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We report the synthesis and structural characterization of a series of heterometallic rings templated via alkylammonium or imidazolium cations. The template and preference of each metal’s coordination geometry can control the structure of heterometallic compounds, leading to octa-, nona-, deca-, dodeca-, and tetradeca-metallic rings. The compounds were characterized by single-crystal X-ray diffraction, elemental analysis, magnetometry, and EPR measurements. Magnetic measurements show that the exchange coupling between metal centres is antiferromagnetic. EPR spectroscopy shows that the spectra of {Cr7Zn} and {Cr9Zn} have S = 3/2 ground states, while the spectra of {Cr12Zn2} and {Cr8Zn} are consistent with S = 1 and 2 excited states. The EPR spectra of {(ImidH)-Cr6Zn2}, {(1-MeImH)-Cr8Zn2}, and {(1,2-diMeImH)-Cr8Zn2} include a combination of linkage isomers. The results on these related compounds allow us to examine the transferability of magnetic parameters between compounds.

We report two dichloride-bridged dinuclear dysprosium(III) complexes based on salen ligands, namely, [Dy(L1)(μ-Cl)(thf)]2 (1; H2L1 = N,Nʹ-bis(3,5-di-tert-butylsalicylidene)phenylenediamine) and [Dy2(L2)2(μ-Cl)2(thf)2]2 (2; H2L2 = N,Nʹ-bis(3,5-di-tert-butylsalicylidene)ethylenediamine). These two complexes have two short Dy−O(PhO) bonds that have angles of ~90° for 1 and ~143° for 2, leading to clear slow relaxation of the magnetization for 2 and not for 1. Compound 2 has a near-identical core to the recently reported compound [Dy2(L3)2(μ-Cl)2(thf)2] (3; H2L3 = N-(2-pyridylmethyl)-N,N-bis(2ʹ-hydroxy-3ʹ,5ʹ-di-tert-butylbenzyl)amine), the only substantial difference being the relative angle of the two O(PhO)−Dy−O(PhO) vectors, which are collinear in 2 owing to inversion symmetry and make an angle of ~68° in 3 owing to a molecular C2 axis. We show that this subtle structural difference leads to large differences in the dipolar ground states, giving rise to open magnetic hysteresis for 3 and not for 2.

A negative tone heterometallic ring resist (HRR) based on a supramolecular assembly [NH₂(allyl)₂][Cr₇NiF₈(piv)₁₆] with previously demonstrated resolution down to sub 10-nm lines is evaluated in terms of its flexibility to be processed either “wet” (spin cast and solvent developed) or “dry” (deposition and development by vacuum sublimation). The implemented sublimation hardware fits easily in the wafer load-lock chamber of extreme ultraviolet and electron beam exposure systems dedicated to research and development activities and allows for HRR films to be uniformly deposited or developed in the same vacuum environment. The HRR shows a sublimation rate dependence on temperature that obeys a Clausius–Clapeyron relation, with thermal stability up to 275°C. Flood exposures of the HRR show identical sensitivity between wet- and dry-deposited films, whereas contrast degradation is observed when dry development is initiated by increasing the temperature prior to system pump down. A modified sublimation setup allows for the dry development of exposed HRR samples inside the electron beam tool without breaking vacuum. In this case, nominally patterned 25 nm L/S are identically resolved at 30 keV for wet- or dry-developed HRR.

A new class of electron bean negative tone resist materials has been developed based on heterometallic rings. The initial resist performance demonstrates a resolution of 15 nm half-pitch but at the expense of a low sensitivity. To improve sensitivity a 3D Monte Carlo simulation is used that utilizes a secondary and Auger electron generation model. The simulation suggests that the sensitivity can be dramatically improved while maintaining high resolution by incorporating appropriate chemical functionality around the metal–organic core. The new resists designs based on the simulation have the increased sensitivity expected and illustrate the value of the simulation approach.

