Insights into the electrochemiluminescence process of a hydrogen bonding iridium(III) complex

Abstract

• An Ir III complex ( 1 ) and pyrimido-[4,5-c]isoquinolin-3-amine ( 3 )complex 1•3 based on the hydrogen-bonding interaction was investigated. • It was discovered that the complex 1•3 displayed a new reduction upon the mixture of 1 and 3 . • The hydrogen-bonding complex 1•3 demonstrated an ECL enhancement. • Our report provides insights into the ECL processes of this hydrogen-bonding complex. Hydrogen-bonding has been reported as a smart strategy in electrochemiluminescence (ECL) mechanism studies and sensing applications. However, the insights into the hydrogen-bonding effect on ECL behavior have never been clearly demonstrated. This work reports ECL of complex 1•3 based on the hydrogen-bonding interaction between an Ir III complex ( 1 ) and pyrimido-[4,5-c]isoquinolin-3-amine ( 3 ). In their cyclic voltammograms (CVs), both complex 1 and compound 3 did not show any reductions; however, the hydrogen-bonding complex 1•3 displayed a new reduction upon the mixture of 1 and 3 , which could be significantly weakened by the addition of DMF. In a co-reactant ECL pathway with BPO, exciplex [PhCO 2 •1] and excimer [3•3] were produced, which were demonstrated by PL and ECL spectroscopies. Furthermore, benzoate radical PhCO 2 could also react with the hydrogen-bonding complex 1•3 to form [PhCO 2 •1•3] and generate the same ECL emission as [PhCO 2 -1] . Our report provides insights into the ECL processes of this hydrogen-bonding complex.