Exploring the Scope of Photo-Induced Electron Transfer–Chelation-EnhancedFluorescence–Fluorescence Resonance Energy Transfer Processesfor Recognition and Discrimination of Zn2+ Cd2+ Hg2+ and Al3+ in a Ratiometric Manner: Applicationto Sea Fish Analysis

摘要

A rhodamine-based smart probe (>RHES) has been developed for trace-level detection and discrimination of multiple cations, viz. Al³⁺, Zn²⁺, Cd²⁺, and Hg²⁺ in a ratiometric manner involving photo-induced electron transfer–chelation-enhanced fluorescence–fluorescence resonance energy transfer processes. The method being very fast and highly selective allows their bare eye visualization at a physiological pH. The optimized geometry and spectral properties of >RHES and its cation adducts have been analyzed by time-dependent density functional theory calculations. >RHES detects as low as 1.5 × 10^–9 M Al³⁺, 1.2 × 10^–9 M Zn²⁺, 6.7 × 10^–9 M Cd²⁺, and 1.7 × 10^–10 M Hg²⁺, whereas the respective association constants are 1.33 × 10⁵ M^–1, 2.11 × 10⁴ M^–1, 1.35 × 10⁵ M^–1, and 4.09 × 10⁵ M^–1. The other common ions do not interfere. The probe is useful for intracellular imaging of Zn²⁺, Cd²⁺, and Hg²⁺ in squamous epithelial cells. >RHES is useful for the determination of the ions in sea fish and real samples.