A new “off–on” fluorescent probe for Pd2+ in aqueous solution and live-cell based on spirolactam ring-opening reaction

Based on spirolactam ring-opening reaction, a chromogenic and “off–on” fluorescent sensor for determination of palladium (II) was developed in this paper. The novel sensor was easily synthesized from rhodamine B hydrazide and diacetyl monoxime named RBM. The structure of the sensor has been characterized by ESI-MS and NMR. EDTA-adding experiment indicated that the binding of chemosensor RBM and Pd 2+ was chemically reversible. The fluorescence intensity and absorbance of the sensor showed a good linearity with the concentration of Pd 2+ in the range of 0–15   μM and 0–17   μM, respectively, with detection limits of 0.015   μM and 0.200   μM. Moreover, it has been successfully applied to detect Pd 2+ in palladium-containing catalyst, natural water samples and imaging of Pd 2+ in living cells with satisfying results. The study indicated that this novel sensor could be an attractive approach to detect Pd 2+ in environmental systems and biological systems.