A novel rhodamine-based colorimetric and fluorometric probe for simultaneous detection of multi-metal ions.

Effective and simultaneous detection of multi-metal ions has been achieved by a colorimetric and fluorometric probe (REHBA) synthesized from rhodamine hydrazide and polyhydroxyl aromatic aldehyde. REHBA can serve as a colorimetric detector for Cu2+ and Co2+, and a fluorometric probe for Pb2+. The colorless solution of REHBA changes to pink for Cu2+/Co2+ and shows a remarkable fluorescence for Pb2+. The further differentiation of Cu2+ and Co2+ depends on whether the colorimetric response of REHBA is reversible upon addition of ethylene diamine tetraacetic acid. The response is reversible for Cu2+, while it is not for Co2+. The spirolactam ring-opening in REHBA and the formation of REHBA-metal complexes with binding stoichiometric ratio of 1:1 are responsible for the UV-visible and fluorescence behaviors. REHBA shows excellent selectivity, anti-interference and good sensitivity. The limit of detection of Cu2+, Co2+ and Pb2+ is 0.11 μM, 0.88 μM and 0.73 μM, respectively. In addition, REHBA has been applied to recognize Pb2+ in living cells by fluorescence image and Cu2+, Co2+ and Pb2+ in real water samples, indicating that REHBA is a potential candidate for multi-metal-ions detection.