Efficacy of 2-nitrobenzylidene-hydrazine-based selective and rapid sensor for Cu2+ ions, histidine, and tyrosine: Spectral and computational study

Abstract

Spectroscopic detection of metal ions and amino acids has gained significant attention owing to the public health domain. In this study, we design and synthesize a rapid UV–visible and fluorescence sensor 1,3-bis(2-methoxy-4-((E)-(((E)-2-nitrobenzylidene)hydrazineylidene)methyl)phenoxy)propane (BMNHMPP) for the selective detection of Cu2+ ions (limit of detection (LOD) ≈ 14–18 × 10−7 M, linear range = 0–130 μM, and the binding constant KCu = 3.30 × 1010 M−2) through turn-off response. The reversibility and snatching of BMNHMPP-Cu2+ complex with EDTA, cysteine (Cys), proline (Pro), and threonine (Thr) in a solvent systemis demonstrated with the restoring of emission intensity. Moreover, the BMNHMPP shows the blue shift in ultraviolet UV–visible and turn-off selective response for the detection of Histidine (His) (LOD ≈ 6–11 × 10−7 M, KHis = 6.53 × 104 M−1 and range of 0–80 μM) and Tyrosine (Tyr) (LOD ≈ 8–13 × 10−7 M, and KTyr = 2.13 × 1010 M−2, range of 0–112 μM). Also, the binding behavior of BMNHMPP with Cu2+, His and Tyr, quantum yields, binding stoichiometry and pH effects are determined using spectroscopic techniques. The mechanistic insights of metal acceptor bonds (BMNHMPP-Cu2+), H-bonding (BMNHMPP-His), H-bonding, and π–π edge to face bondings (BMNHMPP-Tyr-Tyr) were studied. The in-silico study provides a better understanding of the structural behavior and binding mode with the binding and docking energy values. Moreover, the time-dependent density functional theory calculation provides a proper highlight of the frontier molecular orbitals (FMOs).