Bifunctional ZnIILnIII Dinuclear Complexes Combining Field Induced SMM Behavior and Luminescence: Enhanced NIR Lanthanide Emission by 9-Anthracene Carboxylate Bridging Ligands

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• 作者：María A. Palacios ; Silvia Titos-Padilla ; José Ruiz ; Juan Manuel Herrera ; Simon J. A. Pope ; Euan K. Brechin ; Enrique Colacio
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：February 3, 2014
• 年：2014
• 卷：53
• 期：3
• 页码：1465-1474
• 全文大小：416K
• ISSN：1520-510X

文摘

There were new dinuclear Zn<sup>IIsup>鈥揕n<sup>IIIsup> complexes of general formulas [Zn(渭-L)(渭-OAc)Ln(NO<sub>3sub>)<sub>2sub>] (Ln<sup>IIIsup> = Tb (1), Dy (2), Er (3), and Yb (4)), [Zn(渭-L)(渭-NO<sub>3sub>)Er(NO<sub>3sub>)<sub>2sub>] (5), [Zn(H<sub>2sub>O)(渭-L)Nd(NO<sub>3sub>)<sub>3sub>]路2CH<sub>3sub>OH (6), [Zn(渭-L)(渭-9-An)Ln(NO<sub>3sub>)<sub>2sub>]路2CH<sub>3sub>CN (Ln<sup>IIIsup> = Tb (7), Dy (8), Er (9), Yb(10)), [Zn(渭-L)(渭-9-An)Yb(9-An)(NO<sub>3sub>)<sub>3sub>]路3CH<sub>3sub>CN (11), [Zn(渭-L)(渭-9-An)Nd(9-An)(NO<sub>3sub>)<sub>3sub>]路2CH<sub>3sub>CN路3H<sub>2sub>O (12), and [Zn(渭-L)(渭-9-An)Nd(CH<sub>3sub>OH)<sub>2sub>(NO<sub>3sub>)]ClO<sub>4sub>路2CH<sub>3sub>OH (13) prepared from the reaction of the compartmental ligand N,N鈥?i>,N鈥?trimethyl-N,N鈥?bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H<sub>2sub>L), with ZnX<sub>2sub>路nH<sub>2sub>O (X = NO<sub>3sub><sup>鈥?/sup> or OAc<sup>鈥?/sup>) salts, Ln(NO<sub>3sub>)<sub>3sub>路nH<sub>2sub>O, and, in some instances, 9-anthracenecarboxylate anion (9-An). In all these complexes, the Zn<sup>IIsup> ions invariably occupy the internal N<sub>3sub>O<sub>2sub> site whereas the Ln<sup>IIIsup> ions show preference for the O<sub>4sub> external site, giving rise to a Zn(渭-diphenoxo)Ln bridging fragment. Depending on the Zn<sup>IIsup> salt and solvent used in the reaction, a third bridge can connect the Zn<sup>IIsup> and Ln<sup>IIIsup> metal ions, giving rise to triple-bridged diphenoxoacetate in complexes 1鈥?b>4, diphenoxonitrate in complex 5, and diphenoxo(9-anthracenecarboxylate) in complexes 8鈥?b>13. Dy<sup>IIIsup> and Er<sup>IIIsup> complexes 2, 8 and 3, 5, respectively, exhibit field induced single molecule magnet (SMM) behavior, with U<sub>effsub> values ranging from 11.7 (3) to 41(2) K. Additionally, the solid-state photophysical properties of these complexes are presented showing that ligand L<sup>2-sup> is able to sensitize Tb<sup>IIIsup>- and Dy<sup>IIIsup>-based luminescence in the visible region through an energy transfer process (antenna effect). The efficiency of this process is much lower when NIR emitters such as Er<sup>IIIsup>, Nd<sup>IIIsup>, and Yb<sup>IIIsup> are considered. When the luminophore 9-anthracene carboxylate is incorporated into these complexes, the NIR luminescence is enhanced which proves the efficiency of this bridging ligand to act as antenna group. Complexes 2, 3, 5, and 8 can be considered as dual materials as they combine SMM behavior and luminescent properties.