分子轨道法(PPP-MO)计算吲哚双碳菁类染料分子的电子结构和电子光谱

Electronic Spectra of Indodicarbocyanine Dyes by Modified PPP-MO Method

采用改进的半经验分子轨道法 (PPP MO)计算了 1 0种吲哚双碳菁类染料分子的电子结构和电子光谱 ,计算得到的最大吸收波长与实验值较好的一致 ;计算得到的荧光跃迁能ΔEf1 与荧光最大波数 υf1 存在如下关系 : υf1=3 1 376ΔEf1 +1 1 0 2 75 (k·cm- 1 ) ,r=0 981 8;计算得到的激发过程分子平均键级变化Δ p与荧光量子产率f1存在如下关系 :lnf1 =1 4 31 8lnΔ p +7 32 64,r=0 960 6;并讨论了电子结构与光谱性能的关系。

Colour and constitution of indodicarbocyanine dyes were evaluated by means of the modified PPP\|MO method with variable R,β approximation. The calculated wavelengths of maximum absorption are in good agreement with experimental results. It was found that there exists a good correlated relationship between the wavenumber of fluorescence maximum  f1  and the calculated fluorescence emission energy Δ E f1 , as f1 =3 137 6  Δ E f1 +11 027 5( k·cm -1 ),r=0 981 8;fluorescence quantum yield  f1 and average bond order difference Δ between ground state and first excited single state, as ln  f1 =1 431 8 ln Δ + 7 326 4, r=0 960 6; r= 0 960 6 ;The relationship between structure of molecular and properties of electronic spectra has been discussed.