Synthesis, crystal structure, Hirshfeld surface analysis and DFT calculations of a new benzidinium phosphate

A new organic–inorganic benzidinium phosphate, [C₁₂H₁₄N₂]₃(H₂PO₄)₄·HPO₄·H₃PO₄, was synthesized by slow evaporation at room temperature. Its structure was determined by single-crystal X-ray diffraction analysis which does not only reveal that this compound crystallizes in the triclinic system with Pī space group, but also displays a three-dimensional framework stabilized via intermolecular N-H…O and O-H…O hydrogen bonds. These interactions in the crystal network were determined using Hirshfeld Surface analysis. Furthermore, the obtained hybrid was characterized by IR, UV–visible and (¹³C and ³¹P) NMR MAS spectroscopies. Besides, to study the molecular structure and vibrational spectra of the investigated compound in the ground state, theoretical calculations were investigated using density functional theory (DFT). The calculated HOMO–LUMO gap was found to be 1.1924 eV. This small energy gap value implies more interactions and less stability of the compound. As for the optical absorption spectrum inspected by UV–visible, it discloses the appearance of several peaks attributed to the π-π* transitions of the aromatic rings of benzidinium cations and to n-π* and π-π* transitions of the phosphate anions.