Organogels Containing Fe3O4 Nanoparticles as Catalysts for the Synthesis of Pyrano-Fused Benzophenazines

Abstract

A carboxylate-based multifunctional gelator molecule, 4-cyanobenzoyl chloride 3,4-bis(4-cyanobenzamido)benzoate 3,4-diaminobenzoate G9 is synthesized and characterized by various spectroscopic techniques. G9 rapidly forms an organogel in a DMSO-H2O mixture, exhibiting excellent stability in water for an extended time and reversible gelation behavior. The introduction of aqueous solutions of various metal perchlorate salts into a dimethyl sulfoxide solution of G9 led to the formation of a series of metallogels. Rheological studies, including amplitude sweep, frequency sweep, and thixotropic analyses of the gelator molecule G9, revealed robust mechanical properties over time. To explore the mechanism underlying the self-assembly of the gelator G9, FT-IR, powder X-ray diffraction (PXRD), field-emission scanning electron microscopy (FE-SEM), and analysis of both gelator G9 and G9 organogel have been done. Moreover, G9’s xerogel displayed promising catalytic activity in the one-pot synthesis of pyrano-fused benzophenazines. G9Fe3O4 (magnetic xerogel) was strategically synthesized and characterized by using FT-IR, PXRD, FE-SEM, and energy-dispersive X-ray analysis to enhance catalyst separation. A range of pyrano-fused benzophenazine derivatives have been synthesized and characterized through techniques such as 1H NMR, 13C NMR, and FT-IR spectroscopy. Optimization studies were done on solvent, catalyst, and temperature parameters to maximize product yields. This work focuses on understanding G9’s molecular behavior and self-assembly but also highlights its potential applications in catalysis and materials science. This is the first example where a xerogel magnetic nanocomposite is fabricated from a gel system and used for the organo-synthesis of various derivatives of pyrano-fused benzophenazines. Moreover, the catalytically formed product 3-amino-1-(1H-imidazole-2-yl)-1H-benzo[a]pyrano[2,3-c]phenazine-2-carbonitrile [4-imidazole (-IMD)] antibacterial properties were observed against the bacteria Staphylococcus aureus. © 2025 American Chemical Society.