Bis(dimethylamine-κN)bis[4-(1,2,4-triazol-1-yl)benzoato-κO]copper(II)

In the title compound, [Cu(C9H6N3O2)2(C2H7N)2], the Cu2+ cation is situated on an inversion center and is coordinated by the N atoms of two dimethylamine ligands and the carboxylate O atoms of two 4-(1,2,4-triazol-1-yl)benzoate anions, leading to a slightly distorted square-planar N2O2 coordination environment. In the crystal, intermolecular N—H...N hydrogen bonds between the amine function and the central N atom of the triazole ring lead to the formation of ribbons parallel to [1\overline{1}1]. Weak intermolecular C—H...O hydrogen-bonding interactions are also observed that consolidate the crystal packing.

Synthesis and structural characterization of a new heterometallicmolybdate coordination polymer based on a µ3-bridging amino alcohol

The reaction of Na2MoO4·2H2O with 2-amino-2-(hydroxymethyl)propane-1,3-diol (LH) in water at room temperature results in the formation of the heterometallic coordination polymer [Mo2O6L2(Na2(H2O)4)]·2H2O 1 (L = 2-amino-3-hydroxy-2-(hydroxymethyl)propan-1-olato). The structure of 1 consists of a neutral (Mo2O6) unit located on an inversion center. The Mo atoms exhibit hexa-coordination and are bonded to two terminal and two bridging oxido ligands, an alkoxide oxygen and the amine N atoms of an anionic ligand L– resulting in the formation of an edge-sharing {Mo2O8N2} bioctahedron. The Na+ cations of a centrosymmetric bis(μ2-aqua)-bridged (Na2(H2O)4)2+ unit are penta-coordinated and bonded to two symmetry related L– ligands via the oxygen atoms of their OH groups. The µ3-bridging tetradentate binding mode of L– results in the formation of a two-dimensional heterometallic coordination polymer. The constituents of 1 viz. (Mo2O6), (L)–, (Na2(H2O)4)2+ and lattice water molecules are interlinked with the aid of three varieties of hydrogen bonding interactions. The corresponding tungstate reported recently has been obtained through a similar synthetic protocol and is isostructural.

Identification of the position of piezoelectric polarization at the MoS2/metal interface

Transition-metal dichalcogenides, such as MoS2, lack their inversion center in monolayers, exhibiting in-plane piezoelectricity at a nanoscale thickness. In conventional piezoceramics devices, the operating mechanism has been well established that piezocharges appear at crystal edges and how these charges act in capacitor structures. Although TMDC monolayers are expected to possess a unique system due to their semiconductor nature, a strong interaction with contact metals alters physical properties predominantly. In this study, we identify the position of piezocharges in MoS2 generators based on the displacement current under dynamic strain. The present results provide new insights for the future device engineering.

Crystal structure of a TbIII–CuII glycinehydroxamate 15-metallacrown-5 sulfate complex

The core of the title complex, bis[hexaaquahemiaquapentakis(μ3-glycinehydroxamato)sulfatopentacopper(II)terbium(III)] sulfate hexahydrate, [TbCu5(SO4)(GlyHA)5(H2O)6.5]2(SO4)·6H2O (1), which belongs to the 15-metallacrown-5 family, consists of five glycinehydroxamate dianions (GlyHA2−; C2H4N2O2) and five copper(II) ions linked together forming a metallamacrocyclic moiety. The terbium(III) ion is connected to the centre of the metallamacrocycle through five hydroxamate oxygen atoms. The coordination environment of the Tb3+ ion is completed to an octacoordination level by oxygen atoms of a bidentate sulfate and an apically coordinated water molecule, while the copper(II) atoms are square-planar, penta- or hexacoordinate due to the apical coordination of water molecules. Continuous shape calculations indicate that the coordination polyhedron of the Tb3+ ion in 1 is best described as square antiprismatic. The positive charge of each pair of [TbCu5(GlyHA)5(H2O)6.5(SO4)]2 2+ fragments is compensated by a non-coordinated sulfate anion, which is located on an inversion center with 1:1 disordered oxygen atoms. Complex 1 is isomorphous with the previously reported compounds [LnCu5(GlyHA)5(SO4)(H2O)6.5]2(SO4), where Ln III = Pr, Nd, Sm, Eu, Gd, Dy and Ho.

