Chain-end reactivation of polymethacrylates generated by reversible-deactivation radical polymerization (RDRP) has emerged as a powerful tool for triggering depolymerization at significantly milder temperatures than those traditionally employed. In this study, we demonstrate how the facile depolymerization of poly(butyl methacrylate) (PBMA) can be leveraged to selectively skew the molecular weight distribution (MWD) and predictably alter the viscoelastic properties of blended PBMA mixtures. By mixing polymers with thermally active chain ends with polymers of different molecular weights and inactive chain ends, the MWD of the blends can be skewed to be high or low by selective depolymerization. This approach leads to the counterintuitive principle of the "destructive strengthening" of a material. Finally, we demonstrate, as a proof of concept, the encryption of information within polymer mixtures by linking Morse code with the MWDs before and after selective depolymerization, allowing for the encoding of data within blends of synthetic macromolecules.

Due to their strong aromaticity and difficulties in chemo-, regio-, and enantioselectivity control, asymmetric hydrogenation of naphthol derivatives to 1,2,3,4-tetrahydronaphthols has remained a long-standing challenge. Herein, we report the first example of homogeneous asymmetric hydrogenation of naphthol derivatives catalyzed by tethered rhodium-diamine catalysts, affording a wide array of optically pure 1,2,3,4-tetrahydronaphthols in high yields with excellent regio-, chemo-, and enantioselectivities (up to 98% yield and >99% ee). Mechanistic studies with experimental and computational approaches reveal that fluorinated solvent 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) plays vital roles in the control of reactivity and selectivity, and 1-naphthol is reduced via a cascade reaction pathway, including dearomative tautomerization, 1,4-hydride addition, and 1,2-hydride addition in sequence. A novel synergistic activation mode was proposed in which HFIP assists a synergistic activation of both the hydrogen molecule and naphthol in the presence of a base, and the in situ-generated fleeting keto tautomer is immediately trapped and reduced by the Rh(III)-H species before it escapes from the solvent cage. This protocol provides a straightforward and practical pathway for the synthesis of key intermediates for several chiral drugs. Particularly, optically pure Nadolol, a drug for the treatment of hypertension, angina pectoris, congestive heart failure, and certain arrhythmias, is enantioselectively synthesized for the first time.

Triplet-sensitization has been proven invaluable for creating photoswitches operated over a full visible-light spectrum. While designing efficient triplet-sensitizers is crucial for establishing visible-light photochromism, it remains an appealing yet challenging task. In this work, we propose a versatile strategy to fabricate triplet-sensitizers with intermolecular charge-transfer complexes (CTCs). Through fine-tuning interactions between various donor and acceptor units, a series of CTC sensitizers were prepared with intensified visible-light absorption and a distinctive narrow Δ feature. By virtue of this, a bidirectional visible-light photochromism (475 nm/605 nm) was achieved via integrating CTC sensitizers with classic diarylethene (DAE) photoswitches in various substrates upon triplet photoreaction pathways. Proof-of-concept applications, such as photoresponsive printing and mechanic-facilitated inkpad, were subsequently presented. The flexible accessibility and tunability of CTC sensitizers facilitate both generalized and customized production of photoresponsive systems that operate within the visible-light region.

Carbon monoxide (CO) gas therapy, as an emerging therapeutic strategy, is promising in tumor treatment. However, the development of a red or near-infrared light-driven efficient CO release strategy is still challenging due to the limited physicochemical characteristics of the photoactivated carbon monoxide-releasing molecules (photoCORMs). Here, we discovered a novel photorelease CO mechanism that involved dual pathways of CO release via photosensitization. Specifically, the photosensitizer Chlorin e6 (Ce6) sensitized oxygen to produce singlet oxygen (O) and oxidized photoCORM Mn(CO) to release CO in an air-saturated solvent under red light (655 nm, 50 mW/cm) irradiation. Furthermore, Ce6 and Mn(CO) could undergo multistep photochemical reactions to release CO, as well as the degradation of the photosensitizer Ce6 in an oxygen-depleted solution. As a proof of concept, we demonstrated the feasibility and tumor inhibition of this CO release strategy both and . These results provide a robust platform for the development of new approaches to CO-mediated modulation of signaling pathways and further facilitate the practical use of gas therapeutic methods in tumor therapy .

