Marie-Emmanuelle Boulon

imec · Surface and Interface Processing

This article reports the syntheses, characterization, structural description, together with magnetic and spectroscopic properties of two isostructural molecular magnets based on the chiral ligand N,N′-bis((1,2-diphenyl-(pyridine-2-yl)methylene)-(R,R/S,S)-ethane-1,2-diamine), L1, of general formula [Ln2(RR-L1)2(Cl6)]·MeOH·1.5H2O, (Ln = Ce (1) or Nd...

Device performance of two dimensional (2D) material based field effect transistors is severely limited by the relatively high contact resistance encountered at the contact-channel interface. Metal-graphene hybrid contacts have been previously used to improve the contact resistance of devices based on thick exfoliated materials. Here we report a nov...

The three Co(II) complexes [Co(bbp)2][Co(NCS)4]·4DMF (1), [Co(bbp)(NCS)2(DMF)]·2DMF (2), and [Co(bbp)(NCS)2] (3) have been synthesized and characterized by single-crystal X-ray diffraction, magnetic, and various spectroscopic techniques. Complexes 1 and 3 are obtained by the reaction of Co(NCS)2 with 2,6-bis(1H-benzo[d]imidazol-2-yl)pyridine (bbp),...

The concurrent effects of single-ion anisotropy and exchange interactions on the electronic structure and magnetization dynamics have been analyzed for a cobalt(II)-semiquinonate complex. Analogs containing diamagnetic catecholate and tropolonate ligands...

The family of complexes of general formula [Co(Me n tpa)(Xdiox)] ⁺ (tpa = tris(2-pyridylmethyl)amine, n = 0-3 corresponds to successive methylation of the 6-position of the pyridine rings; X = Br 4 , Cl 4 , H 4 , 3,5-Me 2 , 3,5-tBu 2 ; diox = dioxolene) was investigated by density functional theory (DFT) calculations to predict the likelihood of va...

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 t...

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 coordin...

The combination of lanthanoid nitrates with 18‐crown‐6 (18‐c‐6) and tetrahalocatecholate (X4Cat2‐, X = Cl, Br) ligands has afforded two compound series [Ln(18‐c‐6)(X4Cat)(NO3)]·MeCN (X = Cl, 1‐Ln; X = Br, 2‐Ln; Ln = La, Ce, Nd, Gd, Tb, Dy). The 18‐c‐6 ligands occupy equatorial positions of a distorted sphenocorona geometry, while the charged ligand...

Three 1D nickel coordination polymers (CPs) based on P,P’-diphenylethylenediphosphinic acid and three different bis-pyridine co-ligands, namely 4,4’-bipyridine (bipy), 1,2-bis(4-pyridyl)ethane (bpy-ane) and 1,2-bis(4-pyridyl)ethane (bpy-ene), were prepared in mild hydrothermal conditions from water solutions containing the dissolved reagents. The C...

Three families of tetraoxolene-bridged dinuclear rare earth (RE) complexes have been synthesised and characterised, with general formula [((HB(pz)3)2RE)2(μ-tetraoxolene)] (HB(pz)3(-) = hydrotris(pyrazolyl)borate; tetraoxolene = chloranilate (1-RE), the dianionic form of 2,5-dihydroxy-1,4-benzoquinone (2-RE), or its 3,6-dimethyl analogue (3-RE)). In...

In recent work we have reported the synthesis and physical properties of near-linear Ln(II) (Ln = lanthanide) complexes utilizing the bulky bis(silylamide) {N(Si(i)Pr3)2}. Herein, we synthesize trigonal-planar Ln(II) complexes by employing a smaller bis(silylamide), {N(Si(t)BuMe2)2} (N**), to study the effects of this relatively rare Ln geometry/ox...

Supplementary

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.

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.

A series of lanthanide complexes bearing organic radical ligands, [Ln(Cp(R))2(bipy·(-))] [Ln = La, Cp(R) = Cp(tt) (1); Ln = Ce, Cp(R) = Cp(tt) (2); Ln = Ce, Cp(R) = Cp″ (3); Ln = Ce, Cp(R) = Cp‴ (4)] [Cp(tt) = {C5H3(t)Bu2-1,3}(-); Cp″ = {C5H3(SiMe3)2-1,3}(-); Cp‴ = {C5H2(SiMe3)3-1,2,4}(-); bipy = 2,2'-bipyridyl], were prepared by reduction of [Ln(C...

The structural, electronic, magnetic and theoretical study of the complex [Co3(HL)2(μ-AcO)2(AcO)2], 1, (HL is the dianion obtained by deprotonation of N,N’-bis(salicylidene)-2-hydroxy-1,3-propanediamine and AcO is acetate) shows that 1 crystallizes with two independent molecules in the asymmetric unit. Each molecule is a trinuclear complex. Both mo...

