Achieving Strong Positive Cooperativity through Activating Weak Non‐Covalent Interactions

Positive cooperativity achieved through activating weak non‐covalent interactions is common in biological assemblies but is rarely observed in synthetic complexes. Two new molecular tubes have been synthesized and the syn isomer binds DABCO‐based organic cations with high orientational selectivity. Surprisingly, the ternary complex with two hosts and one guest shows a high cooperativity factor (α=580), which is the highest reported for synthetic systems without involving ion‐pairing interactions. The X‐ray single‐crystal structure revealed that the strong positive cooperativity likely originates from eight C?H???O hydrogen bonds between the two head‐to‐head‐arranged syn tube molecules. These relatively weak hydrogen bonds were not observed in the free hosts and only emerged in the complex. Furthermore, this complex was used as a basic motif to construct a robust [2+2] cyclic assembly, thus demonstrating its potential in molecular self‐assembly.     

Metal-free base-promoted sulfenylation for the synthesis of α-arylthio-α,β-unsaturated ketones

A new sulfenylation reaction has been established, stereoselectively affording 37 examples of α-arylthio-α,β-unsaturated ketones with generally good yields via a metal-free three-component reaction of α-thiocyanate ketones with diaryliodonium salts and 1,2-dicarbonyls. The reaction enabled multiple bond-forming events including C(sp²)–S formation to provide a high-efficient and practical method toward α-arylthio-α,β-unsaturated ketones. The reasonable mechanism for forming α-arylthio-α,β-unsaturated ketones was proposed.     

Nickel(II)-catalyzed addition reaction of arylboronic acids to isatins

A Ni-catalyzed addition of arylboronic acids to isatins was first developed. The reaction, driven by Ni(acac)₂ and dppp as the phosphine ligand, gave 3-aryl-3-hydroxy-2-oxindoles in up to 97% yield. Scopes of benzyl-protected isatins and arylboronic acids were examined. Substituted phenylboronic acids along with fused-ring and heterocyclic boronic acids reacted with isatins smoothly. Preliminary asymmetric catalysis was investigated as well, showing moderate enantioselectivity. The mechanism was also described.     

CuX2-mediated halocyclization of 1,1-difluoro-2,3-allenylphosphonic acid monoesters –synthesis of novel cyclic phosphate mimics

Novel six-membered cyclic phosphate mimics (5-halo-3,3-difluoro-3,6-dihydro-2H-1,2-oxaphosphinine 2-oxides) were synthesized via CuX₂ (X?=?Br, Cl)-mediated halocyclization of 1,1-difluoro-2,3-allenylphosphonic acid monoesters in moderate to good yields with high regio-selectivity. This reaction represents the first example of transition metal-mediated intramolecular cyclization of a P-OH moiety to β-allenylphosphonates with a carbon-carbon double bond.     

Thioquinomycins A-D,novel naphthothiophenediones from the marine-derived Streptomyces sp. SS17F

Thioquinomycins A-D (1–4), four novel naphthothiophenediones were isolated from the rice-based medium of the marine-derived Streptomyces sp. SS17F. Their structures were elucidated by spectroscopic methods and HRESIMS data. The absolute configurations of all the compounds were elucidated by X-ray diffraction analysis, ECD and Mosher's method combined with ¹⁹F-NMR. Compounds 1–4 showed moderate cytotoxicity against NCI-H1975 with IC₅₀ values from 17.5 to 50?μM. In addition, compounds 1–4 also exhibited inhibitory activities against PKCα and ROCK2 protein kinase.     

石墨烯在复合热电材料中的应用

热电材料是一种可以实现热能与电能之间直接相互转换的功能材料,在温差发电和热电制冷方面具有广阔的应用空间。石墨烯是一种单原子层厚度的二维碳材料,具有特殊的晶体结构和优异的物理化学性质。大量研究表明石墨烯优异的电学性能、超大的比表面积以及多样的边界结构有利于材料电、热性能的协同调控,使其在热电领域有较大的应用潜力。本文结合热电材料的性能特点,从石墨烯的结构与性能入手,综述了石墨烯自身作为热电材料时结构与性能的优化关系,并总结归纳了石墨烯与Bi₂Te₃、CoSb₃等传统无机热电材料以及与导电高分子热电材料构成纳米复合块体和薄膜时,对材料结构与热电性能的影响,并结合现存的问题对石墨烯在热电领域中的应用进行了展望。     

纳滤膜新型材料研究

纳滤是一种介于超滤与反渗透之间的重要膜分离过程,具有工作压力低、无相转变及分离效率高等独特优势。膜污染及渗透性/选择性之间的平衡是纳滤膜在使用和研发过程中面临的亟待解决的两个主要问题。膜材料是膜与膜分离技术的核心,开发新型的纳滤膜材料是解决上述问题的重要手段。本文从新型纳滤膜材料的设计与选择的角度出发,总结归纳了近年来新型材料在纳滤膜的制备与应用研究现状,包括新型有机纳滤膜材料、新型无机纳滤膜材料和新型有机-无机杂化纳滤膜材料三个方面,拓展了对纳滤膜材料的认知,探讨了新型纳滤膜材料的共性及其存在的主要问题,并对未来高性能纳滤膜材料的研制方向进行了展望。     

Photocatalytic Hydrogen Production Coupled with Selective Benzylamine Oxidation over MOF Composites

Photocatalytic water splitting requires separation of the mixed H₂ and O₂ products and is often hampered by the sluggish O₂‐producing half reaction. An approach is now reported to address these issues by coupling the H₂‐producing half reaction with value‐added benzylamine oxidation reaction using metal–organic framework (MOF) composites. Upon MOF photoexcitation, the electrons rapidly reduce the protons to generate H₂ and the holes promote considerable benzylamine oxidation to N‐benzylbenzaldimine with high selectivity. Further experimental characterizations and theoretical calculation reveal that the highly conjugated s‐triazine strut in the MOF structure is crucial to the efficient charge separation and excellent photocatalytic activity.     

Facile,Quick, and Gram‐Scale Synthesis of Ultralong‐Lifetime Room‐Temperature‐Phosphorescent Carbon Dots by Microwave Irradiation

Long‐lifetime room‐temperature phosphorescence (RTP) materials are important for many applications, but they are highly challenging materials owing to the spin‐forbidden nature of triplet exciton transitions. Herein, a facile, quick and gram‐scale method for the preparation of ultralong RTP (URTP) carbon dots (CDs) was developed via microwave‐assisted heating of ethanolamine and phosphoric acid aqueous solution. The CDs exhibit the longest RTP lifetime, 1.46 s (more than 10 s to naked eye) for CDs‐based materials to date. The doping of N and P elements is critical for the URTP which is considered to be favored by a n→π* transition facilitating intersystem crossing (ISC) for effectively populating triplet excitons. In addition, possibilities of formation of hydrogen bonds in the interior of the CDs may also play a significant role in producing RTP. Potential applications of the URTP CDs in the fields of anti‐counterfeiting and information protection are proposed and demonstrated.