Recently, cobalt-based oxides have received considerable attention as an alternative to expensive and scarce iridium for catalyzing the oxygen evolution reaction (OER) under acidic conditions. Although the reported materials demonstrate promising durability, they are not entirely intact, calling for fundamental research efforts to understand the processes governing the degradation of such catalysts. To this end, this work studies the dissolution mechanism of a model CoO porous catalyst under different electrochemical conditions using online inductively coupled plasma mass spectrometry (online ICP-MS), identical location scanning transmission electron microscopy (IL-STEM), and differential electrochemical mass spectrometry (DEMS). Despite the high thermodynamics tendency reflected in the Pourbaix diagram, it is shown that the cobalt dissolution kinetics is sluggish and can be lowered further by modifying the electrochemical protocol. For the latter, identified in this study, several (electro)chemical reaction pathways that lead to the dissolution of CoO must be considered. Hence, this work uncovers the transient character of cobalt dissolution and provides valuable insights that can help to understand the promising stability of cobalt-based materials in already published works and facilitate the knowledge-driven design of novel, stable, abundant catalysts toward the OER in an acidic environment.

Ni(II) complexes with an integer spin = 1 that behave as clock transition spin qubits at zero magnetic field are resilient to magnetic fluctuations of the spin bath, while Co(II) complexes with a half-integer spin ( = 3/2) lose their coherence when they are subject to the same fluctuating magnetic field as the Ni(II) ones. These findings demonstrate that adequately designed Ni(II) complexes are excellent candidates for spin qubits.

Colloidal quantum dots (QDs) are promising emitters for biological applications because of their excellent fluorescence, convenient surface modification, and photostability. However, the toxic cadmium composition in the state-of-the-art QDs and their inferior properties in the aqueous phase greatly restrict further use. The performance of water-soluble indium phosphide (InP) QDs lags far behind those of Cd-containing counterparts due to the lack of effective surface protection. Here, we present an efficient copassivation strategy via dual hydrophilic ligands to achieve water-soluble InP-based QDs with ideal optical properties. A record photoluminescence quantum yield of near-unity and monoexponential decay dynamics for water-soluble InP-based QDs are achieved. For the first time, we realize a single water-soluble InP-based QD with significantly suppressed blinking. Furthermore, the novel QDs exhibit superior cellular imaging capabilities and high resistance to photobleaching compared with commonly used organic dyes. The results presented here will inspire the development of environmentally friendly water-soluble QDs as a promising class of fluorescence labels for biological applications.

An original approach to characterize electrochemical interfaces at the atomic level, a challenging topic toward the understanding of electrochemical reactivity, is reported. We employed surface resonant X-ray diffraction experiments combined with their simulation using first-principle density functional theory calculations and were thus able to determine the molecular and electronic structures of the partially ionic layer facing the electrode surface, as well as the charge distribution in the surface metal layers. Pt(111) in an acidic medium at an applied potential excluding specific adsorption was studied. The presence of a positively charged counter layer composed of 1.60 water and 0.15 hydronium molecules per platinum surface unit cell at 2.8 Å from the oppositely charged Pt(111) surface was found. Our results give a unique insight into the water-metal interaction at the electrochemical interfaces.

Polyacene analogues, consisting of short acene segments separated by nonbenzenoid rings, offer intriguing electronic properties and magnetic interactions. Pentalene-bridged polyacenes (PPs), in particular, hold promise for enhancing the electrical conductivity and potential open-shell ground states. However, PPs have remained elusive in solution chemistry due to poor solubility and limited synthetic protocols. Here, we report the on-surface synthesis of PPs through the annulation between ortho-xylene groups. Scanning tunneling microscopy and atomic force microscopy reveal that the reconstructed Au(110) surface significantly enhances the chemoselectivity of the annulation process. Scanning tunneling spectroscopy combined with density functional theory suggests that PP exhibits a narrow direct band gap, similar to long acenes. This work demonstrates the potential for band structure engineering in polyacene analogues by incorporating nonbenzenoid rings, paving the way to advancements in organic electronics and spintronics.

