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This article is part of the themed collection: Chemical Communications HOT Articles 2023., Self-assembly of trans-{EuI2} nodes and ditopic ligands leads to isoreticular 2D frameworks featuring a rare, non-kagome Archimedean tessellation. The topology and intra-layer Eu(II)–Eu(II) antiferromagnetic interactions provide the prerequisites for geometrical spin frustration, which, due to the spin state degeneracy, is key for novel phenomena such as enhanced magnetic refrigeration., The authors acknowledge support from the VILLUM Foundation, the Independent Research Fund Denmark, ESS Lighthouses “SMART” and “Q-MAT”, MICINN (PID2021-124734OB-C21), DGA, Danscatt, and the ESRF (ID12 beamline).

A family of Mn(II)Ln(III) dinuclear and tetranuclear complexes (Ln = Gd and Dy) has been prepared from the compartmental ligands N,N′-dimethyl-N,N′-bis(2-hydroxy-3-formyl-5-bromobenzyl)ethylenediamine (H2L1) and N,N′,N′′-trimethyl-N,N′′-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H2L2). The Mn(II)Gd(III) complexes exhibit antiferromagnetic interactions between Mn(II) and Gd(III) ions in most cases, which are supported by Density Functional Theory (DFT) calculations. Experimental magneto-structural correlations carried out for the reported complexes and other related complexes found in bibliography show that the highest ferromagnetic coupling constants are observed in di-μ-phenoxido bridged complexes, which is due to the planarity of the Mn–(μ-O)2–Gd bridging fragment and to the high Mn–O–Gd angles. The effect of these angles has been studied by DFT calculations performed on a di-μ-phenoxido doubly bridged model. The magneto-thermal properties of the Mn(II)Gd(III) based complexes have also been measured, concluding that the magnitude of the Magneto-Caloric Effect (MCE) is due to the strength rather than to the nature of the magnetic coupling. Moreover, when two Mn(II)Gd(III) dinuclear units are connected by two carbonato-bridging ligands the MCE is enhanced, obtaining a maximum magnetic entropy change of 36.4 Jkg−1 K−1 at ΔB = 7 T and T = 2.2 K. On the other hand, one of the dinuclear Mn(II)Dy(III) complexes displays Single-Molecule Magnet (SMM) behaviour with an energy barrier of 14.8 K under an applied external field of 1000 Oe., This work was supported by the Junta de Andalucía (FQM-195 and the Project I + D + i FEDER 2018, A-FQM-172-UGR), MICIU of Spain (Projects PGC2018-102052-B-C21 and RTI2018-098537-B-C22), the University of Granada, the University of The Basque Country UPV/EHU (GIU20/028) and the Gobierno de Aragón (E11 20R). We would like to thank the Centro de Supercomputación de la Universidad de Granada for computational resources. The authors acknowledge the technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF).

Highly sensitive magnetometry reveals paramagnetism in dendrimer-coated gold nanoparticles. Different types of such nanoparticles, as a result of (i) functionalizing with two distinct Percec-type dendrons, linked to gold via dodecanethiol groups, and (ii) postsynthesis annealing in a solvent-free environment that further promotes their growth have been prepared. Ultimately, for each of the two functionalization configurations, we obtain highly monodisperse and stable nanoparticles of two different sizes, with spherical shape. These characteristics allow singling out the source of the measured paramagnetic signals as exclusively arising from the undercoordinated gold atoms on the surfaces of the nanoparticles. Bulk gold and the functional groups of the ligands contribute only diamagnetically., This work was supported by the MINECO-FEDER funds (project PGC2018-097583-B-I00 and RTI2018-094909-J-I00) and Gobierno de Aragón-FSE (Research Group E47_17R). The authors acknowledge the use of SAI (UZ), CEQMA (UZ-CSIC), and LMA (UZ-CSIC) services. J.A.U. thanks the Becas-Chile program of the National Commission for Scientific and Technological Research (CONICYT, Chile) for his PhD grant.

Ligand design remains key to the synthesis of coordination compounds possessing specific topologies, nuclearities and symmetries that direct targeted physical properties. N,O-chelates based on ethanolamine have been particularly prolific in constructing a variety of paramagnetic 3d transition metal complexes with fascinating magnetic properties. Here, we show that combining three ethanolamine moieties within the same organic framework in the form of the pro-ligand 1,3,5-tri(2-hydroxyethyl)-1,3,5-triazacyclohexane (LH3) leads to the formation of two highly unusual Mn wheels. Reaction of Mn(NO3)2·6H2O with LH3 in basic methanolic solutions leads to the formation of [MnIII12MnII4(μ3-O)6(μ-OH)4(μ3-OMe)2(μ-OMe)2(L)4(LH)2(H2O)10](NO3)6(OH)2 (1) and [MnIII10(μ3-O)4(μ-OH)4(μ-OMe)4(L)4(H2O)4](NO3)2 (2), the only difference in the synthesis being the ratio of metal:ligand employed. The structure of the former describes two offset [MnIII6MnII2] square wheels, linked through a common centre, and the latter a single [MnIII10] wheel twisted at its centre, such that the top half is orientated perpendicular to the bottom half. In both cases the L3−/LH2− ligands dictate the orientation of the Jahn-Teller axes of the MnIII ions which lie perpendicular to the triazacyclohexane plane. Direct current magnetic susceptibility and magnetisation data reveal the presence of competing exchange interactions in 1 and strong antiferromagnetic interactions in 2. Given the simplicity of the reactions employed and the paucity of previous work, the formation of these two compounds suggests that LH3 will prove to be a profitable ligand for the synthesis of a multitude of novel 3d transition metal complexes., CJM and TGT thank the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “First Call for H.F.R.I. Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant” (Project Number: 400). EKB thanks the EPSRC for financial support under grant reference numbers EP/I03255X/1 and EP/I031421/1. GL and ME thank the Ministerio de Ciencia e Innovación (RTI2018-094909-J-I00) and CSIC (PIE 201960E002).

