Tuned-Potential Covalent organic framework Electrochemiluminescence platform for lutetium analysis

Covalent organic frameworks (COFs) have emerged as a novel class of electrochemiluminescence (ECL) materials on account of its highly tunable structure and versatile properties. However, decoding the ECL property and its luminophor structure to improve the luminous performance remains challenging, which hinders its deeper development and wider application. Herein, by condensing triphenylarene aldehydes with varying number of nitrogen atoms with 2,4,6-trimethylbenzene-1,3,5-tricarbonitrile, a series of COFs were prepared to regulate the ECL potential, opening up a new way to precisely improve ECL performance. The electron and spatial changes in the precursor are transferred to the generated COFs skeleton, resulting in a progressively decrease in the reduction potential and a gradual increase intensity in ECL with the precise increase of nitrogen content in the skeleton. Introduction of nitrogen into COFs brings electrocatalysis and planarization of the framework for more efficiently carrier transport. The conclusion is confirmed by optical, electrical tests, as well as density functional theory calculations. As a proof-of-methodology, an ECL method was developed for the selective determination of lutetium ion with a detection limit as low as 1.6 nM (S/N = 3). This work exhibits that the advanced potential-tunable ECL-COFs can be obtained accurately and easily through design structure at the molecular level, which is expected to promote the exploration of the relationship between ECL potential and framework structure, and further apply to environment-related sensing analysis.