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There were new dinuclear Zn-II-Ln(III) complexes of general formulas [Zn(mu-L)(mu-OAc)Ln(NO3)(2)] (Ln(III) = Tb (1), Dy (2), Er (3), and Yb (4)), [Zn(mu-L)(mu-NO3)Er(NO3)(2)] (5), [Zn(H2O)(pL)Nd(NO3)(3)]center dot 2CH(3)OH (6), [Zn(mu-L)(mu-9-An)Ln(NO3)(2)]center dot 2CH(3)CN (Ln(III) = Tb (7), Dy (8), Er (9), Yb(10)), [Zn(mu-L)(mu-9-An)Yb(9-An)(NO3)(3)]center dot 3CH(3)CN (11), [Zn(mu-L)(mu-9-An)Nd(9-An)(NO3)(3)]center dot 2CH(3)CN center dot 3H(2)O (12), and [Zn(mu-L)(mu-9-An)Nd(CH3OH)(2)(NO3)]ClO(4 center dot)2CH(3)OH (13) prepared from the reaction of the compartmental ligand N,N',N ''-trimethyl-N,N ''-bis(2-hydroxy-3-methoxy-5methylbenzyl)diethylenetriamine (H2L), with ZnX2 center dot nH(2)O (X = NO3- or OAc-) salts, Ln(NO3)(3)center dot nH(2)O, and, in some instances, 9anthracenecarboxylate anion (9-An). In all these complexes, the Zn-II ions invariably occupy the internal N3O2 site whereas the Ln(III) ions show preference for the O-4 external site, giving rise to a Zn(mu-diphenoxo)Ln bridging fragment. Depending on the Zn-II salt and solvent used in the reaction, a third bridge can connect the Zn-II and Ln(III) metal ions, giving rise to triple-bridged diphenoxoacetate in complexes 1-4, diphenoxonitrate in complex 5, and diphenoxo(9-anthracenecarboxylate) in complexes 8-13. Dy-III and Erni complexes 2, 8 and 3, 5, respectively, exhibit field induced single molecule magnet (SMM) behavior, with [Jeff values ranging from 11.7 (3) to 41(2) K. Additionally, the solid-state photophysical properties of these complexes are presented showing that ligand L2- is able to sensitize Tb-III- and Dy-III-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-III, Nd-III, and Ybm 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.
|Number of pages||10|
|Early online date||17 Dec 2013|
|Publication status||Published - 3 Feb 2014|
- SINGLE-MOLECULE MAGNET
- NEAR-INFRARED EMISSION
- SCHIFF-BASE LIGANDS
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- 1 Finished
Molecular Magnets: From Cages to Supramolecular Assemblies
1/10/13 → 30/09/16