A new rhodamine based 'turn-on' $$\hbox {Cu}^{2+}$$ ion selective chemosensor in aqueous system applicable in bioimaging.

A new rhodamine-based Schiff base ( L) has been synthesized and characterized by physicochemical and spectroscopic tools. This organic molecule selectively reacts with $$\hbox {Cu}^{2+}$$ ions with a remarkably significant optical change, which supports the development of a chemosensor for $$\hbox {Cu}^{2+}$$ ions as low as nanomolar level in aqueous medium. On the basis of the experimental work, the ' turn-on' colorimetric/fluorimetric spectroscopic change is due to $$\hbox {Cu}^{2+}$$ ion-assisted hydrolysis followed by spirolactam ring opening of the probe ( L) in 20 mM HEPES buffer [pH 7.4; water/acetonitrile (9:1 v/v)]. The competitive ions do not affect the selectivity and specificity of the probe ( L) in the detection of $$\hbox {Cu}^{2+}$$ ions. The cell imaging study using fluorescence microscope showed that this non-cytotoxic probe is useful to detect the distribution of $$\hbox {Cu}^{2+}$$ ions in AGS cells lines. Graphical abstract: A new turn-on non-cytotoxic rhodamine hydrazone derivative ( L) senses $$\hbox {Cu}^{2+}$$ ion in nano molar region selectively in 20 mM HEPES buffer [pH 7.4; water/acetonitrile (9:1 v/v)] and is an efficient biomarker to detect $$\hbox {Cu}^{2+}$$ ions in living cells. [ABSTRACT FROM AUTHOR]