Slow magnetisation relaxation in tetraoxolene-bridged rare earth complexes

Two tetraoxolene-bridged dinuclear Dy(iii) complexes exhibit slow relaxation in ac magnetic susceptibility studies with zero-field quantum tunnelling of the magnetisation that is suppressed by the application of a dc magnetic field

Measuring spin ... spin interactions between heterospins in a hybrid [2]rotaxane

Use of molecular electron spins as qubits for quantum computing will depend on the ability to produce molecules with weak but measurable interactions between the qubits. Here we demonstrate use of pulsed EPR spectroscopy to measure the interaction between two inequivalent spins in a hybrid rotaxane molecule

Scaling up Electronic Spin Qubits into a Three-Dimensional Metal-Organic Framework

Practical implementation of highly coherent molecular spin qubits for challenging technological applications, such as quantum information processing or quantum sensing, requires precise organization of electronic qubit molecular components into extended frameworks. Realization of spatial control over qubit–qubit distances can be achieved by coordination chemistry approaches through an appropriate choice of the molecular building blocks. However, translating single qubit molecular building units into extended arrays does not guarantee a priori retention of long quantum coherence and spin–lattice relaxation times due to the introduced modifications over qubit–qubit reciprocal distances and molecular crystal lattice phonon structure. In this work, we report the preparation of a three-dimensional (3D) metal–organic framework (MOF) based on vanadyl qubits, [VO­(TCPP-Zn2-bpy)] (TCPP = tetracarboxylphenylporphyrinate; bpy = 4,4′-bipyridyl) (1), and the investigation of how such structural modifications influence qubits’ performances. This has been done through a multitechnique approach where the structure and properties of a representative molecular building block of formula [VO­(TPP)] (TPP = tetraphenylporphyrinate) (2) have been compared with those of the 3D MOF 1. Pulsed electron paramagnetic resonance measurements on magnetically diluted samples in titanyl isostructural analogues revealed that coherence times are retained almost unchanged for 1 with respect to 2 up to room temperature, while the temperature dependence of the spin–lattice relaxation time revealed insights into the role of low-energy vibrations, detected through terahertz spectroscopy, on the spin dynamics

Single Crystal Investigations Unravel the Magnetic Anisotropy of the “Square-In Square” Cr4Dy4 SMM Coordination Cluster

In the search for new single molecule magnets (SMM), i.e., molecular systems that can retain their magnetization without the need to apply an external magnetic field, a successful strategy is to associate 3d and 4f ions to form molecular coordination clusters. In order to efficiently design such systems, it is necessary to chemically project both the magnetic building blocks and the resultant interaction before the synthesis. Lanthanide ions can provide the required easy axis magnetic anisotropy that hampers magnetization reversal. In the rare examples of 3d/4f SMMs containing CrIII ions, the latter turn out to act as quasi-isotropic anchors which can also interact via 3d-4f coupling to neighbouring Ln centres. This has been demonstrated in cases where the intramolecular exchange interactions mediated by CrIII ions effectively reduce the efficiency of tunnelling without applied magnetic field. However, describing such high nuclearity systems remains challenging, from both experimental and theoretical perspectives, because the overall behaviour of the molecular cluster is heavily affected by the orientation of the individual anisotropy axes. These are in general non-collinear to each other. In this article, we combine single crystal SQUID and torque magnetometry studies of the octanuclear [Cr4Dy4(μ3-OH)4(μ-N3)4(mdea)4(piv)8]·3CH2Cl2 single molecule magnet (piv=pivalate and mdea=N-methyldiethanol amine). These experiments allowed us to probe the magnetic anisotropy of this complex which displays slow magnetization dynamics due to the peculiar arrangement of the easy-axis anisotropy on the Dy sites. New ab initio calculations considering the entire cluster are in agreement with our experimental results

Bistabilité des matériaux moléculaires (de la structure à la photocommutabilité)

