High‐Nuclear Organometallic Copper(I)–Alkynide Clusters: Thermochromic Near‐Infrared Luminescence and Solution Stability

Cu(CF₃COO)₂ reacts with tert‐butylacetylene (tBuC≡CH) in methanol in the presence of metallic copper powder to give two air‐stable clusters, [Cu^I₁₅(tBuC≡C)₁₀(CF₃COO)₅]?tBuC≡CH ( 1 ) and [Cu^I₁₆(tBuC≡C)₁₂(CF₃COO)₄(CH₃OH)₂] ( 2 ). The assembly process involves in situ comproportionation reaction between Cu²⁺ and Cu⁰ and the formation of two different clusters is controlled by reactants concentration. The clusters consist of Cu₁₅ and Cu₁₆ cores co‐stabilized by strong by σ‐ and π‐bonded tert‐butylethynide and CF₃COO^? (together with methanol molecule in 2 ). Their stabilities in solution were confirmed using electrospray ionization mass spectrometry in which the cluster core remains intact for 1 in chloroform and acetone, and for 2 in acetonitrile. Strong thermochromic luminescence in the near infrared (NIR) region was observed in the solid‐state. Of particular interest, the emission maximum of 1 is red‐shifted from 710 nm at 298 K to 793 nm at 93 K, along with a 17‐fold fluorescence enhancement. In contrast, 2 exhibits red shift from 298 to 123 K followed by blue shift from 123 to 93 K. The emission wavelength was correlated with the structural parameters using variable‐temperature X‐ray single‐crystal analyses. The rich cuprophilic interaction plays a significant role in the formation of ³LMCT (tBuC≡C→Cu_x) excited state mixed with cluster‐centered (³CC) characters, which can be considerably influenced by temperature, leading to thermochromic luminescence. The present work provides 1) a new synthetic protocol for the high‐nuclear Cu^I–alkynyl clusters; 2) a comprehensive insight into the mechanism of thermochromic luminescence; 3) unusual emissive materials with the characters of NIR and thermochromic luminescence simultaneously.     

Probing the Catalytic Promiscuity of a Regio‐ and Stereospecific C‐Glycosyltransferase from Mangifera indica

The catalytic promiscuity of the novel benzophenone C‐glycosyltransferase, MiCGT, which is involved in the biosynthesis of mangiferin from Mangifera indica, was explored. MiCGT exhibited a robust capability to regio‐ and stereospecific C‐glycosylation of 35 structurally diverse druglike scaffolds and simple phenolics with UDP‐glucose, and also formed O‐ and N‐glycosides. Moreover, MiCGT was able to generate C‐xylosides with UDP‐xylose. The OGT‐reversibility of MiCGT was also exploited to generate C‐glucosides with simple sugar donor. Three aryl‐C‐glycosides exhibited potent SGLT2 inhibitory activities with IC₅₀ values of 2.6×, 7.6×, and 7.6×10⁻⁷ M , respectively. These findings demonstrate for the first time the significant potential of an enzymatic approach to diversification through C‐glycosidation of bioactive natural and unnatural products in drug discovery.     

Self‐Assembly and Compartmentalization of Nanozymes in Mesoporous Silica‐Based Nanoreactors

Herein, to mimic complex natural system, polyelectrolyte multilayer (PEM)‐coated mesoporous silica nanoreactors were used to compartmentalize two different artificial enzymes. PEMs coated on the surface of mesoporous silica could serve as a permeable membrane to control the flow of molecules. When assembling hemin on the surface of mesoporous silica, the hemin‐based mesoporous silica system possessed remarkable peroxidase‐like activity, especially at physiological pH, and could be recycled more easily than traditional graphene–hemin nanocompounds. The hope is that these new findings may pave the way for exploring novel nanoreactors to achieve compartmentalization of nanozymes and applying artificial cascade catalytic systems to mimic cell organelles or important biochemical transformations     

