脯氨酸的构象及性质  

Conformers and Properties of Proline

作　　者：王朝杰[1] 李永[1] 杨新宇[1] 林丽[1] 

机构地区：[1]温州医学院药学院,浙江温州325035

出　　处：《物理化学学报》2007年第3期305-310,共6页Acta Physico-Chimica Sinica

基　　金：浙江省自然科学基金(Y404085);浙江省教育厅高校青年教师资助项目;温州市科技局基金(Y2004A123)资助项目

摘　　要：用X3LYP法在6-311++G(d,p)和6-311++G(3df,3pd)基组水平上对脯氨酸15种构象的几何结构、相对能量、电子结构、红外光谱、偶极矩、极化率等性质进行了研究,并与PBE1PBE/6-311++G(d,p)的结果和文献相比较,从而得到:(1)的脯氨酸的15种构象中能量最低的有4种,不同构象中存在着强弱不同的5种氢键,其中以N…H—O氢键最强,并存在特殊的C—H…O＝C氢键.两种方法计算的几何结构数据相近,均与实验值吻合;(2)在构象相对能差计算方面,X3LYP具有明显的优势,用中等基组就可以得到与高水平从头算法和大基组相同的结果,而PBE1PBE法计算的相对能值则相差较大;(3)脯氨酸不同构象中偶极矩最大和极化率最小的是最稳定的构象1和2,两种方法计算的结果一致.A total of 15 conformers of proline were found and their geometrical structures, relative energies, harmonic frequencies, dipole moments, rotational constants, polarizabilities, and the difference in energies between HOMO and LUMO were calculated at the X3LYP/6-311＋＋G（d, p） and the PBE1PBE/6-311＋＋G（d, p） levels. Accurate relative energies were given at the X3LYP/6-311＋＋G（3df, 3pd）//X3LYP/6-311＋＋G（d, p） level of theory, which were in good agreement with high-level ab initio methods using large basis sets. The results of X3LYP are superior to those of PBE1PBE method. The characteristic H-bonding types for all the conformers were classified. The four most stable conformers had intramolecular H-bondings of N…H-O and C-H…O=C, and the dipole moments of conformers 1 and 2 were the largest and the polarizabilities were the smallest. An additional H-bonding C-H…O=C was found. In combination with the principles of statistical mechanics, conformational distributions at room temperature were computed.

关 键 词：脯氨酸 X3LYP 构象 偶极矩 转动系数 

分 类 号：O621.13[理学—有机化学]