A Spontaneous Magnetic Moment in an Organic Radical: Synthesis and Characterization of Benzodioxepinyl-1,3,2-dithiazolyl.

The synthesis of the 1,3,2-dithiazolyl radical () derived from 3,4-dihydro-2H-1,5-benzodioxepine is described. Crystals of were grown by vacuum sublimation and adopt the orthorhombic space group . DC SQUID magnetometry reveals Curie-Weiss behavior for > 20 K ( = 0.

Magnetic properties and magnetocaloric effect of Ln = Dy, Tb carborane-based metal-organic frameworks.

We present the synthesis and magneto-thermal properties of carborane-based lanthanide metal-organic frameworks (MOFs) with the formula {[(Ln)(CB-L)(NO)(DMF)]·Solv}, where Ln = Dy or Tb, characterized by dc and ac susceptibility, X-ray absorption spectroscopy (XAS), X-ray magnetic circular dichroism (XMCD) and heat capacity measurements. The MOF structure is formed by polymeric 1D chains of Ln ions with three different coordination environments (Ln1, Ln2, Ln3) running along the -axis, linked by carborane-based linkers thus to provide a 3D structure. Static magnetic measurements reveal that these MOFs behave at low temperature as a system of * = 1/2 Ising spins, weakly interacting ferromagnetically along the 1D polymeric chain (/ = +0.

Luminescent and magnetic [TbEu] 2D metal-organic frameworks.

We present the synthesis, through a simple, microwave-assisted method, of lanthanoid-based 2D metal-organic frameworks (MOFs) of general formula [LnLn'(MeCOO)(PhCOO)], including homonuclear compounds ( = 1), LnEu, Tb, and heterometallic compounds, [TbEu]. The crystalline material is formed by neutral nanosheets held together by van der Waals interactions, which can be easily exfoliated by sonication. Photoluminescent emission in the visible range was observed for all of the synthesized 2D MOF compounds excitation of the ligand, showing benzoates are efficient antenna ligands.

Unraveling the Ordered Phase of the Quintessential Hybrid Perovskite MAPbI─Thermophysics to the Rescue.

Hybrid perovskites continue to attract an enormous amount of attention, yet a robust microscopic picture of their different phases as well as the extent and nature of the disorder present remains elusive. Using specific-heat data along with high-resolution inelastic neutron scattering and ab initio modeling, we address this ongoing challenge for the case of the ordered phase of the quintessential hybrid-perovskite MAPbI. At low temperatures, the specific heat of MAPbI reveals strong deviations from the Debye limit, a common feature of pure hybrid perovskites and their mixtures.

Temperature- and Field-Induced Transformation of the Magnetic State in CoGeBO.

A tetravalent-substituted cobalt ludwigite CoGeBO has been synthesized using the flux method. The compound undergoes two magnetic transitions: a long-range antiferromagnetic transition at = 84 K and a metamagnetic one at = 36 K. The sample-oriented magnetization measurements revealed a fully compensated magnetic moment along the - and -axes and an uncompensated one along the -axis leading to high uniaxial anisotropy.

Origin of the Unusual Ground-State Spin = 9 in a Cr Single-Molecule Magnet.

The molecular wheel [Cr(OMe)(OCCMe)], abbreviated {Cr}, with an unusual intermediate total spin = 9 and non-negligible cluster anisotropy, / = -0.045(2) K, is a rare case among wheels based on an even number of 3d-metals, which usually present an antiferromagnetic (AF) ground state ( = 0). Herein, we unveil the origin of such a behavior.

Anisotropic thermal expansion and electronic transitions in the CoBO ludwigite.

The investigations of the crystal structure, magnetic and electronic properties of CoBO at high temperatures were carried out using powder X-ray diffraction, magnetic susceptibility, electrical resistivity, and thermopower measurements. The orthorhombic symmetry (Sp.gr.

Slow Magnetic Relaxation in {[CoCxAPy)] 2.15 HO} MOF Built from Ladder-Structured 2D Layers with Dimeric SMM Rungs.

We present the magnetic properties of the metal-organic framework {[CoCxAPy]·2.15 HO} (Cx = bis(carboxypropyl)tetramethyldisiloxane; APy = 4,4`-azopyridine) () that builds up from the stacking of 2D coordination polymers. The 2D-coordination polymer in the plane is formed by the adjacent bonding of [CoCxAPy] 1D two-leg ladders with Co dimer rungs, running parallel to the -axis.

Luminescent and Magnetic Tb-MOF Flakes Deposited on Silicon.

The synthesis of a terbium-based 2D metal-organic framework (MOF), of formula [Tb(MeCOO)(PhCOO)] (), a crystalline material formed by neutral nanosheets held together by Van der Waals interactions, is presented. The material can be easily exfoliated by sonication and deposited onto different substrates. Uniform distributions of Tb-2D MOF flakes onto silicon were obtained by spin-coating.

