Electronic Transitions, Inter- and Intra-Bond Interactions of an Azabicycle Single Crystal using DFT

Abstract

2,4-Diphenyl-3-azabicyclo[3.3.1]nonan-9-one O-benzyloxime (ABN-OBn) was synthesized by modified Mannich condensation, purified by recrystallization and single crystals were grown by slow evaporation from ethanol. The empirical formula of the molecule is C27H28N2O as witnessed by HRMS, elemental analysis and the X-ray diffraction. The crystal belongs to triclinic system (α = 73.640, β = 78.505, γ = 87.078) with P-1 space group. The electronic excited states of ABN-OBn have been calculated using TD-DFT/B3LYP/6-31G(d,p) level of theory, in order to investigate the electronic transitions within the molecule. Frontier molecular orbitals (FMOs) of ABN-OBn have been studied to understand the electronic charge distributions and its band gap (5.0514 eV/245.45 nm). Density of states (DOS), partial density of states (PDOS) and total density of states (TDOS) with respect to functional groups were computed to investigate the electron densities of functional groups in the molecule. Natural bond orbital (NBO) has been performed to explore the intramolecular π-π* interaction of the compound.