功能化MCM-41在有机合成中的应用

介孔分子筛MCM-41具有较高的比表面和规整的结构以及表面带有羟基,因此可对MCM-41进行官能团化,从而实现均相催化剂在MCM-41中的组装,达到均相催化剂多相化的目的。本文介绍了最近几年以MCM-41为主体,组装均相配合物得到固相化催化剂在氧化、还原、烷基化、氢甲酰化、Heck、环丙烷化等反应中的应用。     

Silica-metalloporphyrins hybrid materials: preparation and catalysis to hydroxylate cyclohexane with molecular oxygen

Three types of novel silica-metalloporphyrins hybrid materials, Si-S-APTCPPFe, Si-S-APTCPPMn and Si-S-APTCPPCo, were prepared at room temperature by sol–gel method involving a thiol-ene polymerization reaction of 5-(4-allyloxy)phenyl-10,15,20-tri(4-chlorophenyl)porphyrin (APTCPP) with 3-mercaptopropyltrimethoxysilane (MPS). The hybrid materials were characterized by XRD, SEM, FT–IR, UV–Vis and TG, and were investigated as catalysts for the aerobic oxidation of cyclohexane. It is found that these hybrid materials are more efficient catalysts than the analogous non-supported metalloporphyrins for cyclohexane hydroxylation in metalloporphyrin–O₂–ascrobate system and the metal ion in the porphyrins significantly affected the catalytic efficiencies of these hybrid materials.     

Carbonylative Stille coupling reactions of benzyl chlorides with allyltributylstannane catalyzed by palladium nanoparticles

The carbonylative Stille coupling reaction of benzyl chlorides with allyltributylstannane was successfully conducted by using palladium nanoparticles as the catalyst under phosphine ligand-free conditions. The corresponding α,β-unsaturated ketone products were obtained in good to excellent yields.     

Selective carboxylation of substituted phenols with engineered Escherichia coli whole-cells

Selective carboxylation of substituted phenols is realized in the presence of bicarbonate under ambient pressure by engineered Escherichia coli whole-cells expressing various hydroxybenzoate decarboxylases, leading to their corresponding ortho-hydroxybenzoates. This process may be further developed as an efficient route to upgrade lignin-derived phenolic compounds as valuable building blocks.     

The synergistic catalysis on Co nanoparticles and CoN_x sites of aniline-modified ZIF derived Co@NCs for oxidative esterification of HMF

An efficient sustainable and scalable strategy for the synthesis of porous cobalt/nitrogen co-doped carbons(Co@NCs) via pyrolysis of aniline-modified ZIFs,has been demonstrated.Aniline can coordinate and absorb on the surface of ZIF(ZIF-CoZn3-PhA),accelerate the precipitation of ZIFs,thus resulting in smaller ZIF particle size.Meanwhile,the aniline on the surface of ZIF-CoZn3-PhA promotes the formation of the protective carbon shell and smaller Co nanoparticles,and increases nitrogen content of the catalyst.Because of these prope rties of Co@NC-PhA-3,the oxidative esterification of 5-hydroxymethylfurfural can be carried out under ambient conditions.According to our experimental and computational results,a synergistic catalytic effect between CoN_x sites and Co nanoparticles has been established,in which both Co nanoparticles and CoN_x can activate O_2 while Co nanoparticles bind and oxidize HMF.Moreover,the formation and release of active oxygen species in CoN_x sites are reinfo rced by the electronic interaction between Co nanoparticles and CoN_x.     

单颗粒光催化剂光生电荷的全时空传输过程

<正>半导体光催化可利用太阳能引发众多氧化还原反应,其中最受关注的是将水分解为氢气和氧气^[1],将二氧化碳还原为高值化学品^[2],以及将水和空气中污染物进行氧化还原消除^[3],为解决人类面临的能源危机和环境恶化等问题提供了极具前景的解决方案。如何提高效率是光催化应用过程中面临的首要问题,而对光催化机制的深入理解是提高光催化效率的必要前提。最近,中国科学院大连化学物理研究所李灿院士、     

微乳液法制备介孔碳材料

介孔碳材料因具有高比表面积,规则的孔隙结构,低密度,良好的生物相容性及导电性,被广泛应用于催化、能量储存及转化、吸附分离和药物递送等领域。微乳液法具有制备工艺简便、环境友好、可大规模生产及产物结构可控性强等突出优势,在制备孔隙结构可控和特殊形态介孔碳方面取得突破性的进展。本文首先着重分析了微乳液法制备介孔碳的反应机理,包括微乳液诱导协同组装机制、乳液溶胀效应和微流控液滴技术。其次,进一步探讨了控制介孔碳材料孔隙形态、外部形貌及内部结构的影响因素。最后,对新型介孔碳材料在能源储存与转化、催化、吸附以及药物递送领域的应用进行了归纳,并对未来的发展提出了展望。     

钴铁水滑石基材料在电催化析氧中的应用

析氧反应(OER)是电催化裂解水、二次金属-空气电池和可再生燃料电池等绿色可持续能源储存和转化技术中的关键步骤,但其较高的势垒和迟滞的动力学过程限制了反应的效率。因此,设计开发高效、稳定的非贵金属催化剂是新能源领域面临的挑战之一。钴铁水滑石(CoFe LDH)材料具有独特的二维层状结构、丰富多变的化学组成、高分散的金属阳离子、优异的稳定性和成本低廉等优点,在OER反应中有广泛的应用前景。但不良的导电性和有限的活性位点阻碍了CoFe LDH的工业化应用。本文首先介绍了CoFe LDH的结构并阐述了其OER反应机理,接着总结了CoFe LDH的制备工艺,并详细综述了近年来提升其OER性能的改性策略：插层剥离、空位制造、材料复合、离子取代和衍生物等。最后讨论了水滑石材料现阶段存在的问题和未来在能源转化和利用领域的发展方向。     

牛血清白蛋白中氨基酸的高效液相色谱荧光测定及质谱鉴定

利用新型荧光试剂1,2苯-并-3,4二-氢咔唑-9乙-基氯甲酸酯(BCEOC)作为柱前衍生化试剂,在Hypersil BDS C18(4.6 mm×200 mm,5μm)反相色谱柱上,采用梯度洗脱对氨基酸衍生物进行了分离检测。检测的激发和发射波长分别为λex=333 nm,λem=390 nm。采用电喷雾离子源(ESI Source),实现了牛血清白蛋白中氨基酸的定性测定。荧光定量检测的线性回归系数均大于0.999;检出限为6.3~117.6 fmo。l     

EPR studies on H-abstractions/spin-trapping reactions of new 'magic blue' reagents with alcohols

The H-abstractions/spin-trapping reactions with primary, secondary and tertiary alcohols of new 'magic blue' reagents, namely, the blue F113 (CClF₂CCl₂F) solution containing bis{perfluoro[1-(2-fluorosulfonyl)ethoxy]ethyl} nitroxide (2) and perfluoro[1-nitroso-1-(2-fluorosulfonyl)ethoxy]ethane (3) both generated in the reaction of perfluoro[2-(2-fluorosulfonyl)ethoxy]propionyl peroxide (1) with sodium nitrite in F113 at room temperature, were studied by EPR. Based on the interpretation of the EPR spectra of the spin adducts, nitroxides, the region-selectivity of H-abstraction has been disclosed and the possible mechanistic paths of H-abstraction have also been discussed. EPR of H-abstraction by using 'magic blue' reagents can also be used for producing various hydroxyalkyl radicals from common alcohols.