红葡萄酒香气成分色谱保留时间模拟

采用化合物非氢原子固有特征值和非氢原子之间的电性作用为结构描述符,对红葡萄酒香气成分中的65个化合物进行了结构表征。通过多元线性回归(MLR)和逐步回归(SMR)方法建立了该类化合物结构-色谱保留时间关系(QSRR)模型。模型的复相关系数(R)为0.907,标准偏差(SD)为4.507。用留一法(LOO)交互检验对模型进行了评价,得到的复相关系数(RCV)为0.849,标准偏差(SDCV)为5.656。结果表明,采用的分子结构描述符能够较好地表现该类化合物结构特征,所建模型具有较好的预测能力和稳定性。     

苯胺类化合物结构与毒性的密度泛函理论研究

应用密度泛函理论(DFT)在杂化泛函B3LYP和基组6-311G(d,p)水平上对57个标题化合物进行结构优化,计算获得化合物的量化和理化参数,采用最佳变量子集回归构建了化合物对梨形四膜虫的毒性与描述符之间的定量结构-活性关系(QSAR)模型。所建最佳三元QSAR模型的复相关系数R2为0.915,留一法(leave-one-out,LOO)交互检验复相关系数Rcv2为0.891;用随机筛选出的19个预测集样本进行外部预测,所得外部预测集交互检验系数Qext2为0.821,QSAR模型具有较好的稳定性和较强的预测能力。模型结果表明影响毒性的主要因素有化合物最低空轨道能、正辛醇-水分配系数及最负非氢原子净电荷。对模型应用域(AD)进行了表征,所建模型可用于应用域内苯胺类化合物对梨形四膜虫毒性的预测。     

酚类污染物土壤吸收系数定量预测

本文将分子结构表征方法(MEDV)进行改进,得到按非氢原子间距离分类的分子电性距离矢量,将该矢量用于酚类化合物结构表征,并与其土壤吸收系数(lgKoc)建立定量结构与性质关系(QSPR)模型。利用逐步回归(SMR)得到的4变量模型复相关系数(R2)为0.970、标准偏差(SD)为0.198,留一法(LOO)交互校验(CV)预测值的复相关系数(R2cv)为0.916、标准偏差(SDcv)为0.337。结果表明该矢量具有较强的分子结构表达能力,模型具有良好的预测能力与稳定性。     

氯酚化合物对发光细菌毒性的构效关系研究

本文对20种氯酚化合物进行DFT-B3LYP/6-311G**水平全优化计算,据所得量子化学参数构建其对发光细菌毒性的定量构效关系(QSAR)模型。经逐步多元回归分析后,所建立的QSAR模型的相关系数R及去一法(LOO)交互检验复相关系数R2cv分别为0.962和0.876;用预测集样本进行了外部预测,所得外部预测集交互检验Q2ext为0.961,表明所建立的QSAR模型具有较好的稳定性和较强的预测能力。结果表明:分子的体积愈大,化合物毒性愈强;最负非氢原子净电荷愈负,毒性愈强。对模型应用域(AD)进行了表征,所建立的模型可以应用于应用域内氯酚化合物对发光细菌毒性的预测,具有潜在应用价值。     

酚类化合物对梨形四膜虫毒性的构效关系解析

应用密度泛函理论(DFT)在杂化泛函B3LYP和基组6-311G**水平上对81个标题化合物进行结构优化,计算获得化合物的量化和理化参数,采用最佳变量子集回归构建化合物对梨形四膜虫的毒性与描述符之间的定量结构-活性关系(QSAR)模型。所建最佳四元QSAR模型的复相关系数R~2为0.951,去一法(LOO)交互检验复相关系数R~2_(cv)为0.938,用27个验证集样本进行外部预测,所得外部验证集交互检验系数Q_(ext)~2为0.876,模型具有良好的统计学意义及合理、可信的预报能力,影响毒性的主要因素有正辛醇-水分配系数(log P)、分子最低空轨道能(E_(LUMO))、苯环上所有碳原子电荷之和(Q)和4号位取代基电荷(Q_(R4)),研究结果为理解该类化合物的毒性作用机理和设计合成低毒性的新化合物提供理论参考。     