La possibilité de créer des matériaux multifonctionnels rend les matériaux moléculaires particulièrement intéressants pour la miniaturisation des dispositifs électroniques. D autre part, la bistabilité est une propriété nécessaire pour de nombreuses applications notamment pour l électronique et les mémoires informatiques. Nous présentons ici deux exemples de bistabilité. Le premier concerne la réorganisation des charges portée sur les molécules de bis(éthylènedithio)tétrathiofulvalène (ET) par activation thermique dans un matériau multifonctionnel associant un sous-réseau organique constitué de molécules conductrices (les molécules de ET) et un sous-réseau inorganique porteur d un spin (l ion FeIII du complexe hexacyanoferrate). Dans le but d étudier la bistabilité de ce système, après la synthèse par électrocristallisation, la structure cristallographique a tout d abord été résolue à différentes températures. Des mesures physiques en température, conductivité électronique et de résonnance paramagnétique électronique (RPE), complètent la description de la transition thermique mise en évidence. Le second exemple de bistabilité est la commutation de spin thermique et photo-induite dans des complexes à base de FeII. La première étape de ces recherches a consisté en l élaboration d un montage optique permettant d effectuer des mesures physiques sous irradiation et adaptable à plusieurs expériences. Des mesures de susceptibilité magnétiques en température et sous irradiation ont permis de mettre en évidence la transition thermique de nos systèmes et l effet LIESST (Light Induced Exited Spin State Trapping) pour l un d entre eux.Combining multiple properties into one material turns molecular materials very attractive. Moreover, bistability is often a necessary condition to manage electronic or memory devices. We present here two examples of bistabiliy. The first one consists in a thermo-activated charge re-organization on bis(ethylenedithio)tetrathiafulvalene (ET) molecules in a multifunctional material which associates an organic sub-lattice containing conductive moieties (ET molecules) and an inorganic sub-lattice containing spin (on the FeIII ion in the hexacyano-ferrate complex). Aim at describing the bistability of this system, after synthesis by electrocrystallization, crystallographic structure has been solved at different temperatures. Physical measurements under thermal variation were carried out to complete the description of the phenomena we evidenced. The second example is the spin change in FeII based complexes. First step was to elaborate an optical montage allowing under irradiation measurements suitable for various experiences. Magnetic susceptibility measurements were performed. Thermally and optically induced spin change (called LIESST effect for Light Induced Exited Spin State Trapping) were evidence.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

NMR, EPR and UV/Vis spectroscopic data, SQUID magnetometry and cyclic voltammetry data for Inorganics-101167

Abstract: Supporting research data for Inorganics-101167 deposited to align with EPSRC guidelines

Experimental and Theoretical Studies on the Magnetic Anisotropy in Lanthanide(III)-Centered Fe3 Ln Propellers

Compounds [Fe3 Ln(tea)2 (dpm)6 ] (Fe3 Ln; Ln= Tb-Yb, H3 tea=triethanolamine, Hdpm=dipivaloylmethane) were synthesized as lanthanide(III)-centered variants of tetrairon(III) single-molecule magnets (Fe4 ) and isolated in crystalline form. Compounds with Ln=Tb-Tm are isomorphous and show crystallographic threefold symmetry. The coordination environment of the rare earth, given by two tea(3-) ligands, can be described as a bicapped distorted trigonal prism with D3 symmetry. Magnetic measurements showed the presence of weak ferromagnetic Fe⋅⋅⋅Ln interactions for derivatives with Tb, Dy, Ho, and Er, and of weak antiferromagnetic or negligible coupling in complexes with Tm and Yb. Alternating current susceptibility measurements showed simple paramagnetic behavior down to 1.8 K and for frequencies reaching 10000 Hz, despite the easy-axis magnetic anisotropy found in Fe3 Dy, Fe3 Er, and Fe3 Tm by single-crystal angle-resolved magnetometry. Relativistic quantum chemistry calculations were performed on Fe3 Ln (Ln=Tb-Tm): the ground J multiplet of Ln(3+) ion is split by the crystal field to give a ground singlet state for Tb and Tm, and a doublet for Dy, Ho, and Er with a large admixture of mJ states. Gyromagnetic factors result in no predominance of gz component along the threefold axis, with comparable gx and gy values in all compounds. It follows that the environment provided by the tea(3-) ligands, though uniaxial, is unsuitable to promote slow magnetic relaxation in Fe3 Ln species