Ligand design remains key to the synthesis of coordination compounds possessing specific topologies, nuclearities and symmetries that direct targeted physical properties. N,O-chelates based on ethanolamine have been particularly prolific in constructing a variety of paramagnetic 3d transition metal complexes with fascinating magnetic properties. Here, we show that combining three ethanolamine moieties within the same organic framework in the form of the ligand 1,3,5-tri(2-hydroxyethyl)-1,3,5-triazacyclohexane (LH3) leads to the formation of two highly unusual Mn wheels. Reaction of Mn(NO3)2·6H2O with LH3 in basic methanolic solutions leads to the formation of [MnIII 12MnII 4(µ3-O)6(µ-OH)4(µ3-OMe)2(µOMe)2(L)4(LH)2(H2O)10](NO3)6(OH)2 (1) and [MnIII 10(µ3-O)4(µ-OH)4(µ-OMe)4(L)4(H2O)4](NO3)2 (2); the only difference in the synthesis being the ratio of metal:ligand employed. The structure of the former describes two offset [MnIII 6MnII 2] square wheels, linked through a common centre, and the latter a single [MnIII 10] wheel twisted at its centre, such that the top half is orientated perpendicular to the bottom half. In both cases the L 3- /LH2- ligands dictate the orientation of the Jahn-Teller axes of the MnIII ions which lie perpendicular to the triazacyclohexane plane. Direct current magnetic susceptibility and magnetisation data reveal the presence of competing exchange interactions in 1 and strong antiferromagnetic interactions in 2. Given the simplicity of the reactions employed and the paucity of previous work, the formation of these two compounds suggests that LH3 will prove to be a profitable ligand for the synthesis of a multitude of novel 3d transition metal complexes

Certain magnetic molecules and molecular-based frameworks are considered as alternative materials for cryogenic cooling due to their large magneto-caloric effect. This potential is particularly appealing for applications requiring local refrigeration, but so far no study has been aimed at making thin films of efficient molecular coolers on a typical device substrate and evaluating their cooling potential. In this work, the growth of a dense gadolinium metal–organic framework on oxide-free silicon covered by either self-assembled or covalent monolayers with carboxylic end groups is explored. A continuous coverage with nanosized crystallites of the selected gadolinium formate framework is successfully formed on covalent monolayers obtained by hydrosilylation with either undecenoic acid or undecynoic acid. The thickness of the magnetocaloric deposit can be increased by increasing the growth time, as shown by the surface densities derived through determination of the film magnetic properties. An estimation of the cooling potential of the thicker film obtained shows that it would refrigerate a 2 μm thick Si membrane from 5 to 0.8 K, by adiabatic demagnetization from 2 T to zero field. Altogether, this study demonstrates the potential of molecular cooler thin films to develop on-chip magnetic refrigeration at cryogenic temperatures., The authors acknowledge funding from the Spanish MINECO and FEDER through projects MAT2014-53961-R (GL, EN and OR), MAT2015-70868-ERC (OR), MAT2015-68204-R (GL and ME) and MAT2017-86826-R (OR and EN), as well as from the Aragon government (DGA, consolidated groups MOLCHIP E98, PLATON E31_17R and M4 E13_17R).

ortho-Vanillin in the presence of nickel and lanthanide ions yields three types of heteronuclear NiII-GdIII complexes, ranging from dinuclear to tetranuclear defect dicubane complexes, as demonstrated by their structural determinations. These complexes are dependent on the solvents used during the reaction processes and on the retained lanthanide ions, as characterized by an increase in their Lewis acid character on moving from lighter to heavier lanthanide ions. Intramolecular ferromagnetic NiII-GdIII interactions are present in the heterodinuclear NiII-GdIII entities, whereas ferromagnetic NiII-NiII and NiII-GdIII interactions dominate above 2 K in the tetranuclear Ni-Gd compounds, devoid of any GdIII-GdIII interaction. The effect of a magnetic field on the magnetic entropy and adiabatic temperature changes is maximum near the liquid-helium boiling temperature, mainly determined by the relative weakness of the magnetic interactions., This work was n supported by Spanish MINECO through grant MAT2015-68204-R (to M. E. and G. L.) and a postdoctoral contract (to G. L.), by CNRS and MAGMANet (Grant NMP3-CT-2005-515767).

An octahedral {DyIII6} cage within a diamagnetic {ZnII4} rectangle is reported, with magnetic relaxation studies revealing single-molecule magnet behaviour for the complex under zero external dc field with Ueff = 43 K and τo = 1 × 10-5 s.

