分子电性作用矢量法用于取代芳烃的构效关系研究

基于定量结构-活性相关(QSAR)研究取代芳烃类化合物的性质具有重要意义。采用分子电性作用失量(MEIV)表征取代芳烃类有机毒物的分子结构,运用多元线性回归建立定量结构毒性相关(QSTR)模型,同时采用逐步回归结合统计检测筛选模型变量,建立了25个取代芳烃类有机污染物结构与呆鲦鱼(Pimephales Promelas)96h半数致死浓度 回归方程。另外采用内部及外部双重验证的办法深入分析和检验模型的稳定性。建模的复相关系数(Rcum2)、留一法(LOO)交互校验复相关系数(RCV2)和外部样本校验复相关系数(Qext2)分别为0.926、0.870和0.875。表明用MEIV表征取代芳烃类有机物分子结构信息较好,所建QSTR模型的稳定性和预测能力良好。     

分子电性作用矢量法用于硝基苯类化合物的毒性研究

基于定量结构-活性相关(QSAR)研究硝基苯类化合物的性质具有重要意义。采用分子电性作用失量(MEIV)表征硝基苯类有机毒物的分子结构,运用多元线性回归建立定量结构毒性相关(QSTR)模型,同时采用逐步回归结合统计检测筛选模型变量,建立了25个硝基苯类化合物对斜生栅藻(Scenedesmus obliquus)的急性毒性与其结构间的回归方程。另外采用内部及外部双重验证的办法深入分析和检验模型的稳定性。建模的复相关系数(Rcum2)、留一法(LOO)交互校验复相关系数(RCV2)和外部样本校验复相关系数(Qext2)分别为0.927、0.872和0.908。表明用MEIV表征硝基苯类有机物分子结构信息较好,所建QSTR模型的稳定性和预测能力良好。     

分子电性作用矢量法用于硝基苯类化合物的毒性研究

基于定量结构-活性相关(QSAR)研究硝基苯类化合物的性质具有重要意义.采用分子电性作用失量(MEIV)表征硝基苯类有机毒物的分子结构,运用多元线性回归建立定量结构毒性相关(QSTR)模型,同时采用逐步回归结合统计检测筛选模型变量,建立了25个硝基苯类化合物对斜生栅藻(Scenedesmusobliquus)的急性毒性与其结构间的回归方程.另外采用内部及外部双重验证的办法深入分析和检验模型的稳定性.建模的复相关系数(R_(cum)~2)、留一法(LOO)交互校验复相关系数(R_(CV)~2)和外部样本校验复相关系数(Q_(ext)~2)分别为0.927、0.872和0.908.表明用MEIV表征硝基苯类有机物分子结构信息较好,所建QSTR模型的稳定性和预测能力良好.     

酰肼类抗结核病药物的3D-QSAR研究

采用三维全息原子场作用矢量(3D-HoVAIF)对115个酰肼类抗结核病药物进行定量构效关系(QSAR)研究。运用多元线性回归(MLR)和偏最小二乘回归(PLS)建模,同时采用内部及外部双重验证的办法对所得模型稳定性能进行了深入分析和检验。MLR建模和PLS建模的复相关系数(Rcum2)、留一法交互校验复相关系数(QLOO2)以及外部样本校验复相关系数(Qext2)分别为0.765、0.663、0.748和0.733、0.614、0.715。结果表明,3D-HoVAIF能较好表征抗结核药物分子结构信息,所建QSAR模型具有良好稳定性和预测能力,为抗结核病药物的研发提供一定的理论基础。     

聚丙烯酸酯玻璃化转移温度QSPR的研究

对聚丙烯酸酯的定量构性关系（QSPR）研究具有重要意义.采用分子电性作用失量（MEIV）表征聚丙烯酸酯的分子结构,运用多元线性回归（MLR）建立定量结构玻璃化转移温度相关（QSPR）模型,同时采用逐步回归结合统计检测筛选模型变量,建立了22个聚丙烯酸酯玻璃化转移温度（T_g）与其结构间的多元线性回归方程.另外采用内部及外部双重验证的办法深入分析和检验模型的稳定性.建模的复相关系数(R_cum)、留一法（LOO）交互校验复相关系数(R_CV)和外部样本校验复相关系数(Q_cxt)分别为0.982、0.971和0.922.表明用MEIV对聚丙烯酸酯分子结构信息表达较好,所建QSPR模型的稳定性和预测能力良好.     

