手性锌卟啉的非线性光学性质及对咪唑类客体分子识别的构象研究

Nonlinear OpticalProperties and ConformationalStudy on Molecular Recognition of Imidazole Derivatives by ChiralZinc Porphyrins

在纳秒(ns)领域中,利用Z-扫描技术测定了Zn(o-BocTyr)TAPP(主体1)和Zn(p-BocTyr)TAPP(主体2)两种手性锌卟啉的三阶非线性光学性质以及对咪唑类客体的分子识别行为的构象研究.结果表明,(1)两种手性锌卟啉都具有反饱和吸收效应和自散焦效应;(2)由于两种主体中侧链位置的差异,造成两种主体分子极化程度的不同,主体1具有较大的三阶非线性折射率(n2)值;(3)主体1中侧链苯环与卟啉环之间存在一定的相互作用;(4)分子识别出现了配位方向的选择性,客体咪唑(Im)与主体1侧链中的苯环能够形成π-π相互作用,选择从有侧链一方配位于主体1,而2-甲基咪唑(2-MeIm)选择从没有侧链一方进攻主体1,但对于主体2,则没有出现配位方向的选择性.

In order to study the third-order nonlinear optical properties of porphyrin, the nonlinear refractive indexes of two kinds of chiral zinc porphyrin complexes Zn（ο-BocTyr）TAPP（host 1） and Zn（ρ-BocTyr）TAPP（host 2） were measured with nanosecond laser pulses at 532 nm by Z-scan techniques. And then, molecular recognition was studied between hosts and imidazole （Im） derivatives. The conformational searching of chiral zinc porphyrins with imidazole derivatives was studied by simulated annealing method on the basis of Tripos force field. The results illuminate：（1） these compounds showed very strong reverse saturable absorption and self-defocusing effect, （2） because of the different positions of the side chain, hosts had different polarized degrees, host 1 gave the larger nonlinear refractive index n2（-9.85×10^-9 esu）, （3） the aryl-aryl stacking interaction existed between the phenyl ring in side chain and porphyrin plane, （4） the coordinated orientation in which imidazole and 2-methylimidazole （2- MeIm） reacted to host 1 were studied. Irnidazole coordinated to host 1 from the side with lateral chain because the conformation had the lower energy, 2-methylimidazole coordinated to host 1 from the side without lateral chain, but host 2 had no coordination selectivity. The molecular recognition of this host and guest system was calculated by quantum chemistry. Experimental essence was further discussed by theoretical calculation.