et al., The family of compounds of general formula [Ln TM (OH)(L)(OCR)(MeOH)](ClO) {[GdZn(OH)(hmp)(OCPr)](ClO) (1a); [YZn(OH)(hmp)(OCPr)](ClO) (1b); [GdCu(OH)(hmp)(OCPr)](ClO) (2a); [YCu(OH)(hmp)(OCPr)](ClO) (2b); [GdCu(OH)(hep)(OCPr)](ClO) (3a); [GdCu(OH)(Hpdm)(OCBu)](ClO) (4a); [GdCu(OH)(ea)(OCMe)](ClO) (5a); [GdNi(OH)(hmp)(OCEt)(MeOH)](ClO) (6a); [YNi(OH)(hmp)(OCEt)(MeOH)](ClO) (6b); [GdCo(OH)(hmp)(OCEt)(MeOH)](ClO) (7a); [YCo(OH)(hmp)(OCEt)(MeOH)](ClO) (7b)} can be formed very simply and in high yields from the reaction of Ln(NO)·6HO and TM(ClO)·6HO and the appropriate ligand blend in a mixture of CHCl and MeOH in the presence of a suitable base. Remarkably, almost all the constituent parts, namely the lanthanide (or rare earth) ions Ln (here Ln = Gd or Y), the transition metal ions TM (here TM = Zn, Cu, Ni, Co), the bridging ligand L (Hhmp = 2-(hydroxymethyl)pyridine; Hhep = 2-(hydroxyethyl)pyridine; Hpdm = pyridine-2,6-dimethanol; Hea = 2-ethanolamine), and the carboxylates can be exchanged while maintaining the structural integrity of the molecule. NMR spectroscopy of diamagnetic complex 1b reveals the complex to be fully intact in solution with all signals from the hydroxide, ligand L, and the carboxylates equivalent on the NMR time scale, suggesting the complex possesses greater symmetry in solution than in the solid state. High resolution nano-ESI mass spectrometry on dichloromethane solutions of 2a and 2b shows both complexes are present in two charge states with little fragmentation; with the most intense peak in each spectrum corresponding to [LnCu(OH)(hmp)(OCPr)](ClO) . This family of compounds offers an excellent playground for probing how the magnetocaloric effect evolves by introducing either antiferromagnetic or ferromagnetic interactions, or magnetic anisotropy, by substituting the nonmagnetic Zn (1a) with Cu (2a), Ni (6a) or Co (7a), respectively. The largest magnetocaloric effect is found for the ferromagnetically coupled complex 6a, while the predominant antiferromagnetic interactions in 2a yield an inverse magnetocaloric effect; that is, the temperature increases on lowering the applied field, under the proper experimental conditions. In spite of increasing the magnetic density by adding ions that bring in antiferromagnetic interactions (2a) or magnetic anisotropy (7a), the magnetocaloric effect is overall smaller in 2a and 7a than in 1a, where only four Gd spins per molecule contribute to the magnetocaloric properties., EKB thanks the EPSRC for financial support and the Velux Foundation for a Villum Visiting Professor Program grant. JS thanks the Deutsche Forschungsgemeinschaft (SCHN 615/23-1) for continuous support. Supercomputing time at the LRZ Garching (Germany) is gratefully acknowledged. GL and ME thank MINECO/FEDER (MAT2015-68204-R).

In contrast to the mainstream research on molecular refrigerants that seeks magnetically isotropic molecules, we show that the magnetic anisotropy of dysprosium acetate tetrahydrate, [{Dy(OAc)(HO)}]·4 HO (1), can be efficiently used for cooling below liquid-helium temperature. This is attained by rotating aligned single-crystal samples in a constant applied magnetic field. The envisioned advantages are fast cooling cycles and potentially compact refrigerators., We are grateful to Spanish MINECO for financial support (grand number FEDER-MAT2012-38318-C03-01) and for a postdoctoral contract (to G.L.).

An octahedral {DyIII6} cage within a diamagnetic {ZnII4} rectangle is reported, with magnetic relaxation studies revealing single-molecule magnet behaviour for the complex under zero external dc field with Ueff = 43 K and τo = 1 × 10−5 s., GL and ME thank MINECO for funding (MAT2015-68204-R).

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY)., The magnetic ordering structure of GdPO4 is determined at T=60 mK by the diffraction of hot neutrons with wavelength λ=0.4696 Å. It corresponds to a noncollinear antiferromagnetic arrangement of the Gd moments with propagation vector k=(1/2,0,1/2). This arrangement is found to minimize the dipole-dipole interaction and the crystal-field anisotropy energy, the magnetic superexchange being much smaller. The intensity of the magnetic reflections decreases with increasing temperature and vanishes at T≈0.8 K, in agreement with the magnetic ordering temperature TN=0.77 K, as reported in previous works based on heat capacity and magnetic susceptibility measurements. The magnetocaloric parameters have been determined from heat capacity data at constant applied fields up to 7 T, as well as from isothermal magnetization data. The magnetocaloric effect, for a field change ΔB=0-7T, reaches -ΔST=375.8mJ/cm3K-1 at T=2.1 K, largely exceeding the maximum values reported to date for Gd-based magnetic refrigerants., We acknowledge the Spanish MINECO for funding this research through Grant Nos. MAT2012-38318-C03-01 and MAT2013-44063-R. Research at the Oak Ridge National Laboratory for one author (L.A.B.) was sponsored by the U.S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division.

et al., A solvothermal reaction between Ln(NO)·6HO (Ln: Gd, Tb and Dy), 2-hydroxy-1-naphthaldehyde, 2-OH-naphth, and ethylenediamine, en, in MeOH in the presence of a base, NEt, led to the formation of the 1D coordination polymers [Ln(L)(MeO)(MeOH)]·MeOH (Ln = Gd (1·MeOH), Tb(2), Dy (3·MeOH); HL = 1,1′-((1E,1′E)-(ethane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(naphthalen-2-ol), the Schiff-base ligand derived from the condensation of 2-OH-naphth and en), while a similar reaction in an excess of NaN yielded 1D coordination polymers [Ln(L)(N)(MeO)(MeOH)] (Ln = Gd (4), Tb (5), Dy (6)). Finally, upon replacing ethylenediamine with o-phenylenediamine, o-phen, we managed to isolate the discrete dimers [Dy(L′)(MeOH)]·2MeOH (7·2MeOH) and [Gd(L′)(MeOH)]·2MeOH (8·2MeOH) (HL′ = 1,1′-((1E,1′E)-(1,2-phenylenebis(azanylylidene))bis(methanylylidene))bis (naphthalen-2-ol), the Schiff-base ligand from the condensation of 2-OH-naphth and o-phen). Polymers 1-3 describe one-dimensional chains, containing alternating seven- and eight-coordinate Ln metal centers, polymers 4-6 contain eight-coordinate lanthanide ions, while in both 7 and 8 the two Ln centers are eight- and seven-coordinate, adopting square antiprismatic and “piano-stool” geometry, respectively. The magnetocaloric properties of the three Gd analogues were determined from magnetic measurements, yielding the magnetic entropy change-ΔS = 21.8, 23.0 and 16.0 J kg K at T = 3.0 K on demagnetization of 7 T to 0, for 1, 4 and 8, respectively. The study of the magnetic properties also revealed that all three Dy analogues (3, 6 and 7) display out-of-phase signals, therefore suggesting slow magnetic relaxation, while such behaviour was not established in the Tb analogues., The research fund for CJM and ABC has been co-financed by the European Union (European Social Fund – ESF) and Greek national funds through the Operational Program “Education and Lifelong Learning” of the National Strategic Reference Framework (NSRF) – Research Funding Program: THALES. Investing in knowledge society through the European Social Fund. GL and ME thank Spanish MINECO (MAT2015-68204-R). MS, MO and TL: “Project partially supported by Wroclaw Centre of Biotechnology, programme The Leading National Research Centre (KNOW) for years 2014–2018”

