查看更多>>摘要：A regiodivergent synthesis of azetidines,5,6-dihydro-1,3-oxazines and 2,3-dihydro-1,4-oxazines has been achieved through palladi-um-catalyzed tandem allylic substitution reaction.This protocol provides a variety of heterocycles in satisfactory yields with good to excellent regioselectivities under mild reaction conditions.
查看更多>>摘要：Inorganic lead halide perovskite(LHP)nanostructures,represented by formula CsPbX3(X=Cl,Br,I),have garnered considerable inter-est for their exceptional optical properties and diverse applications.Despite their potential,challenges such as environmental degra-dation persist.In-situ synthesis within protective materials pores is a promising way to address this issue.However,confining perov-skite nanostructures into porous matrices during the synthesis can limit their photoluminescence quantum yield(PL QY)and tunability of optical properties.Various post-treatment approaches exist to improve the properties of LHP and achieve their desired functionali-ties,but these strategies have not been explored for LHP confined in mesoporous matrices.Here,we demonstrate the efficacy of in-situ post-synthetic treatments to improve the optical properties of CsPbBr3 nanocrystals grown in nanoporous silica microspheres.Surface passivation with Br-ion-containing precursors boosts PL QY,while anion-assisted cation doping with Mn2+ions introduces a new PL band.The adjustment of precursor amount and doping duration enables precise control over the optical properties of LHP,while additional coating with a SiO2 shell enhances their stability in polar solvents,expanding the potential applications of these com-posites.
查看更多>>摘要：Electrocatalytic reduction of CO2 to valuable products possesses huge potential to alleviate environmental and energy crisis.It is well known that Ag favors the conversion of CO2 to CO but the exposed active sites and stability are still rather limited.In this study,a novel one-dimensional Ag-based metal-organic framework(1D Ag-NIM-MOF)was successfully synthesized and used in the electrocatalytic CO2 reduction reaction(CO2RR)for the first time.As a result,the Faradaic efficiency of CO achieved 94.5％with current density of 12.5 mA·cm-2 in an H-type cell and 98.2％with current density of 161 mA·cm-2 in a flow cell at-1.0 V(vs.RHE),which stands as a new benchmark of Ag-based MOFs in the electrocatalytic CO2RR.The excellent performance of 1D Ag-NIM-MOF is attributed to its peculiar one-dimensional structure,which is beneficial for diffusion of reactants and products,and exposure of much more catalytic sites.Com-pared to commercial Ag nanoparticles,1D Ag-NIM-MOF exhibits superior electrocatalytic CO2RR performance with higher catalytic ac-tivity and stability.
查看更多>>摘要：Inverted(p-i-n)perovskite solar cells(PSCs)are favored by researchers owing to their superior compatibility with flexible substrates and tandem device fabrication.Additionally,the hole transport layer(HTL)serves as a template for perovskite growth,which is critical for enhancing the device performance.However,the current research on how the HTL promotes perovskite crystallization is insuffi-cient.Here,4PADCB,a self-assembled monolayer(SAM)hole transport material,was optimized as a superior template for perovskite growth through comparative analysis;accordingly,compact perovskite film with vertical growth was prepared.The better matched energy level alignment between 4PADCB and perovskite suppressed nonradiative recombination at the interface and enabled rapid hole extraction.Moreover,high-quality perovskite film growth on 4PADCB exhibited lower Young's modulus and less residual stress.By integrating 4PADCB into p-i-n PSCs,the optimal device achieved a power conversion efficiency of 24.80％,with an open-circuit voltage of 1.156 V,thus achieving the best rank among devices without perovskite post-treatment,additives,dopants,or intermediate layers.Furthermore,the unencapsulated device demonstrated exceptional thermostability and photostability under maximum power point tracking.Thus,this work provides a new understanding for the development of novel SAMs and perovskite growth,and it is expected to further improve device performance.
查看更多>>摘要：A greener and more convenient alternative to traditional methods for the generation of thiyl radical as hydrogen atom transfer(HAT)catalyst is developed,using molecular oxygen to oxidize thiol without the need for chemical initiators or light irradiation.The thi-ol/oxygen catalysis enables selective and efficient difunctionalization of borane.
