Ni^(2+)与双甘氨肽相互作用的理论研究

Theoretical Studies on Interactions between Ni^(2+) and Glycylglycine

使用密度泛函的B3PW91方法研究了Ni2+离子与二肽的相互作用,优化了各种可能复合物的三重态、五重态和单重态.研究结果表明所得配合物的基态为三重态,基态复合物基本上是以二肽分子中碳链上的两个O原子和末端N原子形成的二齿或三齿配合物.在气相中基态的最稳定复合物构型为三配位的3I,而在溶液中为两性离子配合物3VIII.在配合过程中,静电相互作用占主导地位.三重态的配位过程中配体的电子主要转移到空3d轨道和4s4p上而五重态中配体的电子主要转移到单占据d轨道上,导致自旋密度转移到配体上去.溶剂化过程中,溶剂与溶质间的静电相互作用起主导作用.

Theoretical calculations were performed to study the interactions between Ni^2＋ and glycylglycine by density functional theory using the B3PW91 functional and optimize coordinated complexes at the singlet, triplet and quintet states with eight complexes of every state found. The ground states of those complexes are all triplet states. In the triplet complexes, the oxygen atom and nitrogen atom of glycylglycine were coordinated with Ni^2＋ to form di- and tridentate compounds. In gas phase, the stablest complex is the structure ^3I. The solvent effects were also taken into consideration and discussed. The results show that the structure ^3VIII, a zwitterionic species, is the complex in solvent phase. In solvation progress, the electrostatic interactions between the zwitterionic species and solvent may play very important role.