Iridium(III) complexes in discs for two-photon excitation applications

Ir(ppy)2(H2dcbpy)PF6 (IrHP, ppy = 2-phenylpyridine, H2dcbpy = 4,4′-dicarboxy-2,2′-bipyridine) as the bridging ligand mixed with Zn(NO3)2·6H2O in a ratio of 1:2 (ZnIrHP) in PMMA discs has been synthesized. The two-photon excitation emission of IrHP and ZnIrHP is ascribed to a 3MLCT transition. The two-photon absorption (2PA) cross section and two-photon induced excited state absorption (ESA) cross section of IrHP were deduced as 1.37 × 104 ± 6.87 × 102 GM and 6.63 × 10−22 ± 3.31 × 10−23 cm2, respectively, at 800 nm (1 GM = 10−50 cm4 s/photon). In contrast, the 2PA of ZnIrHP exhibits higher-order nonlinearity and the cross section was 5.68 × 105 ± 2.84 × 104 GM.