A family of interwoven molecular inorganic knots, shaped like the 'Star of David', was prepared by the employment of naphthalene-2,3-diol in 3d/4f-metal cluster chemistry; the isoskeletal dodecanuclear compounds exhibit slow relaxation of the magnetization and magnetocaloric properties, depending on the metal ion., This work was supported by Brock University, NSERC-DG and ERA (to Th.C.S), the Ontario Trillium Foundation (graduate scholarship to D.I.A), the Fundaçao para a Ciencia e a Tecnologia (FCT, Portugal) financial support to REQUIMTE/LAQV (UID/ QUI/50006/2013), the European Synchrotron Radiation Facility (Grenoble, France) (for granting access time to the Swiss Norwegian BM01a beamline under the CH-3613 and CH-3849 research proposals), MINECO (FEDER-MAT2012-38318-C03 to M. E and postdoctoral contract to G. L), and the National Natural Science Foundation of China (grants 21371166, 21331003 and 21221061 to J. T).

Nine new complexes are reported involving linked heterometallic rings; one ring is designed as a ligand for the second, and the compounds produced can be regarded as molecular prototypes for implementing quantum gates featuring two subtly different qubits., We are grateful to the EPSRC (UK) for funding, especially of the National EPR Facility. M. Albring is a member of the EPSRC supported Centre for Doctoral Training NoWNANO. We acknowledge financial support also from the FIRB Project No. RBFR12RPD1 of the Italian Ministry of Education and Research. This work has been partially supported by EC through the FET-Proactive Project “MoQuaS”, contract N.610449.

Layered gadolinium hydroxides have revealed to be excellent candidates for cryogenic magnetic refrigeration. These materials behave as pure 2D magnetic systems with a Heisenberg-Ising critical crossover, induced by dipolar interactions. This 2D character and the possibility offered by these materials to be delaminated open the possibility of rapid heat dissipation upon substrate deposition., We are grateful to the EU (ERC Advanced Grant SPINMOL), the Spanish MINECO (Projects MAT-2014-56143-R, CTQ-2014-59209-P and FEDER-MAT2012-38318-C03-01), and the Generalitat Valenciana (Prometeo Program and ISIC-Nano). Support from INNCIDE program through Vicerectorat d’lnvestigacio i Política Científica of the University of Valencia is also acknowledged. G. A. thanks the EU for a Marie Curie Fellowship (FP7/2013-IEF-627386). G.M.E. thanks the Spanish MINECO for a Ramón y Cajal Fellowship.

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.-- et al., The reaction of the pro-ligand H4L, which combines the complementary phenolic oxime and diethanolamine moieties within the same organic framework, with Zn(NO3)2·6H2O and Ln(NO3)3·6H2O in a basic methanolic solution generates a family of isostructural heterometallic coordination compounds of general formula [Ln6Zn2(CO3)5(OH)(H2L)4(H3L)2(H4L)]NO3·xMeOH [Ln = Gd, x = 30 (1), Ln = Dy, x = 32 (2), Ln = Sm, x = 31 (3), Ln = Eu, x = 29 (4), Ln = Tb, x = 30 (5)]. The octametallic skeleton of the cage describes a heavily distorted [GdIII6] octahedron capped on two faces by ZnII ions. The metal core is stabilised by a series of μ3- and μ4-CO32− ions, originating from the serendipitous fixation of atmospheric CO2. The magnetic properties of all family members were examined via SQUID magnetometry, with the χMT product and VTVB data of the Gd analogue (1) being independently fitted by numerical diagonalisation to afford the same best-fit parameter JGd–Gd = −0.004 cm−1. The MCE of complex 1 was elucidated from specific heat data, with the magnetic entropy change reaching a value of 22.6 J kg−1 K−1 at T = 1.7 K, close to the maximum entropy value per mole expected from six GdIII spins (SGd = 7/2), 23.7 J kg−1 K−1., S.P. thanks the Danish Ministry of Science, Innovation and Higher Education for a Sapere Aude Fellowship (10-081659), M.E. acknowledges financial support from MINECO through grant MAT2012-38318-C03-01. EKB thanks the EPSRC.

ortho-Vanillin in the presence of nickel and lanthanide ions yields three types of heteronuclear Ni

The synthesis, characterization, crystal structures and magnetic properties of isoskeletal heptanuclear disk‐like MII3LnIII4 coordination clusters with the general formula [CoII3LnIII4(µ3‐OH)6L6(CF3SO3)][(CF3SO3)5] where Ln = Gd (2), Y (3) and [NiII3LnIII4(µ3‐OH)6L6(CF3SO3)][(CF3SO3)5] where Ln = Dy (4), Gd (5), Y (6) are presented. All the compounds are stable in solution as confirmed by ESI‐MS. Magnetic studies were performed for compounds 2, 4, 5 and 6 and indicate ferromagnetic coupling while the magnetocaloric properties of 5 are characterized by ΔSm = –15.4 J kg–1 K–1 at T = 5.0 K and ΔTad = 5.9 K at T = 2.3 K, for µ0ΔH = 7 T., We thank the Engineering and Physical Sciences Research Council (EPSRC) UK National Crystallography Service at the University of Southampton for the collection of the crystallographic data for compounds 3, 4 and 4′, the Research Development Fund (RDF) (V. N. D.) and Junior Research Associate (JRA) summer fellowship (C. H.) from the University of Sussex. A. E., G. L. and M. E. thank the Ministerio de Economía, Industria y Competitividad for financial support (Projects CTQ2015-63614-P and MAT2015-68204-R) and for a postdoctoral contract (to G. L.).

