Rhodamine - Cyclohexane diamine based turn-on fluorescence chemosensor for Cr3+: Photophysical & confocal cell imaging studies

A new rhodamine based fluorescent turn on sensor L has been reported as a highly selective and sensitive chemosensor for the Cr3+ ion in a CH3CN-H2O solution. In presence of Cr3+ ion, the strong fluorescence enhancement is attributed due to the interaction of Cr3+ with L, leading to opening of the spirolactam ring of rhodamine B to the amide form. The Cr3+ sensing mechanism is also supported by the Job's plot, ESI-MS,H-1 NMR titration experiments. Importantly, this probe shows high selectivity over other biologically relevant metal ions. Also, anions do not show any effect. In addition, the detection limit is found to be up to 7.5 nM which is acceptable within the EPA (US) limit. The probe is also able to function within a broad biological pH range of 4-8. Furthermore, the probe L shows cellular penetrability for its potential use in confocal cell imaging studies. (C) 2017 Published by Elsevier B.V.