Weak plasmon modes in periodic structures for terahertz detection and amplification

Weak plasmon modes in periodic structures with a two-dimensional electron gas without an inversion center are studied theoretically. The asymmetry of the electric field and Fourier harmonics of weak plasmon modes can lead to the excitation of a travelling plasmon by an electromagnetic wave normally incident on the structure and to the appearance of nonlinear effects leading to the rectification of the incident radiation. The low radiation damping of weak plasmon modes can be used to increase the efficiency of terahertz plasmon amplifiers.

A new tetrakis-substituted pyrazine carboxylic acid, 3,3′,3′′,3′′′-{[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(sulfanediyl)}tetrapropionic acid: crystal structures of two triclinic polymorphs and of two potassium–organic frameworks

Two polymorphs of the title tetrakis-substituted pyrazine carboxylic acid, 3,3′,3′′,3′′′-{[pyrazine-2,3,5,6-tetrayltetrakis(methylene))tetrakis(sulfanediyl]}tetrapropionic acid, C20H28N2O8S4, (H4L1), have been obtained, H4L1_A and H4L1_B. Each structure crystallized with half a molecule in the asymmetric unit of a triclinic P\overline{1} unit cell. The whole molecules are generated by inversion symmetry, with the pyrazine rings being located about inversion centers. The crystals of H4L1_B were of poor quality, but the X-ray diffraction analysis does show the change in conformation of the –CH2—S—CH2—CH2– side chains compared to those in polymorph H4L1_A. In the crystal of H4L1_A, molecules are linked by two pairs of O—H...O hydrogen bonds, enclosing R 2 2(8) ring motifs forming layers parallel to plane (100), which are linked by C—H...O hydrogen bonds to form a supramolecular framework. In the crystal of H4L1_B, molecules are also linked by two pairs of O—H...O hydrogen bonds enclosing R 2 2(8) ring motifs, however here, chains are formed propagating in the [001] direction and stacking up the a-axis. Reaction of H4L1 with Hg(NO3)2 in the presence of a potassium acetate buffer did not produce the expected binuclear complex, instead crystals of a potassium–organic framework were obtained, poly[(μ-3-{[(3,5,6-tris{[(2-carboxyethyl)sulfanyl]methyl}pyrazin-2-yl)methyl]sulfanyl}propanoato)potassium], [K(C20H27N2O8S4)] n (KH3L1). The organic mono-anion possesses inversion symmetry with the pyrazine ring being located about an inversion center. A carboxy H atom is disordered by symmetry and the charge is compensated for by a potassium ion. A similar reaction with Zn(NO3)2 resulted in the formation of crystals of a dipotassium-organic framework, poly[(μ-3,3′-{[(3,6-bis{[(2-carboxyethyl)sulfanyl]methyl}pyrazine-2,5-diyl)bis(methylene)]bis(sulfanediyl)}dipropionato)dipotassium], [K2(C20H26N2O8S4)] n (K2H2L1). Here, the organic di-anion possesses inversion symmetry with the pyrazine ring being located about an inversion center. Two symmetry-related acid groups are deprotonated and the charges are compensated for by two potassium ions.

