Green-to-blue fluorescence sensor on pesticide starane based on bis-tetraphenylimidazole

The widespread use of pesticide starane calls for the simple, rapid and on-site detection to mitigate its negative impacts on human health and the environment. In this work, a diamino naphthalene Schiff-base bridging bis-tetraphenylimidazole (Bis-TPI, red powder, λabs = 360 nm) prepared by Schiff-base condensation is developed as an effective fluorescence sensor on pesticide starane with very low detection limitation. Bis-TPI in DMSO-H2O with 95% of H2O showed weak green fluorescence but strong blue fluorescence when bound to starane. This binding behavior for starane exhibited good sensing selectivity among various ions and pesticides. The detection limitation was as low as 0.015 μM, which is the smallest value of the fluorescence sensor for starane. The 1:1 binding mechanism is clarified as that starane is bound in the opening cavity of Bis-TPI based on hydrogen bond, π-π stacking and hydrophobic action. Bis-TPI in DMSO-H2O with 95% of H2O is successfully employed to detect starane in various samples including test paper, fresh leaves and real water samples, highlighting its potential as a valuable tool for rapid, simple and on-site examination of starane with high selectivity and sensitivity in agriculture and daily life.