基于异噁唑酮类份菁染料的激发态分子内质子转移的研究

运用量子化学理论计算方法研究了3-甲基-4-(1H-吲哚-3-次甲基)-异噁唑-5-酮(A)及其衍生物份菁染料的激发态分子内质子转移性质.研究表明:在基态3种染料AH(R=H),AO(R=—O(H3))和AP(R=—O(H2Ph))只存在酮式构型,在激发态AH与AP存在酮式和烯醇式2种构型,而AO存在酮式、烯醇式和仲胺式3种构型.红外光谱表明化合物从基态跃迁到激发态存在分子内的氢键增强作用,势能曲线显示激发态的质子转移为放热反应且能垒较低,通过分析电子光谱得到具有较大斯托克位移的激发态分子内质子转移的荧光发射峰,前线分子轨道理论计算进一步说明了其质子转移的发生过程.

Investigation on excited-state intramolecular proton transfer of merocyanine dyes modified with isoxazolone

By theoretical quantum mechanical calculations,the excited state intramolecular proton transfer of 3-methyl-4-(1H-indole-3-methenyl)-isoxazole-5-ketone was thoroughly investigated.The calculated results suggest that in the ground state the three dyes (AH,AO,AP) exist in keto form.In the excited state,AH and AP dyes have keto and enol forms,AO dye also has secondary amine form except keto and enol forms.Intramolecular hydrogen bonding interactions were improved through the IR spectrum of the dyes from the ground state to the excited state.The potential energy curves in the excited state suggested that the proton transfer process is an exothermic reaction with lower energy barrier.Furthermore,the fluorescence emission peaks with large stokes shift were obtained by electronic spectrum.The results showed that the proton transfer reactions occur through the analysis of infrared spectrum and frontier orbital theory calculation.