脂肪酸多聚甘油酯分子结构与性能相关性研究

采用量子化学MM+和AM1方法计算聚甘油和脂肪酸多聚甘油酯的分子结构参数,然后用逐步线性回归方法建立脂肪酸多聚甘油酯HLB值的定量结构性质(QSPR)模型,所得的预测模型中包含四个参数(单位质量分子所含氧原子数Xo、生成热ΔfHm、电子能Ee和水合能Eh),预测值及外部检验的复相关系数(R2)和标准偏差(SD)分别为0.9553、0.73722和0.9678、6.34426。结果表明,量子化学方法计算简单,对脂肪酸多聚甘油酯结构的表征能力较强,所建QSPR模型具有能较好的预测能力和较强的稳健性,并在一定程度上阐明了脂肪酸多聚甘油酯分子结构与性能之间的关系。     

分子电性距离矢量用于稠环芳烃液相色谱保留值的QSPR研究

采用分子电性距离矢量(Molecular Electronegativity Distance Vector,MEDV)表征稠环芳烃类化合物的分子结构.分别运用多元线性回归(Multiple Linear Regres-sion,MLR)和偏最小二乘回归(PLS)建立了稠环芳烃类化合物结构与其液相色谱(LC)保留值的定量结构一性质关系(QSPR)模型,同时采用内部及外部双重验证的办法对所建模型稳定性能进行分析和验证,建模计算值、留一法交互检验预测值和外部样本预测值的复相关系数Rcum、RLOO、Qext分别为0.9970,0.9950,0.9925(MLR);0.9930,0.9790,0.9917(PLS).结果表明,MEDV能较好地表征该类分子结构信息,所建QSPR模型具有良好的稳定性和预测能力.为稠环芳烃类化合物分离、纯化、检测等方法的建立,提供有效的理论依据.     

分子电性距离矢量用于三嗪类化合物的构效关系研究

采用分子电性距离矢量(Molecular Electronegativity Distance Vector,MEDV)表征了三嗪类化合物的分子结构,并运用多元线性回归(Multiple Linear Regression,MLR)建立了该类化合物结构与其发光菌和大型蚤毒性的定量结构-毒性相关(Quanti-tative Structure-Toxicity Relationship,QSTR)模型,同时采用留一法交互检验对所建模型进行了分析和验证,建模计算值的相关系数R分别为0.970和0.952,留一法交互检验预测值的相关系数RLOO分别为0.917和0.921,并进一步阐述了结构与毒性之间的关系。结果表明,三嗪环上π电子离域程度减小有利于毒性增加,侧链N上取代基数目增加,化合物毒性减小。为进一步预测该类化合物的毒性,进行药物筛选提供了有效的理论依据。     

一种新的氨基酸描述符及其在肽QSAR中的应用

从20种天然氨基酸的41个randic molecular profiles非零描述符、44个eigenvalue based indices非零描述符和47个walk and path counts非零描述符分别进行主成分分析,得出一种新的氨基酸描述符-SVREW。将其应用于血管紧张素转化酶(ACE)抑制二肽和ACE抑制三肽、苦味二肽和苦味四肽、后叶催产素类似物、HLA-A*0201限制性CTL表位肽的结构表征,应用多元线性回归(MLR)建立定量构效关系模型,同时采用内部与外部双重验证的方法验证模型的稳定性。所建ACE抑制二肽、ACE抑制三肽、苦味二肽、苦味四肽、后叶催产素类似物、HLA-A*0201限制性CTL表位肽的模型复相关系数(R2cum)分别为0.994,0.797,0.948,0.878,0.686,0.720;留一法交互校验复相关系数(R2cv)分别为0.955,0.859,0.879,0.958,0.796,0.843;外部样本校验相关系数(Q2ext)分别为0.990,0.954,0.890,0.950,0.748,0.773。经研究表明SVREW描述符用于肽分子结构表征所建模型的稳定性与预测能力均较好,有望成为多肽定量构效关系研究中一种有效的结构表征方法,可对新药物的发现和研究提供指导。     

