Charge transfer interaction of organic p-acceptors with the anti-hyperuricemic drug allopurinol: Insights from IR, Raman, ¹H NMR and ¹³C NMR spectroscopies

Abstract

The topic of charge-transfer (CT) complexation of vital drugs has attracted considerable attention in recent years owing to their significant physical and chemical properties. In this study, CT complexes derived from the reaction of the anti-hyperuricemic drug allopurinol (Allop) with organic p-acceptors [(picric acid (PA), dichlorodicyanobenzoquinone (DDQ) and chloranil (CHL)] were prepared, isolated and characterized by a range of physicochemical methods, such as IR, Raman, 1 H NMR and 13 C NMR spectroscopy. The stoichiometry of the complexes was verified by elemental analysis. The results show that all complexes that were formed were based on a 1:1 stoichiometric ratio. This study suggests that the complexation of Allop with either the DDQ or CHL acceptor leads to a direct p®p* transition, whereas the molecules of Allop and PA are linked by intermolecular hydrogen-bonding interactions.

Charge-transfer chemistry of azithromycin, the antibiotic used worldwide to treat the coronavirus disease (COVID-19). Part II: Complexation with several π-acceptors (PA, CLA, CHL)

“…The CLA molecule has two chloro groups and two carbonyl groups, whereas the CHL molecule has four chloro groups and two carbonyl groups. These groups act as electron-withdrawing systems that decrease the electron density of the aromatic rings of CLA and CHL, thereby rendering them robust electron-accepting systems [ 35 , 149 , [164] , [165] , [166] , [167] , [168] ]. The purpose of this work was to investigate the CT interaction of AZM with three π-acceptors (PA, CLA, and CHL) in MeOH solvent.…”