Two-photon absorption properties of simple neutral Ir(III) complexes.

A series of neutral Ir(2-phenylpyridine) 3 derivatives substituted on the para -position of the pyridyl ligands with a π-conjugated substituent possessing different donor abilities has been prepared. Their two-photon absorption properties have been determined using the Z-scan technique. Such simple iridium(III) neutral complexes, which are easy to synthesize, show good two-photon absorption activity, with relevant TPA cross sections (the best is 750 GM), giving rise to multifunctional chromophores, since they present also high second-order NLO properties.