Monomer Emission and Aggregate Emission of an Imidazolium Macrocycle Based on Bridged Tetraphenylethylene and Their Quenching by C60

A novel imidazolium macrocycle based on bridged tetraphenylethylene (TPE) was synthesized. Because it bears the bridged TPE units, this macrocycle not only displays an aggregation-induced emission (AIE) effect but also exhibits monomer emission, which is very rare in ME compounds. With aggregation of the macro cycle, the aggregate emission increases while the monomer emission decreases. It was found that this imidazolium macrocycle can form a stable 2:1 complex with C-60, which gives rise to quenching of both the aggregate emission and the monomer emission. Unexpectedly, the aggregate emission exhibited a higher quenching efficiency than the monomer emission, probably because one adsorbed C-60 molecule could affect more macrocycle molecules in the aggregate.