Bimetallic cyclometalated iridium complexes bridged by a BODIPY linker

Presented here is a new class of supramolecular cyclometalated Ir(III) complexes. The 2 : 1 assemblies include two phosphorescent cyclometalated Ir(III) centers spanned by a BODIPY bridge with pyridine substituents at the beta-pyrrole positions. The three complexes, which vary with respect to the cyclometalating ligand on iridium, are prepared via a simple one-pot procedure, with the target complexes isolated in 31-75% yield. The photophysics of these new compounds are described in detail. All complexes are strongly photoluminescent, with fluorescence from BODIPY being the dominant emission pathway. One member of the series has a near-unity photoluminescence quantum yield, significantly enhanced relative to the free BODIPY. The cyclometalating ligand on iridium controls the energy of the Ir-centered triplet excited state, but in all cases energy transfer from the Ir centers to the BODIPY quenches almost all phosphorescence. This work outlines a new, simple synthetic method for accessing supramolecular complexes.