Charge transfer complex based real-time colorimetric chemosensor for rapid recognition of dinitrobenzene and discriminative detection of Fe2+ ions in aqueous media and human hemoglobin

A cost-effective and easy to prepare colorimetric aqueous medium dual chemosensor (S1) as a charge transfer complex (CTC) in the form of precipitate was synthesized by one step procedure. Si showed a highly selective fluorescence quenching response towards 1,3-dinitrobenzene over other nitro explosives with a low detection limit of 0.084 ppb and binding constant of 8.51 x 10(2) M-1. S1 also showed selective and discriminative detection between Fe2+ and Fe3+ state over other metal ions, which can be noticed in color difference among Fe2+ and Fe3+ by the naked eye. This discriminative detection of two states Fe ion was also found in human deoxyhemoglobin (HHb) and oxyhemoglobin (HbO(2)) with the binding constant of 132.53 M 4 and 26.46 M(-1)respectively. Molecular docking between S1 and hemoglobin provides free energy of binding values of -275 kcal mol(-1) (HHb) and -253 kcal mol(-1) (HbO(2)), represents that S1 binds with HHb more efficiently than HbO(2). The sensing material S1 [(PYRH) + (DNBA)(-)] was characterized by SC-X-ray study, FTIR, H-1 NMR, TG/DTA and Hirshfeld surface analysis. UV-vis spectrophotometry reveals that formation of S1 dependent on the solvent polarity and K-CT and epsilon(CT) with other physical parameters like E-CT, I-D, R-N, Delta(G), f and mu(EN) were also calculated using spectrophotometric data. 1:1 stoichiometry of S1 was depicted by the straight-line method and the Benesi-Hildebrand equation. DFT studies provide comparable theoretical data and the HOMO-LUMO energy band gap Delta E = 3.515 eV. The N+-H-O(-)bonding among reactants was found to have an important role in Fe2+ interaction with S1, proving this approach of CTC synthesis as a chemosensor to be novel.