Substituent and solvent effects on UV-visible absorption spectra of chalcones derivatives: Experimental and computational studies

Hanna S Abbo; Chin Hung Lai; Salam J J Titinchi

doi:10.1016/j.saa.2023.123180

Substituent and solvent effects on UV-visible absorption spectra of chalcones derivatives: Experimental and computational studies

Spectrochim Acta A Mol Biomol Spectrosc. 2023 Dec 15:303:123180. doi: 10.1016/j.saa.2023.123180. Epub 2023 Jul 22.

Authors

Hanna S Abbo¹, Chin Hung Lai², Salam J J Titinchi³

Affiliations

¹ Department of Chemistry, College of Science, University of Basrah, Basrah, Iraq; Department of Chemistry, University of the Western Cape, Cape Town, South Africa.
² Department of Medical Applied Chemistry, Chung Shan Medical University, Taichung 40241, Taiwan.
³ Department of Chemistry, University of the Western Cape, Cape Town, South Africa. Electronic address: stitinchi@uwc.ac.za.

PMID: 37517269
DOI: 10.1016/j.saa.2023.123180

Abstract

The electronic spectra of the title compounds were measured in ethanol and cyclohexane. Three band systems are distinguished in the spectra of which the first and second band systems are attributed to local excitation of Ph_CH and Ph_CO rings. The third absorption band is assigned to a charge transfer (CT) band and is associated with the CO-CH=CH moiety. The solvent plays an important role in the absorption spectra and causes the CT band to consist of two electronic transitions. The effect of substituents on the phenyl rings on the charge transfer band of chalcone derivatives was also established in the two solvents. The converged gas-phase geometries of the studied chalcones was optimized using the DFT PBE0 functional with the basis set 6-311++G**. DFT calculations has been performed for an ethanol solution (using TD-PBE0/6-311++G**) level to understand electronic transitions on terms of energies and oscillator strengths to study the substituent effect on the electronic transitions of the chalcone derivatives. To consider the solvation effect of ethanol on the absorptions, the integral equation formalism variant of the polarizable continuum model (IEFPCM) was used. The calculated energies were in good agreement with experiment results. The molecular modelling technique was followed to monitor the effect of substitutions on the HOMO/LUMO energy and total dipole moment. Transitions between natural transition orbitals are also described as part of this study.

Keywords: Chalcones; Spectroscopy; Time-dependent density-functional theory; UV–Vis.