一种新三维描述子用于Nevirapine类抗艾滋病药物定量构效关系的研究

运用三维全息原子场作用矢量(3D-HoVAIF)对33个Nevirapine类抗艾滋病药物进行了定量构效关系(QSAR)研究。采用偏最小二乘回归(PLSR)建立定量构效关系模型,同时采用内部及外部双重验证的方法对所得模型稳定性能进行深入分析和检验,所建模型的复相关系数(Rcum2)、留一法(LOO)交互校验(CV)复相关系数(Qcum2)和外部样本校验复相关系数(Qext2)分别为0·835、0·530和0·518。结果表明,3D-HoVAIF能较好表征Nevirapine类抗艾滋病药物分子结构信息,且所建模型具有较好稳定性能和预测能力。     

Ab initio studies of the conformations of ethynyl formate, cyano formate and related ethynyl and cyano compounds

The optimized geometries, relative free energies and related thermodynamic properties, harmonic frequencies, and dipole moments have been calculated at the HF and MP2 levels for ethynyl formate (1a), ethynyl acetate (1b), cyano formate, HCO₂CN (1c), cyano acetate (1d), S-ethynyl thioformate (2a), S-ethynyl thioacetate (2b), S-cyano thioformate (2c), S-cyano thioacetate (2d), N-ethynylformamide (3a), N-ethynylacetamide (3b), N-cyanoformamide (3c), and N-cyanoacetamide (3d) with the gaussian 98 program. For ethynyl formate, the calculation for 25 °C at the MP2/6-311++G(df,pd) level predicts that the Z isomer is more stable by 1.23 kcal/mol. For S-ethynyl thioformate, calculations at the MP2/6-311++G(2d,2p) level predict that the E isomer is favored by 0.71 kcal/mol at 25 °C. The E isomers of N-ethynylformamide and N-ethynylacetamide were found at all levels to be more stable than the Z isomers at 25 °C. For cyano formate and cyano acetate, calculations at the MP2/6-311++G(df,pd) level predict that the Z isomers are more stable at 25 °C by 1.50 and 2.72 kcal/mol, respectively. At this level and temperature, the Z isomers of 2c, 2d, 3c, and 3d are predicted to have free energies of 0.46, −0.07, 1.22, and 2.28 kcal/mol, respectively, relative to the E conformations. Z to E free-energy barriers at 25 °C of 8.63, 10.64, 17.63, 7.39, and 14.03 kcal/mol were calculated for 1a, 2a, 3a, 1c, and 3c at the HF/6-311G(d,p) level, and at the HF/6-311+G(d,p) level, the free-energy barrier for 2c was 7.08 kcal/mol.     

Pyrazolones as Building Blocks in Heterocyclic Synthesis: Synthesis of New Pyrazolopyran,Pyrazolopyridazine and Pyrazole Derivatives of Expected Antifungicidal Activity

A series of new pyrazolone and pyrazole derivatives with expected antifungicidal activity have been prepared through the reactions 3‐phenyl‐1‐H‐pyrazol‐5(4H)‐one ( 3 ) and 4‐(dimethylaminomethylene)‐3‐phenyl‐1H‐pyrazol‐5(4H)‐one ( 5 ) with a variety of electrophilic reagents and nucleophilic reagents. The newly synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR and mass spectral studies.     

Characteristics of Lipids from Individual Organs of Veronica beccabunga

Lipids from various organs of the aquatic plant Veronica beccabunga were studied. It has been demonstrated that neutral and polar lipids are qualitatively typical of higher photosynthetic plants. Lipids in various organs of aquatic veronica were unevenly distributed. The most significant differences were observed in neutral lipids for the accumulation of glycerin esters, free fatty acids, alcohols, and hydrocarbons. The ratio of phospholipids varied considerably in the polar lipids.     

