Luminescent On-Off Probe based -Calixarene Linked through Triazole with Ruthenium (II) Polypyridine Complexes to Sense Copper (II) and Sulfide ions
Bis-Ruthenium(II) polypyridyl complex was connected with p-tert-butyl calixarene platform (Ru2L) through 1,2,3-triazole and used as a luminescent probe to detect selected ions. Ru2L acted as a highly sensitive and selective turn off sensor towards Cu2+ ion in CH3CN/10mM HEPES buffer (pH = 7.4) (8/2, v/v) medium. The detection limit of Cu2+ was found to be 4.11 M. The Cu2+ ion binding with Ru2L showed paramagnetic signal in EPR analysis. The ensemble (Ru2L-Cu2+) was investigated with a variety of anions, only sulfide anion enhanced the emission intensity in the presence of other anions. The ensemble works as a turn-on sensor towards S2- via metal ion displacement method to form stable CuS. The detection limit of S2- was estimated from the emission intensity is to be 0.35 M, which is an excellent result from supramolecular platform based sensors in an aqueous medium. The Ru2L also showed low cytotoxicity against Human lung cancer cell lines A549 and hence can be used in cell imaging.