The Ce(III) hydrotris(3,5-dimethylpyrazolyl)borate complex [Ce(TpMe2)2(κ2-dmpz)] (1) (TpMe2 = {HB(dmpz)3}−; dmpz = 3,5-dimethylpyrazolide) was isolated in fair yield from the reaction of [Ce(I)3(THF)4] with two equivalents of [K(TpMe2)] via the facile decomposition of TpMe2. [Ce(TpMe2)2(bipy)] (2) was synthesized in poor yield by the “one-pot” reac...

Single molecule magnets (SMMs) with one transition metal ion often rely on unusual geometry as a source of magnetically anisotropic ground state. Here we report a cobalt(II) cage complex with a trigonal prism geometry showing single ion magnet behavior with very high Orbach relaxation barrier of 152 cm-1. This, to our knowledge, is the largest repo...

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 environme...

Magneto-chiral dichroism (MχD) is a non-reciprocal, i. e. directional, effect observed in magnetised chiral systems featuring an unbalanced absorption of unpolarised light depending on the direction of the magnetisation. Despite the fundamental interest in a phenomenon breaking both parity and time reversal symmetries, MχD is one of the least inves...

The selective replacement of the central iron(III) ion with vanadium(III) in a tetrairon(III) propeller-shaped single-molecule magnet has allowed us to increase the ground spin state from S=5 to S=13/2. As a consequence of the pronounced anisotropy of vanadium(III), the blocking temperature for the magnetization has doubled. Moreover, a significant...

The experimental investigation of the molecular magnetic anisotropy in crystals in which the magnetic centers are symmetry related, but do not have a parallel orientation has been approached by using torque magnetometry. A single crystal of the orthorhombic organometallic Cp*ErCOT [Cp*=pentamethylcyclopentadiene anion (C5Me5−); COT=cyclooctatetraen...

Single-crystal torque magnetometry performed on weakly-coupled polynuclear systems provides access to a complete description of single-site anisotropy tensors. Variable-temperature, variable-field torque magnetometry was used to investigate triiron(iii) complex [Fe3La(tea)2(dpm)6] (), a lanthanum(iii)-centred variant of tetrairon(iii) single molecu...

The [Dy(tta)3(L)] complex behaves as a single ion magnet both in crystalline phase and in solution. Experimental and theoretical magnetic anisotropy axes perfectly match and lie along the most electro-negative atoms of the coordination sphere. Both VSM and MCD measurements highlight the robustness of the complex with the persistence of the memory e...

Angular-resolved single-crystal magnetometry is a key tool to characterise lanthanide-based materials with low symmetry, for which conjectures based on idealised geometries can be totally misleading. Unfortunately the technique is strictly successful only for triclinic structures, thus reducing significantly its application. By collecting out-of-eq...

W-band (ν ≅ 94 GHz) electron paramagnetic resonance (EPR) spectroscopy was used for a single-crystal study of a star-shaped Fe3Cr single-molecule magnet (SMM) with crystallographically imposed trigonal symmetry. The high resolution and sensitivity accessible with W-band EPR allowed us to determine accurately the axial zero-field splitting terms for...

Spotting trends: Upon going from Tb(III) to Yb(III) centers in the complexes of the DOTA(4-) ligand a reorientation of the easy axis of magnetization from perpendicular to parallel to the LnO bond of the apical water molecule is experimentally observed and theoretically predicted. Only ions with an odd number of electrons show slow relaxation of t...

Propeller-like [Fe(4)(L)(2)(dk)(6)] complexes, in which Hdk is a β-diketone and H(3)L is a tripodal alcohol, R-C(CH(2)OH)(3), exhibit tunable magnetic anisotropy barriers and retain their magnetic memory effect when chemically anchored on metal surfaces. Heteronuclear analogues of these M(4) complexes have been sought to afford a library of compoun...

Einem molekularen Schraubstock ähnelt der violette Bis(tert-butylscorpionat)-Eisen(II)-Komplex, der bei Raumtemperatur trotz des sterischen Einflusses von sechs Methylgruppen am Moleküläquator vollständig im Low-Spin-Zustand vorliegt. Die sperrigen tert-Butylsubstituenten an den Molekülenden wirken wie Feststellschrauben, die die bevorzugte Bildung...

Chitosan membranes were subjected to a pre-treatment in a double diffusion system, with a calcium solution in one chamber and a phosphate solution in the other chamber. Both chambers were separated by the chitosan membrane and subject to three mineralization periods (5, 10 and 15 minutes). After this pre-treatment the bioactivity of the different c...

Chitosan membranes were subjected to a pre-treatment in a double diffusion system, with a calcium solution in one chamber and a phosphate solution in the other chamber. Both chambers were separated by the chitosan membrane and subject to three mineralization periods (5, 10 and 15 minutes). After this pre-treatment the bioactivity of the different c...

A series of oxygen deficient perovskites Sr0.8Y0.2Co1−xFexO3−δ, has been prepared by solid state reaction in close ampoules. The structural study by transmission electron microscopy reveals the existence of extra reflection peaks resulting from ordering phenomenon of the oxygen anions. For x=0.5x=0.5 this implies a modulated structure characterized...