Main observation and conclusion

In this study, we communicate a Pd(II)-catalyzed Markovnikov hydroalkynylation of unactivated terminal alkenes, which provides an efficient method to access branched alkynes in good yields and excellent regioselectivity, where IBX was used as alkynyl reagent and hydrosilane as reducing reagent. After the initial alkene insertion into alkynyl-Pd(II) species, the generated alkyl-Pd(II) was reduced by hydrosilane to give the hydroalkynylation product efficiently. Notably, a pyridine-oxazoline (Pyox) plays a key role in the reactivity and selectivity.

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Comprehensive Summary

Transition metal-catalyzed asymmetric transfer hydrogenation has been proved to be a powerful approach for the synthesis of chiral alcohols. Herein, A highly efficient and enantioselective transfer hydrogenation of dibenzoheptaheterocyclic ketones catalyzed by an arene-tethered TsDPEN-based Rh(III) catalyst has been successfully developed, and a variety of dibenzoheptaheterocyclic ketones were reduced by a 1/1 mixture of formic acid and DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) with high yields and enantioselectivities. With this method, the asymmetric reduction of 7,8-difluorodibenzo[b,e]thiepin-11(6H)-one has been realized, providing the key intermediate of baloxavir marboxil with >99% yield and >99% ee at a substrate/catalyst molar ratio of 1000.

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Abstract

The development of highly efficient non-precious-metal-based electrocatalysts for the hydrogen evolution reaction is imperative for promoting the large-scale application of electrochemical water splitting. Herein nitrogen/phosphorus co-doped carbon nanorods encapsulated Mo₂C nanoparticles (Mo₂C@PNC) have been prepared by pre-phosphating treatment in combination of the coordination with polydopamine and the subsequent pyrolysis. The phosphating temperature has a significant effect on the content of phosphorus within the resultant Mo₂C@PNC, and the optimal catalyst delivers superior HER activity with the low overpotential of 104 mV at a current density of 10 mA cm^-2 and good stability for 8 h, which has been theoretically demonstrate to originate from the synergistic effect between P doping and Mo₂C induced electron redistribution of nitrogen-doped carbon layer.

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An unprecedented copper nitrate-mediated bond cleavage of alkynes was developed for the modular synthesis of isoxazoles, where either C—S bond or C≡C triple bond was cleaved selectively.

Comprehensive Summary

An unprecedented copper nitrate-mediated bond cleavage of alkynes was developed for the modular synthesis of isoxazoles, where either C—S bond or C≡C triple bond was cleaved selectively. Substituents attached to the C≡C triple bonds could differentiate the chemical bonds cleavage and reaction pathways disparately. Various transformations of products illustrate promising applications of the given protocols.

Comprehensive Summary

Realizing the hydrogen economy by water electrolysis is an attractive approach for hydrogen production, while the efficient and stable bifunctional catalysts under high current densities are the bottleneck that limits the half-cell reactions of water splitting. Here, we propose an approach of hydrothermal and thermal annealing methods for robust MoO₂/MoNi₄@Ru/RuO₂ heterogeneous cuboid array electrocatalyst with multiplying surface-active sites by depositing a monolayer amount of Ru. Benefiting from abundant MoO₂/MoNi₄@Ru/RuO₂ heterointerfaces on Cu foam, effectively driving the alkaline water splitting with superior hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The synthesized MoO₂/MoNi₄@Ru/RuO₂ has high HER activity, which realizes the working overpotentials of 48 mV at 50 mA cm^-2, further achieving overpotentials of 230 mV for industry-level 1000 mA cm^-2 in alkaline water electrolysis. Moreover, it also showed an enhanced OER activity than commercial RuO₂ with a small overpotential of 280 mV at 200 mA cm^-2 in alkaline media. When building an electrolyzer with electrodes of (-)MoO₂/MoNi₄@Ru/RuO₂IIMoO₂/MoNi₄@Ru/RuO₂ (+), a cell voltage of 1.63 V, and 1.75 V just requires to support the current density of 200 mA cm^-2 and 500 mA cm^-2 in alkaline water electrolysis, much lower than the electrolyzer of (-)Pt/CIIRuO₂(+). This work demonstrates that MoO₂/MoNi₄@Ru/RuO₂ heterogeneous nanosheet arrays are promising candidates for industrial water electrolysis applications, providing a possibility for the exploration of water electrolysis with a large current density.

