Thiazolyl-derived organic motif as Chemosensor: Synthesis, structure elucidation and turn ON/OFF luminescent sensing

•Synthesis and Crystal structure of the probe LR.•Benzothiazolyl-based chemosensor act as ON/OFF luminescent sensor.•Luminescent chemosensor for Fe2+/ Fe3+ and Al3+ ion.•Competitive study. A rationally designed dual chemosensor ‘LR’ selective for Fe2+/Fe3+ and ‘Al3+ cation has been synthesized and characterized using various spectroscopic techniques viz, FT-IR, 1H NMR, 13C NMR, and elemental analysis. Moreover, the receptor ‘LR’ structure was elucidated by single X-ray crystallography. The receptor ‘LR’ was found to have monoclinic geometry with P 21/n space group. The receptor ‘LR’ exhibited selective ‘Turn-OFF’ fluorescence for Fe2+/Fe3+ ions and ‘Turn-ON’ for Al3+ cation in acetonitrile/methanol solution. To quantify, the limit of detection (LOD) was calculated to be 5.42 µM (Fe3+), 7.18 µM (Fe2+) and 8.30 µM (Al3+). Beside this, competitive titration was performed to check the selectivity and specificity of the cations in the presence of other tested cations.