Rhodamine based turn-on dual mode chemosensor for the selective recognition of nickel ions: practical and theoretical...

This work presents the development of a rhodamine-based colorimetric and turn-on fluorescent chemosensor (P1) designed for selective recognition of Ni²⁺ ions. Chemosensor P1 exhibited remarkable sensitivity and selectivity for Ni²⁺ ions, exhibiting clear colorimetric and fluorescence responses. The binding interactions were meticulously examined using UV-Vis. and fluorescence spectroscopy, demonstrating a 1 : 1 stoichiometric ratio between P1 and Ni²⁺ ions via a Job's plot and Benesi-Hildebrand analysis, while the binding constant and limit of detection were established as 0.8919 × 10⁴ M^-1, and 2.15 nM, respectively. Interference studies demonstrated that competing metal ions had a minimal effect on the selectivity of the sensor. Chemosensor P1 showed practical applicability by fabricating paper strips and solid-state silica gel systems, facilitating the rapid and visible detection of Ni²⁺ ions. Their stability and effectiveness were confirmed under a wide range of pH conditions. A molecular INHIBIT logic gate was created utilizing Ni²⁺ and EDTA as inputs in conjunction with memory devices featuring a "write-read-erase-read" binary logic function, highlighting P1's capabilities in logic-based sensing and data storage. Furthermore, P1 demonstrated reversible binding to Ni²⁺ in the presence of EDTA, enhancing its versatility. Density Functional Theory (DFT) calculations offered valuable insights into the molecular interactions, while the analysis of actual juice samples confirmed the efficacy of P1 for detecting Ni²⁺ in complex matrices, making it an exceptional candidate for advanced environmental and analytical sensing technologies with outstanding selectivity and versatility.