Zn2Ln2 complexes with carbonate bridges formed by the fixation of carbon dioxide in the atmosphere: single-molecule magnet behaviour and magnetocaloric effect.

Three novel isostructural Zn2Ln2 cluster complexes with carbonate bridging ligands, {Zn2Ln2(µ3-CO3)2L2(acacF6)2}·CH3OH [H2L = N,N'-dimethyl-N,N'-(2-hydroxy-3-methoxy-5-methyl-benzyl)ethylenediamine; HacacF6 = hexafluoroacetylacetone; Ln = Dy, 1; Ln = Gd, 2; Ln = Eu, 3], have been prepared by fixing carbon dioxide in the atmosphere. Such carbonate bridging ligands may mediate ferromagnetic exchange between Ln3+ ions. The Zn2Dy2 compound (1) displays the properties of a single molecule magnet (SMM), showing slow magnetic relaxation at a 1500 Oe dc field, with an obviously larger Ueff/k value (83 K) with respect to the other carbonate-bridged Zn2Dy2 SMMs (≤34 K) and ZnDy dinuclear SMMs derived from the same ligand H2L used in this work (≤36.5 K), while the Zn2Gd2 compound (2) shows a moderate magnetocaloric effect and can be looked upon as a potential molecular material for low temperature magnetic refrigeration.

A homochiral Zn-Dy heterometallic left-handed helical chain complex without chiral ligands: anion-induced assembly and multifunctional integration.

Both second-order nonlinear optical and single-molecule magnet properties are observed in a novel 1D homochiral Zn-Dy heterometallic left-handed helical chain complex (1) without chiral ligands, which evolves from a Zn3Dy2 pentanuclear cluster complex (2), thanks to the structural guiding role of perchlorate anions.

Single-Molecule Magnet Behavior of 1D Coordination Polymers Based on DyZn2(salen)2 Units and Pyridin- N-Oxide-4-Carboxylate: Structural Divergence and Magnetic Regulation.

Two 1D coordination polymers composed of DyZn2(salen)2 units and pyridin- N-oxide-4-carboxylate have been prepared by solvothermal reactions. Complex 1 with the formula {[DyZn2(La)2(POC)](OH)(ClO4)}·H2O·MeOH [H2La] = N, N'-bis(3-methoxysalicylidene)-1,3-diaminopropane, POC- = pyridin- N-oxide-4-carboxylate] is composed of a zigzag chain cation [DyZn2(La)2(POC)] n2 n+ as well as isolated hydroxide and perchlorate anions. Complex 2 with the formula {[Dy3Zn7(Lb)6(POC)6](OH)3(ClO4)2}·9H2O [H2Lb] = N, N'-bis(3-methoxysalicylidene)-1,2-diaminoethane] is also an ionic compound containing isolated hydroxide and perchlorate anions, but its cation shows a novel nanowire structure, in which six-coordinate zinc(II) ions with C3 symmetry act as the axis and [DyZn2(Lb)2(POC)]2+ structural units as spiral leaves. Complex 1 shows good single-molecule magnet performance with an Ueff/ k value of 235.3(3.1) K ( Hdc = 0 Oe), one of the largest values for coordination polymers. A butterfly-shaped magnetic hysteresis loop can be monitored at as high as 3.8 K for 1, while a dc field is necessary for complex 2 to display slow magnet relaxation owing to the quantum-tunneling effect, with a much smaller Ueff/ k value of 14.6(0.2) K ( Hdc = 1000 Oe). The difference of magnetic properties has been explained using detailed ab initio calculations.

Arraying Octahedral {Cr2Dy4} Units into 3D Single-Molecule-Magnet-Like Inorganic Compounds with Sulfate Bridges.

Two novel 3D pure inorganic compounds based on [Cr2Dy4(µ4-O)2(µ3-OH)4]10+ cluster units and sulfate anions are presented. Both complexes exhibit single-molecule-magnet (SMM)-like behavior. Permutation of the magnetic moment direction among SMM-like cluster units has a significant effect on the performance of molecular nanomagnets, and directional consistency shows obvious advantages.

Etiologies of non-genetic epilepsies of child and adolescent, newly diagnosed in Ouagadougou, Burkina Faso.

