MOLECULAR STRUCTURE, NBO AND TD-DFT ANALYSIS OF 4-METHYL-3-FURALDEHYDE BASED ON DFT CALCULATIONS

Abstract

In this study, molecular structure of 4-methyl-3-furaldehyde (4M3F) was analyzed using density functional theory (DFT) with level of B3LYP/6-311G++(d,p). As a result of the scanning of the CCC=O dihedral angle, two conformers (trans and cis) were found at minimum energy and the trans was more stable than the cis at ca. 6.4 kJ mol-1. Time dependent DFT (TD-DFT) calculations have been used to calculate the low-energy excited states energies and oscillator strengths. As a result of calculations, it was found that the highest transition probability and most effective oscillator strength were in the S0→S3 singlet state for both conformers. This excitation energy corresponds to 5.9 eV for the trans conformer, while it is around 5.6 eV for the cis conformer. The change in electron density in bonding-antibonding orbitals and their interactions as well as stabilization energies E(2) and natural atomic charges were calculated by Natural Bond Orbital (NBO) analysis. Electronic properties were analyzed using HOMO and LUMO energies.