Exploring Interaction Dynamics of Designed Organic Charge Transfer Complex of 6-Aminoindole and Chloranilic Acid: Spectrophotometric, Characterization, Computational, Antimicrobial, and DNA Binding Properties

Abstract

The chemistry of a new charge and proton transfer hydrogen bonded complex (PT CT) between the donor 6-Aminoindole (6 AMI) and the π-acceptor Chloranilic acid (CLA) has been explored in acetonitrile (ACN), methanol (MeOH), and 50% acetonitrile + 50% methanol (ACN-MeOH) at 25 °C by using electronic absorption spectroscopy. By exploiting Job's and the photometric titration methods, the molar proportion of the PT CT complex was confirmed as 1:1. The modified Benesi-Hildebrand principle was used to evaluate the association constant (KCT) and molar absorptivity (ƐCT) of the PT CT complex, and these values indicate that the produced PT CT complex is more stable. In three different solvents, the effect of solvent polarity on charge transfer spectra was also observed. Different spectroscopic physical parameters were assessed in different polar solvents, including energy (ECT), ionization potential (ID), resonance energy (RN), oscillator strength (f), dissociation energy (W), standard gibbs free energy (ΔGo), transition dipole movement (μEN), and these were also within the accepted values, confirming the stability of the formed PT CT complex. The produced solid PT CT complex was analyzed by using FT-IR, NMR, TGA-DTA, and SEM-EDX spectra. Powder XRD analysis was used to determine the PT CT complex nature and crystalline size. The biological activity of the current PT CT complex has been screened in antimicrobial and DNA binding studies. The synthesized PT CT complex was shown to have excellent antimicrobial activity and DNA binding affinity. Therefore, in the future, it may be used as a pharmaceutical drug for bacterial and fungal infections. The computational studies were carried out by using DFT analysis, and the functions were used to B3LYP and CAM B3LYP in the gas phase, with the basis set being 6-31G + (d, p). The bond lengths, bond angles, Mulliken atomic charges, MEP maps, reactivity parameters, and FMO surfaces were also calculated. The computational analysis is additionally supported by the experimental studies of the PT CT complex.