INTRODUCTION: in sub-Saharan Africa, epilepsy is common and mainly concerns children before the age of 15 years. The data on childhood epilepsy is parcel, but a high prevalence of non-genetic epilepsy is frequently reported. EEG, TDM and MRI devices are rare. The aim of this work was to study the etiological aspects of non - genetic epilepsy of the child and adolescent, newly diagnosed in Ouagadougou, Burkina Faso. METHODS: This was a cross-sectional, descriptive, multicentric study, from 01/01/2016 to 31/12/2016, involving patients aged 0 to 18 years old, epileptic, newly diagnosed, in the city of Ouagadougou. Each patient included in the study was to have had an EEG and brain CT scan and/or brain MRI and to gather the anamnestic and electro clinical arguments for non-genetic epilepsy. Sociodemographic, clinical, EEG and neuroradiological data were analyzed. An univariate analysis was used to determine the electro-clinical and neuro-radiological characteristics associated with epilepsies of structural causes. RESULTS: In all 115 patients were collected, with an average age of onset of epilepsy of 8.2 years, a male predominance with a sex ratio to 1.67. Risk factors of epilepsy was present in 74.8%; They were dominated by perinatal events in 79.1%. Focal seizures, daily frequency of these seizures and focal epilepsy, were predominant, respectively in 53%, 58% and 60.9% of cases. Brain scan and Brain MRI where performed in 90.4% and 9.6% of patients, respectively. The brain sequelaes of perinatal adverse events, the sequelae of central nervous system infections, and the sequelae of cranial and brain trauma, with 34.8%, 14.8%, and 5.2% respectively, were the main causes of non- genetic epilepsies of the child and adolescent. No cause was identified in 37.4% of cases. CONCLUSION: The improvement of policies in the field of maternal and child health and the generalization of the control of infectious and parasitic diseases, including malaria, may contribute to the reduction of non-genetic epilepsy in sub-Saharan Africa.

Fine Tuning the Energy Barrier of Molecular Nanomagnets via Lattice Solvent Molecules.

Solvents play important roles in our lives, they are also of interest in molecular materials, especially for molecular magnets. The solvatomagnetic effect is generally used for trigger and/or regulation of magnetic properties in molecule-based systems, however, molecular nanomagnets showing solvatomagnetic effects are very difficult to obtain. Here we report four 3d-4f heterometallic cluster complexes containing ROH lattice solvent molecules, [Cu3Tb2(H3L)2(OAc)2(hfac)4]∙2ROH {H6L = 1,3-Bis[tris(hydroxymethyl)methylamino]propane, hfac- = hexafluoroacetylacetonate; R = CH3, 1; R = C2H5, 2; R = C3H7, 3; R = H, 4}. Single-molecule magnet (SMM) properties of these four complexes were observed to be dependent on the ROH lattice solvent molecule. There is an interesting magneto-structural correlation: the larger the R group, the higher the energy barrier. For the first time, the solvatomagnetic effect is used for the continuous fine adjustment of the energy barrier of 0D molecular nanomagnets. Additionally, [Cu3Dy2(H3L)2(OAc)2(hfac)4]∙2MeOH (5), an analogue of [Cu3Tb2(H3L)2(OAc)2(hfac)4]∙2MeOH (1), is also reported for comparison.

A Chinese Pane-Like 2D Metal-Organic Framework Showing Magnetic Relaxation and Luminescence Dual-Functions.

The discovery of graphene kicked off the curtain of atom-type two-dimensional (2D) materials. Layered metal-organic frameworks (MOFs) as parallel molecule-based 2D materials are more designable and more diverse, and magnetism may be induced by their metal ion nodes. However, the multifunctional 2D plane-like MOFs are very difficult to obtain. Here we describe a Chinese pane-like 2D MOF constructed from the Ln3+ cation and the nanoscale luminescent tritopic ligand tris(4'-carboxybiphenyl)-amine, responding to the slow magnetic relaxation and luminescence properties, respectively. Notably, the Dy-Dy distances separated by the tritopic ligand are up to 2 nm. Such a 2D molecular material is expected to have potential applications in optoelectronics and multimodal sensing.

A 3D MOF constructed from dysprosium(III) oxalate and capping ligands: ferromagnetic coupling and field-induced two-step magnetic relaxation.

A novel 3D MOF based on dysprosium(iii) oxalate and 1,10-phenanthroline (phen), {[Dy(C2O4)1.5phen]·0.5H2O}n (1), has been hydrothermally synthesized. The Dy(3+) ion acts as a typical Y-shaped node, linking to each other to generate an interesting 3D topology structure. Complex 1 is the first 3D DyMOF displaying both ferromagnetic coupling and field-induced two-step magnetic relaxation.

Field-Induced Relaxation of Magnetization in a Three-Dimensional LnMOF with the Second Bridging Ligand Squarate.

