手性Salen Fe与2-乙基-4-甲基咪唑的分子识别研究  

Study on Molecular Recognition of Chiral Salen Fe With 2-Ethyl-4-Methyl-Imidazole

作　　者：朱必学[1] 阮文娟[1] 王树军[1] 曹小辉[1] 朱志昂[1] 

机构地区：[1]南开大学化学系,天津300071

出　　处：《无机化学学报》2005年第2期169-175,共7页Chinese Journal of Inorganic Chemistry

基　　金：国家自然科学基金资助项目(No.20171024;20271030);天津市自然科学基金资助项目(No.023604011)

摘　　要：合成并表征了3个手性主体1(t-Bu-SalenFeⅢ)、2(unsym-SalenFeⅢ)和3(SalenFeⅢ),将其用于对客体4(2-乙基鄄4-甲基咪唑,EMI)逐级缔合反应的分子识别研究,首次测定了主体与EMI缔合反应逐级缔合常数KⅠ、KⅡ和反应过程热力学参数驻rG苓m、驻rH苓m、驻rS苓m,详细地考察了主客体体系的圆二色(CD)光谱性质。实验表明:缔合常数KⅠ和KⅡ均按K(3)>K(2)>K(1)顺序递减,缔合反应是一放热、熵减过程,配位数的变化在UV-Vis电子吸收光谱和CD光谱上呈现出等吸收点位移,但没有改变缔合物双偶氮螯环的Δ构型。采用分子力学和量子化学相结合的方法,从理论上对实验结果作出了合理的解释。Chiral hosts of 1 (t-Bu-Salen Fe-III), 2 (unsym-SalenFe(III)) and 3 (salen Fe-III) complexes were synthesized and characterized. The molecular recognition behavior of chiral hosts towards EMI (2-Ethyl-4-Methyl-imidazole) was studied. The association constants (K-I and K-II) and the thermodynamic parameters of host-guest system were measured for the first time, and the circular dichroism spectra properties were discussed in detail. The results show that the association constants (K-I or K-II)decrease in the orders of K(3) > K(2) > K(1), and the reaction is an exothermic process with decrease in entropy. The isosbestic point shifts towards short wave-length direction in the electronic absorption spectra and CD spectra, and does not cause inversions of the conformation of the chelated ring of host-guest molecular system with coordination number increase. In addition, the results were explained by means of molecular mechanics and quantum chemistry computation.

关 键 词：缔合常数 手性 分子识别 电子吸收光谱 量子化学 配位数 CD光谱 4-甲基咪唑 乙基 反应过程 

分 类 号：O641.3[理学—物理化学] TQ352.1[理学—化学]