A “turn on” fluorescent probe based on Tb(III) complex for the detection of organophosphorus pesticides

Abstract

The abuse of organophosphate pesticides and chemical-warfare agents has made severe effects on human and animal health. Consequently, it is vital to develop sensitive and selective strategies for the detection of organophosphates. In this work, the Tb(III) complex— TbL 3+ , consisting of a 1,4,7-triazacyclononane derivative as ligand was synthesized. As TbL 3+ contains no aromatic groups (function as an antenna), its intrinsic luminescence is thus minimized. The coordination of cyanophos to TbL 3+ could largely sensitize its luminescence ( I / I 0=55) because the energy of the triplet state of benzene is slightly higher in energy than the 5D4 of Tb(III). The detection limit for cyanophos was determined as 59 nmol/L. High resolution mass spectrum measurements, luminescence titration experiment and luminescence lifetime measurements reveal that TbL 3+ is bound with two cyanophos molecules and one methanol molecule. However, other organophosphates such as profenofos, chlopyrifos, dimethoate, diazinon, phoxim, fenthion, methyl parathion and dichlorvos almost did not induce any changes on luminescence intensity under the same conditions. By this work, we prepared a new luminescence probe for cyanophos with good selectivity and sensitivity.