Supramolecular hybrid of 4-aminopyridinium Perchlorate: Synthesis, molecular structure characterization, vibrational spectroscopy, thermal analysis, and optical property evaluation

A hybrid material, 4-aminopyridinium perchlorate salt [C₅H₆N₂][C₅H₇N₂] ClO_4, was synthesized at room temperature by slow evaporation and characterized by single-crystal X-ray, spectroscopic techniques (FT-IR, Raman, and UV–Visible), thermal studies (TGA and DSC). The crystallographic data obtained from single crystal X-ray analysis showed that the compound adopts the monoclinic system, space group P2₁/n, with the following parameters a = 10.8317(8) Å, b = 9.0529(5) Å, c = 13.7032(9) Å, β = 99.243(3) °, Z = 4 and V = 1326.27(15) ų. The stability of the supramolecular structure was ensured by hydrogen bonding contacts with N-H…O lengths ranging between 2.749 and 2.940 Å. According to the results of Hirshfeld analysis, O…H interactions constitute the main intermolecular interaction contacts (46 %). The thermal decomposition of the precursors, studied by TGA and DSC analysis, indicates that the compound exhibits thermal stability up to 130 °C, beyond which it degrades. Infrared and Raman spectra were recorded at room temperature, confirming the existence of vibrational modes corresponding to organic and inorganic groups. Additionally, the optical properties of the synthesized compound exhibit UV–Visible absorption and interesting photoluminescence properties. The related HOMO-LUMO orbital energies were also highlighted using TDDFT calculations the B3LYP/6-31G (d,p) level of theory.