Addition of 1,4,8,11-tetrazacyclotetradecane (cyclam) to a reaction that produces octametallic rings when simpler amines are used, produces {Cr11M2} "pretzels" (M = ZnII or CuII) where the cyclam coordinates to the MII ion which then sits at the centre of a twelve-metal macrocycle. Magnetic studies were fitted using the finite-temperature Lanczos method (FTLM), and the results demonstrate that exchange interactions are transferable from previous exchange-coupled CrIII rings.

The implementation of a quantum computer requires both to protect information from environmental noise and to implement quantum operations efficiently. Achieving this by a fully fault-tolerant platform, in which quantum gates are implemented within quantum-error corrected units, poses stringent requirements on the coherence and control of such hardware. A more feasible architecture could consist of connected memories, that support error-correction by enhancing coherence, and processing units, that ensure fast manipulations. We present here a supramolecular {Cr7Ni}–Cu system which could form the elementary unit of this platform, where the electronic spin 1/2 of {Cr7Ni} provides the processor and the naturally isolated nuclear spin 3/2 of the Cu ion is used to encode a logical unit with embedded quantum error-correction. We demonstrate by realistic simulations that microwave pulses allow us to rapidly implement gates on the processor and to swap information between the processor and the quantum memory. By combining the storage into the Cu nuclear spin with quantum error correction, information can be protected for times much longer than the processor coherence., The implementation of a quantum computer requires protecting of information from noise and the ability to perform quantum gates. We present a molecular architecture providing both these ingredients, via an electronic spin 1/2 processor and a nuclear spin 3/2 memory.

A new family of five‐coordinate lanthanide single‐molecule magnets (Ln SMMs) [Dy(Mes*O)2(THF)2X] (Mes*=2,4,6‐tri‐tert‐butylphenyl; X=Cl, 1; Br, 2; I, 3) is reported with energy barriers to magnetic reversal >1200 K. The five‐coordinate DyIII ions have distorted square pyramidal geometries, with halide anions on the apex, and two Mes*O ligands mutually trans‐ to each other, and the two THF molecules forming the second trans‐ pair. These geometrical features lead to a large magnetic anisotropy in these complexes along the trans‐Mes*O direction. QTM and Raman relaxation times are enhanced by varying the apex halide from Cl to Br to I, or by dilution in a diamagnetic yttrium analogue., Halide influence: A new family of five‐coordinate lanthanide‐based single‐molecule magnets, [Dy(Mes*O)2(THF)2X] (Mes*=2,4,6‐tri‐tert‐butylphenyl), (X=Cl, Br, I) is reported. While the influence of the different halides on the quantum tunnelling of magnetization and Raman processes is clearly established, the Orbach relaxation is independent of the halide substitution.

The detailed analysis of magnetic interactions in a giant molecule is difficult both because the synthesis of such compounds is challenging and the number of energy levels increases exponentially with the magnitude and number of spins. Here, we isolated a {Ni21Gd20} nanocage with a large number of energy levels (≈5 × 1030) and used quantum Monte Carlo (QMC) simulations to perform a detailed analysis of magnetic interactions. Based on magnetization measurements above 2 K, the QMC simulations predicted very weak ferromagnetic interactions that would give a record S = 91 spin ground state. Low-temperature measurements confirm the spin ground state but suggest a more complex picture due to the single ion anisotropy; this has also been modeled using the QMC approach. The high spin and large number of low-lying states lead to a large low-field magnetic entropy (14.1 J kg-1 K-1 for ΔH = 1 T at 1.1 K) for this material., This work was supported by the Natural Science Foundation of China (nos. 21473129, 21620102002, and 21773130), “National Young-1000-Plan” program, State Key Laboratory for Mechanical Behavior of Materials and the Cyrus Chung Ying Tang Foundation.

Molecules that are the size of small proteins are difficult to make. The most frequently examined route is via self-assembly, and one particular approach involves molecular nanocapsules, where ligands are designed that will enforce the formation of specific polyhedra of metals within the core of the structure. Here we show that this approach can be combined with mechanically interlocking molecules to produce nanocapsules that are decorated on their exterior. This could be a general route to very large molecules, and is exemplified here by the synthesis and structural characterization of a [13]rotaxane, containing 150 metal centres. Small angle X-ray scattering combined with atomistic molecular dynamics simulations demonstrate the compound is intact in solution., Mechanically interlocked molecules and molecular cages are two important themes in supramolecular chemistry. Here, the authors combine these concepts to construct a giant [13]rotaxane built around a palladium capsule, one of the most complex metallosupramolecular assemblies yet.