The syntheses, structures, magnetic and thermodynamic properties of three related triethanolamine-based Gd

The syntheses, structures, magnetic and thermodynamic properties of three related triethanolamine-based GdIII complexes are described. The smallest, a dimer ([Gd2]), can be viewed as the subunit from which the two larger complexes, a linear tetramer ([Gd2]2) and a cyclic hexamer ([Gd2]3), are composed by further deprotonation of the triethanolamine ligand. In all cases, nearest neighbour magnetic ions are weakly correlated by antiferromagnetic isotropic exchange, whose strength does not change significantly from one complex to another; J ranging from -0.10 to -0.13 cm-1. Therefore, rather than the strength of the coupling, it is the spin topology that is the dominant factor in determining the differences between the physical properties - specifically, the nuclearity and the transition from open (dimer and tetramer) to cyclic (hexamer) boundary conditions. Indeed the hexanuclear wheel reaches the continuum limit of classical Heisenberg spin chains. In terms of the magnetocaloric properties, the smaller the nuclearity, the larger the magnetic entropy and adiabatic temperature changes., EKB thanks the EPSRC for funding. SGC, GL, ER and ME thank the Spanish Ministry of Economy, Industry and Competitiveness (MAT2015-68204-R and CTQ2015-64579-C3-1-P) and for a postdoctoral grant (to GL). ER acknowledges the Generalitat de Catalunya for an ICREA Academia grant and the BSC (Barcelona Supercomputer Center) for computational resources. KSM thanks the Australian Research Council for a Discovery grant.

The adiabatic temperature change of the star-shaped {CoGd} magnetocaloric ring is enhanced via topological control over the assembly process, by using a pre-formed {Co

The employment of 2-amino-isobutyric acid, Haib, and 2-hydroxy-1-naphthaldehyde, Hnaphth, in Ni

Compounds of general formula [Cr7MF3(Etglu)(O2C(t)Bu)15(Phpy)] [H5Etglu = N-ethyl-d-glucamine; Phpy = 4-phenylpyridine; M = Zn (1), Mn (2), Ni (3)] have been prepared. The structures contain an irregular octagon of metal sites formed around the penta-deprotonated Etglu(5-) ligand; the chirality of N-ethyl-d-glucamine is retained in the final product. The seven Cr(III) sites have a range of coordination environments, and the divalent metal site is crystallographically identified and has a Phpy ligand attached to it. By using complementary experimental techniques, including magnetization and specific heat measurements, inelastic neutron scattering, and electron paramagnetic resonance spectroscopy, we have investigated the magnetic features of this family of {Cr7M} rings. Microscopic parameters of the spin Hamiltonian have been determined as a result of best fits of the different experimental data, allowing a direct comparison with corresponding parameters found in the parent compounds. We examine whether these parameters can be transferred between compounds and compare them with those of an earlier family of heterometallic rings.

In this work we study the assisted translocation of a polymer across a membrane nanopore, inside which a molecular motor exerts a force fuelled by the hydrolysis of ATP molecules. In our model the motor switches to its active state for a fixed amount of time, while it waits for an ATP molecule which triggers the motor, during an exponentially distributed time lapse. The polymer is modelled as a beads-springs chain with both excluded volume and bending contributions, and moves in a stochastic three dimensional environment modelled with a Langevin dynamics at a fixed temperature. The resulting dynamics shows a Michaelis-Menten translocation velocity that depends on the chain flexibility. The scaling behavior of the mean translocation time with the polymer length for different bending values is also investigated., The authors acknowledge funding from the Spanish MINECO and EU FEDER through projects MAT2013-44063-R (E. P.), MAT2014-53961-R (O. R., E. N., G. L.), MAT2015-70868-ERC (O. R.) and MAT2015-68204-R (M. E., G. L.), as well as for a postdoctoral contract (to G. L.).

The employment of 2-amino-isobutyric acid, Haib, and 2-hydroxy-1-naphthaldehyde, Hnaphth, in NiII/LnIII chemistry has led to the isolation and characterization of two new isostructural 3d–4f tetradecanuclear [NiII6LnIII8] clusters (Ln = GdIII, DyIII), with the Dy analogue displaying temperature and frequency dependent out-of-phase signals, and the Gd analogue showing interesting magnetocaloric properties., CJM: This work was supported by the ARISTEIA Action (Project code 84, acronym MAGCLOPT) of the Operational Programme Education and Lifelong Learning”, co-funded by ESF and National Resources. GL and ME thank Spanish MINECO (MAT2015-68204-R). MS and TL: “Project partially supported by Wroclaw Centre of Biotechnology, programme The Leading National Research Centre (KNOW) for years 2014–2018”. RI thanks the Royal Society of Edinburgh for funding.

The employment of the tetradentate ligand acenaphthenequinone dioxime (acndH2) for a first time in heterometallic CuII/LnIII (Ln = Gd and Dy) chemistry has afforded the one-dimensional coordination polymers [Cu6Gd2(acnd)6(acndH)6(MeOH)6]n (1) and [Cu6Dy2(acnd)6(acndH)6(MeOH)2]n (2), which consist of repeating {Cu6Ln2} clusters that are intermolecularly linked to each other through the oximate groups of two η2:η1:η1:μ3 acnd2– ligands. The [Cu6Ln2(μ3-NO)6(μ-NO)8]4+ core is unprecedented in heterometallic cluster chemistry and comprises two symmetry-related {Cu3Ln} subunits, each with a distorted trigonal pyramidal topology. Magnetic susceptibility studies revealed the presence of predominant ferromagnetic exchange interactions within the {Cu3Ln} subunits and weak antiferromagnetic interactions between them. As a result, the magnetic and magnetocaloric properties of the {Cu6Gd2}n compound could be rationalized in terms of two weakly coupled S = 5 spins that yield a magnetic entropy change of −ΔSm = 11.8 J kg–1 K–1 at T = 1.6 K for μ0ΔH = 7 T., This work was supported by Brock University (Chancellor’s Chair for Research Excellence, to Th.C.S), NSERC-DG and ERA (to Th.C.S), MINECO (MAT2015-68204-R to M.E. and postdoctoral contract to G.L.), and the National Natural Science Foundation of China (Grants 21371166, 21331003, and 21221061 to J.T.). This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231.

