Rhodamine-derived highly sensitive and selective colorimetric and off-on optical chemosensors for Cr3+

Two novel fluorescent rhodamine derivatives L1 and L2 have been synthesized and characterized by various analytical techniques. The sensors exhibited an extremely selective and sensitive turn-ON fluorescent and colorimetric response toward Cr3+ in methanol. Upon the addition of Cr3+, the spirolactam ring of probes was opened and a 1:1 metal-ligand complex was formed. The stoichiometry between Cr3+ and probe was further clarified by mass spectra. The chemodosimeter (L1 and L2) exhibited a good binding constant and lowest detection limit towards Cr(III), and also successfully examined the reversibility of complexation of metal to ligand (opened ring to spirolactam ring). (C) 2015 Elsevier B.V. All rights reserved.