The proposal that paramagnetic transition metal complexes could be used as qubits for quantum information processing (QIP) requires that the molecules retain the spin information for a sufficient length of time to allow computation and error correction. Therefore, understanding how the electron spin-lattice relaxation time (T1) and phase memory time (Tm) relate to structure is important. Previous studies have focused on the ligand shell surrounding the paramagnetic centre, seeking to increase rigidity or remove elements with nuclear spins or both. Here we have studied a family of early 3d or 4f metals in the +2 oxidation states where the ground state is effectively a 2S state. This leads to a highly isotropic spin and hence makes the putative qubit insensitive to its environment. We have studied how this influences T1 and Tm and show unusually long relaxation times given that the ligand shell is rich in nuclear spins and non-rigid., Molecular spin qubits show great promise for quantum information processing, but loss of phase information due to noise interference hinders their applicability. Here the authors engineer the electronic configurations of the metal centres in a series of divalent rare-earth complexes and succeed in prolonging their phase memory times.

A viable qubit must have a long coherence time $T_2$. In molecular nanomagnets $T_2$ is often limited at low temperatures by the presence of dipole and hyperfine interactions, which are often mitigated through sample dilution, chemical engineering and isotope substitution in synthesis. Atomic-clock transitions offer another route to reducing decoherence from environmental fields by reducing the effective susceptibility of the working transition to field fluctuations. The Cr$_7$Mn molecular nanomagnet, a heterometallic ring, features a clock transition at zero field. Both continuous-wave and spin-echo electron-spin resonance experiments on Cr$_7$Mn samples diluted via co-crystallization, show evidence of the effects of the clock transition with a maximum $T_2\sim350$ ns at 1.8 K. We discuss improvements to the experiment that may increase $T_2$ further., 4 pages, 4 figures, submitted to Magnetochemistry

We report an empirical correlation between the blocking temperature of large energy barrier SMMs and the relaxation time at the point where the Raman and Orbach relaxation mechanisms have the same rate; this supports the idea that the ability to retain magnetisation is controlled by the Raman relaxation process in these novel materials.

Field-emission devices are promising candidates to replace silicon fin field-effect transistors as next-generation nanoelectronic components. For these devices to be adopted, nanoscale field emitters with nanoscale gaps between them need to be fabricated, requiring the transfer of, for example, sub-10 nm patterns with a sub-20 nm pitch to substrates like silicon and tungsten. New resist materials must therefore be developed that exhibit the properties of sub-10 nm resolution and high dry etch resistance. A negative tone, metal–organic resist is presented here. It can be patterned to produce sub-10 nm features when exposed to helium ion beam lithography at line doses on the order of tens of picocoulombs per centimeter. The resist was used to create 5 nm wide, continuous, discrete lines spaced on a 16 nm pitch in silicon and 6 nm wide lines on an 18 nm pitch in tungsten, with line edge roughness of 3 nm. After the lithographic exposure, the resist demonstrates high resistance to silicon and tungsten dry etch conditions (SF_6 and C_4F_8 plasma), allowing the pattern to be transferred to the underlying substrates. The resist’s etch selectivity for silicon and tungsten was measured to be 6.2:1 and 5.6:1, respectively; this allowed 3 to 4 nm thick resist films to yield structures that were 21 and 19 nm tall, respectively, while both maintained a sub-10 nm width on a sub-20 nm pitch.

We report a six coordinate DyIII single-molecule magnet (SMM) with an energy barrier of 1110 K for thermal relaxation of magnetization. The pure compound shows no retention of magnetization even at 2 K.

