Abstract
The newly synthesized Eu(III) and Yb(III) complexes with the new carbazole-based ligands CPAD(2-) and CPAP(4-) display the characteristic long-lived metal-centered emission upon one- and two-photon excitation. The Eu(III) complexes show the expected narrow emission bands in the red region, with emission lifetimes between 0.382 and 1.464 ms and quantum yields between 2.7% and 35.8%, while the Yb(III) complexes show the expected emission in the NIR region, with emission lifetimes between 0.52 and 37.86 μs and quantum yields between 0.028% and 1.12%. Two-photon absorption cross sections (σ(2PA)) as high as 857 GM were measured for the two ligands. The complexes showed a strong dependence of the one- and two-photon sensitized emission intensity on solvent viscosity in the range of 0.5-200 cP in the visible and NIR region.