Spectroscopic and theoretical study on organic donors: DIET, DIEDO, and DIETS

The comparative analysis of IR and Raman spectra of three unsymmetrical donors in solid state was carried out. The harmonic vibrational frequencies, infrared intensities, and Raman scattering activities were calculated at the B3LYP/3-21G* theory level at restricted and unrestricted models for neutral molecules and cations, respectively. For the predicted spectra, a potential energy distribution (PED) of normal modes was also calculated. Solid-state electronic (UV–vis) spectra of donors were investigated. The electronic excited states of DIET, DIEDO, DIETS donors have been determined using time-dependent density functional theory (TD-DFT). The character and energy of the first 30 singlet–singlet electronic transitions were investigated.