5,5′-Bis(trifluoromethyl)-2,2′-bipyridine (5,5′-dCF3bpy), CAS number 142946-80-3, is a bipyridyl ligand with two electron withdrawing trifluoromethyl groups at 5,5'-positions on the conjugated bipyridyl rings. It is normally used as a chelating ligand for the preparation of the well-established [Ir(dFCF3ppy)2 (5,5′-dCF3bpy)]PF6 and other Ir(III) photocatalysts. [Ir(dFCF3ppy)2-(5,5′-dCF3bpy)]PF6 is a cyclometalated iridium(III) complex that are widely used in visible-light mediated photocatalytic organic transformations including the alkylation of remote C-H bonds and alkene aminoarylation.
Yellow light emitting cyclometalated iridium(III) complexes coordinated with ligand 5,5′-bis(trifluoromethyl)-2,2′-bipyridine, [Ir(Hppy)2(dCF3bpy)]PF6 and [Ir(HF2ppy)2(dCF3bpy)]PF6, show relative long lifetimes at room temperature owing to the phosphorescence derived from the mixed metal-ligand-to-ligand charge transfer (MLLCT) excited states. The system engaging the photosensitizers, K2PtCl4, and triethylamine showed highly efficient H2 evolution activities. The turnover numbers (TONs) of H2 evolution based on [Ir(Hppy)2(dCF3bpy)]PF6 and [Ir(HF2ppy)2(dCF3bpy)]PF6 at 96 h of irradiation were reached at 758 and 832 TONs, respectively.