[EN] Supramolecular coordination compounds (SCCs) represent the power of coordination chemistry methodologies to self-assemble discrete architectures with targeted properties. SCCs are generally synthesized in solution, with isolated fully coordinated metal atoms as structural nodes, thus severely limited as metal-based catalysts. Metal-organic frameworks (MOFs) show unique features to act as chemical nanoreactors for the in situ synthesis and stabilization of otherwise not accessible functional species. Here, we present the self-assembly of Pd-II SCCs within the confined space of a pre-formed MOF (SCCs@MOF) and its post-assembly metalation to give a Pd-II-Au-III supra molecular assembly, crystallography underpinned. These SCCs@MOFs catalyze the coupling of boronic acids and/or alkynes, representative multi-site metal-catalyzed reactions in which traditional SCCs tend to decompose, and retain their structural integrity as a consequence of the synergetic hybridization between SCCs and MOFs. These results open new avenues in both the synthesis of novel SCCs and their use in heterogeneous metal-based supramolecular catalysis., This work was supported by the MINECO (Spain) (Projects CTQ2016-75671-P and 2017-86735-P, and Excellence Units "Severn Ochoa" and "Maria de Maeztu" SEV-2016-0683 and MDM-2015-0538), the Ministero dell'Istruzione, dell'Universita e della Ricerca (Italy), and the Engineering and Physical Sciences Research Council (UK). M.M. thanks the MINECO for a predoctoral contract. RA. thanks UPV and R.G. thanks ITQ for the corresponding contracts. D.A. thanks the "Fondo per it finanziamento delle attivita base di ricerca". E.P. acknowledges financial support from the European Research Council under the European Union's Horizon 2020 research and innovation programme/ERC Grant Agreement No. 814804, MOF-reactors. Thanks are also extended to the "Subprograma Atraccio de Talent-Contractes Post-doctorals de la Universitat de Valencia" and the "2018 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation"(J.F.-S.). We thank the Diamond Light Source for awarded beamtime (proposal number MT18768) and provision of synchrotron radiation facility, and Dr. David Allan and Dr. Sarah Barnett for their assistance at the 119 beamline.

Understanding quantum tunnelling of the magnetisation (QTM) in single-molecule magnets (SMMs) is crucial for improving performance and achieving molecule-based information storage above liquid nitrogen temperatures. Here, through a field- and temperature-dependent study of the magnetisation dynamics of [Dy(tBuO)Cl(THF)5][BPh4]·2THF, we elucidate the different relaxation processes: field-independent Orbach and Raman mechanisms dominate at high temperatures, a single-phonon direct process dominates at low temperatures and fields >1 kOe, and a field- and temperature-dependent QTM process operates near zero field. Accounting for the exponential temperature dependence of the phonon collision rate in the QTM process, we model the magnetisation dynamics over 11 orders of magnitude and find a QTM tunnelling gap on the order of 10−4 to 10−5 cm−1. We show that removal of Dy nuclear spins does not suppress QTM, and argue that while internal dipolar fields and hyperfine coupling support QTM, it is the dynamic crystal field that drives efficient QTM., Understanding quantum tunnelling of the magnetisation in single-molecule magnets is crucial for their potential application in information storage. Here the authors conduct a field- and temperature-dependent study of the magnetisation dynamics of a dysprosium-based SMM, finding four distinct relaxation processes that dominate in different regimes.

Chemical science 9(14), 3555-3562 (2018). doi:10.1039/C8SC00163D, Published by RSC, Cambridge