Electronic and magnetic states of Fe ions in CoFeBO.

The ludwigite Co2FeBO5 has been studied experimentally using 57Fe Mössbauer spectroscopy and theoretically using DFT + GGA calculations. The room-temperature Mössbauer spectra are composed of four quadrupole doublets corresponding to the high-spin Fe3+ ions in octahedral oxygen coordination. All components undergo splitting below 117 K due to the magnetic hyperfine fields.

A Multifunctional Dysprosium-Carboxylato 2D Metall-Organic Framework.

We report the microwave assisted synthesis of a bidimensional (2D) MOF of formula [Dy(MeCOO)(PhCOO) ] (1) and its magnetically diluted analogue [La Dy (MeCOO)(PhCOO) ] (1 d). 1 is a 2D material with single-ion-magnet (SIM) behaviour and 1 d is a multifunctional, magnetic and luminescent 2D material. 1 can be exfoliated into stable nanosheets by sonication.

Reactions of Late First-Row Transition Metal (Fe-Zn) Dichlorides with a PGeP Pincer Germylene.

The reactivity of the PGeP germylene 2,2'-bis(di-isopropylphosphanylmethyl)-5,5'-dimethyldipyrromethane-1,1'-diylgermanium(II), Ge(pyrmPiPr ) CMe , with late first-row transition metal (Fe-Zn) dichlorides has been investigated. All reactions led to PGeP pincer chloridogermyl complexes. The reactions with FeCl and CoCl afforded paramagnetic square planar complexes of formula [MCl{κ P,Ge,P-GeCl(pyrmPiPr ) CMe }] (M=Fe, Co).

Coumarin-lanthanide based compounds with SMM behavior and high quantum yield luminescence.

Coumarin-based lanthanide complexes of general formula [Ln(coum)3(phen)(H2O)x]·yH2O (Ln-phen, x = 0,1, 0 ≤ y ≤ 1.5; phen = 1,10-phenanthroline; coum = 3-acetyl-4-hydroxylato-coumarin; Ln = Eu, Tb, Dy, Tm) and [Ln(coum)3(batho)]·0.7EtOH (Ln-batho, batho = 4,7-diphenyl-1,10-phenanthroline; Ln = Eu, Tb, Dy, Tm) were synthesized.

Magnetic chains of Fe clusters in the {FeYO} butterfly molecular compound.

The "butterfly" molecule [Fe3Y(μ3-O)2(CCl3COO)8(H2O)(THF)3] (in brief {Fe3YO2}) includes three Fe3+ ions which build a robust Fe3 cluster with a strong intracluster antiferromagnetic exchange and a total spin S = 5/2. It represents the starting magnetic system to study further interactions with magnetic rare earths when Y is replaced with lanthanides. We present heat capacity and equilibrium susceptibility measurements below 2 K, which show that each cluster has a sizeable magnetic anisotropy pointing to the existence of intercluster interactions.

Inclusion and reactivity of main group radicals in the porous framework MIL-53(Al).

Inclusion of the dithiadiazolyl and diselenadiazolyl radicals PhCNEEN (E = S, Se) into the porous framework, Al(bdc)(OH) [MIL-53(Al); bdc = 1,4-benzenedicarboxylate] was achieved by vacuum sublimation. PXRD studies reveal the inclusion complexes adopt the orthorhombic space group Imma. Variable temperature PXRD studies coupled with thermal analysis reveal that for PhCNSSN@MIL-53(Al), radical elimination from the pores at elevated temperatures is accompanied by an opening of the pore channels.

Exploring through-bond and through-space magnetic communication in 1,3,2-dithiazolyl radical complexes.

Reaction of the methyl-benzodithiazolyl radical (MBDTA) with M(hfac)2 complexes (M = Mn, Co, Zn) affords the complexes M(hfac)2(MBDTA)2. Strong antiferromagnetic exchange interactions are observed between M(ii) ions and the two S = 1/2 radicals (M = Mn, Co), whereas weak antiferromagnetic interactions are observed between radicals when using the diamagnetic Zn(ii) ion. Strong intermolecular exchange coupling is also evident in Mn(hfac)2(MBDTA)2 and attributed to π*-π* contacts between MBDTA radicals which are absent for the Co and Zn derivatives.

High relaxation barrier in neodymium furoate-based field-induced SMMs.

Two new neodymium molecular magnets of formula {[Nd(α-fur)(HO)]·DMF} (1) and {[NdLa(α-fur)(HO)]} (2), α-fur = CHOCOO, have been synthesized. In (1) the furoate ligands, in bidentate bridging mode, consolidate zig-zag chains running along the a-direction. Compound (2) is a magnetically diluted complex of a polymeric chain along the b-axis.