A three-dimensional (3D) dysprosium(III) metal-organic framework with nicotinate N-oxide (NNO-) and squarate (C4O4 2-) mixed bridging ligands, [Dy(NNO)(C4O4)(H2O)] n (1), has been hydrothermally synthesized. The dysprosium(III) ions are linked to each other by the squarate anions to form a unique dysprosium(III) squarate double-layered network; the NNO- anions then bridge such layers to complete the 3D framework. Complex 1 exhibits a two-step relaxation of magnetization under a dc field of 1000 Oe, with effective energy barrier values of 8.5 and 14.3 K, respectively.

Trinuclear [CoIII 2 -LnIII] (Ln=Tb, Dy) single-ion magnets with mixed 6-chloro-2-hydroxypyridine and Schiff base ligands.

The Schiff base ligand N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H(2)valdien) and the co-ligand 6-chloro-2-hydroxypyridine (Hchp) were used to construct two 3d-4f heterometallic single-ion magnets [Co(2) Dy(valdien)2 (OCH(3))(2) (chp)(2)]⋅ClO(4)⋅5 H(2)O 1 and [Co(2) Tb(valdien)(2) (OCH(3))(2)(chp)(2)]⋅ClO(4)⋅(2) H(2)O⋅CH(3)OH(2). The two trinuclear [Co(III) 2 Ln(III)] complexes behave as a mononuclear Ln(III) magnetic system because of the presence of two diamagnetic cobalt(III) ions. Complex 1 has a molecular symmetry center, and it crystallizes in the C2/c space group, whereas complex 2 shows a lower molecular symmetry and crystallizes in the P(2)1/c space group. Magnetic investigations indicated that both complexes are field-induced single-ion magnets, and the Co(III)(2)-Dy(III) complex possesses a larger energy barrier [74.1(4.2) K] than the Co(III)(2) -Tb(III) complex [32.3(2.6) K].

A single-molecule magnet featuring a parallelogram [Dy4(OCH2-)4] core and two magnetic relaxation processes.

An alkoxido-bridged tetranuclear Dy(iii) complex, [Dy4(H3L)2(OAc)6]·2EtOH {, H6L = 1,3-bis[tris(hydroxymethyl)methylamino]propane}, has been solvothermally synthesized and characterized. An X-ray crystallographic study revealed that complex possesses a novel "parallelogram" [Dy4(OCH2-)4] core, and a new binding mode η(3):η(3):η(1):η(1):η(1):η(2):µ(4) of the Bis-tris propane ligand was observed. Magnetic investigations indicated that it is a single-molecule magnet (SMM), showing two distinct magnetic relaxation processes with the energy barriers of 44 K and 107 K, respectively. Such a two-step magnetic relaxation process could be well described by the sum of two modified Debye functions.

Field-induced single-ion magnets based on enantiopure chiral ß-diketonate ligands.

A pair of homochiral ß-diketonate ligands (+)-3-trifluoroacetyl)camphor (d-Htfc) and (-)-3-trifluoroacetyl)camphor (l-Htfc) were used to construct two enantiomeric pairs of Dy(III) single-ion magnets [Dy(d-tfc)3(bpy)]2 (d-1)/[Dy(l-tfc)3(bpy)]2 (l-1) (bpy = 2,2'-bipyridine) and [Dy(d-tfc)3(phen)]·2H2O (d-2)/[Dy(l-tfc)3(phen)] (l-2) (phen = 1,10-phenanthroline). The capping aromatic N,N'-donors have a dramatic influence on the structural and magnetic characteristics of the Dy(III) ß-diketonate enantiomeric pairs: the cocrystal of two homochiral Dy(III) ß-diketonate stereoisomers with the 2,2'-bipyridine ligand was formed, showing field-induced single-ion magnet behaviors with a two-step relaxation process, while no stereoisomerization happened for the homochiral Dy(III) ß-diketonate with the 1,10-phenanthroline coligand, exhibiting a single relaxation process of the magnetization only. The anisotropy barriers of d-1 (36.5 and 46.1 K) are slightly smaller than those of l-1 (37.0 and 49.3 K), while d-2 has a larger energy barrier (30.5 K) with respect to l-2 (25.1 K).

Production of graphite chloride and bromide using microwave sparks.

Chemically modified graphite is an economical material with promising applications in its own right or as an intermediate in the synthesis of graphene. However, because of its extreme chemical inertness, to date only two methods-oxidation and fluorination-have been found which can modify graphite with high yield and large throughput. Herein, we describe a third chemical approach for the synthesis of large quantities of highly modified graphite which uses a microwave-sparks-assisted halogenation reaction. The resulting graphite halide can easily be exfoliated into monolayer graphene in organic solvents. The structure and electronic properties of the original graphene can be recovered after thermal annealing of the graphene halide. Furthermore, the graphene halide can be further modified by a variety of organic functional groups. Solution-processed field-effect transistors based on the graphene halides resulted in device performances were comparable to, or even better than, that of graphene oxide.

