Preparation, Crystal Structure, Optical Properties, Hirshfeld Surface Analysis and Antibacterial Activity of 4-Nitrobenzyl-4-aminopyridinium Tetrachlorocuprate(II)

In this study, we have synthesized a novel organic–inorganic hybrid crystal 4-nitrobenzyl-4-aminopyridinium tetrachlorocuprate(II) [4NO₂Bz-4NH₂Py]₂[CuCl₄](1). The single-crystal X-ray diffraction analysis revealed that the crystal belongs to the triclinic space group P–1, and consists of four [4NO₂Bz-4NH₂Py]⁺ cations and two [CuCl₄]²⁻ anions. O⋯π, C–H⋯π, π⋯π, N–H⋯Cl, C–H⋯Cl, C–H⋯O, and C–H⋯N weak interactions in the crystals play an important role in facilitating the stacking and stabilization of the crystals. The different types of contribution have been quantified by the calculation of Hirshfeld surface percentage and depicted by fingerprint plots. The bulk phase purity, homogeneity, and morphology of the desired compound were checked using powder XRD, and SEM–EDX analysis. Vibrational, optical, and thermal properties were investigated by FT-IR, UV–Vis spectrum, and TG–DTA measurements of [4NO₂Bz-4NH₂Py]₂[CuCl₄](1), respectively. The low energy gap (2.41 eV) suggested that the crystal was a suitable semiconductor material for optical applications. In addition, the compound presented good bactericidal activity against E. coli and S. aureus.

A novel organic–inorganic hybrid material, 4-nitrobenzyl-4-aminopyridinium tetrachlorocuprate(II), has been synthesised and characterized with a study of its crystal structure, vibrational spectra, weak interaction, Hirshfield surface, thermal stability and antibacterial activity.