Exploring interaction dynamics of designed organic cocrystal charge transfer complex of 2-hydroxypyridine and oxalic acid with human serum albumin: Single crystal, spectrophotometric, theoretical and antimicrobial studies

As human serum albumin (HSA) being the most abundant blood protein involved in the role of transport of molecules (drugs), we have designed HSA binding organic charge transfer complex between 2-hydroxypyridine (donor) and oxalic acid (acceptor) showing antimicrobial activities. The type of interactions between HSA and synthesized complex at the molecular level was studied through fluorescence spectroscopy. Binding constant along with the type of quenching mechanism was shown through the Stern Volmer equation. Molecular docking tool also justifies the binding results obtained from fluorescence by providing different interactions, FEB, hydrogen bonding and H-bonding surfaces. Antimicrobial activity was screened against three bacteria - Escheichia coli, Bacteria subtilis and Staphylococus aureus strain and three fungi - Aspergillus Niger, Candida Albicans and Fusarium Oxysporun using disc diffusion method. The characterization of the complex was done through different techniques (FTIR, UV–vis spectroscopy, TGA-DTA). Job's method along with single crystal XRD provides 2:1 stoichiometry and O⋯H-O type of H-bonding between acceptor and donor molecule. Physical parameters (KCT, εCT, ID, ΔG°, μEN, f and RN) were also calculated for the synthesized complex. Theoretical computational data (DFT and Hirshfeld surface) have also been calculated for the complex. © 2020 Elsevier Inc.