Molecular uranium complexes are the most widely studied in actinide chemistry, and make a significant and growing contribution to inorganic and organometallic chemistry. However, reliable computational procedures to accurately describe the properties of such systems are not yet available. In this contribution, 18 experimentally characterized molecular uranium compounds, in oxidation states ranging from III to VI and with a variety of ligand environments, are studied computationally using density functional theory. The computed geometries and vibrational frequencies are compared with X-ray crystallographic, and infra-red and Raman spectroscopic data to establish which computational approach yields the closest agreement with experiment. NMR parameters and UV–vis spectra are studied for three and five closed-shell U(VI) compounds respectively. Overall, the most robust methodology for obtaining accurate geometries is the PBE functional with Grimme's D3 dispersion corrections. For IR spectra, different approaches yield almost identical results, which makes the PBE functional with Grimme's D3 dispersion corrections the best choice. However, for Raman spectra the dependence on functional is more pronounced and no clear recommendation can be made. Similarly, for 1 H and 13 C NMR chemical shifts, no unequivocal recommendation emerges as to the best choice of density functional, although for spin-spin couplings, the LC- ω PBE functional with solvent corrections is the best approach. No form of time-dependent density functional theory can be recommended for the simulation of the electronic absorption spectra of uranyl (VI) compounds; the orbitals involved in the transitions are not calculated correctly, and the energies are also typically unreliable. Two main approaches are adopted for the description of relativistic effects on the uranium centres: either a relativistic pseudopotential and associated valence basis set, or an all-electron basis set with the ZORA Hamiltonian. The former provides equal, if not better, agreement with experiment vs all-electron basis set calculations, for all properties investigated.

Chromium lanthanide heterometallic wheel complexes {Cr8Ln8} (Ln=Gd, Dy and Y) with alternating metal centres are presented. Quantum Monte Carlo simulations reveal antiferromagnetic exchange-coupling constants with an average of 2.1 K within the {Cr8Gd8} wheel, which leads to a large ground spin state (ST=16) that is confirmed by magnetization studies up to 20 Tesla. The {Cr8Dy8} wheel is a single-molecule magnet.

The {Cr8 } metallacrown [CrF(O2 C(t) Bu)2 ]8 , containing a F-lined internal cavity, shows high selectivity for CO2 over N2 . DFT calculations and absorption studies support the multiple binding of F-groups to the C-center of CO2 (C⋅⋅⋅F 3.190(9)-3.389(9) A), as confirmed by single-crystal X-ray diffraction.

The creation of a perfect hollow nanoscopic sphere of metal centres is clearly an unrealisable synthetic challenge. It is however an inspirational challenge, from the viewpoint of chemical architecture and also as finite molecular species may provide unique microscopic insight into the origin and onset of phenomena such as topological spin-frustration effects found in infinite 2D and 3D systems. Herein, we report a series of high symmetry gadolinium(III) (S = 7/2) polyhedra, Gd20, Gd32, Gd50 and Gd60, to test an approach based on assembling polymetallic fragments that contain different polygons. Structural analysis reveals the Gd20 cage resembles a dodecahedron; the vertices of the Gd32 polyhedron exactly reveal symmetry Oh; Gd50 displays an unprecedented polyhedron in which an icosidodecahedron Gd30 core is encapsulated by an outer Gd20 dodecahedral shell with approximate Ih symmetry; and the Gd60 shows a truncated octahedron geometry. Experimental and theoretical magnetic studies show that this series produces the expected antiferromagnetic interaction that can be modelled based on classical spins at the Gd sites. From the magnetization analyses we can roughly correlate the derivative bands to the Gd-O-Gd angles. Such a magneto-structural correlation may be used as “fingerprints” to identify these cages.

Quantum information processing (QIP) could revolutionize how we simulate and understand quantum systems. Any QIP scheme requires both individual units (qubits) that have long phase memories and switchable units that can be placed between the qubits. Here, we describe supramolecular systems where {Cr7Ni} rings are used as qubits, linked by redox-switchable {Ru2M} oxo-centered triangles (M = Zn, Ni, or Co). The supramolecular assemblies have been structurally characterized and involve two {Cr7Ni} rings bound to {Ru2M} triangles through iso-nicotinate ligands. Detailed physical studies, including electrochemistry and electron paramagnetic resonance spectroscopy, show that when M = Co, the supramolecular assembly has the physical characteristics needed to implement the √iSWAP gate, which is an important entangling two-qubit gate. Detailed simulations show that the fidelity of this gate is potentially very high and depends on the phase memory time of the {Cr7Ni} qubits but not the {Ru2Co} switch.

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).

Doping a Cr7Zn molecular nanomagnet into a diamagnetic and isostructural host allows pulsed X-band EPR on single crystals, including relaxation and nutation experiments on the S = 3/2 ground state. © 2014 The Royal Society of Chemistry.

