含水杨醛缩苯胺双Schiff碱和吡啶配体的Zn(Ⅱ)配合物的电子结构和二阶非线性光学性质

Electronic Structures and Second-order Nonlinear Optical Properties of Zinc(Ⅱ) Complexes with Bis(salicylaldiminatio) Schiff Bases and Pyridine Ligands

以实验测定的晶体结构为基础,用密度泛函理论的B3LYP方法,在6-31G(d)基组水平上计算4个水杨醛缩苯胺类双Schiff碱和吡啶为配体的Zn(Ⅱ)配合物的电子结构,并结合有限场(FF)方法得到二阶NLO系数.结果表明,在4个五配位配合物中,双Schiff碱配体的共轭性减弱,在Schiff碱配体引入叔丁基以及连接双Schiff碱的桥对配合物的结构影响很小.同时4个配合物的配键性质、原子电荷分布、前线分子轨道能级等方面具有相似性.但引入叔丁基改变了配合物前线分子轨道组成,Zn—O配位键的极性有所加强,从而使配合物的极化率和二阶NLO系数增加,而连接两个Schiff碱的桥对配合物二阶NLO性质影响不大.

Based on the crystal structure measured experimentally, the density functional theory （DFT） B3LYP method was employed to calculate the electronic structures of four zinc （ Ⅱ ） complexes with double schiff bases ligands containing salicylaldehyde with aniline and pyridine ligands at 6-31 G（d） level. Moreover, the finite field（FF） method was combined to investigate second-order nonlinear optical coefficient. The results indicate that the double schiff bases ligands have a lower conjugation degree. And the introduction of ten-butyl to Schiff bases and the bridge connecting the double Schiff bases ligands affect the complex structures slightly. Meanwhile, the coordinate bonds, atomic charge distributions, energy levels of frontal molecule orbital and the other properties of the four complexes have similar trends. However, the introduction of ten-butyl changed compositions of the frontal molecule orbital of complexes, which enforced the polarity of Zn-O coordinate bonds. As a result, the linear and second-order nonlinear optical（NLO） coefficients are increased. However, the bridge connecting the double Schiff bases ligands have less influence to the second-order NLO properties.