Potentiometric and thermodynamic studies of 2-mercapto-5-(2-hydroxynaphthylideamino)-1,3,4-thiadiazole and its metal complexes

Summary Proton-ligand dissociation constant of 2-mercapto-5-(2-hydroxynaphthylideamino)-1,3,4-thiadiazole (MHT) and the stepwise stability constants of its metal complexes were determined potentiometrically in 40 mass/mass% ethanol-water mixture containing 0.1 M KCl. The stabilities of the complexes follow the order: Cu²⁺>Ni²⁺>Co²⁺>Mn²⁺. The dissociation constant (pK^H) of MHT and the stability constants (logK) of its metal complexes were determined at different temperatures and the corresponding thermodynamic parameters were calculated and discussed. The proton dissociation process is non-spontaneous, endothermic and entropically unfavoured. The formation of the metal complexes was found to be spontaneous, endothermic and entropically favoured.     

溶质迁移研究进展

溶质迁移研究已成为水文地质等领域的一个重要研究课题。综述了溶质迁移研究进展,重点介绍了溶质迁移在地下水污染与防治、土壤盐碱化防治、海水入侵和咸水入侵防治等方面的研究现状,并指出应进一步研究的问题。     

Synthesis and spectral properties of malononitrile-based merocyanine dyes

Di-, tetra-, and hexamethine merocyanines derived from malononitrile and heterocycles with moderate (dyes 1–6), strong (7–9), and weak (10 and 11) electron-releasing ability were synthesized. The electronic structures of merocyanines 10 and 11 are similar to the neutral polyene state, whereas those of 7–9 are similar to the ideal polymethine state. These tendencies become more pronounced with increasing length of the polymethine chain. The merocyanines derived from heterocyclic residues with weak or moderate electron-releasing ability exhibit a positive solvatochromism, whereas those with strong electron-releasing ability show a negative solvatochromism. An increase in the polarity of the solvent makes the former compounds more similar to polymethines, whereas the latter become more similar to polyenes bearing opposite charges on the end groups. The nature of the factors (nonspecific solvation, specific nucleophilic and electrophilic solvation, and vibronic interactions) responsible for the observed characteristic features was analyzed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2726–2735, December, 2005.     

Studies of some monocyclic and bicyclic arylacetonitriles

The high-resolution (1)H, (13)C, (1)H-(1)H COSY and (1)H-(13)C COSY NMR spectra have been recorded in CDCl(3) for arylacetonitriles 1-12 and analyzed. The arylacetonitriles 3-7 exist in two isomeric forms E (methyl group is anti to cyano group) and Z (the methyl group is syn to cyano group) in solution. Normal chair conformation with equatorial orientations of phenyl rings at C-2 and C-6 for monocyclic nitriles 1 and 2, epimeric chair structure EC (axial configuration of methyl group at C-3) for both the E and Z isomers of arylacetonitrile derivatives (3-7) and a distorted boat form, B(3), for the N-acylacetonitrile derivatives (8-10) have been proposed based on NMR data. The bicyclic nitriles 11 and 12 exist in twin chair conformations in solution. DFT calculations and chemical shifts also support these conformations. Geometry optimizations for 1-12 were carried out according to density functional theory using B3LYP/6-31G(d,p) basis set and for 1 and 8 the theoretical geometrical parameters have been compared with those of single crystal measurements.     

Elucidation of activity of copper and copper oxide nanomaterials for electrocatalytic and photoelectrochemical reduction of carbon dioxide

Copper- and copper oxide–based materials are, in principle, promising components (supports, reactive sites, and visible light–absorbing semiconductors) of electrocatalysts and photocathodes for reduction of carbon dioxide. Electrochemical and photoelectrochemical approaches are generally suitable for the low-temperature CO₂-conversion to carbon-based simple organic fuels or utility chemicals.Different concepts of utilization, including nanostructuring, doping, admixing, preconditioning, modification, or functionalization of various copper- and copper oxide–based systems for catalytic electroreduction and photoelectrochemical reduction of CO₂ are elucidated, as well as important strategies to enhance the systems' overall activity and stability are discussed.