On the structural and spectroscopic properties of the thienyl chalcone derivative: 3-(5-Bromo-2-thienyl)-1-(4-nitrophenyl)-prop-2-en-1-one

Abstract In this study, we investigate the structural and spectroscopic properties of the thienyl chalcone derivative 3-(5-Bromo-2-thienyl)-1-(4-nitrophenyl)-prop-2-en-1-one, C 13 H 8 BrNO 3 S, using nuclear magnetic resonance ( 1 H and 13 C NMR), UV–vis and Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy at room conditions combined with density functional theory (DFT) and time-dependent DFT (TD-DFT) augmented with B3LYP/6-311G(d,p) and CAM-B3LYP/6-311G(d,p) basis sets, yielding valuable information on the molecular conformational preferences, vibrational assignments, optical properties and electronic transitions. The vibrational mode assignments of the most stable conformer of C 13 H 8 BrNO 3 S are discussed based on potential energy distribution (PED) analysis and establishing a comparison with a similar chemical structure. The temperature dependence on the Raman spectra of the C 13 H 8 BrNO 3 S shows a reversible phase transition in the range 443–443 K pointed out by the discontinuity in the dω/dT of bands in the external and internal modes region. The UV–vis spectrum of the C 13 H 8 BrNO 3 S indicates a semiconductor behavior with an optical band gap of 2.6 eV, corresponding to the predicted value of 3.42 eV assigned as the electronic transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). TD-DFT calculations reveal that the electron donor and acceptor group substitution on the 1-phenyl-3-(thiophen-2-yl)prop-2-en-1-one affects its absorption and nonlinear activity.