三维全息原子场作用失量用于苦味肽QSAR的研究

本文提出利用三维原子场相互作用矢量(3D-VAIF)对苦味二肽分子结构进行表征,并利用逐步回归(SMR)结合多元性性回归(MLR)建立苦味二肽定量构效关系模型,同时采用内外部双重验证的方法检验模型的稳定性。所建模型相关统计参量如下：复相关系数(Rcum2)、留一法（LOO）交互校验复相关系数(Rcv2)和外部样本校验复相关系数（Qext2）分别为0.983、0.934、0.876。结果表明,三维全息原子矢量法能较好的对苦味二肽结构进行表征,优于以往传统的氨基酸描述子。从而可以为新的强活性肽类药物的分子设计和改造提供了指导。     

苯并噁嗪酮衍生物类抗艾滋病药物3D-QSAR研究

采用三维全息原子场作用矢量（3D-HoVAIF）对36个苯并噁嗪酮衍生物类抗艾滋病药物进行定量构效关系（QSAR）研究.运用偏最小二乘回归（partialleast square regression,PLS）建模,同时采用内部及外部双重验证的办法对所得模型稳定性能进行了深入分析和检验.PLS建模的复相关系数(R_cum)、留一法（leave-one-out,LOO）交互校验（cross-validation,CV）复相关系数(Q_CV)和外部样本校验复相关系数(Q_ext)分别为0.906、0.865、0.815.结果表明,3D-HoVAIF能较好表征苯并噁嗪酮衍生物类抗艾滋病药物分子结构信息,因而能建立具有良好稳定性和预测能力的QSAR模型,为抗艾滋病药物的研发提供一定的理论基础.     

酰肼类抗结核病药物的3D-QSAR研究

采用三维全息原子场作用矢量(3D-HoVAIF)对115个酰肼类抗结核病药物进行定量构效关系(QSAR)研究.运用多元线性回归(MLR)和偏最小二乘回归(PLS)建模,同时采用内部及外部双重验证的办法对所得模型稳定性能进行了深入分析和检验.MLR建模和PLS建模的复相关系数(R2cum)、留一法交互校验复相关系数(Q2LOO)以及外部样本校验复相关系数(Q2ext)分别为0.766、0.663、0.748和0.733、0.614、0.715.结果表明,3D-HoVAIF能较好表征抗结核药物分子结构信息,所建QSAR模型具有良好稳定性和预测能力,为抗结核病药物的研发提供一定的理论基础.     

苯乙基噻唑硫脲衍生物抗艾滋病药物3D-QSAR研究

采用三维全息原子场作用矢量（3D-HoVAIF）对61个苯乙基噻唑硫脲衍生物类抗艾滋病药物进行定量构效关系（QSAR）研究.运用偏最小二乘回归（partial 1east square regression,PLS）建模,同时采用内部及外部双重验证的办法对所得模型稳定性能进行了深入分析和检验.PLS建模的复相关系数(R_cum)、留一法交互校验复相关系数(Q_CV)和外部样本校验复相关系数(Q_ext)分别为0.907、0.878、0.913.结果表明,3D-HoVAIF能较好表征苯乙基噻唑硫脲衍生物抗艾滋病药物分子结构信息,因而能建立具有良好稳定性和预测能力的QSAR模型,为抗艾滋病药物的研发提供一定的理论基础.     

苯并噁嗪酮衍生物类抗艾滋病药物3D-QSAR研究

摘要：采用三维全息原子场作用矢量（3D-HoVAIF）对36个苯并噁嗪酮衍生物类抗艾滋病药物进行定量构效关系(QSAR)研究.运用偏最小二乘回归（partial least square regression, PLS）建模,同时采用内部及外部双重验证的办法对所得模型稳定性能进行了深入分析和检验.PLS建模的复相关系数（Rcum）、留一法（leave-one-out, LOO）交互校验（cross-validation, CV）复相关系数（QCV）和外部样本校验复相关系数（Qext）分别为0.906、0.865、0.815.结果表明,3D-HoVAIF能较好表征类苯并噁嗪酮衍生物抗艾滋病药物分子结构信息,因而能建立具有良好稳定性和预测能力的QSAR模型,为抗艾滋病药物的研发提供一定的理论基础.     

Classification of bioaccumulative and non-bioaccumulative chemicals using statistical learning approaches

The present work aimed at developing in silico models allowing for a reliable prediction of bioaccumulative compounds and non-bioaccumulative compounds based on the definition of Bioconcentration Factor (BCF) using a diverse data set of 238 organic molecules. The partial least squares analysis (PLS), C4.5, support vector machine (SVM), and random forest (RF) algorithms were applied, and their performance classifying these compounds in terms of their quantitative structure-activity relationships (QSAR) was evaluated and verified with 5-fold cross-validation and an independent evaluation data set. The obtained results show that the overall prediction accuracies (Q) of the optimal PLS, C4.5, SVM and RF models are 84.5-87.7% for the internal cross-validation, with prediction accuracy (CO) of 86.3-91.1% in the external test sets, and C4.5 is slightly better than the three other methods which presents a Q of 87.7%, and a CO of 91.1% for the test sets. All these results prove the reliabilities of the in silico models, which should be valuable for the environmental risk assessment of the substances.     