The discovery of new transformations drives the development of synthetic organic chemistry. While the main goal of synthetic chemists is to obtain the maximum yield of a desired product with minimal side product formation, meticulous characterization of the latter offers an opportunity for discovering new reaction pathways, alternative mechanisms, and new products. Herein, we present a case study on the discovery and development of a new chemical transformation using online mass spectrometry. This highly sensitive method enabled the discovery of a new reaction pathway in a catalyst-free cross-dehydrogenative coupling of 1,2,3,4-tetrahydroisoquinoline with acetone via peroxide intermediate, ultimately yielding a tricyclic pyridinium compound. Mass spectrometry was instrumental in detecting and identifying the structure of the pyridinium compound, initially formed as a trace byproduct, which allowed us to develop a general methodology for its exclusive formation.

Imine-containing azaarene-based triarylmethanes are vital molecular motifs that are prevalent in a wide array of bioactive compounds. Recognizing the limitations of current synthetic methodologies─marked by a scarcity of examples and difficulties in flexible functional group modulation─we have developed an efficient and modular asymmetric photochemical strategy employing pyridotriazoles and boronic acids as substrates. Utilizing novel chiral diamine-derived pyrroles and primary amines as catalysts, we successfully synthesized a diverse range of triarylmethanes with high yields and excellent enantioselectivities. This method not only exhibits a broad substrate scope and outstanding functional group tolerance but also enables the precise synthesis of deuterated derivatives using inexpensive DO as the deuterium source. Mechanistic studies reveal that an unusual 1,4-boron shift is a critical step in generating the boronated enamine intermediate, while also shedding light on the potential enantiocontrol mechanisms facilitated by the chiral catalyst.

Photocatalytic upcycling of waste polyolefins into value-added chemicals provides promise in plastic waste management and resource utilization. Previous works demonstrate that polyolefins can be converted into carboxylic acids, with CO as the final oxidation product. It is still challenging to explore more transformation products, particularly mild-oxidation products such as alcohols, because of their instability compared with polymer substrates, which are prone to oxidation during catalytic reactions. In this work, we propose an efficient strategy to regulate the product type through precise control of radicals, intermediates, and reaction paths. Taking the commonly used photocatalyst CN as an example, its major products are carboxylic acids and CO. When MoS is introduced to construct a -scheme heterostructure, gas products are significantly reduced and alcohols appear with a high yield of 1358.8 μmol g and a high selectivity up to 80.3%. This is primarily attributed to the presence of •OH radicals from oxygen reduction, acting a key role in alcohol formation while simultaneously suppressing the competing pathways oxygen to •O and O, thus reducing the overoxidation products. The β-scission of the C-C bonds in the polymer chains generates intermediate alkyl species, followed by the combination with •OH to produce methanol, which is more energetically favorable for MoS/CN. In contrast, alkyl species couple with oxygen species to form formic acid, which is favorable for CN. This work provides new approaches for controlling the product types and offers new insights into the reaction pathways involved in polyolefin photorefinery.

Anode materials with high capacity and suitable redox potential are crucial for improving the energy density of aqueous sodium-ion batteries (ASIBs). And organic anode materials play a promising role due to their tunable electrochemical performance. However, the insufficient electroactive sites lead to a low capacity, hindering the elevation of energy density. Thus, it is essential to design organic molecules with multiple redox-active sites. Herein, we propose a strategy to activate redox sites by regulating the spatial distribution of delocalized electrons within the conjugation system, and the quinone rings are successfully activated as new reversible Na-ion storage sites via enhancing the electron density. The obtained 2,5-dihydroxy-1,4-benzoquinonatocobalt (Co-DHBQ) with electroactive quinone rings exhibits a superior capacity of 183 mA h g accompanied by a multiple-electron transfer. Benefiting from the high capacity, the Co-DHBQ||NaMn[Fe(CN)]·2HO (MnHCF) full cell outputs a ultrahigh energy density of 110 W h kg (based on the total active material mass of the anode and cathode) with a lifespan of 3000 cycles. This work proposes a strategy to activate new redox sites, providing a new impetus for designing high-performance organic electrode materials and developing high energy density ASIBs.

