Novel hexapodal triazole linked to a cyclophosphazene core rhodamine-based chemosensor for selective determination of Hg 2+ ions

The hexapodal Rhodamine B derivative compound 3 containing a cyclotriphosphazene core was synthesized and characterized by spectroscopic techniques such as FT-IR, 1 H, 13 C and 31 P NMR, HR-MS, MALDI MS and microanalysis. Compound 3 is a naked eye selective sensor with colorimetric and fluorescent properties for Hg 2+ ions in the presence of other metal ions such as Na + , K + , Ca 2+ , Ba 2+ , Mg 2+ , Ag + , Mn 2+ , Cu 2+ , Ni 2+ , Co 2+ , Pb 2+ , Cd 2+ , Zn 2+ , Fe 2+ , Fe 3+ , and Cr 3+ . The optical sensor properties of compound 3 were investigated using UV–vis and fluorescence spectroscopy. The lowest detection limit of compound 3 was determined as 3.76 × 10 −9 M (0.75 ppb) for Hg 2+ ions. The stoichiometry of compound 3 -Hg 2+ complex was found to be 1:3 (ligand/metal ion). The reusable test strip was improved by the immobilization of compound 3 into a hydrogel network. The reusability of the sensor and test strip was tested with S 2− ion solutions.