Charge-Transfer Complexation and Electron Donor–Acceptor Interaction between 4-Aminoantipyrene as a Donor and 3,5-Dinitrobenzoic Acid as a π-Acceptor: A Combined Experimental and DFT Study

Abstract Due to a hybrid electronic state at the interface of charge-donor and charge-acceptor molecules, the charge-transfer state influences a wide variety of physical processes that occur in organic semiconductor devices. This work describes the formation of a novel charge-transfer complex in solution at room temperature, employing 3,5-dinitrobenzoic acid as the acceptor and 4-aminoantipyrine as the electron donor. The charge-transfer study was carried out by UV–vis and fluorescence spectroscopy. Further, the ground-state electronic transfer was confirmed by cyclic voltammetry. In addition, density functional theory calculations indicate the limits of the highest occupied molecular orbital and the lowest unoccupied molecular orbital to optimize the ground-state geometry and visually verify charge localization along the intricate interface. Strong intermolecular forces, such as hydrogen bonding and π–π interactions, are confirmed by both theoretical and experimental analyses. These forces play a major role in the thermodynamic stability and electron delocalization of the charge-transfer complex. The study highlights the critical importance of noncovalent interactions in stabilizing donor–acceptor systems. The study also highlights that intermolecular interactions and π–π stacking contribute to the formation and stability of donor–acceptor complexes, which have potential applications in molecular electronics.