Studies On The Xanthone-crown Ether And Their Rare-earth Complexes

Rare-earth coordination polymers have drawn much attention in recent years, mainly due to their luminescent properties and novel coordinational structures when different metal ions were coordinated to novel ligands.1. In this dissertation, two kinds of new xanthone-crown ether ligands and their rare-earth complexes with Pr3+,Eu3+,Gd3+,Tb3+ have been synthesized and characterized by elemental analysis and IR spectra. Crystal structures of three complexes were determined by X-ray diffraction analysis. The luminescent properties of the complexes have also been investigated.Ligand L1:3-ethoxy-1,8-(3,6,9-Trioxaundecane-1,11-diylioxy)xanthoneLigand L2:3-benzyloxy-1,8-(3,6,9-Trioxaundecane-1,11-diylioxy)xanthone2. Crystal structures of (Gd-L1)CH3CN,(Tb-L1)CH3CN,(Pr-L2)DMF show that the ions are located on one side of the macrocycle and the carbonyl oxygen coordinated to the ions is bent out of the xanthone plane. Every ion is eight coordinated by one nitrogen of CH3CN at axial positions, three oxygens from three water molecules and four ligand oxygens in CH3CN and the geometry around ions is a distorted two-capped trigonal prism, but it is different in DMF. The general formulas are: [RE-L(CH3CN)(H2O)3]·(ClO4)3 and [RE·L(DMF)2(H2O)(ClO4)]·(ClO4)23. The luminescent properties of the complexes:Photoluminescence studies of europium and terbium complexes show that the terbium perchlorate complexes with L1 and L2 in CH3CN display higher intense emission while the other do not. The energy levels of the triplet state of the ligands were determined and the results indicate that the triplet states of the ligands match better to Tb3+ than Eu3+; The terbium complexe with L2 in CH3CN displays higher intense emission than with L1; The luminescent properties were influenced by the solvent duo to the "solvent effect"...