手性SalenZn配合物的合成及对咪唑类、吡啶类客体的分子识别研究

合成并表征了手性Salen配体1及其Zn配合物2。详细讨论了配体及配合物的电 子光谱和圆二色光谱性质。用紫外—可见光谱滴定法测定了主体2与4种咪唑、5种 吡啶客体轴向配位反应的平衡常数，研究了主体分子2的分子识别行为。实验结果 表明：各种客体的缔合常数，咪吡类按K(Im)＞K(2—MeIm)＞K(SMIm)＞K(EMIm)顺 序递减;吡啶类按K(Py)＞K(3-Py)＞K(3，5-Py)＞K(2，4—Py)＞K(2，4，6—Py)顺 序递减。测定了识别过程的△rGm^-,△rHm^-,△rSm^-，发现该反应是放热、熵减 小的过程。采用分子力学的方法考察了主客体的最低能量构象，并对该构象进行量 子化学计算，从理论上对实验事实给予较好的解释。

Synthesis and Molecular Recognition of Chiral Salen Zn with Imidazoles and Pyridines

Chiral salen 1 and chiral salen Zn complex 2 were synthesized and characterized. The electronic spectra and circular dichroism spectra properties were discussed. By method of UV-vis spectrophotometer technique, the equilibrium constants of axial coordination reaction were measured between complex 2 and series of imidazoles or pyridines. The molecular recognition of the host 2 was studied. The results show that the equilibrium constants decrease in the orders of K(lm) > ￡(2- MeIm) > ￡(SMIm) > ￡(EMIm) (imidazoles) and K(Py) > K(3-Py) > K(3,5-Py) > K(2,4-Py) > K(2,4,6-Py) (pyridines) . The thermodynamic parameters Ar?, and? of the recognition process were determined. It is found that the reaction is an exothermic process with entropy decreasing. In addition, the conformations with minimal energy of each host-guest molecular system were sought by molecular dynamics method. Quantum chemical calculations were performed on these conformations to explain the experimental data. A model of the recognition mechanism was constructed