Synthesis and crystal structures of mono-helical complexes of zinc(II) andeuropium(III) with 1,2-bis{[3-(2-pyridyl)pyrazol-1-yl]ethoxy} ethane

A new multidentate ligand L, 1,2-bis{[3-(2-pyridyl)pyrazol-1-yl]ethoxy}etha ne, has been synthesized by linking two 3-(pyridin-2-yl)pyrazoles with a 1, 2-bis(ethoxy)ethyl spacer. Coordination Di L with zinc(II) and europium(III ) centres has led to mononuclear complexes of [Zn(L)](ClO4)(2) (1) and [Eu( L)Cl-2](ClO4) (2). X-ray crystal structures of both complexes have shown th at L adopted a helical coordination geometry around both metal centres. The spectroscopic properties of both complexes have also been determined. In 1 , photoluminescence was dominated by ligand centred (1)(pi-pi*) fluorescenc e. In 2, ligand-to-metal energy transfer leading to D-5(0) --> F-7(n) lumin escence at the europium(III) centre was observed.