Aggregation induced phosphorescent N-oxyde-2,2'-bipyridine bismuth complexes and polymorphism-dependent emission.

ABSTRACT

Unprecedented bismuth complexes, based on the rarely used ditopic ligand N-oxide-2,2'-bipyridine (bp2mo), crystallizing as three polymorphs, α- (), ß- () and γ-[BiBr3(bp2mo)2] (), exhibit phosphorescence with a quantum yield up to 17% for the crystal phase (), while the complex displays a weak fluorescence in solution. A study of the luminescence properties combined with DFT/TDDFT calculations reveals that the lighting phenomenon originated by aggregation induced phosphorescence correlated with the weak intermolecular interactions present in the different crystal phases.