)-formulated LNPs could exclusively deliver mRNA to the lung after systemic administration. Notably, following intravenous administration of 0.2 mg kg–1 Cre mRNA, Zn-9C-SCC-10 LNPs enabled the highly efficient gene editing of all lung epithelial and endothelial cells up to 43 and 61%, respectively, outperforming the current state-of-the-art LNPs in lung epithelial cell delivery. Moreover, compared to DLin-MC3-DMA LNPs with the addition of cationic lipid (DOTAP), our approach yielded a 44.6-fold enhancement in pulmonary mRNA expression and significantly improved biosafety in vivo. Taking advantage of paramagnetic gadolinium ion, Gd-12C-SCC-10 LNPs allowed the potent mRNA delivery to cancer cells and successfully illuminated lung tumors by magnetic and bioluminescent dual-mode imaging, facilitating the early discovery and diagnosis of lung cancer. This work will open a new avenue to rationally design predictable LNPs, as well as address the major challenges of mRNA delivery to specific cells in the lung tissues for treating a wide variety of diseases.

Total Synthesis of Euphorbialoid A
Junichi Taguchi - ,
Shintaro Fukaya - ,
Haruka Fujino - , and
Masayuki Inoue *
Euphorbialoid A (1) belongs to the rare diterpenoid family of premyrsinanes and exhibits potent anti-inflammatory effects. The 5/7/6/3-membered carbocycle (ABCD-ring) of 1 contains 11 contiguous stereocenters and seven oxygen-containing functional groups. Moreover, four of the six hydroxy groups of 1 are concentrated in the southern sector and flanked by four structurally different acyl groups. The dense array of various functional groups with disparate reactivities on the tetracyclic ABCD-ring presents a daunting challenge for the chemical synthesis of 1. As a reflection of its formidable complexity, synthesis of 1 or any other premyrsinane diterpenoids has not yet been reported. Here, we devised a novel strategy comprising two stages and achieved the first total synthesis of 1 (35 steps as the longest linear sequence). In the first stage, the ABCD-ring was expeditiously assembled by integrating three powerful transformations: (1) Pt-doped TiO2-catalyzed radical coupling to attach a northern chain to a 6/3-membered CD-ring, (2) Pd-catalyzed decarboxylative asymmetric allylation to construct a quaternary carbon with a southern chain, and (3) a Co-mediated Pauson–Khand reaction to cyclize the two chains into the 5/7-membered AB-ring. In the second stage, three-dimensional structures of the ABCD-ring intermediates were utilized to stereoselectively fabricate the A-ring and site-selectively append the four different acyl groups. In the present total synthesis, we revealed the significance of orchestrating the multistep reaction sequence and incorporating cyclic protective groups. The overall strategy and tactics provide new insights into designing synthetic routes to premyrsinanes and densely oxygenated terpenoids decorated with diverse acyl groups.

Mechanistic Investigation of the Pseudo-Halogen Effect in Enantioselective Aminocatalyzed [6 + 4] and [10 + 6] Cycloadditions: Enabling Unique Favorskii-Like Rearrangements
Casper Džabbarov Barløse - ,
René Slot Bitsch - ,
Jonas Faghtmann - ,
Cristina Domínguez Escobar - ,
Maria Edith Casacchia - ,
Anne Kristensen - , and
Karl Anker Jørgensen *
A mechanistic investigation into the novel combination of the pseudo-halogen effect with enantioselective aminocatalysis unravels the mechanistic intricacies of [6 + 4] and [10 + 6] higher-order cycloadditions and the succeeding new Favorskii-like rearrangements. By introducing the OTf-group into the tropone framework, it can serve both as an activator for the cycloaddition and as a proficient leaving group within the corresponding cycloadduct, thus enabling unprecedented ring-contracting Favorskii-like rearrangements. Integrating the -OTf group creates an electron-deficient 6π-component leveraging the pseudo-halogen effect by enhancing the polarization and introducing new strategic interaction points. This modification complements electron-rich 4π- and 10π-components from amino-activated 2,4-dienals or indene-carbaldehydes. A comprehensive DFT investigation supported by experimental results demonstrates that the [6 + 4] system proceeds through a rate-limiting stepwise exo-cycloaddition leading to a cycloadduct initially in a boat-conformation, subsequently transitioning to the more stable chair-conformation. The change in conformation ensures an SN1-like expulsion of the -OTf group, generating a stable carbocation bridgehead primed for a novel Favorskii-like seven-to-six ring-contracting rearrangement, resulting in the experimentally observed product. As proof-of-concept for the cycloaddition/Favorskii-like rearrangement, it is demonstrated that this approach can be extended to an unprecedented [10 + 6] cycloaddition. In contrast to the [6 + 4] system, the [10 + 6] system distinguishes itself with a concerted SN1-like/Favorskii-like six-to-five ring-contracting rearrangement, representing the rate-limiting step. This novel concept results in the experimental isolation of structurally complex products in high peri-, diastereo-, and enantioselectivity with moderate yield. These findings demonstrate the pseudo-halogen effect’s multifaceted role in promoting and enabling novel reactivity.
Retractions
Retraction of “Two-Dimensional Violet Phosphorus P11: A Large Band Gap Phosphorus Allotrope”
Gary Cicirello - ,
Mengjing Wang - ,
Quynh P. Sam - ,
James L. Hart - ,
Natalie L. Williams - ,
Huabing Yin - ,
Judy J. Cha - , and
Jian Wang
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