Electrochemiluminescence of Carboxyl-Tetraphenylethylene Derivatives in the Unitary System Originated from Intramolecular Electron Transfer.

The development of effective unitary electrochemiluminescence (ECL) systems holds important significance but is extremely restricted by traditional individual luminophores with low ECL efficiency. Surprisingly, we find that the unitary system of carboxyl-tetraphenylethylene (TPE) derivatives exhibits outstanding ECL performance without a coreactant via carboxyl-triggered intramolecular electron transfer, which provides a brand path for developing unitary ECL systems. Through solvent screening, dimethyl sulfoxide can enhance the electrochemical performance of luminophores and accelerate the deprotonation of carboxyl, thus lighting up the ECL of the unitary system. The special structure design of carboxyl-TPE derivatives is crucial. Comparison of eight carboxyl-TPE derivatives reveals that promoting carboxyl deprotonation is conducive to improving the ECL performance. After regulation of the solvent and structure, carboxyl-TPE derivatives demonstrate higher ECL performance than that of a classical Ru(bpy)32+/Tripropylamine system, with distinct ECL imaging without coreactants at the electrode surface, displaying great potential in ECL imaging analysis. The electrochemiluminescent channel and mechanism based on carboxyl-mediated intramolecular electron transfer has been proposed. This finding abandons the reliance on unstable exogenous coreactants, transforming the ECL process from a "multicomponent combinatorial chemistry" into a highly controllable "single-molecule interfacial chemistry", which is expected to provide a path in developing a new generation of high-effective unitary ECL systems and facilitates more convenient ECL applications.