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A nickel single-atom heterogeneous photocatalyst was prepared and employed in visible-light-driven C—O cross-coupling reactions under mild conditions, which exceeded the catalytic activity of a semi-heterogeneous catalytic system. The reaction system exhibited good isolated yields for a broad range of aryl bromides (e.g., ketones, aldehydes, esters, and amides) and both primary and secondary alcohols. Experimental characterizations showed that nickel single atoms could facilitate C—O cross-coupling by extending the visible absorption range, improving the charge transfer, and inhibiting the recombination of carriers.

Comprehensive Summary

Solar-driven cross-coupling reactions by dual nickel/photocatalysis under mild conditions have received considerable attention. However, the existing photo/nickel dual catalytic cross-coupling reactions require the addition of expensive photosensitizers and organic ligands, and the catalytic activity is inadequate. Herein, we report a nickel single-atom heterogeneous catalyst supported on mesoporous carbon nitride for photocatalytic C—O coupling reaction between 4-bromobenzonitrile and ethanol, affording 4-ethoxybenzonitrile in excellent yield compared to a semi-heterogeneous catalytic system. The catalytic system exhibits a broad substrate scope including ketones, aldehydes, esters, and amides. This work presents a simple and cost-effective strategy for anchoring metal single atoms onto carbon nitride, providing a new platform for enabling high-performance photocatalytic production of aryl ether compounds.

We study the organoboron catalyzed ring-opening copolymerization of epoxides and isothiocyanates and the performance of the resultant polythioimidocarbonates. Copolymerizations only take place on free -OC(=N)S⁻, and excess TEB or intramolecular synergy are adverse. Additionally, aromatic isothiocyanates polymerize much faster than aliphatic ones, which facilitated the one-step synthesis of block polymers from mixed monomers. This protocol can deliver sulfur-containing polymers with both high T _g and refractive index. Moreover, polythioimidocarbonates can also serve as positive resists for electron beam lithography.

Comprehensive Summary

Synthesis of diverse polythioimidocarbonates via ring-opening copolymerization of epoxides and isothiocyanates catalyzed by organoboron catalyst was reported herein. Both aromatic and aliphatic isothiocyanates underwent successful copolymerization with terminal and internal epoxides, allowing for the precise tuning of the performance of the resultant copolymers over a broad range. The wide scope of available isothiocyanates and epoxides enables the direct construction of sulfur-containing functional polymers featuring both high glass transition temperature and refractive index. Additionally, it was observed that aromatic isothiocyanates polymerize much faster than aliphatic ones, and the reactivity difference facilitated the one-step synthesis of block polymers from mixed aromatic isothiocyanates, aliphatic isothiocyanates and epoxides due to the preferential incorporation of aromatic isothiocyanates over the aliphatic analogues during their alternating copolymerization with epoxides. The produced polythioimidocarbonates can be used as positive resists for electron beam lithography (sensitivity of 130 μC/cm² and contrast of 1.53 for poly(CHO-alt-EITC)). Coupling with their high refractive index (1.58—1.68), polythioimidocarbonates might find functional applications in optics. These results render ring-opening copolymerization of epoxides and isothiocyanates a facile route to enrich functional polymer library.