The adiabatic temperature change of the star-shaped {CoIII3GdIII3} magnetocaloric ring is enhanced via topological control over the assembly process, by using a pre-formed {CoII(H6L)} building block that undergoes oxidation to CoIII, successfully separating the GdIII ions., The UK Engineering and Physical Sciences Research Council are thanked for financial support (grant ref. EP/I027203/1). GL and ME thank the Spanish Ministry of Economy, Industry and Competitiveness for funding (MAT2015-68204-R) and a postdoctoral contract (to GL).

The family of compounds of general formula [Ln

We report the synthesis and structure of a molecular {Gd7} cage of the formula (iPr2NH2)6[Gd7(μ3-OH)3(CO3)6(O2CtBu)12] which has crystallographic C3h symmetry. Low temperature specific heat and adiabatic demagnetization experiments (the latter achieving temperatures below 100 mK), lead to the observation of the effects of both intramolecular dipolar interactions and geometric spin frustration. The dipolar interaction leads to a massive rearrangement of energy levels such that specific heat and entropy below 2 K are strongly modified while magnetic susceptibility and magnetization above 2 K are not affected. The consequences of these phenomena for low temperature magnetocaloric applications are discussed., EMP thanks the Panamanian agency SENACYT-IFARHU. KZ thanks the KRG-Scholarship program in “Human Capacity Development (HCDP)”. JS thanks the Deutsche Forschungsgemeinschaft (DFG SCHN 615/20-1) for continuous support. Supercomputing time at the LRZ Garching is gratefully acknowledged. GL and ME thank Spanish MINECO (MAT2015-68204-R). We also thank EPSRC (UK) for funding an X-ray diffractometer (grant number EP/K039547/1).

A family of interwoven molecular inorganic knots, shaped like the ‘Star of David’, was prepared by the employment of naphthalene-2,3-diol in 3d/4f-metal cluster chemistry; the isoskeletal dodecanuclear compounds exhibit slow relaxation of the magnetization and magnetocaloric properties, depending on the metal ion.

International audience; We present a synthetic, structural, theoretical, and spectroscopic study of a family of heterometallic ring dimers which have the formula [{Cr(7)NiF(3)(Etglu)(O(2)CtBu)(15)}(2)(NLN)], in which Etglu is the pentadeprotonated form of the sugar N-ethyl-d-glucamine, and NLN is an aromatic bridging diimine ligand. By varying NLN we are able to adjust the strength of the interaction between rings with the aim of understanding how to tune our system to achieve weak magnetic communication between the spins, a prerequisite for quantum entanglement. Micro-SQUID and EPR data reveal that the magnetic coupling between rings is partly related to the through-bond distance between the spin centers, but also depends on spin-polarization mechanisms and torsion angles between aromatic rings. Density functional theory (DFT) calculations allow us to make predictions of how such chemically variable parameters could be used to tune very precisely the interaction in such systems. For possible applications in quantum information processing and molecular spintronics, such precise control is essential.

Under the terms of the Creative Commons Attribution license.-- et al., We have investigated the magnetocaloric effect in single and polycrystalline samples of quantum paraelectric EuTiO3 by magnetization and heat capacity measurements. Single crystalline EuTiO3 shows antiferromagnetic ordering due to Eu2+ magnetic moments below TN=5.6K. This compound shows a giant magnetocaloric effect around its Néel temperature. The isothermal magnetic entropy change is 49Jkg-1K-1, the adiabatic temperature change is 21 K, and the refrigeration capacity is 500Jkg-1 for a field change of 7 T at TN. The single crystal and polycrystalline samples show similar values of the magnetic entropy and adiabatic temperature changes. The large magnetocaloric effect is due to suppression of the spin entropy associated with the localized 4f moment of Eu2+ ions. The giant magnetocaloric effect, together with negligible hysteresis, suggest that EuTiO3 could be a potential material for magnetic refrigeration below 40 K., R.M. acknowledges the support of MOE Tier 1 Grant No. R144-000-308-112. J.-S.W. acknowledges the support of MOE Tier 2 Grant No. R144-000-349-112. M.E. acknowledges financial support from MINECO through Grant No. FEDER-MAT2012-38318-C03-01.

et al., The reaction of a Schiff base ligand (LH3) with lanthanide salts, pivalic acid and triethylamine in 1:1:1:3 and 4:5:8:20 stoichiometric ratios results in the formation of decanuclear Ln10 (Ln=Dy(1), Tb(2), and Gd (3)) and pentanuclear Ln5 complexes (Ln=Gd (4), Tb (5), and Dy (6)), respectively. The formation of Ln10 and Ln5 complexes are fully governed by the stoichiometry of the reagents used. Detailed magnetic studies on these complexes (1–6) have been carried out. Complex 1 shows a SMM behavior with an effective energy barrier for the reversal of the magnetization (Ueff)=16.12(8) K and relaxation time (τo)=3.3×10−5 s under 4000 Oe direct current (dc) field. Complex 6 shows the frequency dependent maxima in the out-of-phase signal under zero dc field, without achieving maxima above 2 K. Complexes 3 and 4 show a large magnetocaloric effect with the following characteristic values: −ΔSm=26.6 J kg−1 K−1 at T=2.2 K for 3 and −ΔSm=27.1 J kg−1 K−1 at T=2.4 K for 4, both for an applied field change of 7 T., We are thankful to the Department of Science and Technology, New Delhi, for financial support. S.D., A.D., S.K., and S.B. thank CSIR, India for Senior Research Fellowship. V.C. is thankful to the Department of Science and Technology for a J.C. Bose National Fellowship. EC is thankful for financial support to Ministerio de Economía y Competitividad (MINECO) for Projects CTQ-2011-24478, CTQ2014-56312-P, the Junta de Andalucía (FQM-195 and the Project of excellence P11-FQM-7756), the University of Granada financial support. M.E. acknowledges financial support from MINECO through grant MAT2012-38318-C03-01. ST thanks the Junta de Andalucía for a postdoctoral contract.

