固载脯氨酸的毛发状纳米粒子的合成及其应用研究

毛发状粒子表面的聚合物链是一个具有一定流动性的动态体系,其负载的催化剂综合了均相和非均相负载催化剂的优点,为手性催化剂的负载和实用化提供了一条新的途径。本文利用Si O2纳米粒子表面修饰制得的功能基,通过表面RAFT聚合,并经过氨基去保护后制得负载脯氨酸的毛发状纳米粒子。通过热重、红外和透射电镜对毛发状二氧化硅纳米粒子的结构进行表征,并将获得的毛发状纳米粒子作为催化剂直接催化不对称Aldol反应。     

高效可回收聚(4-乙烯基吡啶)高氯酸催化剂用于合成双香豆素和双吲哚(英文)

Poly(4-vinylpyridinium) perchlorate has been used as an efficient solid acid catalyst for the synthesis of 3,3'-(arylmethylene)bis(4-hydroxycoumarins) and bis(indolyl)methanes, with the products being formed in excellent yields over very short reaction times under mild and environmentally friendly conditions. This catalyst can be reused several times without any appreciable loss in its activity.     

Gadolinium Photocatalysis: Dearomative [2+2] Cycloaddition/Ring‐Expansion Sequence with Indoles

Lanthanide photocatalysts are much less investigated in synthetic chemistry than rare and expensive late transition metals. We herein introduce Gd^III photocatalysis of a highly regioselective, intermolecular [2+2] photocycloaddition/ring‐expansion sequence with indoles, which could provide divergent access to cyclopenta[b]indoles and indolines. A simple and commercially available Gd(OTf)₃ salt is sufficient for this visible‐violet‐light‐induced transformation. The reaction proceeds either through a transient or start‐to‐end dearomatization cascade and shows excellent regioselectivity (usually >95:5 r.r.), broad scope (59 examples), good functional group tolerance and facile scale‐up under mild, direct visible‐light‐excitation conditions. Mechanistic investigations reveal that direct excitation of the Gd(OTf)₃/indole mixture gives an excited state intermediate, which undergoes the subsequent [2+2] cycloaddition and cyclobutane‐expansion cascade.     

脯氨酸类N-酰胺衍生物的核磁共振研究

脯氨酸类衍生物结构独特,鲜有报道利用核磁共振（nuclear magnetic resonance,NMR）技术对氨基酸的手性进行鉴别.利用多种NMR技术:1H NMR、1H-1H同核位移相关谱（1H-1H COSY）、1H-1H质子全相关谱（1H-1H TOCSY）、1H-1H核Overhauser效应谱（1H-1H NOESY）、13C NMR、无畸变的极化转移增强法（DEPT135°）、1H-13C检出1H的异核单量子相干（1H-13C HSQC）和1H-13C检出1H的异核多键相关（1H-13C HMBC）,对脯氨酸类N-酰胺衍生物两种构象异构体的1H和13C NMR进行了全归属,确定了室温下在二甲基亚砜（DMSO）中L型和D型的顺反异构体以相同的比例同时存在.     

纳米银自组装电极的制备及对高氯酸二茂铁的电化学响应

采用自组装的方法制备了纳米银粒子修饰金电极,并运用循环伏安法、交流阻抗谱探讨了该电极的电化学特性.研究了高氯酸二茂铁在该修饰电极上的直接电化学行为.实验结果表明,高氯酸二茂铁在该修饰电极上具有良好的电流响应.用示差脉冲法测定高氯酸二茂铁,其氧化峰电流与浓度在4.0×10-6～5.0×10-4 mol/L范围呈良好线性关系,线性方程为:Ip(μA)=0.0236c(μmol/L)-0.0975,线性相关系数为0.9982,检出限为2.3×10-7 mol/L(信噪比为3).     

在苯基苯甲酰甲基亚砜体系中高氯酸铥对高氯酸镝的荧光增强效应

合成了九种不同摩尔比的苯基苯甲酰甲基亚砜高氯酸镝、铥异核配合物,通过元素分析、稀土滴定确定其组成为(DyxTmy)L5(ClO4)3·2H2O(x∶y=1.000∶0.000,0.999∶0.001,0.995∶0.005,0.990∶0.010,0.900∶0.100,0.800∶0.200,0.700∶0.300,0.600∶0.400,0.500∶0.500,L=C6H5SOCH2COC6H5).红外光谱及摩尔电导表明,配体通过亚砜基上的氧原子与稀土离子配位,羰基氧不参与配位,三个ClO4-均在外界不参与配位.荧光光谱表明:当Tm3 的掺入量在0.001～0.300 mol之间时,对Dy3 的荧光有极强的敏化作用,且当Tm3 的掺入量为0.010 mol时,敏化强度最大,可使Dy3 荧光强度增加246%.     

