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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Labrador Garcia, Ana Maria
Institute for Globally Distributed Open Research and Education
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (3/3 displayed)
- 2016Direct monitoring of calcium-triggered phase transitions in cubosomes using small-angle X-ray scattering combined with microfluidicscitations
- 2013Synthesis, Crystal Structure and Magnetic Characterization of a Series of Cu-II-Ln(III) Heterometallic [Ln = La, Ce, Pr, Nd and Sm) Metal-Organic Compounds with an Unusual Single Crystal to Single Crystal Phase Transitioncitations
- 2013Two Sets of Metal Organic Frameworks along the Lanthanide Series Constructed by 2,3-Dimethylsuccinate: Structures, Topologies, and Strong Emission without Ligand Sensitizationcitations
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article
Synthesis, Crystal Structure and Magnetic Characterization of a Series of Cu-II-Ln(III) Heterometallic [Ln = La, Ce, Pr, Nd and Sm) Metal-Organic Compounds with an Unusual Single Crystal to Single Crystal Phase Transition
Abstract
The synthesis and structural characterization of five Cu(II)-Ln(III) heteronuclear metal-organic frameworks of formula {[Ln(4)Cu(4)(H2O)(26)(bta)(5)]center dot mH(2)O} and {[Ln(4)Cu(4)(H2O)(24)(bta)(5)]center dot pH(2)O} [Ln = La-III (1A/1B), Ce-III (2A/2B), Pr-III (3A/3B), Nd-III (4A/4B) and Sm-III (5A/5B) with m/p = 20 (1A)/16 (1B), 18 (2A)/16 (2B), 14 (3016 (3B), 22 (4A)/16 (4B) and 21 (5A)/14 (5B); H(4)bta =1,2,4,5-benzenetetracarboxylic acid (1-5)] have been performed. These compounds present a single-crystal to single-crystal phase transition from expanded A phases toward the B shrinking networks, which is triggered only in the presence of a dry environment. This phase transition is accompanied by a compression of the crystallographic b-axis in the range 2.4 to 2.8 angstrom with the consequent decrease of the unit cell volume from 9.5% to 12%. The isomorphous crystal structures of 1A-5A can be described as two crystallographically independent [Cu(II)-Ln(III)] heterometallic dinuclear units which are connected through two crystallographically independent bta(4-) ligands in the ac-plane, leading to 4,4-rectangular grids. These layers are connected along the crystallographic b-axis, through a pillaring bta(4-) group. The phase transition implies a change of the coordination mode of the bta4- pillar from bis-monodentate (1A-5A) to tetrakis-monodentate (1B-5B). Magnetic susceptibility measurements of polycrystalline samples of 1A-5A in the temperature range 2.0-300 K have in common the decrease of the chi T-M product with T which in the case of 1A is due to weak antiferromagnetic interactions between the copper(II) ions through the bta4- skeleton, the Lam cation being diamagnetic [J = -3.5 cm(-1) with the Hamiltonian defined H = -JS(Cu1)center dot S-Cu2,]. For the 2A-5A compounds, the additional exchange interaction between Cu-II and the paramagnetic Ln(II) is masked by the crystal field effects (which partially removes the 2J + 1 degeneracy of the L-2S+1(J) free-ion ground state in zero magnetic field) (2A-5A) and the thermal population of excited free-ion states (5A).