A new family of isomorphous [Cu4Ln] clusters (LnIII = Gd, Tb, Dy) with a ‘propeller’-like topology was obtained from the use of naphthalene-2,3-diol in CuII/LnIII chemistry; all complexes are ferromagnetically-coupled and display either magnetocaloric properties or SMM behavior depending on the central Ln ion., This work was supported by Brock University, NSERC-DG and ERA (to Th. C. S), the Ontario Trillium Foundation (graduate scholarship to D. I. A), Fundação para a Ciência e a Tecnologia (FCT, Portugal) for financial support to REQUIMTE/LAQV (UID/QUI/50006/2013), the MINECO (MAT2012-38318-C03, to M. E), and the National Natural Science Foundation of China (grants 21371166, 21331003 and 21221061 to J. T).

Compounds of general formula [Cr7MF3(Etglu)(O2C(t)Bu)15(Phpy)] [H5Etglu = N-ethyl-d-glucamine; Phpy = 4-phenylpyridine; M = Zn (1), Mn (2), Ni (3)] have been prepared. The structures contain an irregular octagon of metal sites formed around the penta-deprotonated Etglu(5-) ligand; the chirality of N-ethyl-d-glucamine is retained in the final product. The seven Cr(III) sites have a range of coordination environments, and the divalent metal site is crystallographically identified and has a Phpy ligand attached to it. By using complementary experimental techniques, including magnetization and specific heat measurements, inelastic neutron scattering, and electron paramagnetic resonance spectroscopy, we have investigated the magnetic features of this family of {Cr7M} rings. Microscopic parameters of the spin Hamiltonian have been determined as a result of best fits of the different experimental data, allowing a direct comparison with corresponding parameters found in the parent compounds. We examine whether these parameters can be transferred between compounds and compare them with those of an earlier family of heterometallic rings.

Two new infinite coordination chain compounds [Gd(CH3CO2)3(dmf)]∞ (1) and {[Gd(HO(CH2)3CO2)3(H2O)]·H2O}∞ (2) have been obtained attempting to modify a prototype molecular cooler. The structures of both compounds as determined by single-crystal X-ray diffraction are reported, together with a detailed study of their magnetic and thermal properties, describing for both compounds a large magneto-caloric effect. The dominant ferromagnetic interaction present in 2 clearly favours this material at low applied magnetic fields, with respect to 1 that exhibits antiferromagnetic interactions. Magneto-structural correlations of the sign and strength of the magnetic interactions are derived for carboxylato-bridged Gd(III) systems., This work has been supported by the Spanish MINECO and FEDER through grants MAT2011-24284 and MAT2012-38318-C03-01 and by an EU Marie Curie IEF (PIEF-GA-2011-299356 toG. L.).

Under the terms of the Creative Commons Attribution 3.0 Unported License., We acknowledge financial support by MINECO through Grant MAT2012-38318-C03-01.

et al., A CO3 2--panelled [GdIII 6Cu II 3] cage conforming to a tridiminished icosahedron is synthesised by bubbling CO2 through a solution of GdIII and CuII ions. © 2014 The Royal Society of Chemistry., EKB thanks the EPSRC for funding. G.L. and M.E. acknowledge financial support by the Spanish MINECO through grant MAT2012-38318-C03-01. G.L. is also grateful to EC for a Marie Curie-IEF (PIEF-GA-2011-299356).

et al., The linear [M(CN)2]- (M = Au, Ag) anions can be used as metalloligands in oxime-based Mn chemistry to afford 1D chains of [Mn III 6] single-molecule magnets (SMMs). © 2014 The Royal Society of Chemistry., We thank MINECO (MAT2012-38318-C03), the EC for a Marie Curie-IEF to GL (PIEF-GA-2011-299356) and the EPSRC.

A comprehensive study of the complexes A4[U(NCS)8] (A = Cs, Et4N, nBu4N) and A3[UO2(NCS)5] (A = Cs, Et4N) is described, with the crystal structures of [nBu4N]4[U(NCS)8]·2MeCN and Cs3[UO2(NCS)5]·O0.5 reported. The magnetic properties of square antiprismatic Cs4[U(NCS)8] and cubic [Et4N]4[U(NCS)8] have been probed by SQUID magnetometry. The geometry has an important impact on the low-temperature magnetic moments: at 2 K, μeff = 1.21 μB and 0.53 μB, respectively. Electronic absorption and photoluminescence spectra of the uranium(IV) compounds have been measured. The redox chemistry of [Et4N]4[U(NCS)8] has been explored using IR and UV–vis spectroelectrochemical methods. Reversible 1-electron oxidation of one of the coordinated thiocyanate ligands occurs at +0.22 V vs Fc/Fc+, followed by an irreversible oxidation to form dithiocyanogen (NCS)2 which upon back reduction regenerates thiocyanate anions coordinating to UO22+. NBO calculations agree with the experimental spectra, suggesting that the initial electron loss of [U(NCS)8]4– is delocalized over all NCS– ligands. Reduction of the uranyl(VI) complex [Et4N]3[UO2(NCS)5] to uranyl(V) is accompanied by immediate disproportionation and has only been studied by DFT methods. The bonding in [An(NCS)8]4– (An = Th, U) and [UO2(NCS)5]3– has been explored by a combination of DFT and QTAIM analysis, and the U–N bonds are predominantly ionic, with the uranyl(V) species more ionic that the uranyl(VI) ion. Additionally, the U(IV)–NCS ion is more ionic than what was found for U(IV)–Cl complexes., We thank TCD (R.J.B. and E.H.) for funding this work. J.A.P. is grateful to UK National Service for Computational Chemistry Software. M.E. and G.L. thank MINECO (MAT2012-38318-C03).

