A Highly Sensitive and Selective “Off-On” Fluorescent Probe for Cu²⁺ Based on Rhodamine B Hydrazone

Abstract

Ethyl 5-formyl-3,4-dimethyl-pyrrole-2-carboxylate and rhodamine B hydrazide were used to synthesize a rhodamine derivative R1. Notably, the as-synthesized R1 displayed great sensitivity and selectivity, which was utilized to be an off-on fluorescence probe for Cu 2＋ detection in mediums that contained water. Besides, the Cu 2＋ ions limit of detection (LOD) was 0.201 µmol•L-1 , and R1 was able to sense Cu 2＋ by "naked-eye" according to the change in color to pink from colorless. In addition, Cu 2＋ detection was assessed within the actual water samples for testing the probe actual application.