Samarium diiodide (SmI) exhibits high selectivity for NR catalyzed by molybdenum complexes; however, it has so far been employed only as a stoichiometric reagent (0.3 equiv of NH per Sm) combined with coordinating proton sources (e.g., HO, ROH). The latter inhibit catalytic turnover of Sm owing to buildup of stable hydroxide/alkoxide sinks. Here, we report a tandem Sm/Mo-catalyzed NR system that achieves the lowest overpotential and highest Faradaic efficiency (82%) reported to date for nonaqueous NR at ambient pressure. Up to 8.4 equiv of NH is produced per Sm, representing a 25-fold increase over NR with stoichiometric SmI. A noncoordinating proton source enables electrochemical SmI/SmI cycling at the applied potential of -1.45 V vs Fc.

The reduction of CO mediated by transition metals has garnered significant interest, yet little is known about the reduction of CO using f-element compounds. Herein, the reduction of CO to CO by tetravalent uranium (U) compound UO is investigated via matrix isolation infrared spectroscopy and quantum chemical study. Our results reveal that a stable carbonate intermediate OUCO () can be prepared at low temperatures (4-12 K). Through photolytic reactions of under irradiations (495 nm < λ < 580 nm), the charge-separated pentavalent U isomer [UO][(η-OC)] () is produced through electron transfer from the quasi-atomic U-7s orbital to the CO moiety. Sequentially, one C═O bond in CO breaks by successive irradiation (250 nm < λ < 580 nm), and the photolysis generates the products CO and hexavalent U compound UO following two intermediates UO(CO) () and UO(OC) () with a physiosorbed carbonyl group. Moreover, the evolution of oxidation states from electron-rich U to U on multiple potential energy surfaces of different electronic states involving configurations U(fs → f → f → f) is further demonstrated. Our findings unveil a mechanism for the photoreduction of CO by a UO molecule. This strategy can be used to design molecular and solid-state catalysts for depleted uranium for CO reduction reactions.

Nitrenes (R-N) have been subject to a large body of experimental and theoretical studies. The fundamental reactivity of this important class of transient intermediates has been attributed to their electronic structures, particularly the accessibility of triplet vs singlet states. In contrast, electronic structure trends along the heavier pnictinidene analogues (R-Pn; Pn = P-Bi) are much less systematically explored. We here report the synthesis of a series of metallodipnictenes, {M-Pn═Pn-M} (M = Pd, Pt; Pn = P, As, Sb, Bi) and the characterization of the transient metallopnictinidene intermediates, {M-Pn} for Pn = P, As, Sb. Structural, spectroscopic, and computational analysis revealed spin triplet ground states for the metallopnictinidenes with characteristic electronic structure trends along the series. In comparison to the nitrene, the heavier pnictinidenes exhibit lower-lying ground state SOMOs and singlet excited states, thus suggesting increased electrophilic reactivity. Furthermore, the splitting of the triplet magnetic microstates is beyond the phosphinidenes {M-P} dominated by heavy pnictogen atom induced spin-orbit coupling.

