Eu-MOFs with 2-(4-Carboxyphenyl)imidazo[4,5-f]-1,10-phenanthroline and Ditopic Carboxylates as Coligands: Synthesis, Structure, High Thermostability, and Luminescence Properties

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• 作者：Sheng Zhang ; Yang Yang ; Zheng-Qiang Xia ; Xiang-Yu Liu ; Qi Yang ; Qing Wei ; Gang Xie ; San-Ping Chen ; Sheng-Li Gao
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：October 20, 2014
• 年：2014
• 卷：53
• 期：20
• 页码：10952-10963
• 全文大小：844K
• ISSN：1520-510X

文摘

Hydrothermal reactions of europium(III) salt with 2-(4-carboxyphenyl)imidazo[4,5-f]-1,10-phenanthroline and dicarboxylic acid as coligands鈥攂enzene-1,4-dicarboxylic acid, 4,4鈥?biphenyldicarboxylic acid, 2,5-dibromoterephthalic acid, and naphthalene-1,4-dicarboxylic acid鈥攍ead to four europium fluorescent materials (1鈥?b>4). Structural analyses reveal that 1鈥?b>4 have binuclear 3D metal鈥搊rganic frameworks with different channels, void volumes, and conjugated structures tuned by ditopic carboxylates. There are no latticed and coordinated water molecules occurring in 1鈥?b>3, while the free water molecules fill in 1D channels of 4. 4鈥?/b> was readily obtained via water removal of 4. Thermal analyses of all compounds show the high thermal stability of the main framework up to 450 掳C. Optical studies indicate that 1鈥?b>4 and 4鈥?/b> show the characteristic red luminescence emission of the Eu^III ion in the visible regions at room temperature. On the basis of emission spectra, their luminescence lifetimes were determined. In particular, compound 4鈥?/b> shows a longer lifetime (蟿 = 0.942 ms) and significantly enhanced quantum yield (39%) compared with those of 1 (11%, 0.770 ms), 2 (4%, 0.414 ms), 3 (18%, 0.807 ms), and 4 (26%, 0.858 ms).