Heptanuclear 3d-4f cluster complexes with a coaxial double-screw-propeller topology and diverse magnetic properties.

Two novel coaxial double-screw-propeller heptanuclear 3d-4f cluster complexes are ferromagnetic: one exhibits a large magnetocaloric effect while the other a magnetic relaxation behavior, depending on the lanthanoid ions used.

A chiral screw propeller-like scalene triangle manganese(III) cluster.

The screw propeller-like cluster complex [Mn(3)(OMe)(L(Schiff))(3)(H(2)O)Cl(2)].2H(2)O {H(2)L(Schiff) = 2-[(E)-(R)-1-hydroxypropan-2-ylimino]methyl-6-methoxyphenol} is the first chiral triangle manganese cluster compound. It is also a rare nonsymmetrical triangle compound with an unequilateral arrangement of three manganese(iii) atoms. Both ferromagnetic and antiferromagnetic interactions exist between the Mn(3+) ions, exhibiting a magnetic anisotropy.

Nanoscale homochiral C(3)-symmetric mixed-valence manganese cluster complexes with both ferromagnetic and ferroelectric properties.

Both ferromagnetic and ferroelectric properties were observed in two enantiomerically pure nanoscale manganese cluster complexes supported by chiral Schiff base ligands, each of which comprises a 22-nucleus mixed-valence manganese(II/III) supratetrahedral cluster cation and an equilateral-triangle trinuclear manganese(III) cluster anion with C(3) symmetry.

Revealing novel telomere proteins using in vivo cross-linking, tandem affinity purification, and label-free quantitative LC-FTICR-MS.

Telomeres are DNA-protein structures that protect chromosome ends from the actions of the DNA repair machinery. When telomeric integrity is compromised, genomic instability ensues. Considerable effort has focused on identification of telomere-binding proteins and elucidation of their functions. To date, protein identification has relied on classical immunoprecipitation and mass spectrometric approaches, primarily under conditions that favor isolation of proteins with strong or long lived interactions that are present at sufficient quantities to visualize by SDS-PAGE. To facilitate identification of low abundance and transiently associated telomere-binding proteins, we developed a novel approach that combines in vivo protein-protein cross-linking, tandem affinity purification, and stringent sequential endoprotease digestion. Peptides were identified by label-free comparative nano-LC-FTICR-MS. Here, we expressed an epitope-tagged telomere-binding protein and utilized a modified chromatin immunoprecipitation approach to cross-link associated proteins. The resulting immunoprecipitant contained telomeric DNA, establishing that this approach captures bona fide telomere binding complexes. To identify proteins present in the immunocaptured complexes, samples were reduced, alkylated, and digested with sequential endoprotease treatment. The resulting peptides were purified using a microscale porous graphite stationary phase and analyzed using nano-LC-FTICR-MS. Proteins enriched in cells expressing HA-FLAG-TIN2 were identified by label-free quantitative analysis of the FTICR mass spectra from different samples and ion trap tandem mass spectrometry followed by database searching. We identified all of the proteins that constitute the telomeric shelterin complex, thus validating the robustness of this approach. We also identified 62 novel telomere-binding proteins. These results demonstrate that DNA-bound protein complexes, including those present at low molar ratios, can be identified by this approach. The success of this approach will allow us to create a more complete understanding of telomere maintenance and have broad applicability.

Thymine-protected gold nanoparticles: assembly and disassembly of gold nanoparticles in the presence of Hg2+.

In this paper, we describe thymine-protected gold nanoparticles. Assembly of thymine-protected gold nanoparticles into interconnected network was observed by gradual addition of Hg2+. Moreover, the plasmon absorption intensity varied almost linearly with the concentration of Hg2+, indicating that thymine-protected gold nanoparticles are potentially useful for signaling Hg2+. It is interesting to note that disassembly of gold nanoparticles occurred when the concentration of Hg2+ in the solution was high. It is proposed that the assembly of gold nanoparticles is due to the coordination of Hg2+ with thymine groups of adjacent nanoparticles, while the disassembly of gold nanoparticles is attributed to the electrostatic repulsion among the nanoparticles with positive charges which are generated through the coordination of Hg2+ with thymine groups absorbed on the surface of each nanoparticle.