Electrochemiluminescence of iridium complexes with ammonia in dimethylformamide and its analytical application for ammonia detection

The electrochemiluminescence (ECL) of four iridium complexes ((phenylpyridine)2Ir(acetylaniline), (phenylpyridine)2Ir(N-phenylmethacrylamide), (phenylpyridine)3Ir [Ir(ppy)3] and (phenylquinoline)2Ir(acetylacetone) [(pq)2Ir(acac)]) was studied in the presence of ammonia as the coreactant in dimethylformamide (DMF) solution. The frontier orbital theory was utilized to elucidate their electrochemistry and ECL properties. The (pq)2Ir(acac), exhibiting the highest ECL efficiency with NH3, was chosen to be luminophore and its ECL reaction with ammonia was further explored for the detection of NH3. At the optimized conditions, a good linear relationship between the logarithm of the ECL intensity and the logarithm of the NH3 concentration was obtained in the concentration range from 1.0 × 10−7 to 1.0 × 10−3 M. The detection limit is 4 × 10−8 M (S/N = 3). The method was applied to the detection of NH3 in the atmosphere with recovery of 92.5–101.9%.