α-丙氨酸构象的理论计算

Theoretical Calculation on the Conformers of α-Alanine

用Hyperchem软件中的构象搜寻模块,对α-丙氨酸进行系统构象搜索,寻找分子低能构象.用B3LYP/6-311++G(d,p)法优化计算13个低能构象,PCM(Polarizable Continuum Models)用于水相计算,获得低能构象的优化几何结构、分子总能量和标准吉布斯自由能.较详细地讨论了α-丙氨酸各构象的相对稳定性,水的溶剂化作用对其能量、几何构型和偶极距的影响等问题.此外,还探讨了一水合丙氨酸的几何构型和能量性质.

Using the conformational search model of hyperchem, we have searched low energy conformations of α-alanine by the parameter of the dihedral angle. Molecular structures of 13 conformers of α-alanine were calculated by the B3LYP/6-311 ＋＋ G（ d, p） method both in the gas and aqueous phases with full geometry optimization, The PCM（ Polarizable Continuum Models） was employed for aqueous solution calculations, The optimized Structures, total molecular energy and standard free energy were obtained, The solvent effects on the optimized structures, energies and dipole moments were discussed in detail, Finally, the structures and energies of monohydrate alanine have been investigated at the same level in the gas phase.