A ferromagnetically coupled diphenoxo-bridged Gd3+-Mn2+ dinuclear complex with a large magneto-caloric effect

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.A novel diphenoxo-bridged Gd3+-Mn2+ dimer is proposed as a good candidate for cryogenic magnetic refrigeration. The large MCE is enhanced by the ferromagnetic interaction between the two metal ions. © 2013 The Royal Society of Chemistry.We are grateful to MINECO (contracts MAT2012-38318-C03 and CTQ2011-24478), EC for a Marie Curie-IEF (PIEF-GA-2011-299356 to GL). EKB thanks the EPSRC and Leverhulme Trust.The authors also thank the Unit of Information Resources for Research (URICI-CSIC) for the co-financing of this publication in Open Access.Peer Reviewe

Aurophilicity as a cofactor in crystal engineering. Dicyanoaurate(I) anion as a building block in a novel Co(II)–Au(I) bimetallic assembly

A 2D grid-shaped cyanide-bridged Co(II)–Au(I) bimetallic coordination polymer, [Co(DMF)2{Au(CN)2}2], has been prepared from the [Au(CN)2]2 building block; sheets associate pair-wise by aurophilic interactions and the compound exhibits zeolite-like properties.Lloret Pastor, Francisco, [email protected]

Lanthanide tetrazolate complexes combining single-molecule magnet and luminescence properties: the effect of the replacement of tetrazolate n3 by β-diketonate ligands on the anisotropy energy barrier

Three new sets of mononuclear LnIII complexes of general formulas [LnL3]⋅CH3OH [LnIII=Yb (1), Er (2), Dy (3), Gd (4), and Eu (5)], [LnL2(tmh)(CH3OH)]⋅n H2O⋅m CH3OH [LnIII=Yb (1 b), Er (2 b), Dy (3 b), Gd (4 b)], and [LnL2(tta)(CH3OH)]⋅CH3OH [LnIII=Yb (1 c), Er (2 c), Dy (3 c), Gd (4 c)] were prepared by the reaction of Ln(CF3SO3)⋅n H2O salts with the tridentate ligand 2-(tetrazol-5-yl)-1,10-phenanthroline (HL) and, for the last two sets, additionally with the β-diketonate ligands 2,2,6,6-tetramethylheptanoate (tmh) and 2-thenoyltrifluoroacetonate (tta), respectively. In the [LnL3]⋅CH3OH complexes the LnIII ions are coordinated to three phenanthroline tetrazolate ligands with an LnN9 coordination sphere. Dynamic ac magnetic measurements on 1–3 reveal that these complexes only exhibit single-molecule magnet (SMM) behavior when an external dc magnetic field is applied, with Ueff values of 11.7 K (1), 16.0 K (2), and 20.2 K (3). When the tridentate phenanthroline tetrazolate ligand is replaced by one molecule of methanol and the β-diketonate ligand tmh (1 b–3 b) or tta (1 c–3 c), a significant increase in Ueff occurs and, in the case of the DyIII complexes 3 b and 3 c, out-of-phase χ′′ signals below 15 and 10 K, respectively, are observed in zero dc magnetic field. CASSCF+RASSI ab initio calculations performed on the DyIII complexes support the experimental results. Thus, for 3 the ground Kramers’ doublet is far from being axial and the first excited state is found to be very close in energy to the ground state, so the relaxation barrier in this case is almost negligible. Conversely, for 3 b and 3 c, the ground Kramers’ doublet is axial with a small quantum tunneling of the magnetization, and the energy difference between the ground and first Kramers’ doublets is much higher, which allows these compounds to behave as SMMs at zero field. Moreover, these calculations support the larger Ueff observed for 3 b compared to 3 c. Additionally, the solid-state photophysical properties of 1, 2, 4, and 5 show that the phenanthroline tetrazolate ligand can act as an effective antenna to sensitize the characteristic YbIII, ErIII, and EuIII emissions through an energy-transfer process

A novel two-dimensional honeycomb-like bimetallic iron(iii)–nickel(ii) cyanide-bridged magnetic material [Ni(cyclam)]3[Fe(CN)6]2·nH2O (cyclam = 1,4,8,11-tetraazacyclodecane)

The 2D honeycomb-like layered iron(iii)–nickel(ii) cyanidebridged complex [Ni(cyclam)]3[Fe(CN)6]2·nH2O exhibits ferromagnetic intralayer and antiferromagnetic interlayer interactions; above 3 K the magnetic properties are typical of a metamagnet with Hc = 5000 G, whereas below 3 K a canted structure is formed, leading to a long range ferromagnetic ordering.Lloret Pastor, Francisco, [email protected]

Frontispiece: Lanthanide tetrazolate complexes combining single-molecule magnet and luminescence properties: The effect of the replacement of tetrazolate N3 by β-Diketonate Ligands on the anisotropy energy barrier

