几种2-取代-4,5-双(α-呋喃基)噁唑的结构与光谱性质

Structure and Spectrum Properties of the 2-Substituted-4,5-di(α-furyl)oxazole

在密度泛函DFT-B3LYP/6-31+G水平上对2-甲基-4,5-双(α-呋喃基)噁唑(化合物A)、2-苯基-4,5-双(α-呋喃基)噁唑(化合物B)、2-α-呋喃基-4,5-双(α-呋喃基)噁唑(化合物C)和2-α-呋喃乙烯基-4,5-双(α-呋喃基)噁唑(化合物D)S0基态进行构型优化,并用单取代组态相互作用方法(CIS)优化其S1激发态结构。从理论上探讨了A,B,C和D四种化合物的前线分子轨道能量、吸收和发射光谱等性质与结构的关系,并与实验值进行了对比,发现理论计算数据能够与实验结果一致,特别是采用纯密度泛函DFT-OLYP方法计算发射光谱时,理论计算数据与实验结果相差比混合密度泛函DFT-B3LYP方法更小。计算结果表明,分子共轭体系越大,前线轨道间能隙越小,吸收光谱红移越显著。

The ground states（S0）of the 2-methyl-4,5-di（α-furyl）oxazole（compound A）,2-phenyl-4,5-di（α-furyl）oxazole（compound B）,2-α-furyl-4,5-di（α-furyl）oxazole（compound C）and 2-α-furan ethenyl-4,5-di（α-furyl）oxazole（compound D）were optimized with density functional theory（DFT）at B3LYP/6-31＋G level,respectively.Single-excitation configuration interaction（CIS）method was used to calculate and optimize the excited states（S1）of the four compounds.The relation among the frontier molecular orbital energy,the absorption spectra,the emission spectra and the structure of the four compounds were discussed.The results show that the theoretically calculated spectrum data well agrees with the experimental value,and especially,the calculated maximum emission spectrum wavelength is more close to the experimental data when the pure density functional theory（DFT-OLYP）method is used.In addition,the frontier molecular orbital energy gap analysis indicates that the larger the conjugation system is the more distinct the red shift of absorption spectrum is.