Correlating Structures to Electrochemiluminescence Efficiencies of Silole Compounds in Coreactant Systems

To develop efficient electrochemiluminescence (ECL) of activated silole chromophores, the relative ECL efficiencies of eight thiophene-containing compounds are firstly studied in a coreactant pathway. The experimental results show that the extended pi-conjugated systems and donor groups of the silole emitters affect both the radical stability and emission efficiencies. It is found that the 1,1-di-tert-butyl-2,5-bis[(2,2 '-bithiophen)-5-yl]-3,4-diphenylsilole (2c) compound with benzoyl peroxide (BPO) as a coreactant exhibits the highest relative ECL efficiencies among the studied systems due to its structural properties. Moreover, the absolute ECL efficiency of the potential pulsing/ECL experiment in the coreactant pathway is 6-fold larger than that in the potentiodynamic experiment due to the short time interval for the radical species to meet and react. This work provides a guidance for structural modification of silole compounds to tune ECL performance.