Cyanostilbene-Naphthalimide: First fluorescent probe for pesticide pyraclostrobin with high "turn-on" fluorescence...

Pyraclostrobin is an important fungicide, but its excessive residue pose a significant hazard to the environment and human health. The current detecting methods for pyraclostrobin are characterized by a lack of simplicity and the inability of real-time and on-site testing. This work provides the first fluorescence probe for simple, rapid, real-time and on-site examination for pyraclostrobin based on a cyanostilbene-naphthalimide. Upon binding with pyraclostrobin, the probe exhibits a significant fluorescence enhancement (approximately 15-fold) and an obvious fluorescence color shift from orange-red to bright yellow. The high sensing selectivity and interference resistance on detecting pyraclostrobin were observed among 36 competitive molecules and ions, with a response time of 30 s and a low limitation of detection 34.3 nM. A 1:1 binding mechanism was confirmed by fluorescence Job's plot, ¹H NMR, MS, FT-IR, DLS analysis and fluorescence lifetime. The disruption of PET effect, the formation of hydrogen bonds, π-π stacking and hydrophobic interaction contributed to the fluorescence enhancement on binding pyraclostrobin. The qualitative detection capability for pyraclostrobin was validated using test papers and real samples (crop seedlings, soil and river water). A portable smartphone detection platform was developed by combining the fluorescent probe and agarose hydrogel (or flexible filter paper). These application experiments suggested the outstanding capability of novel probe for simple, rapid, real-time and on-site detection of pyraclostrobin, offering a novel approach to pesticide residue analysis.