Absorption and Fluorescence Emission Spectra of Molecules Containing Azo and/or Oxadiazole Units

The ground state structures of a series of organic molecules containing azo and/or oxadiazole units were obtained by means of density functional theory B3LYP/6-31G(d) method. The first singlet excited state structures were optimized by virtue of singlet-excitation configuration interaction CIS/6-31G(d) method. The absorption and fluorescence emission spectra were then evaluated via the time-dependent density functional theory B3LYP and PBE1PBE methods with 6-311++G(3df,2p) basis set. The calculation results show that compared with those of their parent molecules A-H, B-H, C-H, D-H, the absorption and emission wavelength values of all the derivatives show red shifts. The derivatives containing both the oxadiazole and methoxyl units are good candidates for longer absorption wavelength materials. The effects of azo, oxadiazole, and methoxyl units on the absorption and emission wavelength were discussed.