Deciphering the Structural Dynamics and Attributes of Cocrystals Engineered from 2-Amino, 5-Nitrobenzoic Acid with Neutral Coformers: A Synergistic Experimental and Computational Exploration

Abstract

Cocrystallization of heterofunctional ligand, 2-amino-5-nitrobenzoic acid (ANBA), in conjunction with coformers, namely, 2,2′-bipyridine (2,2′-BP), imidazole (IMD), and trans-1,2-bis(4-pyridyl) ethylene (BPE), afforded two novel cocrystals, i.e., [(ANBA)(2,2′-BP)] (compound 1) and [(ANBA)(BPE)] (compound 3) and a salt, i.e., [(ANB^–)(IMD⁺)] (compound 2), where ANB^– = 2-amino-5-nitrobenzoate, and IMD⁺ = Imidazolium ion. The compounds (1–3) were synthesized by the facile hydrothermal method and subjected to comprehensive characterization, employing powder X-ray diffraction (PXRD), single-crystal X-ray diffraction (SCXRD), thermogravimetric analysis (TGA), and various spectroscopic techniques, such as Fourier transform infrared (FTIR), UV–vis, and ¹H NMR spectroscopy. ANBA was chosen to investigate the hydrogen-bonding interactions within cocrystals owing to its diverse hydrogen bond donor and acceptor sites. The interaction of imidazole with ANBA resulted in a salt formation in compound 2 instead of a cocrystal, culminating in the generation of an ANB anion and an imidazolium cation. This study employs a computational technique to explore the nature of hydrogen-bonding and π···π interactions in the molecular systems and compares them with SCXRD data. Electronic excitation, Hirshfeld surface, noncovalent interaction, and topological analyses provided insights into the structure and properties of the molecular compounds.