Comprehensive Summary

Since 1986, the donor-acceptor (D:A) heterojunction has been regarded a necessity for high-efficiency organic photovoltaics (OPVs), due to its unique advantage in compensating the intrinsic limitations of organic semiconductors, such as high exciton binding energy and poor ambipolar charge mobility. While this adversely causes tremendous non-radiative charge recombination and instability issues, which currently become the most critical limits for commercialization of OPVs. Here, we present a concept-to-proof study on the potential of D:A heterojunction free OPV by taking advantage of recent progress of non-fullerene acceptors. First, we demonstrate that the “free carriers” can be spontaneously generated upon illumination in an NFA, i.e. the 6TIC-4F single layer. Second, the 6TIC-4F layer also exhibits good ambipolar charge transporting property. These exceptional characteristics distinguish it from the traditional organic semiconductors, and relieve it from the reliance of D:A heterojunction to independently work as active layer. As a result, the subsequent OPV by simply sandwiching the 6TIC-4F layer between the cathode and anode yields a considerably high power conversion efficiency ~ 1%. Moreover, we find the D:A heterojunction free device exhibits two order of magnitude higher electroluminescence quantum efficiency and significantly reduced V_OC loss by 0.16 eV compared to those of the D:A BHJ structure, validating its promise for higher efficiency in the future. Therefore, our work demonstrates the possibility of using D:A heterojunction-free device structure for high performance, that can potentially become the next game changer of OPV.

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Main observation and conclusion

Chiral supramolecular assembly of π-conjugated luminophores provides a promising avenue for enhancing circularly polarized luminescence. In this study, we shed light on the impact of π-conjugation length on circularly polarized luminescent performance of the resulting supramolecular assemblies, by designing a tetra-cyanostilbene monomeric compound alongside two dicyanostilbene control compounds. These cyanostilbene-based compounds possess the ability to form chiral supramolecular polymers in toluene, driven by a synergistic combination of intermolecular hydrogen bonding and π–π stacking interactions. The extended π-aromatic skeleton brings bathochromic-shifted fluorescence and enhanced intermolecular stacking capability for the tetra-cyanostilbene compound. Consequently, chiral supramolecular assemblies formed by the tetra-cyanostilbene compound demonstrate a remarkable two-fold increase in g _lum values relative to the assemblies formed by the dicyanostilbene compounds. Overall, this study provides valuable insights into the relationship between π-conjugation length and the circularly polarized luminescent performance of π-conjugated supramolecular assemblies.

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Two Hantzsch ester derived fluorescent probes were constructed based on asymmetric BODIPY-matrix. These probes both exhibited significant fluorescence turn-on with ultra-high sensitivity (LoD < 1 nmol/L), response to hypochlorite (ClO^–) in 5 s, and displayed excellent selectivity to ClO^– and favourable quantum yield. Notably, MeDHP-BCl achieved the real-time visualization of endogenous ClO^– in living cells for its lower cytotoxicity and more remarkable fluorescence increment after activation.

Comprehensive Summary

Hypochlorite (ClO^–) is an important reactive oxygen species produced by the immune system to fight off invading pathogens, but its over-expression can interfere with normal physiological process and induce serious diseases. Although a variety of molecular probes have been reported for detecting ClO^–, the development of advanced fluorescent tools with faster response and higher sensitivity to precisely monitor ClO^– remains a challenge. In this work, two Hantzsch ester (a derivative of 1,4-dihydropyridine) derived fluorescent probes MeDHP-BCl and MeDHP-PhBCl were constructed based on asymmetric BODIPY-matrix. These probes exhibit significant fluorescence turn-on in the ultra-sensitive (detection limit < 1 nmol/L) and ultra-fast response (≤ 5 s) to ClO^–. The reaction has been determined to be a highly selective N-chlorination of Hantzsch ester which cannot be activated by various common bioactive species, including nitric oxide (NO) that could oxidize Hantzsch ester under aerobic physiological conditions in most reports. MeDHP-PhBCl possessed a relatively longer fluorescence emission wavelength and higher quantum yield after activation, while more notably, MeDHP-BCl displayed lower cytotoxicity and more remarkable fluorescence increment in the response to ClO^–, enabling selective and precise visualization of endogenous ClO^– over-expression in living RAW264.7 cells.