Static/dynamic first and second order hyperpolarizabilities, optimized structures, IR, UV–Vis, 1H and 13C NMR spectra for effective charge transfer compounds: A DFT study

Abstract

The effective charge transfer compounds, 4-N,N-dimethylamino–4′-N′-methyl-stilbazolium m-trifluoromethylbenzene-sulfonate (DSMFS) and 4-N,N-dimethylamino–4′-N′-methyl-stilbazolium p-trifluoromethylbenzene-sulfonate (DSPFS), were simulated in terms of geometric structure, IR, UV–Vis, 1H NMR and 13C NMR spectra. UV–vis spectra for both molecules give two peaks at 290 and 436 nm assigned as n-π* and π-π* transitions. The HOMO-LUMO energy gap for DSMFS (2.8174 eV) was calculated as lower than that of DSPFS (4.6649 eV). The detailed frontier molecular orbital analysis also indicated that the intra- and inter-molecular charge transfers occur in DSMFS and DSPFS. The static and dynamic (ω = 532 and 1064 nm) nonlinear optical properties were also investigated by using B3LYP/6–311++G(d,p) level. Static first and second order hyperpolarizabilities (β and γ) of DSMFS were obtained 1.5726 × 10−28 esu and 271.63 × 10−36 esu, and those for DSPFS were obtained as 1.5528 × 10−28 esu and 303.31 × 10−36 esu. The dynamic β and γ were obtained as higher than the static corresponding parameters. However, the increasing wavelength in dynamic NLO calculations led to a decrease in β and γ parameters.