Study On The Rare Earth Complexes Of The Podand Using Multiple Aryl Rings As Framework

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 four kinds of multipodal ligands and six series of rare earth complexes, and their luminescent properties were also determined.1. The following multipodal ligands were synthesized and characterized:9,10-bis {[(2 '-benzylaminoformyl)phenoxyl]methyl} anthracene. (L^â… ) 1,4-bis {[(2'-benzylaminoformyl)phenoxyl]methyl}naphthalene. (L^â…¡) 1,4-bis [(2'-carboxyphenoxy) methyl] naphthalene(L^â…¢) 1,4-bis [(4'-carboxyphenoxy) methyl] naphthalene(L^â…£)2. The following rare earth complexes were prepared and characterized by elemental analysis, molar conductivity measurements IR spectra and thermal analysis:[REL^â…  (NO₃)₃] (RE = La, Eu, Gd, Tb,Y ) [REL^â…  (pic)₃].H₂O .CH₃CO₂Et (RE = La, Eu, Gd, Tb,Y) [RE L^â…¡ (NO₃)₃(H₂O)] (RE = La, Eu, Gd, Tb, Y) [RE L^â…¡ (pic)₃·]·3H2O (RE = La, Eu, Gd, Tb,Y) [RE₂L₃^â…¢(H₂O)_n](RE = La,Eu,Gd, Tb,Y;n=3,6) [RE₂L^â…£₃]·nH₂O (RE = La, Eu, Gd, Tb,Y;n=3, 5, 6)3. Studies on the luminescent properties of the rare earth complexes in the solid state indicate that: N-benzylsalicylamide terminal group like salicylic acid has good antenna effect to the metal ions. The luminescence of Tb³⁺ complexes is much stronger than that of Eu³⁺ complexes in the nitrate complexes. The determination of the lowest triplet energy of the ligands show that it matches better to Tb³⁺ than to Eu³⁺ in the nitrate complexes. Two newmultipodal ligands (H2L , H2L ) with salicylic acid or p-hydroxy benzoic acid terminal groups and their rare earth complexes with Eu3+ and Tb3+ all show strong luminescence, indicating both of them have good antenna effect to the metal ions. But their luminescent spectrograms show that the luminescence of Tb3+ complexes are much stronger than that of Eu3+ complexes, suggesting the lowest triplet-state energy of the ligands match better to Tb3+ than to Eu3+. It is also discussed that the effect of the anions and the terminal groups of the ligands on the luminescent properties of the rare earth complexes.