Synthesis, characterization, structural, spectrophotometric and antimicrobial activity of charge transfer complex of p-phenylenediamine with 3,5-dinitrosalicylic acid

The formation of the intermolecular charge transfer or proton transfer complex between donor, p-phenylenediamine (PPD) and acceptor, 3,5-dinitrosalicylic acid (DNS) has been studied in methanol as well as in solid state at room temperature. Based on elemental analysis and FTIR spectrum of the semicrystalline charge transfer (CT) complex along with the Benesi–Hildebrand plots for the reactions, obtained data indicate the formation of 1:1 charge transfer complex [(PPD)+(DNS)−] was proposed. In the CT complex, FTIR and 1H NMR spectroscopic data indicate a proton transfer interaction is associated with hydrogen bonding due to transfer of phenolic proton. The CT complex was screened for its antibacterial and antifungal activity against various bacterial and fungal strains, and shows good antimicrobial activity. The stoichiometry apparent formation constant and molecular extinction coefficient of the formed CT complex, were determined and also other physicals parameters have been estimated. The sharp and well defined Bragg Peaks at specific 2θ angles have been identified from the powder X-ray diffraction. Thermal analysis (TGA–DTA) was also used to confirm the thermal stability of the synthesized solid CT complex.