Three new sets of mononuclear LnIII complexes of general formulas [LnL3]·CH3OH (LnIII = Yb (1), Er (2), Dy (3), Gd (4) and Eu (5)), [LnL2(tmh)(CH3OH)]·n H2O·m CH3OH (LnIII = Yb (1b), Er (2b), Dy (3b), Gd (4b)) and [LnL2(tta)(CH3OH)]·CH3OH (LnIII = Yb (1c), Er (2c), Dy (3c), Gd (4c) have been prepared from the reaction of Ln(CF3SO3)·nH2O salts with the tridentate ligand 2-(tetrazolate-5-yl)-1,10- phenanthroline (HL). For the two latter sets, additionally with the respective β- diketonate ligands 2,2,6,6-tetramethylheptanoate (tmh) or 2-thenoyltrifluoroacetonate (tta). In the [LnL3]·CH3OH complexes the LnIII ions are coordinated to three phenanthroline-tetrazolate ligands showing a LnN9 coordination sphere. Dynamic ac magnetic measurements for 1 – 3 reveal that these complexes only exhibit single molecule magnet (SMM) behaviour when an external dc magnetic field is applied, with Ueff values of 11.7 K (1), 16.0 K (2) and 20.2 K (3). When the tridentate phenanthrolinetetrazolate ligand is replaced by one molecule of methanol and the β-diketonate ligand tmh (1b – 3b) or tta (1c – 3c), a significant increase in Ueff occurs and, in the case of the DyIII derivates 3b and 3c, out-of-phase χ’’ signals below 15 K and 10 K, respectively, are observed under zero-dc magnetic field. CASSCF+RASSI ab initio calculations performed on the DyIII derivates support the experimental results. Thus, for 3 the ground Kramers’ doublet is far from being axial and the first excited state is found to be very close in energy to the ground state so the relaxation barrier in this case is almost negligible. Conversely, for 3b and 3c, the ground Kramers’ doublet is axial with a small quantum tunneling of the magnetization (QTM) and the energy difference between the ground and first Kramers’ doublets is much higher, which allows these compounds to behave as SMMs at zero-field. Moreover, these calculations support the larger Ueff observed for 3b compared to 3c. Additionally, the solid-state photophysical properties of 1, 2, 4 and 5 show that the phenanthroline tetrazolate ligand can act as an effective antenna to sensitize the characteristic YbIII, ErIII and EuIII emissions through an energy transfer process

Supramolecular assemblies involving metal organic ring interactions: Heterometallic Cu(II)-Ln(III) two dimensional coordination polymers

Three isostructural two-dimensional coordination polymers of the general formula [Ln2(CuL)3(H2O)9]$5.5H2O, where Ln is La (1), Nd (2), and Gd (3), have been synthesized and isolated from aqueous solutions and their single-crystal structures determined by X-ray diffraction. The supramolecular interaction between the non-aromatic metallorings plays an important role in stabilizing the structure of these compounds. The thermal stability, reversible solvent uptake, electronic properties and magnetic studies of these compounds are also reported

Dinuclear Fluoride Single-Bridged Lanthanoid Complexes as Molecule Magnets: Unprecedented Coupling Constant in a Fluoride- Bridged Gadolinium Compound

The authors thank the Spanish Ministerio de Ciencia e Innovacion projects (PGC2018-102052-B-C21, PGC2018093863-B-C21, MCIN/AEI/10.13039/501100011033/FEDER "Una manera de hacer Europa") for financial support. E.C. acknowledges Junta de Andalucia for the FEDER Andalucia project A-FQM-172-UGR18. J.C.-V. also thanks Xunta de Galicia for his Ph.D. fellowship (ED481A-2018/136). The authors acknowledge computer resources, technical expertise, and assistance provided by the CSUC.The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.inorgchem.2c00773. Figures S1−S9 and Tables S1−S9 (PDF) https://pubs.acs.org/doi/suppl/10.1021/acs.inorgchem.2c00773/suppl_file/ic2c00773_si_001.pdfA new synthetic method allows isolating fluoride-bridged complexes Bu4N{[M(3NO(2),5Br-H3L1,1,4)](2)(mu-F)} (M = Dy, 1; M = Ho, 2; M = Gd, 3) and Bu4N{[Dy(3Br,5Cl-H3L1,2,4)](2)(mu-F)}center dot 2H(2)O, 4 center dot 2H(2)O. The crystal structures of 1 center dot 5CH(3)C(6)H(5),center dot 2 center dot 2H(2)O center dot 0.75THF, 3, and 4 center dot 2H(2)O center dot 2THF show that all of them are dinuclear compounds with linear single fluoride bridges and octacoordinated metal centers. Magnetic susceptibility measurements in the temperature range of 2-300 K reveal that the Gd-III ions in 3 are weakly antiferromagnetically coupled, and this constitutes the first crystallographically and magnetically analyzed gadolinium complex with a fluoride bridge. Variabletemperature magnetization demonstrates a poor magnetocaloric effect for 3. Alternating current magnetic measurements for 1, 2, and 4 center dot 2H(2)O bring to light that 4 center dot 2H(2)O is an SMM, 1 shows an SMM-like behavior under a magnetic field of 600 Oe, while 2 does not show relaxation of the magnetization even under an applied magnetic field. In spite of this, 2 is the first fluoride-bridged holmium complex magnetically analyzed. DFT and ab initio calculations support the experimental magnetic results and show that apparently small structural differences between 1 and 4 center dot 2H(2)O introduce important changes in the dipolar interactions, from antiferromagnetic in 1 to ferromagnetic in 4 center dot 2H(2)O.Spanish Ministerio de Ciencia e Innovacion projects PGC2018-102052-B-C21, PGC2018093863-B-C21Junta de Andalucia A-FQM-172-UGR18Xunta de Galicia ED481A-2018/13

Analysis of Improper Standing Posture on the Knee Joint

Analysis of Improper Standing Posture on the Knee Joint Andre Colacio Mechanical Engineering 2018-0