手性Salen金属配合物与咪唑类客体分子识别的研究

Studies on Molecular Recognition of Chiral Salen Metal Complexes with Imidazoles

用光谱滴定法研究了手性Salen金属配合物(SalenFe~Ⅲ,SalenCo~Ⅱ)与四种咪唑类客体在CH_2Cl_2中的分子识别行为,发现手性Salen金属配合物与咪唑,N-甲基咪唑,2-甲基咪唑的配位数为2,与克霉唑的配位数为1.各识别体系缔合常数的顺序对SalenFe~Ⅲ为:K(Im)>K(2-MeIm)>K(N-MeIm)>K(GMZ),对SalenCo~Ⅱ为:K(Im)>K(2-MeIm)>K(N-MeIm).测定的识别反应的△_rG_m^0,△_rH_m^0,△_rS_m^0表明此类识别反应为放热、熵减少的过程,反应体系中存在焓-熵补偿关系.采用分子力学和量子化学方法进行的理论研究对实验结果作出了合理的解释.

Molecular recognition behavior of chiral Salen metal complexes (SalenFe(III), SalenCo(II)) towards imidazole derivatives in CH2Cl2 was studied by means of spectra technique. The coordination number for Im, 2-MeIm, N-MeIm are all 2, but for GMZ is only 1. The association constants of host-guest system decrease in the orders of K(Im) > K(2-MeIm) > K (N-MeIm) > K (GMZ) for host SalenFe(III) and K (Im) > K (2-MeIm) > K (N-MeIm) for SalenCo(II). The thermodynamic parameters Delta(r) G(m)(0), Delta(r)H(m)(0), Delta(r)S(m)(0), were determined. The results showed that recognition process was exothermic and entropy decrease. In addition, the theory studies by means of molecular mechanics and quantum chemistry computation were performed, which gave the reasonable explanation for the experimental results.