Comment on ‘aggregation-induced phosphorescent emission (AIPE) of iridium(iii) complexes’: origin of the enhanced phosphorescence

Abstract

An investigation of the photophysics of Ir(III) complexes with controlled ligand structures and our quantum chemical calculations attest that the most probable explanation for the reported 'aggregation-induced phosphorescent emission', which was originally claimed to be related to an intermolecular excimer, is restricted intramolecular motion.

Aggregation induced phosphorescence of metal complexes: From principles to applications

“…Similar behavior was observed for Ir(III) complexes featuring b-diketonate ligands and the authors interpreted the results as in the case of complexes 7b-c [48]. These reports fostered a debate: restriction of intramolecular rotation around the N-aryl bond was proposed as an alternative explanation [49] since phosphorescence of similar complexes was observed not only in the solid state, but also when the complex was embedded in a polymer matrix at very low concentration. On the other hand, the authors of the first paper reported that even complexes with iminic ligands in which the phenyl ring could not rotate due to covalent bonding exhibited AIP properties, thus rejecting the thesis of restriction of intermolecular motion [50].…”

‘Aggregation induced emission’ active iridium(iii) complexes with applications in mitochondrial staining

“…Park and coworkers. 48 Complex 2 has been used for specic mitochondrial imaging and the MTT cytotoxicity study has been carried out. 2 ) were prepared according to the procedure reported in the literature.…”

Dual emission and multi-stimuli-response in iridium(iii) complexes with aggregation-induced enhanced emission: applications for quantitative CO2 detection

“…A key step in developing new materials based on the AIEE effect is to understand its origin at a fundamental level. The mechanism behind AIEE is, however, still under debate [29][30][31][32] since many types of different systems, ranging from purely organic molecules to organometallic complexes, sometimes containing highly flexible parts, but in other cases quite rigid, have been identified as AIEE active compounds. In order to understand the origin of this photophysical phenomenon and identify the key parameters controlling its efficiency to optimize the implementation of AIEE materials in technological applications, it is necessary to combine experimental investigations with theoretical and computational studies.…”