Synthesis and Fluorescence Spectra of Europium(III) and Terbium(III) Complexes with a New Bis-Schiff Base Ligand N,N'-Bis(2,4-di-hydroxyacetonephenone)-2,6-diaminopyridine (H_4L)

摘要

Metal complexes of Schiff base ligand have received considerable attention over the past two decades [1].This may be attributed to unusual structural features in the resultant metal complexes and their biological activities.Some of the metal complexes have antitumor properties [1,2],antioxidative activities [3],electronic and photophysical properties [4].Although a lot of research has been reported,the lantha-nide complexes of these ligands are rare.It has been indicated that lanthanide luminescence enhancement can be facilitated in complexes possessing an aromatic ring that has a nitrogen atom,such as 1,10-phenanthroline or bipyridine.The nitrogen lone pair appears to form an efficient energy bridge to the lanthanide ion [5,6],which exhibits a good light conversion process,the antenna effect [7].In order to understand further the coordination and the properties of rare earth complexes with Schiff base ligands,we designed and synthesized a new and doubly functionalized bis-Schiff base ligand (having both selective ability to coordinate lanthanide ions and to enhance their luminescence),N,N'-bis(2,4-dihydroxyacetonephenone)-2,6-diaminopyridine (H_4L),and studied the synthesis,spectroscopic properties of europium and terbium nitrates complexes with the new bis-Schiff base ligand.