Diastereoselective Formation of Chiral Tris-Cyclometalated Iridium (III) Complexes: Characterization and Photophysical Properties

Chiral, facial tris-cyclometalated Ir(III) complexes, fac-Δ-Ir(pppy)3, fac-Λ-Ir(pppy)3, fac-Λ-IrL (where
pppy is (8R,10R)-2-(2‘-phenyl)-4,5-pinenopyridine and L is a tripodal ligand comprising three pppy moieties
connected through a mesityl spacer) have been synthesized and characterized. In IrL, NMR and CD studies
indicate that only one diastereomer is formed, with the Λ configuration at the metal center, whereas
enantiopure pppy yields the fac-Λ- and the fac-Δ-stereoisomer in a ratio 2:3. fac-Λ-IrL was structurally
characterized using X-ray crystallography. The luminescence properties including CPL, of the three
complexes and their sensitivity to dioxygen were examined.