Synthesis, Antibacterial, Antifungal and DFT Studies on Structural, Electronic and Chemical Reactivity of (E)-7-((1H-Indol-3-yl)methylene)-1,2,6,7-tetrahydro-8H-indeno[5,4-b]furan-8-one

The present study deals with the theoretical investigation of structural, molecular, electronic, and chemical reactivity details of (E)-7-((1H-indol-3-yl)methylene)-1,2,6,7-tetrahydro-8H-indeno[5,4-b]furan-8-one (ITHF). The ITHF molecule is characterized by proton nuclear magnetic resonance (1H NMR) and carbon nuclear magnetic resonance (13C NMR) spectral techniques. The Becke-3-Lee-Yang-Parr functional (B3LYP) level of theory at the 6-311G(d,p) basis set was used for the density functional theory (DFT) investigation. Bond lengths were predicted from the optimized molecular structure, and the physical and chemical properties of the molecules were inferred as a consequence. The HOMO and LUMO are computed and their energies were established. The calculated HOMO-LUMO energy gap is 3.67 eV indicating inevitable electron transfer phenomenon within the ITHF molecule. Amongst all carbon atoms, the C6 carbon as more positive and C21 as more negative carbon atoms. The molecular electrostatic surface potential revealed that the negative electrostatic potential is present over oxygen atoms and the positive, on the other hand, is located over two aromatic rings' hydrogen atoms in the ITHF molecule.  Importantly, the ITHF compound were evaluated for antibacterial activities against two Gram positive bacteria namely Bacillus subtilis and Staphylococcus aureus and two Gram negative bacteria namely Escherichia coli and Proteus vulgaris and two fungal agents namely Aspergillus niger and Candida albicans. The ITHF compound was found to show good antimicrobial action.