The polycrystalline nature of perovskites, stemming from their facile solution-based fabrication, leads to a high density of grain boundaries (GBs) and point defects. However, the impact of GBs on perovskite performance remains uncertain, with contradictory statements found in the literature. We developed a machine learning force field, sampled GB structures on a nanosecond time scale, and performed nonadiabatic (NA) molecular dynamics simulations of charge carrier trapping and recombination in stoichiometric and doped GBs. The simulations reveal long, microsecond carrier lifetimes, approaching experimental data, stemming from charge separation at the GBs and small NA coupling, 0.01-0.1 meV. Stoichiometric GBs exhibit transient trap states, which, however, are not particularly detrimental to the carrier lifetime. Halide dopants form interstitial defects in the bulk, but have a stabilizing influence on the GB structure by passivating undersaturated Pb atoms and reducing the transient trap state formation. On the contrary, excess Pb destabilizes GBs, allowing formation of persistent midgap states that trap charges. Still, the charge carrier lifetime reduces relatively little, because the midgap states decouple from the bands, and charges are more likely to escape back into bands upon a GB structural fluctuation. The atomistic study into the structural dynamics of perovskite GBs and its influence on charge carrier trapping and recombination provides valuable insights into the complex properties of perovskites and the intricate role of GBs in the material performance.

Epoxides are versatile chemical intermediates that are used in the manufacture of diversified industrial products. For decades, thermochemical conversion has long been employed as the primary synthetic route. However, it has several drawbacks, such as harsh and explosive operating conditions, as well as a significant greenhouse gas emissions problem. In this study, we propose an alternative electrocatalytic epoxidation reaction, using [Co(TAML)] (TAML = tetraamido macrocyclic ligand) as a molecular catalyst. Under ambient conditions, the catalyst selectively epoxidized olefin substrates using water as the oxygen atom source, affording an efficient catalytic epoxidation of olefins with a broad substrate scope. Notably, [Co(TAML)] achieved >60% Faradaic efficiency (FE) with >90% selectivity for cyclohexene epoxidation, which other heterogeneous electrocatalysts have never attained. Electrokinetic studies shed further light on the detailed mechanism of olefin epoxidation, which involved a rate-limiting proton-coupled electron transfer process, forming reactive cobalt oxygen active species embedded in 2eoxidized TAML. Operando voltammetry-electrospray ionization mass spectrometry (VESI-MS) and electron paramagnetic resonance (EPR) analyses were utilized to identify a cobalt oxygen active intermediate during an electrocatalytic epoxidation by [Co(TAML)]. Our findings offer a new possibility for sustainable chemical feedstock production using electrochemical methods.

Transitions between chiral rotational locomotion modes occur in a variety of active individuals and populations, such as sidewinders, self-propelled chiral droplets, and dense bacterial suspensions. Despite recent progress in the study of active matter, general principles governing rotational chiral transition remain elusive. Here, we study, experimentally and theoretically, rotational locomotion and its chiral transition in a 2D polyacrylamide (PAAm)-based BZ gel driven by Belousov-Zhabotinsky reaction-diffusion waves. Analysis reveals that the phase difference (Δφ) between orthogonal components of kinematic quantities, such as chemomechanical force, displacement, and velocity, determines rotational chirality, i.e., chiral locomotion transition occurs when Δφ changes sign. This criterion is illustrated with a kinematic equation, which can be applied to biological and physical systems, including super-rotational/superhelical locomotion reported recently during swimming and sperm navigation. This work has potential applications for the design of functional materials and intelligent robots.

Handedness-controllable macroscopic helices are needed for understanding the chirality transfer through scales and design of high-performance devices. Bottom-up self-assembly rarely affords macroscopic helical superstructures because of accumulating disorder that is difficult to avoid during hierarchical self-assembly. Here, we demonstrate that tetragold clusters can assemble into macroscopic helices at the centimeter scale. Halogen-bond induces hierarchical self-assembly from nanotubes to aslant stacked nanotubes and finally to macrohelices. Sacrificial template synthesis via solvent-corrosion sufficiently removes the embedded 1,3,5-trifluoro-2,4,6-triiodobenzene to produce helical skeletons. Homochiral macroscopic tendrils are controllably synthesized by chiral halogen bonding donors, allowing high-fidelity chiral amplification. This work contributes to the development of macroscopic helical superstructures by hierarchical assembly.