Four Salamo-type 3d-4f hetero-bimetallic [ZnIILnIII] complexes: syntheses, crystal structures, and luminescent and magnetic properties

Four hetero-bimetallic [Zn(II)Ln(III)] complexes with the general formula [Zn(L)(OAc)Ln(NO3)(2)] (Ln = Sm, Eu, Tb and Dy) were synthesized by the Salamo-type ligand H2L (6,6'-diethoxy-2,2'-[1,2-ethylenedioxybis-(nitrilomethylidyne)]diphenol) with Zn(OAc)(2)center dot 2H(2)O and Ln(NO3)(3)center dot 6H(2)O (Ln = Sm, Eu, Tb and Dy), respectively. X-ray crystal diffraction analyses revealed that all the Zn(II) atoms were penta-coordinated, adopting distorted square pyramidal geometries, and the Ln(III) atoms were nona-coordinated, forming distorted tricapped trigonal prism geometries. In addition, three-dimensional supramolecular structures were assembled through intermolecular hydrogen-bond interactions. In the [Zn(II)Ln(III)] complexes, only [Zn(L)(OAc)Sm(NO3)(2)] showed obvious orange-red light emission under UV light due to the characteristic f-f transitions of Sm3+ ions, which meant that the ligand H2L could transfer energy from its excited state to the lowest excited state of the Sm3+ ion effectively. A decrease in the chi T-M value illustrated weak antiferromagnetic interaction exciting in the [Zn(L)(OAc) Tb(NO3)(2)] and [Zn(L)(OAc)Dy(NO3)(2)] complexes.