Chiral-at-Metal BODIPY-Based Iridium(III) Complexes: Synthesis and Luminescence Properties

Abstract

The synthesis of enantiomerically pure Ir(III) complexes with one or two BODIPY moieties has been achieved through the enantioselective C–H insertion from homochiral triazolium salts, containing a sulfoxide functionality in their structures. These homochiral salts were prepared by the sequential Cu-catalyzed alkyne-azide cycloaddition (CuAAC) of an azide and one alkynyl sulfoxide, followed by a Suzuki coupling in the preformed triazole with a BODIPY containing aryl boronic acid, followed by methylation of the N3-triazole nitrogen. The configuration at the metal in these chiral complexes was established by using a combination of CD and X-ray diffraction techniques. The optical properties of these complexes were thoroughly studied using spectroscopic (absorption and fluorescence) and computational (TD-DFT and DFT) methods. The fluorescence of complexes with the BODIPY attached to the sulfoxide moiety (including the two BODIPYs-based complex) was quenched upon introduction of the Ir(III) fragment, most likely due to an a-PET mechanism. On the contrary, the fluorescence of Ir(III) complexes with the BODIPY attached to the triazolium ring remains unquenched.