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Wada, Atsushi*; Watanabe, Masayuki; Yamanoi, Yoshinori*; Nankawa, Takuya; Namiki, Kosuke*; Yamasaki, Mikio*; Murata, Masaki*; Nishihara, Hiroshi*
Bulletin of the Chemical Society of Japan, 80(2), p.335 - 345, 2007/02
Times Cited Count：22 Percentile：57.38(Chemistry, Multidisciplinary)Lanthanide complexes with linear and cyclic octadentate oligopyridine-amine ligands were synthesized, and their molecular structures were determined by single-crystal X-ray crystallography. All of the complexes had a distorted capped square antiprism (CSAP) geometry, and the coordination environments of lanthanide complexes were more distortedfor the complexes with the linear ligand than those with the cyclic ligand. The Eu
complexes with the linear ligand showed more intense emissions, which were attributed to the 
D
F
transition, than the complex withthe cyclic ligand in acetonitrile, which can be attributed to the distortion in the coordination environments. These results indicate that the coordination environments of lanthanide complexes, and thus the luminescence properties, can be controlled by tuning the geometrical structures of polydentate ligands.
Wada, Atsushi; Watanabe, Masayuki; Yamanoi, Yoshinori*; Murata, Masaki*; Nishihara, Hiroshi*
no journal, ,
Lanthanide complexes with linear and cyclic octadentate oligopyridine-amine ligands were newly synthesized, and their molecular structures were determined by single-crystal X-ray crystallography. All of the complexes formed with the distorted CSAP geometry, the symmetry of which was higher for the complexes with the cyclic ligand than those with the linear ligand. The Eu and Tb complexes showed intense luminescence due to energy transfer from the ligand to the metal center (antenna effect). The Eu complexes with the linear ligand showed more intense emissions attributed to the 5D07F2 transition than the complex with the cyclic ligand, which can be explained by the decrease in symmetry around the lanthanide ion. The coordination of water molecules to Eu and Tb ions was strongly inhibited by surrounding the metal ions with the cyclic ligand, resulting in an appearance of intense luminescence in water. These results indicate that the symmetry and stability of lanthanide complexes, and thus the luminescence properties, can be successfully controlled by tuning the geometrical structures of multi-dentate ligands.