1,3-丁二烯选择性加氢催化剂的设计策略以及构效关系

催化裂化是石油化工的核心单元之一.从催化裂化尾气中分离出来的碳四馏分富含许多的不饱和烯烃,如1-丁烯、顺、反式-2-丁烯以及少量的1,3-丁二烯,这些不饱和烯烃可以通过后续聚合反应,生成合成橡胶和工程塑料的重要原料,具有重要的应用价值.上述工艺过程对原料中1,3-丁二烯的含量(<100~200 ppm)有严苛的要求.采用选择性加氢技术对碳四馏分中的1,3-丁二烯进行选择性加氢,将其转化为更高附加值的单烯烃是一个理想的解决方案.然而,1,3-丁二烯加氢反应得到的单烯烃可能发生深度加氢得到副产物丁烷.因此,开发高效选择性加氢催化剂对碳四资源的利用具有重要的现实意义.另一方面,1,3-丁二烯加氢反应可以作为模型反应,用来考察选择性加氢催化剂的性能.基于此,该反应无论在工业界还是学术界均受到广泛关注.尽管如此,有关1,3-丁二烯加氢催化剂研究进展方面的综述极少.仅有关于1,3-丁二烯加氢作为模型反应的综述报道.本文对过去半个世纪以来1,3-丁二烯加氢反应中不同催化剂的发展历程进行系统综述,特别是包括Pd,Pt和Au等的单一贵金属催化剂.重点介绍以下内容:(1)固体催化剂构效关系,包括活性金属尺寸效应、晶面和形貌效应以及载体效应(晶相、孔道和酸碱性);(2)高性能催化剂的设计新策略,如单原子催化剂、核壳结构催化剂、金属-离子液复合催化体系以及载体的形貌调控;(3)催化剂的反应机理和失活机理.提出了1,3-丁二烯选择性加氢高性能催化剂开发面临的挑战,并对潜在的发展方向进行了展望.本文认为随着纳米技术和金属纳米材料合成方法的快速发展,对贵金属活性组分进行原子层面上的调控(包括形貌、尺寸以及单原子配位环境等)已成为可能.这将有助于研制出一类新型高性能选择性加氢催化材料,从而实现高转化率条件下高附加值单烯烃的定向转化.此外,载体的酸碱性和孔道结构的调控有助于进一步调节催化剂的抗积炭性能,也是未来发展的一个重要方向.     

Facile fabrication of oxygen-doped carbon nitride with enhanced visible-light photocatalytic degradation of methyl mercaptan

Research on Chemical Intermediates - Element doping has demonstrated an effective strategy for enhancing photocatalytic performance of carbon nitride (CN). Herein, we reported that oxygen-doped CN...     

d-Orbital Reconstructions Forced by Double Bow-Shaped Deformations and Second Coordination Sphere Effects of Cu(II) Heme Analogs in HER**

Both geometric architecture and electronic configurations of heme proteins contribute to its activity. In this work we designed and synthesized a series of four copper(II) porphyrin complexes ( 4 -, 3 -, 2 - and 1 -Cu) where the molecular conformations are modulated by a pair of stepwise shortened straps on the same porphyrin side (cis-ortho) to give double bow-shaped skeletons. Single crystal structures demonstrate that the straps gradually increase the saddle deformation and the deviation of the metal centers, which is in accordance with two, unusual d-orbital reconstructions of two different ground states, as revealed by 4 K EPR and DFT calculations. In the study of the electrocatalytic hydrogen evolution reaction (HER), 1 -Cu, with the shortest straps, showed the most apparent improvement of activity. Second coordination sphere (SCS) effects created by the double bow-shaped architecture and the strong saddle porphyrin core in 1 -Cu are found to play key roles in proton trapping during the catalytic process. The work contributes a novel strategy to improve the catalytic performance of heme analogs through ligand geometric modulation.     

Two-Dimensional Covalent and Supramolecular Polymers: From Monolayer to Bilayer and the Thicker

Selective preparation of two-dimensional polymers (2DPs) and supramolecular polymers (2DSPs) with defined thickness is crucially important for controlling and maximizing their functions, yet it has remained as a synthetic challenge. In the past decade, several approaches have been developed to allow selective preparation of discrete monolayer 2DPs and 2DSPs. Recently, crystal exfoliation and self-assembly strategies have been employed to successfully prepare bilayer 2DP and 2DSP, which represent the first step towards the controlled “growth” of 2D polymers from the thinnest monolayers to thicker few-layers along the third dimension. This Concept review discusses the concept of accurate synthesis of 2D polymers with defined layers. Advances in this research area will pave the way to rational synthetic strategies for 2D polymers with controlled thickness.