查看更多>>摘要：Carbohelicenes have garnered considerable attention for their inherent chirality and structural flexibility.Increasing multi-helicity and incorporating non-six-membered rings to substitute benzenoid rings within helicenes are effective strategies for introducing unique photoelectric properties.Despite the disclosure of numerous helicenes,the inaccessible precursors and the lack of synthetic routes pose a challenge in achieving desired helicene structures fused with non-benzenoid rings.Herein,we report the synthesis of multiple non-benzenoid carbohelicenes fused with fluorene unit(s)through intramolecular cyclodehydrogenation of 9,10-di(naphthalen-1-yl)anthracene on Au(111)surface.Two potential cyclodehydrogenation manners between naphthyl and anthracene lead to the for-mation of fluorene-fused[5]helicene and[4]helicene moiety.Consequently,a total of four stable products were observed.The atomic topographies of products are characterized by bond-resolving scanning tunneling microscopy.The chiral helicity of targeted products can be switched by tip manipulation.Density-functional-theory calculations unveils the reaction pathway of four products.The com-parative analysis of their respective energy barriers exhibits a correlation with the experimentally determined yields.Furthermore,we synthesize the polymer chains incorporating non-benzenoid carbohelicenes via the Ullmann reaction of 2,6-dibromo-9,10-di(1-naph-thyl)anthracene precursors.Our work proposes a synthetic methodology for several novel helicene-like structures fused with fluorene units and the polymer bearing helicene subunits,thus highlighting the immense potential of these compounds in the application fields of luminescent electronic devices.
查看更多>>摘要：Catalytic dehydrogenation,with its exceptional atom economy and chemoselectivity,offers a highly desirable yet challenging approach for converting multiple environmentally friendly alcohols into crucial molecules.Furthermore,the utilization of catalysts based on abundant elements found on Earth for alcohol dehydrogenation to produce acryl ketone holds significant promise as a versatile strategy in synthesizing key building blocks for numerous pharmaceutical applications.The present study describes a practical Co-catalyzed cascade dehydrogenative Claisen condensation of secondary alcohols with esters,facilitating the synthesis of a wide range of 3-hydroxy-prop-2-en-1-ones.We introduce a catalytic system based on novel and scalable indazole NNP-ligands coordinated to cobalt for efficient dehydrogenations of secondary alcohols,and propose a plausible reaction mechanism supported by control experiments and labeling studies.Notably,it allows for the streamlined synthesis of multiple pharmaceuticals in one-pot.
查看更多>>摘要：The morphology of the active layer plays a crucial role in the performance of organic photovoltaics.Although volatile additives are commonly used to manipulate the morphology,their mechanism of action remains poorly understood.In this study,we conducted a systematic exploration of the mechanism of the traditional volatile additive 1-CN in film formation kinetics of typical PM6:Y6 system.We found that 1-CN induces a secondary aggregation effect,improving film morphology and promoting face-on crystalline orientation.Through elucidating its impact on exciton dynamics,we established a link between morphology optimization and increased exciton diffusion length and accelerated charge separation.Our findings unveil the unique mechanism of action of volatile additive,providing a new perspective for improving the morphology and enhancing the performance of organic photovoltaic devices.
查看更多>>摘要：The first catalytic asymmetric total synthesis of(+)-propolisbenzofuran B,enabled by a highly enantioselective rhodium-catalyzed hy-drogenation of a tetrasubstituted olefin,was described.Other noteworthy aspects include the construction of the central hydrodi-benzo[b,d]furan core through a sequence of Zn(Ⅱ)-mediated regioselective benzofuran formation and Dieckmann condensation,as well as C-H oxidations,involving a visible light-induced Fe(Ⅲ)-catalyzed benzylic C(sp3)-H oxidation.Additionally,the absolute configu-ration was confirmed by X-ray analysis of a carbonate intermediate.
查看更多>>摘要：Poly-NHC-based organometallic assemblies 3-PF6,3-SbF6 and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spec-trometry and single-crystal X-ray diffraction analyses.Controllable structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration,solvent and metal ion.1H NMR spectra of assembly 3-PF6 in CD3CN at different concentrations demonstrated controllable structural interconversion,and 19F NMR spectrum of assembly 3-PF6 at high concentration further evidenced the presence of the free hexafluorophosphate anion and encapsulated hexafluorophosphate anion for its two sets of signals.In addition,single-crystal X-ray diffraction analysis provided clear evidence that in the solid state,two assemblies 3-PF6 were vertically stuck,forming a self-aggregated dimer with an encapsulated hexafluorophosphate anion.Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.
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