Charge transfer interaction between 2, 3-Diamino-5-bromopyridine and 2, 4-Dinitrophenol: Synthesis, spectroscopic characterization, DNA binding analysis, and density functional studies

Abstract

The e-donor 2, 3-Diamino-5-bromopyridine (5BPY) and the e-acceptor 2, 4-Dinitrophenol (DNP) were both involved in the synthesis of a new charge transfer complex, which was then characterized experimentally as well as theoretically. Several spectroscopic techniques were used to analyze the produced solid compound. 1H NMR, FT-IR, P-XRD and SEM-EDX analyses all confirmed the presence of charge and proton transfers in the resulting complex. Analysis of the complex DNA binding ability was carried out using electron absorption spectroscopy; the CT complex binding mechanism was determined to be intercalative, and the intrinsic binding constant (Kb) value was determined to be 7.2 × 106 M−1. To corroborate the results of the experiments, theoretical calculations were performed using DFT with a basis set of CAM-B3LYP/6-31 G (d, p). In accordance with the experimental findings, we calculated and analyzed the molecular electrostatic potential maps (MEPs), geometrical parameters and Mullikan atomic charges. The presence of an H-bond also affects the stability of the complex, in addition to e-transfer. The experimental findings are in agreement with the DFT calculations.