Slow relaxation in a {TbBa(α-fur)} polymer with Ln = Tb(iii) non-Kramers ions.

We report the synthesis, crystal structure and magnetic properties of a new heteronuclear polymeric complex based on non-Kramers Tb ions and carboxylic α-fur = C4H3OCOO ligands: {[Tb2Ba(α-fur)8(H2O)4]·2H2O}n. The α-furoate ligands consolidate 1D zig-zag chains running along the c-axis, formed by Tb2 dimers separated by Ba ions. Ab initio calculations, in combination with the fit of experimental data, predict that the single-ion magnetic ground state is highly anisotropic () and consists of a quasi-doublet with a ΔTb/kB = 3.

Structural, Magnetic, and Optical Studies of the Polymorphic 9'-Anthracenyl Dithiadiazolyl Radical.

The fluorescent 9'-anthracenyl-functionalized dithiadiazolyl radical (3) exhibits four structurally determined crystalline phases, all of which are monomeric in the solid state. Polymorph 3α (monoclinic P2/ c, Z' = 2) is isolated when the radical is condensed onto a cold substrate (enthalpically favored polymorph), whereas 3β (orthorhombic P2 2 2, Z' = 3) is collected on a warm substrate (entropically favored polymorph). The α and β polymorphs exhibit chemically distinct structures with 3α exhibiting face-to-face π-π interactions between anthracenyl groups, while 3β exhibits edge-to-face π-π interactions.

Localized magnetic moments in metallic SrB single crystals.

The specific heat [Formula: see text] of metallic SrB single crystals shows an anomalous behavior for [Formula: see text] K which varies strongly with an applied magnetic field. This is consistent with a two-level Schottky system. We ascribe the excess of [Formula: see text] in this temperature range to localized magnetic moments.

Correction: Magnetic properties of the seven-coordinated nanoporous framework material Co(bpy)(NO) (bpy = 4,4'-bipyridine).

Correction for 'Magnetic properties of the seven-coordinated nanoporous framework material Co(bpy)1.5(NO3)2 (bpy = 4,4'-bipyridine)' by Elena Bartolomé et al., Dalton Trans.

Chemical tunnel-splitting-engineering in a dysprosium-based molecular nanomagnet.

Total control over the electronic spin relaxation in molecular nanomagnets is the ultimate goal in the design of new molecules with evermore realizable applications in spin-based devices. For single-ion lanthanide systems, with strong spin-orbit coupling, the potential applications are linked to the energetic structure of the crystal field levels and quantum tunneling within the ground state. Structural engineering of the timescale of these tunneling events via appropriate design of crystal fields represents a fundamental challenge for the synthetic chemist, since tunnel splittings are expected to be suppressed by crystal field environments with sufficiently high-order symmetry.

Inclusion of a dithiadiazolyl radical in a seemingly non-porous solid.

Inclusion of the dithiadiazolyl radical PhCNSSN˙ into the dynamically porous metallocycle [Cu(L1)Cl], where L1 is the bidentate ligand 1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene, has been achieved by gas phase diffusion. Single crystal X-ray diffraction, powder X-ray diffraction, UV-visible spectroscopy, EPR and SQUID magnetometry studies confirm inclusion of the radical into this seemingly non-porous material, and illustrate the antiferromagnetic coupling between the paramagnetic host and guest species. The radical guest is readily released by heating or by the addition of solvent (CHCl).

Slow magnetic relaxation in a dimeric MnCa complex enabled by the large Mn(iii) rhombicity.

In this paper we present the characterization of a complex with the formula [MnCa(hmp)(HO)(CHCN)](ClO) (1), where hmp-H = 2-(hydroxymethyl)pyridine. Compound 1 crystallizes in the monoclinic space group C2/c with the cation lying on an inversion centre. Static magnetic susceptibility, magnetization and heat capacity measurements reflect a unique Mn(iii) valence state, and single-ion ligand field parameters with remarkable large rhombic distortion (D/k = -6.

Studies on a "Disappearing Polymorph": Thermal and Magnetic Characterization of α-p-NCCFCNSSN

The α-and β-phases of the thiazyl radical p-NCCFCNSSN (1) can be selectively prepared by careful control of the sublimation conditions, with the α-phase crystallizing preferentially when the substrate temperature is maintained below -10 °C, whereas the β-phase is isolated when the substrate temperature is maintained at or above ambient temperature. Differential scanning calorimatry studies reveal that the α-phase converts to the β-phase upon warming over the range 111-117 °C (ΔH = +4 kJ·mol) via a melt-recrystallization process, with the β-phase itself melting at 167-170 °C (ΔH = 27 kJ·mol). IR and Raman spectroscopy can be used to clearly discriminate between 1α and 1β.