Construction of a coumarin based fluorescent sensing platform for palladium and hydrazine detection

Abstract

Designing high performance signal turn on or ratiometric fluorescent probes for detecting hazardous substances is of great importance and challenging. In this paper, two coumarin-based fluorescent probes C1 and C2 with allyl carbonate and propargyl as their respective fluorescence masking groups were designed and synthesized for detecting both palladium and hydrazine. Probe C1 showed highly selective and sensitive fluorescence turn on response towards Pd0 over all other tested metal ions including Pd2+. Whereas a large ratiometric fluorescence response towards Pd0 was observed for probe C2. The detection limits for Pd0 were determined to be 33nM and 14nM for C1 and C2, respectively. Taking advantages of the high Pd0 selectivity of C1 and the metal ion reducing ability of hydrazine, we further successfully developed a new strategy for hydrazine detection, which is based on the reduction of Pd2+ to Pd0 by hydrazine and subsequent Pd0-induced removal of the allyl carbonate fluorescence masking group in C1. The C1-Pd2+ sensing system was determined to be selective for hydrazine detection over other tested amines with a detection limit calculated to be 37nM (∼1.2ppb).