Fabrication of a dual-fluorescent hybrid material based on post-modification of covalent organic frameworks for the detection of herbicides and the design of a smartphone sensing platform

Abstract

For covalent organic framework (COF)-based sensors, the synthesis of fluorescent active materials is still a challenge. Taking advantage of the stability of COFs and their porous structure, COF-based hybrid materials with dual-fluorescence can be skillfully synthesised by means of post-modification and be designed for ratiometric fluorescence sensing. TpTta has excellent red fluorescence and abundant N, O chelation sites to coordinate with metal ions. In this work, a hybrid material with dual fluorencence centers, Tb(Terpy)@TpTta (Tb@1), has been successfully prepared by post-coordination modification with lanthanide ions. Tb@1 is able to detect herbicides glyphosate (Gly), glufosinate (Glu), as well as their metabolite aminomethylphosphonic acid (AMPA) with high sensitivity, anti-interference ability, and low limit of detection (LOD) (LOD_Gly = 0.033 μM, LOD_Glu = 0.11 μM, and LOD_AMPA = 0.26 μM). Soil sample analysis is also capable of sensitive detection. Additionally, the application of portable film to detect herbicide residues in actual samples appears a potential method. A smartphone sensing platform was developed to identify the presence of AMPA, illustrating the enormous potential of the device for in-situ monitoring. This method offers a useful way to quickly determine whether herbicide residues are present.