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Title: | Pentanuclear 3d-4f heterometal complexes of MII3LnIII2 (M = Ni, Cu, Zn and Ln = Nd, Gd and Tb) combinations: syntheses, structures, magnetism and photoluminescence properties |
Author: | Maity, Manoranjan Majee, Mithun Chandra Kundu, Sanchita Samanta, Swarna Kamal Sañudo Zotes, Eva Carolina Ghosh, Sanjib Chaudhury, Muktimoy |
Keywords: | Metalls de terres rares Propietats magnètiques Luminescència Lligands Rare earth metals Magnetic properties Luminescence Ligands |
Issue Date: | 19-Oct-2015 |
Publisher: | American Chemical Society |
Abstract: | A new family of pentanuclear 3d-4f heterometal complexes of general composition [LnIII2(MIIL)3(μ3-O)3H](ClO4)·xH2O (1-5) [Ln = Nd, M = Zn, 1; Nd, Ni, 2; Nd, Cu, 3; Gd, Cu, 4; Tb, Cu, 5] have been synthesized in moderate yields (50-60%) following a self-assembly reaction involving the hexadentate phenol-based ligand, viz., N,N-bis(2-hydroxy-3-methoxy-5-methylbenzyl)-N′,N′-diethylethylenediamine (H2L). Single-crystal X-ray diffraction analyses have been used to characterize these complexes. The compounds are all isostructural, having a 3-fold axis of symmetry that passes through the 4f metal centers. The [MIIL] units in these complexes are acting as bis-bidentate metalloligands and, together with μ3-oxido bridging ligands, complete the slightly distorted monocapped square antiprismatic nine-coordination environment around the 4f metal centers. The cationic complexes also contain a H+ ion that occupies the central position at the 3-fold axis. Magnetic properties of the copper(II) complexes (3-5) show a changeover from antiferromagnetic in 3 to ferromagnetic 3d-4f interactions in 4 and 5. For the isotropic CuII-GdIII compound 4, the simulation of magnetic data provides very weak Cu-Gd (J1 = 0.57 cm-1) and Gd-Gd exchange constants (J2 = 0.14 cm-1). Compound 4 is the only member of this triad, showing a tail of an out-of-phase signal in the ac susceptibility measurement. A large-spin ground state (S = 17/2) and a negative value of D (-0.12 cm-1) result in a very small barrier (8 cm-1) for this compound. Among the three NdIII2MII3 (M = ZnII, NiII, and CuII) complexes, only the ZnII analogue (1) displays an NIR luminescence due to the 4F3/2 → 4I11/2 transition in NdIII when excited at 290 nm. The rest of the compounds do not show such NdIII/TbIII-based emission. The paramagnetic CuII and NiII ions quench the fluorescence in 2-5 and thereby lower the population of the triplet state |
Note: | Versió postprint del document publicat a: https://doi.org/10.1021/acs.inorgchem.5b01142 |
It is part of: | Inorganic Chemistry, 2015, vol. 54, num. 20, p. 9715-9726 |
URI: | http://hdl.handle.net/2445/159720 |
Related resource: | https://doi.org/10.1021/acs.inorgchem.5b01142 |
ISSN: | 0020-1669 |
Appears in Collections: | Articles publicats en revistes (Química Inorgànica i Orgànica) |
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