多溴代芴热力学性质的理论预测研究

为了预测环境污染物多溴代芴的热力学性质,计算了60种多溴代芴的分子连接性指数、电性距离矢量指数、电性拓扑状态指数以及分子形状指数.采用多元线性回归的方法建立了多溴代芴化合物的标准生成焓(Δ_fH~0)、标准熵(S~0)、标准生成吉布斯自由能(Δ_fG~0)及等容热容等热力学性质的QSPR相关性模型,方程的相关系数值均在0.99以上.与相关文献的相关系数R和标准误差S进行比较,该模型具有良好的预测能力和稳定性.     

二芳基甲烷衍生物保留因子与分离因子的神经网络理论研究

为了研究手性二芳基甲烷衍生物的保留因子和分离因子,基于分子结构及邻接矩阵,计算了63个手性二芳基甲烷衍生物的分子连接性指数和电性拓扑状态指数。建立了这些分子保留因子、分离因子与优化得到的结构指数之间的相关性模型,并将筛选的结构参数作为BP神经网络的输入层变量,采用不同的网络结构,获得了令人较为满意的三个预测模型,模型的总相关系数R分别为0.981、0.972和0.992。利用模型计算得到的保留因子和分离因子预测值与实验值的平均误差分别为0.041、0.042和0.010,吻合度较好。结果表明手性二芳基甲烷衍生物的保留因子及分离因子与分子结构参数之间有良好的非线性关系。     

应用分子电性距离矢量预测烷烃和一元醇的折光指数

应用分子电性距离矢量对81个烷烃、22个一元醇进行了结构表征,通过多元线性回归与逐步回归的方法建立了分子电性距离矢量与折光指数的定量结构性质模型,模型的相关系数分别为0.980和0.979.采用留一法对模型进行交互检验复相关系数R2cv分别为0.927和0.898.说明定量结构性质模型具有很好的稳定性和预测功能.     

地下水中挥发性有机物结构与色谱保留关系研究

本文采用分子电性距离矢量( Molecular Electronegativity-distancevector,MEDV)对地下水中26个挥发性化合物进行了结构表征,并与其色谱保留时间建立定量结构-保留关系(QSRR)模型.得到的MLR模型复相关系数(R2)为0.901,留一法(LOO)交互校验(CV)预测值的复相关系数(R2cv)为0.806;PLSR模型复相关系数(R2)为0.882,留一法(LOO)交互校验(CV)预测值的复相关系数(R2cv)为0.750.结果表明分子电性距离矢量(MEDV)能较好地表征该体系化合物结构,所建模型具有良好的稳定性与预测能力.     

基于图论方法建立二取代吲哚酮类的拓扑数学模型

新型的二取代吲哚酮类衍生物对人转移胰腺癌细胞Hela有抑制作用,根据密度泛函理论(DFT),通过计算该类化合物的分子连接性指数、电性拓扑状态指数、分子电性距离矢量、分子形状指数,得到153个分子描述符,对它们进行多元逐步回归,得到四个最佳变量,其中R~2=0.908,采用遗传算法进行优化,建立3-3-1型神经网络,得到的训练集的关联度R~2=0.968 5,验证了参数间的非线性关系,影响该类化合物抑制率的主要因素为电性与拓扑环境,影响分子的二维结构的是-CH_2-、=CH-、=C等结构碎片。     

苯甲酰硫脲类化合物生物活性的QSAR模型和结构修饰的理论研究

基于分子拓扑邻接矩阵,计算了18种苯甲酰硫脲衍生物的原子类型电性拓扑状态指数(En)。通过多元线性逐步回归方法,建立了令人满意的En与苯甲酰硫脲衍生物对金黄色葡萄球菌的抑制活性(D)的定量结构-活性相关模型(QSAR)。该模型的相关系数(R2)、标准偏差(S)分别为0.861及1.273,该模型的计算值与相应实验值基本吻合。经Rcv2、VIF、FIT、AIC等指标检验,所建模型具有良好的预测能力与稳健性。利用该模型探讨了苯甲酰硫脲衍生物对金黄色葡萄球菌的抑制机理。根据进入模型的2个电性拓扑状态指数E1、E7可知,影响苯甲酰硫脲衍生物对金黄色葡萄球菌的抑制活性的主要因素是分子的二维结构特征-CH3和在芳环中=CH-等结构碎片。由结构修饰提出5种化合物,其中3种的抑菌活性均超出18mm,有待以后生物实验予以证实。     

