X-ray diffraction, spectroscopic characterization and quantum chemical calculations by DFT and HF of novel 2-hydroxy-12-(4-hydroxyphenyl)-9,9-dimethyl-9,10-dihydro-8H-benzo[a]xanthen-11(12H)-one

In this paper, the title compound, 2-hydroxy-12-(4-hydroxyphenyl)-9,9-dimethyl-9,10-dihydro-8H-benzo[a]xanthen-11(12H)-one (2HBX), has been characterized by using MS, FTIR, 1H and 13C NMR spectroscopic, and X-ray crystallographic techniques. X-ray studies revealed the presence of intermolecular hydrogen bonding and π-π stacking interactions. Quantum chemical calculations have also been performed on the title compound to calculate the molecular geometry and vibrational frequencies in the ground state using density functional theory (B3LYP) and Hartree–Fock (HF) methods with the 6-311G(d,p) basis set. The calculated results show that the optimized geometry parameters can well reproduce the crystal structure, and the theoretical vibrational frequency values show good agreement with experimental values. Application of scaling factors for FTIR frequency predictions showed good agreement with experimental values. In addition, Mulliken atomic charges of the title compound were calculated and discussed. 1H NMR analysis also shows good agreement with experimental observations. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. TDDFT calculations were used to compare the experimental and theoretical absorption spectra. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. In addition, the molecular electrostatic potential (MEP) analysis of the title compound was investigated using theoretical calculations.