Giant c-axis nonlinear anomalous Hall effect in Td-MoTe2 and WTe2

While the anomalous Hall effect can manifest even without an external magnetic field, time reversal symmetry is nonetheless still broken by the internal magnetization of the sample. Recently, it has been shown that certain materials without an inversion center allow for a nonlinear type of anomalous Hall effect whilst retaining time reversal symmetry. The effect may arise from either Berry curvature or through various asymmetric scattering mechanisms. Here, we report the observation of an extremely large c-axis nonlinear anomalous Hall effect in the non-centrosymmetric Td phase of MoTe2 and WTe2 without intrinsic magnetic order. We find that the effect is dominated by skew-scattering at higher temperatures combined with another scattering process active at low temperatures. Application of higher bias yields an extremely large Hall ratio of E⊥/E|| = 2.47 and corresponding anomalous Hall conductivity of order 8 × 107 S/m.

Synthesis and crystal structure of a heterobimetallic nickel–manganese 12-metallacrown-4 methanol disolvate monohydrate compound

The synthesis and crystal structure of the title compound [systematic name: di-μ-acetato-tetrakis(μ4-N,2-dioxidobenzene-1-carboximidato)hexamethanoltetramanganese(III)nickel(II) methanol disolvate monohydrate], [Mn4Ni(C7H4NO3)4(C2H3O2)2(CH4O)6]·2CH4O·H2O or Ni(OAc)2[12-MCMn(III)N(shi)-4](CH3OH)6·2CH3OH·H2O, where MC is metallacrown, −OAc is acetate, and shi3− is salicylhydroximate, are reported. The macrocyclic metallacrown is positioned on an inversion center located on the NiII ion that resides in the central MC cavity. The macrocycle consists of an MnIII–N–O repeat unit that recurs four times to generate an overall square-shaped molecule. Both the NiII and MnIII ions are six-coordinate with an octahedral geometry. In addition, the MnIII ions possess an elongated Jahn–Teller distortion along the z-axis of the coordination environment. The interstitial water molecule is slightly offset from and disordered about an inversion center.

Synthesis and crystal structure of 1,1′-bis{[4-(pyridin-2-yl)-1,2,3-triazol-1-yl]methyl}ferrocene, and its complexation with CuI

The title compound, [Fe(C13H11N4)2], was synthesized starting from 1,1′-ferrocenedicarboxylic acid in a three-step reaction sequence. The dicarboxylic acid was reduced to 1,1′-ferrocenedimethanol using LiAlH4 and subsequently converted to 1,1′-bis(azidomethyl)ferrocene in the presence of NaN3. The diazide was treated with 2-ethynylpyridine under `click' conditions to give the title compound in 75% yield. The FeII center lies on an inversion center in the crystal. The two pyridyltriazole wings are oriented in an anti conformation and positioned exo from the FeII center. In the solid state, the molecules interact by C—H...N, C—H...π, and π–π interactions. The complexation of the ligand with [Cu(CH3CN)4](PF6) gives a tetranuclear dimeric complex.

Crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the di-enol tautomeric form of the compound 3,3′-[(2-sulfanylidene-1,3-dithiole-4,5-diyl)bis(sulfanediyl)]bis(pentane-2,4-dione)

The reaction between [TBA]2[Zn(dmit)2] and 3-chloro-2,4-pentanedione yielded single crystals of the title compound, (3E,3′E)-3,3′-[(2-sulfanylidene-1,3-dithiole-4,5-diyl)bis(sulfanediyl)]bis(4-hydroxypent-3-en-2-one), C13H14O4S5, after solvent evaporation. The title compound crystallizes in the triclinic space group P\overline{1} with two molecules related by an inversion center present in the unit cell. The central thione ring moiety contains a carbon–carbon double bond covalently linked to two sulfoxide substituents located outside of the plane of the ring. The S—C—C—S torsion angles are −176.18 (8) and −0.54 (18)°. Intramolecular hydrogen bonds occur within the two dione substituents (1.67–1.69 Å). Adjacent asymmetric units are linked by C—H...S (2.89–2.90 Å), S...S [3.569 (1) Å] and O...H [2.56–2.66 Å between non-stacked thione rings] short contacts.