A novel hydrogen‐bonded microporous framework constructed from two different metal complexes

A hydrogen‐bonded coordination supramol­ecule, (meso‐5,7,­7,­12,14,14‐hexa­methyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐κ⁴N)­nickel(II) [N,N‐o‐phenylenebis­(oxamato)­‐κ⁴O,N,N′,O′]nickelate(II) dihydrate, [Ni(C₁₆H₃₆N₄)][Ni(C₁₀H₄N₂O₆)]·2H₂O or [Ni(meso‐cth)]­[Ni(opba)]·2H₂O, has been prepared and characterized by X‐ray crystallographic analysis. The two complex ions, i.e. [Ni(meso‐cth)]²⁺ and [Ni(opba)]^2?, are hydrogen bonded to each other, resulting in two‐dimensional neutral supramolecular sheets. The sheets stack along the a direction to produce a three‐dimensional architecture with one‐dimensional channels in which hydrogen‐bonded chains of water mol­ecules are included.     

醇系溶剂中冠醚与碱金属离子的配位反应

The enthalpy changes, entropy changes and equilibrium constants of coordination reactions of 18-crown-6 with the alkali ions Na+ and K+ at 298.15K were measured by using RD-496 microcalorimeter with methanol, ethanol, n-propanol and n-butanol as solvents respectively. The results indicated that the enthalpy changes △rHm, entropy changes △rSm, and the stability of the complexes are closely related with the polarity of the solvents, and the order of the stability is ethanol>methanol>n-propanol>n-butanol>H2O for the same complex in the solvents investigated. The stability order was reasonably explained by relating the stability constants of the complexes with the dielectric constants of these solvents, and by using the model of solvated-desolvated ions and ion pair in the coordination reactions.     

Thermophysical Properties of High-Temperature Reacting Mixtures of Carbon and Water in the Range 400–30,000 K and 0.1–10 atm. Part 1: Equilibrium Composition and Thermodynamic Properties

This paper is devoted to the calculation of the chemical equilibrium composition and thermodynamic properties of reacting mixtures of carbon and water at high temperature. Equilibrium particle concentrations and thermodynamic properties including mass density, molar weight, entropy, enthalpy and specific heat at constant pressure, sonic velocity, and heat capacity ratio are determined by the method of Gibbs free energy minimization, using species data from standard thermodynamic tables. The calculations, which assume local thermodynamic equilibrium, are performed in the temperature range from 400 to 30,000 K for pressures of 0.10, 1.0, 3.0, 5.0 and 10.0 atm. The properties of the reacting mixture are affected by the possible occurrence of solid carbon formation at low temperature, and therefore attention is paid to the influence of the carbon phase transition by comparing the results obtained with and without considering solid carbon formation. The results presented here clarify some basic chemical process and are reliable reference data for use in the simulation of plasmas in reacting carbon and water mixtures together with the need of transport coefficients computation.     

稀土金属作用下芳香醛、酮的还原偶联反应

由Ln/ROH/TMSCl组成的体系能选择性地使芳香族醛、酮还原偶联形成频哪醇, 产率优良, 而对脂肪族醛酮呈惰性。     

Alkoxy substituted MeO-BIPHEP-type diphosphines ligands for asymmetric hydrogenation of aryl ketones

<正>In this paper,a series of optically active MeO-BIPHEP-type ligands,(S)-6,6′-dimethoxy-2,2'-bis(di-p-alkoxyphenylphosphine)- 1,1′-biphenyl were synthesized and used to prepare the ruthenium complex.The effects of para-substituted were observed,the results showed that the ruthenium catalysts[diphosphine RuCl_2 diamine]containing both t-Bu and i-Pr substitutions have better activities and enantioselectivities than the non-substituted ruthenium catalysts in the asymmetric hydrogenation of acetophenone.     

