H＋CH2CO反应机理的G2计算

分别在UQCISD/6-311G(d,p)和G2理论计算水平上，对CH2CO和H反应可能存在的四条反应通道进行了研究，详细分析了每个通道的反应机理;通过振动分析的虚频数和内禀反应坐标(IRC)计算,确认了反应涉及的每一个过渡态.通过反应位能剖面的比较，发现经过一个中间体生成CH3＋CO的一条途径是主反应通道，该通道是个放热反应，总焓变为－146.07 kJ•mol－1，速控步骤的位垒为55.09 kJ•mol－1.理论计算结果较好地解释了实验观察到的主要产物和副产物并存的现象。     

Immobilization of heterobimetallic multifunctional asymmetric catalyst

Immobilization of an asymmetric AlLibis(binaphthoxide) catalyst (ALB) is described. The immobilized ALBs (poly-ALBs) are readily prepared from polymeric BINOL derivatives and LiAlH(4). The combined use of 9 mol % of BuLi with ca. 10 mol % (as a monomeric catalyst) of 6,6'-aryl-tethered poly-ALB gave the Michael adducts with up to 93% ee. After completion of the reaction, the insoluble catalyst was recovered in air and is reusable.     

Stereoselective total syntheses of the racemic form and the natural enantiomer of the marine alkaloid lepadiformine via a novel N-acyliminium ion/allylsilane spirocyclization strategy

Stereoselective total syntheses of the racemic form and the natural enantiomer of the tricyclic marine alkaloid lepadiformine (6) have been accomplished using a novel intramolecular spirocyclization of an N-acyliminium ion with an allylsilane to form the A/C rings as the key step. Introduction of the hydroxymethyl group at C-13 of the racemic spirocycle 11 was achieved using our methodology for oxidative radical-based remote functionalization of o-aminobenzamides, followed by copper-catalyzed addition of Grignard reagent 16 to the N-acyliminium ion intermediate derived from 15. Subsequent Tamao oxidation of silane 17 then afforded the requisite hydroxymethyl compound 19, which was converted to the dimethyl acetal 25 via hydroformylation followed by aldehyde protection. Hydrolysis of the benzamide moiety of 25 and subsequent protection of the primary alcohol gave amino acetal 27. The synthesis was concluded from 27 by a four-step procedure: acid-catalyzed ring closure, amino nitrile formation, introduction of the hexyl chain by a Grignard reaction to an iminium salt, and removal of the O-benzyl protecting group to give (+/-)-lepadiformine (6). The enantioselective total synthesis of 6 started from known optically pure bromide 37, derived from (S)-pyroglutamic acid, and followed a similar sequence involving the key spirocyclization of N-acyliminium ion 42. This synthesis has established the absolute configuration of naturally occurring lepadiformine to be 2(R),5(S),10(S),13(S).     

Discovery of cryptic allosteric sites using reversed allosteric communication by a combined computational and experimental strategy

Allostery, which is one of the most direct and efficient methods to fine-tune protein functions, has gained increasing recognition in drug discovery. However, there are several challenges associated with the identification of allosteric sites, which is the fundamental cornerstone of drug design. Previous studies on allosteric site predictions have focused on communication signals propagating from the allosteric sites to the orthosteric sites. However, recent biochemical studies have revealed that allosteric coupling is bidirectional and that orthosteric perturbations can modulate allosteric sites through reversed allosteric communication. Here, we proposed a new framework for the prediction of allosteric sites based on reversed allosteric communication using a combination of computational and experimental strategies (molecular dynamics simulations, Markov state models, and site-directed mutagenesis). The desirable performance of our approach was demonstrated by predicting the known allosteric site of the small molecule MDL-801 in nicotinamide dinucleotide (NAD⁺)-dependent protein lysine deacetylase sirtuin 6 (Sirt6). A potential novel cryptic allosteric site located around the L116, R119, and S120 residues within the dynamic ensemble of Sirt6 was identified. The allosteric effect of the predicted site was further quantified and validated using both computational and experimental approaches. This study proposed a state-of-the-art computational pipeline for detecting allosteric sites based on reversed allosteric communication. This method enabled the identification of a previously uncharacterized potential cryptic allosteric site on Sirt6, which provides a starting point for allosteric drug design that can aid the identification of candidate pockets in other therapeutic targets.

Using reversed allosteric communication, we performed MD simulations, MSMs, and mutagenesis experiments, to discover allosteric sites. It reproduced the known allosteric site for MDL-801 on Sirt6 and uncovered a novel cryptic allosteric Pocket X.     

Ni-Fe催化剂乙醇部分氧化制氢的研究

研究了Ni Fe催化剂对乙醇部分氧化制氢反应,系统地考察了不同O2/C2H5OH摩尔比及反应温度下催化剂的性能.发现Ni Fe催化剂对乙醇部分氧化制氢具有较好的催化活性,其中组成为Ni50Fe50催化剂最好,最佳的反应条件是O2/C2H5OH=1.0,T=573 K.XRD谱图表明催化剂主要由尖晶石结构的铁酸盐和FeNi3合金相组成. XPS结果说明,催化剂体相以还原态FeNi3合金相为主,表面以氧化态的铁酸盐为主.稳定性考察的结果表明,催化剂经40 h反应后,对氢的选择性明显下降,此时对应的FeNi3物相衍射峰强度也明显降低,表明催化剂对H2选择性的下降与FeNi3物相的转变有关.     

Electric field-decoupled electroosmotic pump for microfluidic devices

An electric field-free electroosmotic pump has been constructed and its pumping rate has been measured under various experimental conditions. The key component of the pump is an ion-exchange membrane grounding joint that serves two major functions: (i) to maintain fluid continuity between pump channels and microfluidic conduit and (ii) to ground the solution in the microfluidic channel at the joint through an external electrode, and hence to decouple the electric field applied to the pump channels from the rest of the microfluidic system. A theoretical model has been developed to calculate the pumping rates and its validity has been demonstrated.     

Combination of Micro-fluidic Chip with Fluorescence Correlation Spectroscopy for Single Molecule Detection

A single molecule detection technique was developed by the combination of a single channel poly (dimethylsiloxane)/glass micro-fluidic chip and fluorescence correlation spectroscopy (FCS). This method was successfully used to determine the proportion of two model components in the mixture containing fluorescein and the rhodamine-green succinimidyl ester.     

Characterization of tetrathiofulvalene compounds using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Tetrathiofulvalene compounds are important components of charge-transfer complexes, which may be applied in various fields of scientific research and practical applications. Some of these compounds cannot be characterized by mass spectrometry. Here, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was used for the characterization of tetrathiofulvalenes. The samples could be easily desorbed and ionized to form singly charged ions, and mass spectra with isotopic resolution readily obtained. The mass spectrometric results for 26 compounds have shown that MALDI-TOF is more effective and convenient than other mass spectrometry methods, and resolves the problem of mass spectrometric characterization of tetrathiofulvalene compounds.     

Mesoporous polyhedral cages and shells formed by textured self-assembly of ZnO nanocrystals

We report a new structure, mesoporous structured polyhedral drum and spherical cages and shells formed by textured self-assembly of ZnO nanocrystals, which are made by a novel self-assembly process during epitaxial surface oxidation. The cages/shells exhibit unique geometrical shapes, and their walls are composed of mesoporous and textured ZnO nanocrystals. The structures of the cages and shells are studied, and a growth mechanism is proposed to be a process following solidification of the Zn liquid droplets, surface oxidation, and sublimation.     

Crystal and Molecular Structure of Di－chloro－bis（р－methylphenylbutylsulfide） Palladium（Ⅱ）

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