Synthesis,Crystal Structures,and Spectroscopic Properties of Novel Gadolinium and Erbium Triphenylsiloxide Coordination Entities

In alkali metal and lanthanide coordination chemistry, triphenylsiloxides seem to be unduly underappreciated ligands. This is as surprising as that such substituents play a crucial role, among others, in stabilizing rare oxidation states of lanthanide ions, taking a part of intramolecular and molecular interactions stabilizing metal-oxygen cores and many others. This paper reports the synthesis and characterization of new lithium [Li₄(OSiPh₃)₄(THF)₂] (1), and sodium [Na₄(OSiPh₃)₄] (2) species, which were later used in obtaining novel gadolinium [Gd(OSiPh₃)₃(THF)₃]·THF (3), and erbium [Er(OSiPh₃)₃(THF)₃]·THF (4) configuration, it can result in res were determined for all 1–4 compounds, and in addition, IR, Raman, absorption spectroscopy studies were conducted for 3 and 4 lanthanide compounds. Furthermore, direct current (dc) variable-temperature magnetic susceptibility measurements on polycrystalline samples of 3 and 4 were carried out in the temperature range 1.8–300 K. The 3 shows behavior characteristics for the paramagnetism of the Gd³⁺ ion. In contrast, the magnetic properties of 4 are dominated by the crystal field effect on the Er³⁺ ion, masking the magnetic interaction between magnetic centers of neighboring molecules.     

脯氨酸催化的不对称Aldol反应的研究进展

不对称合成是手性药物制备的核心环节,A ldol反应是重要的形成C—C键的反应之一,在全合成中有广泛应用.脯氨酸的两个异构体均价廉易得,作为一个非金属不对称催化试剂,它催化的不对称A ldol反应立体选择性高,有很好的应用前景.本文就近二十年来脯氨酸催化A ldol反应的机理,溶剂效应,最新进展三方面进行了介绍.     

A Molecular-Wide and Electron Density-Based Approach in Exploring Chemical Reactivity and Explicit Dimethyl Sulfoxide (DMSO) Solvent Molecule Effects in the Proline Catalyzed Aldol Reaction

Modelling of the proline (1) catalyzed aldol reaction (with acetone 2) in the presence of an explicit molecule of dimethyl sulfoxide (DMSO) (3) has showed that 3 is a major player in the aldol reaction as it plays a double role. Through strong interactions with 1 and acetone 2, it leads to a significant increase of energy barriers at transition states (TS) for the lowest energy conformer 1a of proline. Just the opposite holds for the higher energy conformer 1b. Both the ‘inhibitor’ and ‘catalyst’ mode of activity of DMSO eliminates 1a as a catalyst at the very beginning of the process and promotes the chemical reactivity, hence catalytic ability of 1b. Modelling using a Molecular-Wide and Electron Density-based concept of Chemical Bonding (MOWED-CB) and the Reaction Energy Profile–Fragment Attributed Molecular System Energy Change (REP-FAMSEC) protocol has shown that, due to strong intermolecular interactions, the HN-C-COOH (of 1), CO (of 2), and SO (of 3) fragments drive a chemical change throughout the catalytic reaction. We strongly advocate exploring the pre-organization of molecules from initially formed complexes, through local minima to the best structures suited for a catalytic process. In this regard, a unique combination of MOWED-CB with REP-FAMSEC provides an invaluable insight on the potential success of a catalytic process, or reaction mechanism in general. The protocol reported herein is suitable for explaining classical reaction energy profiles computed for many synthetic processes.     

三元体系Y(ClO4)3·3H2O—B15C5—CH3OH(25℃)的半微量相平衡研究

采用半微量相平衡方法研究了三元体系Ｙ（ＣｌＯ４）３．３Ｈ２Ｏ－Ｂ１５Ｃ５－ＣＨ３ＯＨ在２５℃的溶解度，测定了各饱和溶液的折光率。该体系在２５℃生成三种化学计量的配合物，其组成分别为：４Ｙ（ＣｌＯ４）３．３Ｂ１５Ｃ５．１２Ｈ２Ｏ．１２Ｃｈ３ＯＨ（Ｉ），Ｙ（ＣｌＯ４）３．２Ｂ１２Ｃ５．３Ｈ２Ｏ．Ｃｈ３ＯＨ（Ⅲ），其中配合物（Ｉ）和（Ⅱ）是溶解不一致化合物。在甲醇溶剂中，分离制备了配合物（Ⅲ），在６９－