DFT calculations on three 2,3-dihydrobenzofuran linked chalcones: Structural, HOMO-LUMO and spectroscopic (UV-Vis and IR) interpretation

Abstract

Three chalcones with a 2,3-dihydrobenzofuran linkage were analyzed by applying the density functional theory (DFT) and B3LYP approach with the 6-311G(d,p) basis set in this report. Spectroscopic and theoretical analyses were used to examine the structures of these three chalcones. The chalcone molecules' HOMO-LUMO energy was determined. Chemical reactivity parameters and molecular electrostatic surface potential (MESP) plots were obtained to gain useful insight into the distribution of charge density. The HOMO-LUMO gap of all three chalcones were calculated and discussed. The (E)-3-(2,3-dihydrobenzofuran-5-yl)-1-phenylprop-2-en-1-one (DBPP) is discussed in detailed for the theoretical and experimental correlation. The captodative phenomenon appears to be the most polar molecule, with a dipole moment of 8.53 Debye. The decreased bandgap indicates that charge transfer occurs within the DBNPP molecule. When the solvent polarity is changed to DCM and DMSO from the gas phase, there is an event of a hyperchromic shift. The C19 carbon atom has the highest negative atomic charge while C21 is the carbon with the largest positive charge. From the MESP plots, we can conclude that the most electropositive region is located over the hydrogen atoms of the five-membered ring, and the electronegative region is located over the oxygen atoms. Time- dependent density functional theory (TD-DFT) using B3LYP functional with 6-311G(d,p) as basis set were used for the electronic absorption study in gas phase, dichloromethane and dimethyl sulfoxide. The UV-Vis absorption peaks and fundamental vibrational wavenumbers were calculated and a good agreement between observed and theoretical results has been achieved.