We present the results of muon spin relaxation (μ+SR) studies on low dimensional molecular magnet systems. μ+SR measurements have been carried out on the Cu-based chain compounds CuX2(pyz) (where X = Br, Cl, NCS and pyz = pyrazine) as a function of temperature and applied longitudinal magnetic field. Oscillations in the time dependence of the muon polarization, characteristic of magnetic order at two distinct muon sites, are detected in both CuBr2(pyz) (below TN = 3.6(1) K) and CuCl2(pyz) (below TN = 3.2(2) K). No evidence of magnetic order is observed in Cu(NCS)2(pyz) down to 0.35 K. The results are discussed in terms of the estimated Cu-X-Cu and Cu-(pyz)-Cu exchange constants. The theory of μSR in high spin molecule (HSM) systems, which are effectively zero-dimensional magnets, is discussed and results are presented on [Ni 12(chp)12(O2CMe)12(H 2O)6(THF)6] (S = 12), [Mn9O 7(OAc)11(thme)(py)3(H2O) 2] (S = 17/2) and [Fe14(bta)6(O) 6(OMe)18 Cl6] (S ≥ 23). Measurements made in applied longitudinal magnetic fields on HSM materials at dilution refrigerator temperatures strongly suggest that dynamic local magnetic field fluctuations are responsible for the relaxation of the muon spin ensemble. Trends in temperature and field dependent behaviour in these systems, as probed by the muon, are discussed.

We report a monometallic dysprosium(iii) single molecule magnet with record energy barriers and unusual spin relaxation behaviour., We report a dysprosium(iii) bis(methanediide) single molecule magnet (SMM) where stabilisation of the highly magnetic states and suppression of mixing of opposite magnetic projections is imposed by a linear arrangement of negatively-charged donor atoms supported by weak neutral donors. Treatment of [Ln(BIPMTMS)(BIPMTMSH)] [Ln = Dy, 1Dy; Y, 1Y; BIPMTMS = {C(PPh2NSiMe3)2}2–; BIPMTMSH = {HC(PPh2NSiMe3)2}–] with benzyl potassium/18-crown-6 ether (18C6) in THF afforded [Ln(BIPMTMS)2][K(18C6)(THF)2] [Ln = Dy, 2Dy; Y, 2Y]. AC magnetic measurements of 2Dy in zero DC field show temperature- and frequency-dependent SMM behaviour. Orbach relaxation dominates at high temperature, but at lower temperatures a second-order Raman process dominates. Complex 2Dy exhibits two thermally activated energy barriers (Ueff) of 721 and 813 K, the largest Ueff values for any monometallic dysprosium(iii) complex. Dilution experiments confirm the molecular origin of this phenomenon. Complex 2Dy has rich magnetic dynamics; field-cooled (FC)/zero-field cooled (ZFC) susceptibility measurements show a clear divergence at 16 K, meaning the magnetic observables are out-of-equilibrium below this temperature, however the maximum in ZFC, which conventionally defines the blocking temperature, TB, is found at 10 K. Magnetic hysteresis is also observed in 10% 2Dy@2Y at these temperatures. Ab initio calculations suggest the lowest three Kramers doublets of the ground 6H15/2 multiplet of 2Dy are essentially pure, well-isolated |±15/2, |±13/2 and |±11/2 states quantised along the C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 Dy 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 C axis. Thermal relaxation occurs via the 4th and 5th doublets, verified experimentally for the first time, and calculated Ueff values of 742 and 810 K compare very well to experimental magnetism and luminescence data. This work validates a design strategy towards realising high-temperature SMMs and produces unusual spin relaxation behaviour where the magnetic observables are out-of-equilibrium some 6 K above the formal blocking temperature.

The complete molecule of the title compound, C24H30N4O4, is generated by crystallographic inversion symmetry. The molecule is S-shaped and the pyrrole groups have anantiortransconfirmation with respect to the central benzene ring, to which they are inclined by 76.38 (9)°. In the crystal, molecules are linkedviaC—H...O hydrogen bonds, forming layers parallel to theacplane. Within the layers there are C—H...π interactions present. There are, however, no significant interactions between the layers.

