Enantioselective aggregation and luminescence properties of europium(III) and terbium(III) complexes of an acetate and a tripodal ligand containing three imidazole groups

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• 作者：Mami Murase^a ; Suguru Yamauchi^a ; Soichiro Sakamoto^a ; Saori Takahashi^a ; Naohide Matsumoto^a ; ^{naohide@aster.sci.kumamoto-u.ac.jp} ; Masanobu Tsuchimoto^b
• 关键词：Europium(III) complex ; Terbium(III) complex ; Tripod ligand ; Luminescence ; Chirality ; Enantioselective ; Assembly ; Hydrogen bond ; Imidazole ; Acetate
• 刊名：Polyhedron
• 出版年：2013
• 出版时间：1 August, 2013
• 年：2013
• 卷：59
• 期：Complete
• 页码：76-84
• 全文大小：2630 K

文摘

The aggregation and luminescence properties of three pairs of Eu^III (1-3) and isomorphous Tb^III (4-6) complexes ligated to tripodal heptadentate N₇ ligands and bidentate acetate ion, [Eu^III or Tb^III (H₃L^2-Me)(OAc)](ClO₄)₂¡¤2MeOH¡¤H₂O (1, 4), [Eu^III or Tb^III (H₃L^2-Me)(OAc)](ClO₄)₂¡¤2EtOH (2, 5), and [Eu^III or Tb^III(H₃L^5-Me)(OAc)](ClO₄)₂¡¤MeOH (3, 6), were studied, where H₃L^2-Me = tris[2-(((2-methylimidazol-4-yl)methylidene)amino)ethyl]amine and H₃L^5-Me = tris[2-(((5-methylimidazol-4-yl)methylidene)amino)ethyl]amine, and OAc = acetate ion. Each Eu^III or Tb^III ion is coordinated by a heptadentate tripodal and a bidentate acetate ligand, resulting in ¦¤- and ¦«-enantiomorphs because of the screw coordination arrangement of the tripodal ligand. Intermolecular imidazole?acetate hydrogen bonding gives rise to three types of enantioselective assemblies. Compounds 1 and 4 form homochiral 1D chains comprising an undulating double layer that crystallizes into a conglomerate, whereas 2 and 5 form homochiral, single-layer, 1D chains, and crystallize into a racemic crystal. 3 and 6 form heterochiral dimers possessing an inversion center. The solid-state emission spectra of the complexes display sharp bands corresponding to the f-f transitions. Quantum yields (§¶) of 0.21, 0.24, and 0.24 and lifetimes (¦Ó) of 1.03, 0.98, and 0.97 ms were obtained for the Eu^III complexes 1, 2, and 3, respectively, under 310 nm excitation. The corresponding values for the Tb^III complexes 4, 5, and 6 were §¶ = 0.088, 0.10, and 0.043 and ¦Ó = 0.46, 0.48, and 0.50 ms, respectively.