Enantioselective Synthesis of Quaternary Carbon Stereocenters: Addition of 3‐Substituted Oxindoles to Vinyl Sulfone Catalyzed by Pentanidiums

A pentanidium‐catalyzed highly enantioselective conjugate addition of 3‐alkyloxindoles to phenyl vinyl sulfone has been demonstrated. This approach allows the construction of 3,3‐dialkyl‐substituted oxindole frameworks with high yield and excellent enantioselectivity (up to 99 %) under simple phase‐transfer conditions. A variety of oxindoles bearing all‐carbon quaternary stereogenic centers were obtained in the presence of 0.25 mol % pentanidium. Meanwhile, practicality was illustrated by a gram‐scale asymmetric synthesis of two 3,3‐dialkyl‐substituted oxindoles. The resulting adduct can be smoothly transformed to the natural product analogue in a short synthetic route.     

固定化酶在生物医学上的应用(Ⅰ)——聚丙烯酰胺固定化尿酶的制备及性能

本文以交联聚丙烯酰胺对尿酶包埋进行了研究,制备出了球形固定化尿酶,其含酶量高(1份酶对1份聚合物),相对活性为50%左右,对尿素的分解活性:120m/ml(固定化尿酶,37℃,2小时),提高了稳定性,在4℃下,66天后活性降低8%,106天后活性降低22%,37℃下11天后活性降低18%,并且不泄漏酶。基于以上特点,该固定化尿酶为吸附型人工肾提供了一个较合适的活性材料。     

In silico prediction and screening of γ‐secretase inhibitors by molecular descriptors and machine learning methods

γ‐Secretase inhibitors have been explored for the prevention and treatment of Alzheimer's disease (AD). Methods for prediction and screening of γ‐secretase inhibitors are highly desired for facilitating the design of novel therapeutic agents against AD, especially when incomplete knowledge about the mechanism and three‐dimensional structure of γ‐secretase. We explored two machine learning methods, support vector machine (SVM) and random forest (RF), to develop models for predicting γ‐secretase inhibitors of diverse structures. Quantitative analysis of the receiver operating characteristic (ROC) curve was performed to further examine and optimize the models. Especially, the Youden index (YI) was initially introduced into the ROC curve of RF so as to obtain an optimal threshold of probability for prediction. The developed models were validated by an external testing set with the prediction accuracies of SVM and RF 96.48 and 98.83% for γ‐secretase inhibitors and 98.18 and 99.27% for noninhibitors, respectively. The different feature selection methods were used to extract the physicochemical features most relevant to γ‐secretase inhibition. To the best of our knowledge, the RF model developed in this work is the first model with a broad applicability domain, based on which the virtual screening of γ‐secretase inhibitors against the ZINC database was performed, resulting in 368 potential hit candidates. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

KF/Al203催化下由芳醛、丙二腈和2-(1,2-二氢-3-亚茚基)丙二腈或2-(2,3-二氢-4H-亚萘基)丙二腈-步合成芴或菲衍生物

以芳醛、丙二腈、2-(1,2-二氢-3-亚茚基)丙二腈或2-(2,3-二氢-4H-亚萘基)丙二腈为原料,乙醇为溶剂,在80℃下以KF/Al2O3为催化剂合成了一系列芴或菲的衍生物,该方法具有反应条件温和,产率高(72%～88%)和操作简单等优点.产物的结构通过IR,1H NMR和元素分析表征.     

Simultaneous determination of fluorine and iodine in urine by ion chromatography with electrochemical pretreatment

A new method for the simultaneous determination of fluorine and iodine in urine by ion chromatography(IC) with electrochemical pretreatment has been developed.The pretreatment was performed in a novel electrochemical oxidation-neutralization device(EOND),in which iodide of the sample was oxidized to iodate and the alkaline digestion sample solution was neutralized.Under the optimized conditions,the limits of detection(LOD,S/N = 3) were 2.5μg/L for fluoride and 20μg/L for iodate,respectively.The recoverie...