Studies On The Rare Earth Supramolecular Complexes With Amide Type Podands

Over the past decades, there has been much interesting in design and synthesis of lanthanide complexes due to their unique photophysical properties (microsecond to millisecond lifetimes, characteristic and narrow emission bands, and large Stokes shifts). Among the luminescent lanthanide complexes, Eu(III) and Tb(III) compounds show strong luminescence in the visible region, making them to be good candidates for fluoroimmunoassays and structural probes. In order to investigate the effects of the different frameworks or terminal groups of podands on the compositions, structures and properties of the rare earth complexes, we have designed and synthesized eight kinds of amide type podands and their rare earth complexes. The complexes have been characterized by elemental analysis, molar conductance, IR spectra, 1H NMR, electronic spectra and X-ray crystal structure analysis. Under the excitation of UV light, Eu and Tb complexes exhibit characteristic emission of corresponding lanthanide ions. Studies on the luminescent properties of the rare earth complexes indicate that aromatic salicylamide functional group has maintained the conjugate chromogen of salicylic acid to activate the luminescence of Eu3+and Tb3+. The luminescent properties of the complexes are influenced by the skeleton structure, terminal groups, the different position of the substituents of the ligands and the counter anions. The lowest triplet state energy levels of the ligands are calculated from the phosphorescence spectra of their Gd3+complexes at 77K. The results indicate that the triplet state energy levels of ligands match better to the resonance levels of Tb(III) than to Eu(III) in the nitrate complexes.The ligands are listed below: 1,2-bis{[(2'-furfurylaminofofmyl)phenoxyl]methyl}benzene (Lâ… ) 1,2-bis{[2'-(2-pyridylmethylaminoformyl)phenoxyl]methyl}benzene (Lâ…¡) 1,2-bis{[2'-(3-pyridylmethylaminoformyl)phenoxyl]methyl}benzene (Lâ…¢) 1,3-bis{[(2'-furfurylaminofofmyl)phenoxyl]methyl}benzene (Lâ…£) 1,3-bis{[2'-(2-pyridylmethylaminoformyl)phenoxyl]methyl} benzene (Lâ…¤) 1,3-bis{[2'-(3-pyridylmethylaminoformyl)phenoxyl]methyl}benzene(Lâ…¥) 1,2-bis[(2' -furfurylaminofofmyl)phenoxyl]ethane (Lâ…¦) 1,2-bis(morpholino)phenoxyethanone (Lâ…§)...