Near infrared organic light-emitting diodes based on acceptor-donor-acceptor (ADA) using novel conjugated isatin Schiff bases

Fabrications of a single layer organic light emitting diodes (OLEDs) based on two conjugated acceptor-donor-acceptor (ADA) isatin Schiff bases are described. The electroluminescent spectra of these materials range from 630 to 700 nm and their band gaps were measured between 1.97 and 1.77 eV. The measured maximum external quantum efficiencies (EQE) for fabricated OLEDs are 0.0515% and 0.054% for two acceptor-donor-acceptor chromophores. The Commission International De L’Eclairage (CIE) (1931) coordinates of these two compounds were attained and found to be (0.4077, 0.4128) and (0.4411, 0.4126) for two used acceptor-donor-acceptor chromophores. The measured I-V curves demonstrated the apparent diode behavior of two ADA chromophores. The turn-on voltages in these OLEDs are directly dependent on the thickness. These results have demonstrated that ADA isatin Schiff bases could be considered as promising electroluminescence-emitting materials for fabrication of OLEDs.     

Four‐component relativistic chemical shift calculations of halogenated organic compounds

The calculation of nuclear magnetic resonance (NMR) properties of organic compounds with heavy elements has been a computational challenge due to the importance of relativistic effects and the cost of relativistic calculations capable of capturing these effects. The heavy‐atom effect on the chemical shift of light atoms also challenges the interpretation of NMR spectra of organic compounds, since relativistic effects can affect the predicted values of protons bonded to heavy atoms by as much as 20 ppm. Here, we investigate the chemical shifts of six organic compounds with/without halogen atoms using non‐relativistic and state‐of‐the‐art four‐component relativistic methods, comparing the results to available experimental data. Our study confirms the importance of relativistic effects in modeling NMR properties of organic compounds involving heavy atoms and shows that these effects cannot be properly described by non‐relativistic methods. We also demonstrate that relativistic four‐component calculations of NMR chemical shifts now have reached a level of maturity that allows these methods to be used routinely in theoretical studies of NMR properties of large organic compounds containing heavy elements. The accuracy of these calculations is high enough to allow them to be used in assisting in the structural characterization of natural compounds. Comparison of the GGA functionals used in the four‐component relativistic density functional theory calculations shows that the PBE functional seems to be well suited for such studies. Copyright © 2013 John Wiley & Sons, Ltd.     

Electron transfer reaction in the radiation chemistry of some biologically important disulphlde compounds

It is found that some biologically important organic disulphides behave in an unique way under gamma irradiation when they are added in small amounts to the well-known Fricke dosimetry solution. On irradiation, it is noted that addition of these organic solutes reduces the G(Fe⁺² → Fe⁺³) yield instead of the usual increase found in the case of most other organic compounds. It is argued that these compounds behave as sacrificial radiation protective agents. The observation has been explained on the basis of an electron transfer reaction between the disulphides and OH radical. The resulting radical cations of these compounds then dissociate into non-chain propagating species. An attempt has been made to correlate the protective ability of such compounds towards (Fe⁺² → Fe⁺³) system with their biological radiation Drotective abilities. The electron transfer mechanism also seems to operate into their radiation protective action towards biological systems.     

New concept of organic homo‐rank compounds and its application in estimating enthalpy of formation of mono‐substituted alkanes

Based on the topological characteristics of distance matrices and adjacency matrices of molecular graphs, a new concept of organic homo‐rank compounds was proposed. Based on this concept, compounds can be classified into new groups other than the traditional homologues. Furthermore, novel structure–property relationship approach named as homo‐rank compounds method can be developed. The feasibility of homo‐rank compounds method was explored by estimating the enthalpy of formation of organic compounds. The group contribution index (GCI_X) and group polarizability potential index (GPI_X) of substituents X were defined and determined for mono‐substituted alkanes RX (X includes 20 substituents). The research results show that the enthalpies of formation of organic homo‐rank compounds and their isomers can be correlated very well with the parameters GCI_X and GPI_X. Combining the method of homologues with that of homo‐rank compounds, a general and simple quantitative correlation equation (8) was established to estimate the enthalpy of formation for RX, and the calculation precision is within the chemical accuracy ‘1 kcal/mol’. For 242 samples of RX, the average absolute deviation between the experimental and the calculated values is 2.42 kJ/mol. In addition, the enthalpies of formation of more than 2800 samples of RX were estimated. The approaches of organic homo‐rank compounds and organic homologues are independent of but complementary to each other. The combination of these two methods can help us to understand the organic molecular structure–property relationships more deeply, and to investigate these relationships more conveniently and accurately. Copyright © 2015 John Wiley & Sons, Ltd.     

