Isatin‐Triazole‐Functionalized Rhodamine: A Dual Sensor for Cu 2+ and Fe 3+ Ions and Its Application to Cell Imaging

A new isatin‐triazole tethered rhodamine based fluorescent probe R1 (1‐(2’’‐(4’‐(((3’’’,6’’’‐ bis (diethylamino)‐3’’‐oxospiro[isoindoline‐1’’,9’’’‐xanthen]‐2’’‐yl)amino)methyl)‐1 H ‐1’,2’,3’‐triazolyl)ethyl)indoline‐2,3‐dione) has been synthesized using click chemistry approach. Probe R1 exhibits a dual sensor property for Cu 2+ and Fe 3+ ions through turn‐on fluorescence response. A prominent colour change from colourless to pink allows the naked eye identification of aforementioned metal ions. R1 forms a 1:2 complex with Cu 2+ and Fe 3+ ions with binding constants 8.0 × 10 8 and 2.93 × 10 7  M −2 , respectively. The binding mode is scrutinised through various spectroscopic techniques which is further supported by theoretical calculations. The detection limit of R1 for Cu 2+ and Fe 3+ ions is found to be 12.2 nM and 0.33 μM, respectively. Further, R1 has been evaluated for its potential to detect Cu 2+ ions in biological systems using fluorescence cell imaging studies.