A dual functional probe for “turn-on” fluorescence response of Pb2+ and colorimetric detection of Cu2+ based on a rhodamine derivative in aqueous media

Abstract

A dual functional probe L based on rhodamine was devised and synthesized. Probe L can sense Pb²⁺ and Cu²⁺ in aqueous solution through two approaches: a significant fluorescence enhancement caused by Pb²⁺ and a visible color change from colorless to orchid induced by Cu²⁺. Competitive experiments showed that probe L had high fluorescence sensitivity for Pb²⁺ and excellent colorimetric selectivity for Cu²⁺ over many environmentally relevant ions. The mechanisms of L for sensing Pb²⁺ and Cu²⁺ have been well demonstrated by ESI-MS, ¹H NMR titration, IR, the crystal structure of L-Pb²⁺ and density functional theory calculation of L-Cu²⁺. In addition, fluorescence image detection of Pb²⁺ in living cells displayed an enhanced fluorescence effect.