Studies On The Rare Earth Supramolecular Complexes With Amide Type Bridging Podands

Rare earth elements are a group of special inorganic ions with good luminescent,electronic and magnetic properties.So it is important to study their functional complexes.There has been considerable recent interests in the design of organized supra -molecular architectures containing lanthanide metal ions,which can be used as efficient light-converting devices and luminescent probes,in metallo-supramolecular chemistry and biochemistry.Multipodal compounds represent a unique class of complex agents and much effort has been made in the study of multipodal compounds using in electrochemistry,biochemistry,medicine and functional material due to their high selectivity and coordination capability to the metal ions.In order to investigate the effect of multipodal ligands of the different frameworks or terminal groups on the compositions,structures and properties of the rare earth complexes,we have synthesized and characterized seven kinds of bridging podands and eight series of rare earth complexes.The luminescent properties of the complexes in solid state and in solution were also investigated.This dissertation includes following four parts:1.A brief review on the research developments of the structures of the supramolecular complexes and the luminescent rare earth complexes.2.The following bridging podands were synthesized and characterized:1,4-bis {[(2′-m-picolylaminoformyl)phenoxyl]methyl} naphthalene(L^â… )1,5-bis {[(2′-m-picolylaminoformyl)phenoxyl]methyl} naphthalene(L^â…¡)2,3-bis {[(2′-m-picolylaminoformyl)phenoxyl]methyl} quinoxalinone(L^â…¢)2,2′-bis {[(2′-m-picolylaminoformyl)phenoxyl]methyl} biphenyl(L^â…£)2,6-bis {[(2′-m-picolylaminoformyl)phenoxyl]methyl} pyridine(L^â…¤)1,4-bis {[(2′-o-picolylaminoformyl)phenoxyl]methyl} naphthalene(L^â…¥)1,5-bis {[(2′-o-picolylaminoformyl)phenoxyl]methyl} naphthalene(L^â…¦)3.The following rare earth complexes were prepared and characterized by elemental analysis, molar conductivity measurement,IR spectra analysis,electronic spectra and the single-crystal X-ray analysis:[REL^â… (NO₃)₃]·2H₂O(RE=Pr,Sm,Eu,Gd,Tb,Dy,Er,Y)[REL^â…¡(NO₃)₃]·2H₂O(RE= Pr,Nd,Eu,Gd,Tb,Dy)[REL^â…¢(NO₃)₃]·2H₂O(RE= Eu,Gd,Tb,Dy)[REL^â…£(NO₃)₃]·2H₂O(RE= Ce,Pr,Nd,Eu,Gd,Tb,Er)[RE₃L^â…¤₂(NO₃)₇](NO₃)₂·2H₂O·CH₃CO₂Et(RE= Pr,Eu,Gd,Tb,Dy,Y)[REL^â…¤(pic)₃]·CH₃CO₂Et(RE= Nd,Sm,Eu,Gd,Tb,Y)[REL^â…¥(NO₃)₃]·2H₂O(RE= Pr,Nd,Sm,Eu,Gd,Tb,Er) [REL^â…¦(NO₃)₃]·3H₂O(RE= Pr,Nd,Sm,Eu,Gd,Th,Dy)The results indicate that the bridging podands L^Ⅰ～L^â…¦all can form stable complexes with the rare earth ions.In the complexes,the ligands,which have bis-monodentate nature,link the metal ions to form the coordination polymers.4.Studies on the luminescent properties of the rare earth complexes indicate that N-picolyl salicylamide functional group has maintained the conjugate chromogen of salicylic acid to activate the luminescence of Eu³⁺and Tb³⁺.The central skeleton of ligands,the terminal groups of the ligands and the counter anion have great effect on the intensity of the luminescence of complexes.The lowest triplet state energy levels of the ligands are calculated from the phosphorescence spectra of their Gd complexes at 77K.The results indicate that the triplet state energy levels of ligands match better to the resonance levels of Tb(â…¢)than to Eu(â…¢).And we deduce that the weak luminescence of the complex of Tb(pic)₃ is due to the absorption of emission of Tb(â…¢)by the picrate ions.