DFT study of frontier orbitals and NLO properties of a phenanthroline and nitrophenol complex

The hydrogen-bond charge transfer complex (HB-CTC) formed between the donor, 1,10-phenanthroline (Phen), and the π-acceptor, p-nitrophenol (PNP), has been thoroughly investigated through theoretical studies. The molecular structure and the HOMO–LUMO energy gap (ΔEH–L) of this complex have been investigated by the density functional theory. This work has studied the HB-CTC complex through FTIR, 1HNMR, 13CNMR, and electronic absorption spectra. A molecular electrostatic potential surface (MESP) study allowed us to explore key aspects of intermolecular interaction. Moreover, reduced density gradient analysis was conducted to visualize valuable insights into non-covalent interactions within the complex components. Quantum Theory of Atoms in Molecules was used to analyze the interaction between the 1,10-phenanthroline and p-nitrophenol. The findings from this research not only enhance our understanding of HB-CT complexes but also highlight their exciting potential for innovative applications in various fields.