1,3,4-Thiadiazole rings as π-spacers in triphenylamine based dyes: A density functional theory study of reactivity, UV/Visible spectra, structural and optical properties

The geometry, electronic structure, polarizability and reactivity of triphenylamine based organic dyes, which contain 1,3,4-thiadiazole rings as an electron donor–acceptor moiety, were studied using density functional theory (DFT), and the electronic absorption spectrum was investigated via time-dependent DFT (TD-DFT) with B3LYP/6-31G(d) level of theory. All the computations were done in gas phase at 298.15 K temperature and 1 atmosphere pressure. The results of computations indicate that the increasing number of 1,3,4-thiadiazole ring as π-spacer size in the structures of triphenylamine based dyes cause the more kinetic stability of molecules. an‎d also, the UV-Visible spectra of molecules are gradually broadened and red-shifted increasing number of 1,3,4-thiadiazole units.