Benzothiazole-based Schiff base for sensing Ca2+ ions: Synthesis, DFT studies, toxicity evaluation in zebrafish embryo and in silico analysis of MMP-9 inhibition

[Display omitted] •A benzothiazole-based heterocyclic Schiff BTAZ was designed and synthesized.•The probe BTAZ has good selectivity towards Ca2+ ions in presence of other competitive cations with LOD upto 5.1 × 10−6 M.•DFT and TD-DFT studies also supported the binding characteristics between the probe and calcium ion.•Antibacterial, antioxidant, anti-inflammatory, and in vivo toxicity towards zebra fish were assessed.•Molecular docking and ADME experiments showed that BTAZ possesses significant inhibitory potential against MMP-9. A new heterocyclic Schiff base, 2-(2-benzo(d)thiazol-2yl)hydrazono)methyl)phenol (BTAZ) synthesized from 2-hydrazinobenzothaizole and salicyclaldehyde was characterized by spectral, mass and single crystal XRD data and subjected to sense Ca2+ ions in methanol–water mixture (1:1, v/v) using UV–visible absorption and fluorescence emission spectral studies. The probe BTAZ showed specific detection of Ca2+ ions in a solution containing various metal ions with a detection limit as low as 5.1 × 10−6 M via photo-induced electron transfer (PET) pathway. The binding stoichiometry between BTAZ and Ca2+ was determined to be 2:1 by Job’s plot method. The stoichiometry and optical properties of both BTAZ and BTAZ-Ca2+ complex showed good correlation with theoretical results based on DFT and TD-DFT calculations. The pharmacological evaluation of the probe BTAZ against bacterial and fungal stains also demonstrated its notable efficacy to control their growth in vitro along with anti-oxidant capabilities. Further, toxicity assay of the probe BTAZ against zebrafish embryo did demonstrate that it is non-toxic to the test model in vivo. Ability of the probe BTAZ to inhibit matrix metalloproteinase-9 (MMP-9) enzyme was analyzed in detail using in silico experiments.