Study on electronic spectra of 2-styryl-ß-naphthathiazole dyes with time-dependent density functional theory

Theoretical studies on a series of 2-styryl-beta-naphthathiazole dyes were carried out using the Density Functional Theory (DFT) at B3LYP/6-31g level to obtain optimized equilibrium structure. The effects of p-substituting groups (CH3, OCH3, N(CH3)(2), 3,4-OCH2O, NO2) on the molecular charge transfer. energies of frontier molecular orbitals and the electronic absorption spectra have been investigated. On this basis, the first excited state electronic transition energy has been calculated using time-dependent density functional theory, and lambda(max) was obtained. The computed results indicate that the introduction of those substituting groups leads to bathochromic shift of maximal absorption wavelength. The predicted characteristics accord quite well with the available experimental ones, and the relative deviation is in the range from 0.0085 to 0.0501.