A Novel Rhodamine Probe Acting as Chemosensor for Selective Recognition of Cu²⁺ and Hg²⁺ Ions: An Experimental and...

Copper and Mercury ions have vital role to play in biological world as their excess or deficiency can cause different type of diseases in human being as well as biological species including plants and animals. Therefore, their detection at trace level becomes very important in term of biological. The current studies embody the fabrication, structural characterization and recognition behavior of a novel rhodamine B hydrazone formed when hydrazide of rhodamine B was condensed with 5-Allyl-3-methoxy salicylaldehyde (RBMA). RBMA was found to be responsive towards the very trace level of Cu²⁺ and Hg²⁺ among other tested cations so far. The sensing procedure is based on the classical opening of the spiroatom ring of rhodamine. The limit of detection (LOD) and binding constant is 5.35 ppm, 2.06 × 10⁴ M^-1 and 5.16 ppm, 1.26 × 10⁴ M^-1 for Cu²⁺ and Hg²⁺ ions respectively. The probable mechanism correlates the specific binding of RBMA with Cu²⁺ and Hg²⁺ ions. The 1:1 stoichiometry of RBMA with Cu²⁺ and Hg²⁺ ions have been supported by HRMS, FT-IR data, Job's plot, and binding constant data. Reversibility is well exhibited by RBMA by the involvement of CO₃^2- ions via demetallation process. The real time application is well demonstrated by the use of paper strip test. The DFT study also carried out which agrees well with the experimental findings. The results displayed the novelty of this current work towards the trace level analysis of the Cu²⁺ and Hg²⁺ of the cations which are play the crucial role in industry.