Hydrothermal synthesis, crystal structure and fluorescence quenching in oxamidato-bridged tetranuclear NiII 3 LnIII complexes containing macrocyclic ligands (LnZTb, Dy)

Two novel oxamidato-bridged complexes incorporating macrocyclic oxamide of formula [(NiL)3Tb(DMF)2(H2O)](ClO4)32DMF 1, [(NiL)3Dy(DMF)2](ClO4)3DMF CH3OH$H2O 2 (NiL, H2LZ2,3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-dien), have been hydrothermally synthesized and structurally determined. Both crystals crystallize in the triclinic system, space group PK1, for 1 aZ13.959(4) A ° , bZ15.038(5) A ° , cZ19.488(6) A ° , aZ104.653(5)8, bZ92.431(5)8, gZ97.328(5)8; for 2 aZ13.949(4) A ° , bZ15.031(4) A ° , cZ19.487(6) A ° , aZ104.633(5)8, bZ92.439(5)8, gZ97.351(6)8. In both complexes, the central LnIII and external nickel ions are bridged by macrocyclic oxamide groups. Fluorescences of TbIII and DyIII are almost completely quenched in 1 and 2. q 2004 Elsevier B.V. All rights reserved.