Theoretical studies of the structural,electronic and optical properties of carbazole‐based compounds

Carbazole derivatives have drawn increasing attention recently in organic electronic device applications because of their particular optoelectronic properties. An in‐depth theoretical investigation was elaborated in this paper to reveal the molecular structures, optoelectronic properties, and the structure‐property relationships of different carbazole‐linked functional groups. The geometric and electronic structures in ground and the mobility for the hole and electron are both calculated by density functional theory method. The excited‐state geometries of these compounds were obtained through Single‐excitation Configuration Interaction method, and time‐dependent density functional theory calculation results described the absorption and emission spectra properties, respectively. Some conclusions are as follows: (1) enlarging the π‐conjugated area, the corresponding spectra red shifted markedly; (2) by introducing the electron‐donor such as carbazole, the spectra blue shifted slightly; (3) compared with compound 1, the spectra for these compounds are hardly influenced by introducing an electron‐acceptor or heterocyclic substitution. On all accounts, these compounds are interesting optoelectronic functional materials. On the basis of their structural modifiability, the arylamine derivatives substituted carbazole compounds have great potential in the applications of organic light‐emitting diodes, organic solar cells, and sensors. Copyright © 2011 John Wiley & Sons, Ltd.     

A novel chemical ionization reagent ion for organic analytes: the aquachloromanganese(II) cation [ClMn(H2O)+

The reactivity of ClMn(H(2)O)(+) towards small organic compounds (L) was examined in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The organic compounds studied are aliphatic and aromatic alcohols, aliphatic amines, ketones, an epoxide, an ether, a thiol and a phosphine. All the reactions lead to the formation of the ClMn(H(2)O)(L)(+) complex, which dissociates by loss of the H(2)O molecule. In general, the reactions were found to occur with high efficiencies (>85%), indicating them to be exothermic. Electron transfer was also observed between ClMn(H(2)O)(+) and compounds with low ionization energies (IE), to form the molecular ion (L(+?)) of the analyte. Based on these observations, the IE of ClMn(H(2)O)(+) is approximated to be 8.1?±?0.1 eV. Thus, the utility of ClMn(H(2)O)(+) as a chemical ionization reagent in mass spectrometry is expected to be limited to organic compounds with IEs greater than 8 eV.     

A Novel RBF Neural Network Training Methodology to Predict Toxicity to Vibrio Fischeri

Summary This work introduces a neural network methodology for developing QSTR predictors of toxicity to Vibrio fischeri. The method adopts the Radial Basis Function (RBF) architecture and the fuzzy means training strategy, which is fast and repetitive, in contrast to most traditional training techniques. The data set that was utilized consisted of 39 organic compounds and their corresponding toxicity values to Vibrio fischeri, while lipophilicity, equalized electronegativity and one topological index were used to provide input information to the models. The performance and predictive ability of the RBF model were illustrated through external validation and various statistical tests. The proposed methodology can be used to successfully model toxicity to Vibrio fischerifor a heterogeneous set of compounds.     

Local enhancement of a uniform electrostatic field near the tip of a spheroidal drop

The enhancement in a uniform electrostatic field at the tip of a spheroidal drop is shown to depend on the dielectric constant of the drop material, its initial radius, and the external electric field and to become greater as these increase. The loss of stability of a drop in an external electrostatic field that is accompanied by a very rapid growth in the magnitude of the spheroidal deformation causes a rapid, transient enhancement of the field at its tip. Zh. Tekh. Fiz. 69, 49–54 (August 1999)     

三种五元化合物的荧光光谱的量子化学研究

采用密度泛函理论(DFT)中的B3LYP方法,在6-31G^*水平上对三种五元杂环物质进行了构型优化,对优化后的构型做振动分析,均未出现虚频率。在此基础上通过轨道分析,探索了分子内部电子跃迁的机理。结果表明,这三种五元化合物HOMO到LUMO的跃迁是电子从C1、C2、C3和C4转移到杂原子(吡咯中的N原子,呋喃中的O原子和噻吩中的S原子)上,并在6-31G^*水平上用单激发组态相互作用(CIS)方法分别计算了三种物质的荧光光谱,所得计算结果与实验值基本符合。