et al., The reaction of fac-[MIIIF3(Me3tacn)] ×x H2O with Gd(NO3)3×5H 2O affords a series of fluoride-bridged, trigonal bipyramidal {GdIII 3MIII 2} (M=Cr (1), Fe (2), Ga (3)) complexes without signs of concomitant GdF3 formation, thereby demonstrating the applicability even of labile fluoride-complexes as precursors for 3d-4f systems. Molecular geometry enforces weak exchange interactions, which is rationalized computationally. This, in conjunction with a lightweight ligand sphere, gives rise to large magnetic entropy changes of 38.3 J kg-1 K-1 (1) and 33.1 J kg-1 K-1 (2) for the field change 7 T→0 T. Interestingly, the entropy change, and the magnetocaloric effect, are smaller in 2 than in 1 despite the larger spin ground state of the former secured by intramolecular Fe-Gd ferromagnetic interactions. This observation underlines the necessity of controlling not only the ground state but also close-lying excited states for successful design of molecular refrigerants., K.S.P. and S.P. thank the Danish Ministry of Science Innovation and Higher Education for an EliteForsk travel grant and a Sapere Aude Fellowship (10-081659), respectively. G.L., J.J.M., and M.E. acknowledge financial support by the Spanish MINECO through grant MAT2012-38318-C03-01. G.L. is also grateful to the EC for a Marie Curie-IEF (PIEF-GA-2011-299356). G.R. would like to thank DST, India (SR/S1/IC-41/2010; SR/NM/NS-1119/2011) for funding and IITB for HPC resources. S.K.S. thanks CSIR for a SRF fellowship.

Trabajo presentado a la V European School on Molecular Nanoscience (ESMolNa) celebrada en Cuenca (España) del 28 de octubre al 2 de noviembre de 2012., An excellent molecule-based cryogenic magnetic refrigerant, gadolinium acetate tetrahydrate, is here used to decorate selected portions of silicon substrate. By quantitative magnetic force microscopy for a variable applied magnetic field near liquid-helium temperature, the molecules are demonstrated to hold their magnetic properties intact, and therefore their cooling functionality, after their deposition. These results represent a step forward towards the realization of a molecule-based micro-refrigerating device at very low temperatures., This work was supported by the Spanish MINECO through grants CSD2007-00010, MAT2011-24284 and MAT2012-38318, by a CSIC JAE-technician fellowship (to P.G.-M.) and by an EU Marie Curie IEF (PIEF-GA-2011-299356, to G.L.).

The employment of pyridine-2,6-dimethanol in 3d/4f metal cluster chemistry has resulted in a new {CuII15GdIII7} cagelike molecule with a beautiful structure and an overall ferrimagnetic behavior with an appreciable ground-state spin value. The compound shows a satisfactory magnetocaloric effect with −ΔSmmax = 22.2 J kg−1 K−1., This work was supported by the CICYT (Project CTQ2012-30662) and Excellence in Research ICREA-Academia Award (to A.E.), the MINECO (Grant MAT2012-38318-C03 to M.E. and G.L.), an EU Marie Curie IEF (Grant PIEF-GA-2011-299356 to G.L.), the ARISTEIA Action (Project code 84, acronym MAGCLOPT) of the Operational Programme “Education and Lifelong Learning”, cofunded by ESF and National Resources (to S.P.P.), and the NSERC Discovery Grant (to T.C.S.).

(magnetization, susceptibility, and specific heat) allow us to determine the total spin of the ground state and to estimate the spin-Hamiltonian parameters related to magnetic anisotropy. X-ray spectroscopies (XAS and XMCD) are used to probe the local magnetization of the Cr and Cu ions, and provide results that are consistent with the bulk magnetization data. We finally investigate the relation between heterometallicity and entanglement in these prototypical spin systems. In particular, we focus on the spatial modulation of entanglement induced by the Cu defect spins and on the long-distance entanglement between them induced by the two Cr chains.

Trabajo presentado a la 5th International Conference on Molecular Materials (MolMat) celebrada en Barcelona (España) del 3 al 6 de julio de 2012., The magnetothermal properties of a coordination polymer and a metal-organic framework (MOF) based on Gd 3+ ions are reported. An equally large cryogenic magnetocaloric effect (MCE) is found, irrespective of the dimensionality. This combined with their robustness makes them appealing for widespread magnetic refrigeration applications. © 2012 The Royal Society of Chemistry., We are grateful to MINECO (contracts MAT2009-13977-C03, MAT2011-24284 and CSD2007-00010), EC (for a Marie Curie-IEF to GL), University of Granada (for a postdoctoral fellowship to MAP), and EPRSC for funding.

We report an in-depth study on how spin information propagates at supramolecular scale through a family of heteroaromatic linkers. By density-functional theory calculations, we rationalize the behavior of a series of Cr7Ni dimers for which we are able to systematically change the aromatic linker thus tuning the strength of the magnetic interaction, as experimentally shown by low temperature micro-SQUID and specific heat measurements. We also predict a cos2 dependence of the magnetic coupling on the twisting angle between the aromatic cycles in bicyclic linkers, a mechanism parallel to charge transport on similar systems [L. Venkataraman et al., Nature (London) 442, 904 (2006)].

We have extensively studied the magnetic features of a heterometallic molecular trimer, ${\text{Cr}}_{2}\text{Cu}$. We have characterized molecular ${\text{Cr}}_{2}\text{Cu}$ by low-temperature ac susceptibility and specific-heat measurements and this allowed us to determine the microscopic parameters of the spin Hamiltonian. Then, we used x-ray magnetic circular dichroism to selectively probe local symmetries, electronic configuration, orbital, and spin magnetic moments of the magnetic ions. We found that at low temperatures only the ground state $S=3/2$ is occupied and the spin of Cu is found opposite to that of Cr in agreement with spin-Hamiltonian calculations.