Syntheses, structures and photophysical properties of heterotrinuclear Zn(2)Ln clusters (Ln = Nd, Eu, Tb, Er, Yb)

Heterotrinuclear Zn(2)Ln (Ln = Nd 2, Eu 3, Tb 4, Er 5, Yb 6) clusters [(Znq(2))(2)](mu-CH3COO){Ln(hfac)(2)} (q = 8-hydroxylquinolinate, hfac = hexafluoroacetylacetonate) have been synthesized. The Zn(2)Ln framework is ligated by two q ligands featuring mu-phenoxo and two q ligands featuring mu(3)-phenoxo coordination modes, and one mu-CH3COO- anions. Since the short intramolecular separations of Zn center dot center dot center dot Ln (ca. 3.354-3.373 angstrom) allow energy transfer from Znq(2)-based sensitizers to the Ln(III) centres through two energy transfer pathways, the lanthanide luminescence is indeed lighted up by excitation of the Znq(2)-based chromopores. Photophysical measurements revealed that these Zn(2)Ln complexes exhibit the so-called dual emission originating from both Znq(2)-based luminophores and lanthanide emitters. By virtue of the dual luminescence with complementary colours, the Znq(2)-based cyan emission and Eu-III-centred red luminescence are combined to generate a white-light emission in the Zn2Eu (3) complex.