Tunable covalent organic framework electrochemiluminescence from non-electroluminescent monomers

It is hard to find new electrochemiluminescence (ECL) luminophores using existing research strategies, especially from ECL non-active monomers. Here, fully conjugated covalent organic frameworks with trithiophene (BTT-COFs) are found to have ultra-high ECL efficiencies (up to 62.2%), even in water and without exogenous co-reactants. Quantum chemistry calculations confirm that the periodic BTT-COFs arrays promote intramolecular electron transfer generating ECL from non-ECL monomers. Modulation of ECL performance is possible by substituting the monomers for those with different electron-withdrawing properties. In addition, the cyano group weaved in the skeleton provides the dense sites for post-functionalization. As a typical use case, a highly selective ECL probe for uranyl ions is reported. The tunable ECL luminophore family possesses a broader development space than the traditional emitters, demonstrates the prospects of ECL-COFs, and affords an idea for detecting various contaminants through the rational design of target ligands.