The original version of this Article contained an error in the spelling of the author Benjamin H. Williams, which was incorrectly given as Benjamin H. Willams. This has now been corrected in both the PDF and HTML versions of the Article.

The synthesis and structural characterization of two families of low-valent vanadium(III) {V6P4} and vanadium(III/IV) {V13P8} phosphonate complexes are reported. Magnetic characterization is reported for representative examples.

Proposals for systems embodying condensed matter spin qubits cover a very wide range of length scales, from atomic defects in semiconductors all the way to micron-sized lithographically-defined structures. Intermediate scale molecular components exhibit advantages of both limits: like atomic defects, large numbers of identical components can be fabricated; as for lithographically defined structures, each component can be tailored to optimize properties such as quantum coherence. Here, we demonstrate what is perhaps the most potent advantage of molecular spin qubits, the scalability of quantum information processing structures using bottom-up chemical self-assembly. Using Cr7Ni spin qubit building blocks, we have constructed several families of two-qubit molecular structures with a range of linking strategies. For each family, long coherence times are preserved, and we demonstrate control over the inter-qubit quantum interactions that can be used to mediate two-qubit quantum gates., Manuscript: 20 pages. Supplementary Information: 16 pages. npj Quantum Information, in press

The complete molecule of the title compound, C26H30N4O4, is generated by crystallographic inversion symmetry. The dihedral angle between the planes of the benzene and pyrrole rings is 45.20 (11)°; the N atom bonded to the the benzene ring and the pyrrole N atom are in asynconformation. The side chain adopts an extended conformation [N—C—C—C = 169.07 (17)° and C—O—C—C = −176.54 (17)°]. No directional interactions could be identified in the crystal packing.

We present a practical setup to perform continuous-wave X-band electron paramagnetic resonance spectroscopy by using planar microstrip lines and general purpose instrumentation. We fabricated Ag/alumina and Nb/sapphire microstrip resonators and transmission lines and compared their performance down to 2 K and under applied magnetic field. We used these devices to study single crystals of molecular Cr$$_{3}$$3 nanomagnets. By means of X-band planar resonators we measured angle-dependent spectra at fixed frequency, while broadband transmission lines were used to measure continuous wave spectra with varying frequency in the range 2-25 GHz. The spectra acquired at low temperatures allowed to extract the essential parameters of the low-lying energy levels of Cr$$_{3}$$3 and demonstrate that this method is particularly suitable to study small crystals of molecular nanomagnets.

Among the factors determining the quantum coherence of the spin in molecular magnets is the presence and the nature of nuclear spins in the molecule. We have explored modifying the nuclear spin environment in Cr$_7$Ni-based molecular nanomagnets by replacing hydrogen atoms with deuterium or the halogen atoms, fluorine or chlorine. We find that the spin coherence, studied at low temperatures by pulsed electron spin resonance, is modified by a range of factors, including nuclear spin and magnetic moment, changes in dynamics owing to nuclear mass, and molecular morphology changes., 8 pages, 5 figures, including supplemental material

Two new decametallic lanthanide complexes are reported, that are large odd-numbered rings with a further central metal site. This type of structure appears to be unprecedented. Magnetic studies show weak exchange interactions between the spin sites for the {Gd10} disc.

