DFT和热力学研究氢键协同效应及对关联~1H NMR的影响  

DFT and Thermodynamic Studies on Hydrogen Bond Cooperativity and Its Effects on the^1H NMR Correlation

作　　者：蓝蓉[1] 李浩然[1] 韩世钧[1] 

机构地区：[1]浙江大学化学系,杭州310027

出　　处：《化学学报》2005年第14期1288-1292,i002,共6页Acta Chimica Sinica

基　　金：国家自然科学基金(No.29976035);浙江省青年人才专项基金(No.RC01051)资助项目.

摘　　要：用DFT方法在B3LYP/6-311++G(d,p)水平下研究了甲醇线性和环状分子簇.对于不同大小的分子簇之间定义了协同因子.计算得到的协同因子可以验证氢键的强协同效应,环状分子簇之间的协同效应远远大于线性分子簇.做为理论验证和比较,热力学模型分别采用含氢键缔合的格子流体状态方程(LFHB),以及含氢键协同效应的LFHB,关联醇-惰性体系的1H核磁共振化学位移.考虑协同效应的关联结果优于原始的LFHB.比较量子化学计算的和热力学模型中采用的协同因子,认为甲醇和乙醇在溶液中更可能大部分以线性缔合形式存在.In this paper systematic DFT calculations were carried out to study hydrogen bond cooperativity of linear and cyclic clusters consisting of up to 5 molecules of methanol at B3LYP/6-311++G (d,p) level. A definition has been proposed for cooperative factor for clusters of different size. Calculated cooperative factors are far greater for cyclic clusters than for linear ones. For comparison, LFHB model (the lattice-fluid hydrogen-bonding equation of state model) with or without cooperative effects was used to fit the 1H NMR chemical shift data of (methanol or ethanol+inert solvent) mixtures. More satisfactory results were obtained by including the cooperative effects in the thermodynamic model. Comparing the calculated cooperative factors with those used in cooperative LFHB, liquid methanol could be considered to exist mostly as linear clusters.

关 键 词：协同效应 ^1H 力学研究 对关联 NMR 热力学模型 量子化学计算 B3LYP DFT方法 分子簇 理论验证 状态方程 氢键缔合 化学位移 核磁共振 因子 线性 环状 甲醇 流体 格子 溶液 

分 类 号：O621.13[理学—有机化学]