Highly luminescent, neutral, nine-coordinate lanthanide(III) complexes

Using a simple ligand design, we have prepared neutral, nine-coordinate lanthanide complexes that exclude water from the inner coordination sphere, thus leading to high emission quantum yields and long excited-state lifetimes. The complexes form in high synthetic yields (49-87 %) by simply mixing the ligand and the lanthanide. Visible luminescence from Eu-III (phi = 60 %, tau = 2.2 ms) and Tb-III (phi = 7 %, tau = 0.2 ms) and near-infrared luminescence from Yb-III. (0 = 0.7 %), Nd-III. and Er-III were observed in acetonitrile and CH2Cl2 at room temperature. In addition, the Gd-III complex was prepared to gain information about the triplet state of the ligand. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).