Reaction of [Fe-3(mu(3)-O)(O2C'Bu)(6)(HO2C'Bu)(3))](O2C'Bu) and [Ln(2)(O2C'Bu)(6)(HO2C'Bu)(6)] (Ln = lanthanide) with three different phosphonic acids produce a family of highly symmetrical {Fe(6)Ln(6)P(6)} clusters with general formula [Fe(6)Ln(6)(mu(3)-O)(2)(CO3)(O3PR)(6)(O2C'Bu)(18)], where R = methyl 1, phenyl 2, or n-hexyl 3. All the clusters present an analogous metal frame to the previously reported {Ni(6)Ln(6)P(6)} both being related to the well-known Wells-Dawson ion from polyoxometallate chemistry. These highly symmetrical clusters have, or approximate very closely to, D-3d point symmetry. Both Fe-III and Gd-III ions are magnetically isotropic and could thus exhibit promising magnetocaloric properties; hence we investigated the {Fe6Gd6P6} compounds accordingly. Modeling the magnetic data of [Fe6Gd6(mu(3)-O)(2)(CO3)(O3PPh)(6)(O2C'Bu)(18)] by the finite-temperature Lanczos method gave a strong antiferromagnetic Fe center dot center dot center dot Fe interaction (J(Fe-Fe) = -30 cm(-1)) and very weak Gd center dot center dot center dot Gd and Gd center dot center dot center dot Fe exchange interactions (vertical bar J vertical bar < 0.1 cm(-1)). The strong antiferromagnetic Fe center dot center dot center dot Fe interaction could account for the relatively smaller -Delta S-m value observed, compared against the {Ni6Gd6P6} analogues.

Ring a ring of roses: Spectacular nanoscale molecular assemblies have been created by design of individual polymetallic components that are then linked together through simple reactions. These include an assembly where six octametallic rings surround a dodecametallic central ring. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Researchers demonstrate that lanthanide single-molecule magnets (SMM) have the potential for new technological applications. SMMs can be considered as molecular analogues of classical bulk ferromagnets, making it possible to develop them for applications involving the storage and processing of digital information. The molecular nature of SMMs offers unique attributes that will allow information to be stored with higher densities and to be processed at significantly high speeds. Completely new applications of SMMs have also been considered, including in the development of molecular spintronics. SMM-based technology can only be realized when two major problems have been solved. Researchers will need to address the challenge of designing and synthesizing efficient SMMs that function at temperatures of practical use or which show physics beyond those achieved with classical magnets.

Understanding the anisotropic electronic structure of lanthanide complexes is important in areas as diverse as magnetic resonance imaging, luminescent cell labelling and quantum computing. Here we present an intuitive strategy based on a simple electrostatic method, capable of predicting the magnetic anisotropy of dysprosium(III) complexes, even in low symmetry. The strategy relies only on knowing the X-ray structure of the complex and the well-established observation that, in the absence of high symmetry, the ground state of dysprosium(III) is a doublet quantized along the anisotropy axis with an angular momentum quantum number mJ=±(15)/2. The magnetic anisotropy axis of 14 low-symmetry monometallic dysprosium(III) complexes computed via high-level ab initio calculations are very well reproduced by our electrostatic model. Furthermore, we show that the magnetic anisotropy is equally well predicted in a selection of low-symmetry polymetallic complexes.

The synthesis, structure and magnetic properties of an octametallic iron(III) ring is reported. Alternate edges of the ring are bridged by a hydroxide and two pivalates, or by one pivalate and two phenoxides. By addition of biphenol to the reaction a hexadecametallic iron(III) cage can be made where the 16 metals are arranged in two linked {Fe-8} rings. The rings are staggered with respect to one another, and lie on the vertices of an octagonal anti-prism. Magnetic studies on the octametallic ring allows exchange parameters to be obtained. Similar studies on the {Fe-16} barrel shows the exchange interactions within the rings to be similar, with a significant paramagnetic impurity present. (C) 2013 Elsevier Ltd. All rights reserved.

Three octanuclear phosphonate clusters, formulated as [Ln(8)((O3PBu)-Bu-t)(6)(mu(3)-OH)(2)(H2O)(2)((HOBu)-Bu-i)((O2CBu)-Bu-t)(12)]((NH3Pr)-Pr-i)(2) (Ln = Gd, Dy and Tb), were synthesised by refluxing a mixture of pivalic acid ((HO2CBu)-Bu-t), Ln(NO3)(3)center dot 6H(2)O, tert-Butyl phosphonic acid ((H2O3PBu)-Bu-t) and isopropylamine ((PrNH2)-Pr-i) in isobutyl alcohol (BuOH)-Bu-i.