TD-DFT Calculations, Electronic Structure, Biological Activity, NBO, NLO Analysis and Electronic Absorption Spectra of Some 3-Formylchromone Derivatives

The electronic structure and spectra of 3-formylchromone and some of its derivatives are investigated using TD-DFT/B3LYB/6-311G (d, p) level of theory. The results of calculations show that all the studied compounds 1–6 are planar, as indicated from the dihedral angles. The electronic absorption spectra of the studied compounds are recorded in the UV-Vis region, in both ethanol (as polar solvent) and dioxane (as non-polar solvent). The observed vertical electronic transitions assignments are facilitated via time-dependent density functional theory TD-DFT. The theoretical spectra computed at CAM-B3LYP/6-311G (d, p) in gas phase, ethanol and dioxane nicely reproduce the observed spectra. The natural bond orbital (NBO) analysis were discussed in terms of the extent of delocalization, intermolecular charge transfer and second order perturbation interactions between donor and acceptor MOs. The calculated EHOMO and ELUMO esame level of theory and compared with the proto type Para-Nitro-Aniline (PNA), show promising optical properties. 3D-plots of the molecular electrostatic potential (MEP) for some of the studied compounds are investigated and analyzed showing the distribution of electronic density of orbital's describing the electrophilic and nucleophilic sites of the selected molecules. The biological activity of the studied compounds was tested against gram positive, gram negative and Fungi.