Europium and Terbium Coordination Polymers Assembled from Hexacarboxylate Ligands: Structures and Luminescent Properties

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• 作者：Yanli Gai ; Feilong Jiang ; Lian Chen ; Mingyan Wu ; Kongzhao Su ; Jie Pan ; Xiuyan Wan ; Maochun Hong
• 刊名：Crystal Growth & Design
• 出版年：2014
• 出版时间：March 5, 2014
• 年：2014
• 卷：14
• 期：3
• 页码：1010-1017
• 全文大小：555K
• 年卷期：v.14,no.3(March 5, 2014)
• ISSN：1528-7505

文摘

Six lanthanide coordination polymers of the formula [Ln(L<sup>1sup>)<sub>0.5sub>(H<sub>2sub>O)<sub>2sub>]路2H<sub>2sub>O [where Ln<sup>3+sup>: Eu<sup>3+sup> (1), Tb<sup>3+sup> (2), and Gd<sup>3+sup>(3)] and [Me<sub>2sub>NH<sub>2sub>][Ln(H<sub>2sub>L<sup>2sup>)(H<sub>2sub>O)<sub>4sub>]路0.5DMF路xH<sub>2sub>O [where Ln<sup>3+sup>: Eu<sup>3+sup> (4), Tb<sup>3+sup> (5), and Gd<sup>3+sup>(6)], based on p-terphenyl-2,2鈥?2鈥?5,5鈥?5鈥?hexacarboxylate acid (H<sub>6sub>L<sup>1sup>), and p-terphenyl-3,2鈥?3鈥?5,5鈥?5鈥?-hexacarboxylate acid (H<sub>6sub>L<sup>2sup>), have been solvothermally synthesized and structurally characterized. Complexes 1鈥?b>3 are 3D frameworks exhibiting 6-connected pcu alpha-Po primitive cubic network with topology (4<sup>12sup>.6<sup>3sup>), while complexes 4鈥?b>6 show two-dimensional (2D) architectures showing simplified 3,4-connected binodal net and (4.6<sup>2sup>)(4<sup>2sup>.6<sup>2sup>.8<sup>2sup>) topology. Detailed photophysical behaviors have been explored on Eu<sup>3+sup>, Tb<sup>3+sup>, and Gd<sup>3+sup> complexes. The calculated triplet state energies of H<sub>6sub>L<sup>1sup> and H<sub>6sub>L<sup>2sup> lie above the emissive levels of Eu<sup>3+sup> or Tb<sup>3+sup> in an ideal range for sensitizing. Furthermore, it is demonstrated that the optimum energy gap between the triplet state of ligand H<sub>6sub>L<sup>1sup> and the emissive level of Tb<sup>3+sup> ion makes the overall quantum yield of Tb<sup>3+sup> complex (2) larger than its corresponding Eu<sup>3+sup> complex (1). In addition, the coordinated water in the inner sphere has a significant negative influence on the overall quantum yield, especially for the Eu<sup>3+sup> complex (4) compared to the Tb<sup>3+sup> complex (5), due to the deactivation process caused by vibrational OH oscillators.