香豆素类分子与CH3OH的复合物的密度泛函理论研究

Study on Complexes of Coumarin and its Derivative with CH3OH by Density Functional Theory

本研究采用密度泛函理论方法M06-2X,以6-311++G(d,p)为基组,对香豆素和7-氟-香豆素分子与甲醇(CH3OH)形成的复合物进行了研究。结果表明,香豆素和7-氟-香豆素上有不同的氢键结合位点,吸电子的氟取代基的存在,对复合物的构型和稳定性均造成影响。应用分子中的原子(AIM)理论证明了复合物中氢键的存在。构型和振动频率分析的结果显示,CH3OH形成氢键后,O-H键的键长伸长,伸缩振动频率红移。应用自然键轨道(NBO)理论对红移氢键的形成进行了解释。

The complexes of coumarin and 7-fluoro-coumarin with CH3OH were studied by the density functional theory. The calculations were performed at M06-2X/6-311++G(d,p) level. The results indicated that different binding sites existed in coumarin and 7-fluoro-coumarin. The optimized geometries and the binding energies of the complexes were influenced by the fluorine substituent. The AIM theory was applied to prove the existence of the hydrogen bonds. The analysis of the geometries and vibrational frequencies indicated that O-H bond of CH3OH elongates and its stretching vibrational frequency decreased. The NBO analysis was used to help explain the formation of the red-shifted hydrogen bonds.