醇类化合物热值改进剂的定量结构-色谱保留相关性研究

计算表征了醇类化合物热值改进剂的部分分子连接性指数和5个量子化学参数,同时运用多元线性回归方法对参数进行了优化筛选,在2种不同极性强弱的固定相(PH-5、RTX-WAX)上,分别建立了9种和11种醇类化合物热值改进剂的气相色谱保留值(t)与分子连接性指数和量子化学参数的定量结构-色谱保留关系(QSRR)模型。其相关系数分别为R=0.997和R22=0.971,关系式可分别表示为模型1:t1=-5.972-0.047 ET-1.857~3X_p~v和模型2:t_2=-2.409-0.034 ET,在2种固定相上的QSRR模型的建模计算值复相关系数(R)、采用留一法(leave-one-out)交互检验复相关系数(R)分别为:R_1=0.998、R_(1CV)=0.999和R_2=0.985、R_(2CV)=0.999,结果表明:模型1和模型2与色谱保留指数显著相关的分别有总能量ET、三阶分子连接性指数~3X_p~v和总能量ET,所建模型具有良好稳定性和预测能力,分子连接性指数和量子化学参数能较好地反映化合物的结构特征。     

萜类化合物13C NMR化学位移的定量构谱相关研究

利用原子电性作用矢量(Atomic electro-negativity interaction vector,AEIV)和原子杂化状态指数(Atomic hybridization state index,AHSI)对萜类化合物中的C原子进行结构表征并与其核磁共振碳谱(13C NMR)建立了优良的定量构谱相关(QSSR)模型.其中29个单萜类化合物中的290个C原子建模的计算值经留一法(Leave-one-out,LOO)交互校验(Cross-validation,CV)预测值的复相关系数(R)分别为0.9900和0.9867,进一步使用倍半萜、二萜、三萜化合物分子中65个C原子的13C NMR化学位移值来检测该模型的稳定性,模型预测值和观测值间复相关系数(R)为0.9777,取得了令人满意的结果.     

人工神经网络用于N-甲基氨基甲酸酯类农药急性毒性的预测

基于拓扑理论计算了N-甲基氨基甲酸酯化合物的电拓扑状态指数(E_n)和分子电性距离矢量(M_k),同时计算了它们理化参数.把2类结构参数用逐步回归分析法进行筛选,确定了4个变量组合E_(31),M_1,M_(60)和SAA.用筛选后的结构参数建立N-甲基氨基甲酸酯农药急性毒性(log1/LD_(50))的神经网络模型,并用模型对log1/LD_(50)值进行了预测,预测结果和实验值比较接近,平均误差为0.071.该方法为开发高效低毒的新型氨基甲酸酯类农药提供理论依据.     

基于DFT和分子连接性指数方法研究醇类化合物的水溶解度和分配系数

将DFT方法计算得到的量化参数和分子连接性指数联合应用到60个醇类化合物的溶解度和辛醇/水分配系数的QSPR研究中,分别通过逐步回归得到具有显著统计意义的4个参数和5个参数的QSPR方程.以此4个参数和5个参数分别作为输入参数,采用BPNN,RBFNN方法建立了QSPR预测模型,使用Latin-partition交叉验证方法评价模型的预测能力.BPNN,RBFNN模型对溶解度预测的相关系数分别为0.993和0.994,而对辛醇/水分配系数预测的相关系数分别0.990和0.997,结果令人满意.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.