Aggregation-induced phosphorescence of iridium(III) complexes with 2,2'-bipyridine-acylhydrazone and their highly selective recognition to Cu2+.

Two cationic cyclometallated iridium(III) complexes with 2,2'-bipyridine-acylhydrazone were synthesized and characterized by spectroscopic and photophysical measurements. They exhibit remarkable aggregation-induced phosphorescent emission (AIPE) phenomenon which is caused by the restriction of rapid isomerization of the C=N bond in the acylhydrazone moiety and are supported by TD-DFT studies. They also act as a significant 'off-on' luminescent switch for Cu(2+) which works as both catalyzer and oxidant in the sensing process, resulting in hydrolysis and cyclization products which are highly emissive. The sensing properties of iridium(III) complexes are also investigated by ESI-MS spectrometry and (1)H NMR spectroscopy.