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

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 Pd-0 over all other tested metal ions including Pd2+. Whereas a large ratiometric fluorescence response towards Pd-0 was observed for probe C2. The detection limits for Pd-0 were determined to be 33 nM and 14 nM for C1 and C2, respectively. Taking advantages of the high Pd-0 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 Pd-0 by hydrazine and subsequent Pd-0-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 37 nM (similar to 1.2 ppb). (C) 2017 Elsevier B.V. All rights reserved.