Highly sensitive and selective "turn-on" chemodosimeter based on Cu2+- promoted hydrolysis for nanomolar detection of Cu2+ and its application in confocal cell imaging

Based on Cu2+-promoted hydrolysis reaction a rhodamine B derivative L containing a napthalene moiety has been synthesized as a fluorescence turn-on chemodosimetric probe for Cu2+ in EtOH:H2O (3:1, v/v, 10 mM HEPES Buffer, pH approximate to 7). The Ce2+ promoted ring opening and hydrolysis reaction of L leads to formation of the 2:1 ligand metal intermediate complex which rapidly converts to rhodamine-B and bis-Cu2+ complex of 1, 8 diaminonaphthalene. The proposed sensing mechanism has been supported by ESI-MS, H-1 NMR, C-13 NMR, IR analysis and DFT calculations. The dye L exhibits high selectivity toward Cu2+ over other relevant metal ions and anions in the physiological pH range 5-8 with a low detection limit of 60 nM. Application in confocal cell imaging in HeLa cells is also demonstrated in the current work. Additionally, L has been shown to be non-toxic and biocompatible for mammalian cells. (C) 2016 Elsevier B.V. All rights reserved.