Space Group Pna21 Research Articles

Synthesis and Characterization of [Fe(picolinate)<sub>3</sub>][MnNi(oxalate)<sub>3</sub>].CH<sub>3</sub>OH Polymeric Complex

Polymeric complex [Fe(picolinate)3][MnNi(oxalate)3].CH3OH has been successfully synthesized using H-tube technique. The chemical composition of the synthesized product was determined by Elemental Analysis and Atomic Absorption Spectrometry. Infrared spectrum shows that the oxalate ligand acts as a bridging ligand. The crystalline product exists in the form of monoclinic structure and space group P21n as shown on the pattern of X-Ray Diffraction and has a similar structure with [Fe(bpp)2][MnCr(oxalate)3] complex. The magnetic susceptibility of the polymeric complex exhibits high spin and paramagnetic behavior.

A Tridentate In Situ Generated Ligand Leading the Self-Assembly of a Transition Metal Coordination Polymer: Solvothermal Synthesis and Structural Characterization of 1D Cadmium Pyridine-2-Carboxylate

This work involves the synthesis and characterization of a transition metal based one-dimensional coordination polymer, [Cd2(2-pc)4]n, (2-pc = pyridine-2-carboxylate), which is the first example of a Cd-pyridin-2-carboxylate solid state structure with no other ligands. 2-pc ligand was not originally included in the reaction mixture. This ligand formed in situ from the mixture of cadmium acetate, 2,4,6-Tris(2-pyridyl)-s-triazine and ethyl alcohol under solvothermal reaction conditions. The coordination polymer was characterized by elemental analysis, IR spectroscopy, thermogravimetry and single crystal X-ray diffraction. The coordination compound crystallizes in the orthorhombic space group Pna21 with unit cell dimensions a = 8.2570(7) Å, b = 19.4647(14) Å, and c = 7.6715(6) Å. The structure of the compound consist of edge sharing distorted octahedrons (CdN2O4) and each cadmium atom is N/O chelated by two 2-pc ligands where the oxygen atoms act as bridging toward the adjacent cadmium ions.

Employing tetrahedral {Zn4O} clusters as building subunits to construct a new acentric metal–organic framework

Hydrothermal reaction of H3L and Zn(NO3)2 produced a new noncentrosymmetric Zn(II) compound, namely [Zn4(μ4-O)(L)2(H2O)3]n (1 H3L=biphenyl-3,4,5-tricarboxylic acid). Single-crystal X-ray diffraction analysis reveals that compound 1 crystallizes in the acentric Pna21 space group and features a 3D framework based on isolated tetrahedral {Zn4O} clusters as building subunits. Topological analysis reveals that it can be simplified into a 3-nodal (3,3,6)-connected topological network with the Schläfli symbol of {4·62}2{42·67·86}. In addition, the nonlinear optic and luminescent properties of this compound were also investigated at room temperature.

Hydrogen bond order/disorder in a polar one-dimensional confined ice

Ice is one of the most well-studied substances yet forming a polar, bulk phase, where the water molecule dipoles are all aligned, has proved to be challenging. One approach is to confine the water in nanotubes, such that the molecules are restricted in orientation [1], however this hinders their use as ferroelectric devices – the primary application of polar ices. An alternative is to exploit the voids in nanoporous crystalline hosts but there are, as yet, no reported confined ice systems where the water molecules are able to switch between paraelectric and ferroelectric states whilst retaining a crystalline structure. One such porous system is 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) tetrahydrate, where columnar stacks of the HHTP molecules are arranged in a pseudo-square arrangement and the water molecules occupy the pores, forming one-dimensional, meso-helical chains. The structure, determined previously [2], crystallises in Pbcn, however this places inversion centres within the water chains leading to unphysical intermolecular H...H contacts. A variable-temperature single-crystal X-ray diffraction investigation is described where careful consideration of the data shows how long-range dipole ordering within and between the water chains is induced, by varying temperature, transforming the crystal structure to the polar Pna21 space group [3]. Subsequent reassessment of the ambient temperature structure reveals a superposition of opposing polarisation states.

Polar octahedral rotations, cation displacement and ferroelectricity in multiferroic SmCrO3

Our thorough synchrotron diffraction studies provide a clue on the origin of ferroelectricity in SmCrO3. Careful observation demonstrates that polar order develops in the paramagnetic state. Rietveld refinement of the diffraction data confirms that emergence of polar order is correlated with the structural transformation from centrosymmetric Pbnm to non-centrosymmetric Pna21 space group of the distorted orthorhombic structure. Rotations of polar CrO6 octahedra and Sm displacement are proposed to be correlated with the emergence of polar order, which is extended over a wide temperature range and increases gradually with decreasing temperature. This is consistent with the relaxor behavior as evident from the frequency-dependent dielectric response satisfying the Vogel-Fulcher law. A non-collinear to collinear spin transformation is suggested well below the spin reorientation transition. Appearance of ferroelectricity without any correlation to the antiferromagnetic order in SmCrO3 suggests a new class of ferroelectricity. All-electron full-potential first-principles calculation demonstrates significant Sm-Cr hybridization near the Fermi level, which substantiates the experimental findings.

Topological analysis of the three-dimensional coordination polymer poly[(μ4-azido)[μ4-5-(pyridin-4-yl)tetrazolido]disilver(I)

The title compound, [Ag2(C6H4N4)(N3)]n, was obtained under hydrothermal conditions at 433 K. The asymmetric unit of the orthorhombic space group (Pna21) consists of two Ag(+) cations, an anionic 5-(pyridin-4-yl)tetrazolide (4-ptz(-)) ligand and an anionic azide ligand. Both Ag(+) centres are coordinated by four N atoms, forming a distorted tetrahedral coordination environment. When all the component ions are viewed as 4-connected nodes, the whole three-dimensional network can be regarded topologically as a new kind of 4,4,4,4-connected net with the Schläfli symbol (4.8(5))(4(2).8(4))(4(3).8(3))2.

Highly chemical and thermally stable luminescent EuxTb1−xMOF materials for broad-range pH and temperature sensors

New luminescent Ln-MOFs, [Ln2(D-cam)(Himdc)2(H2O)2] (Ln = Eu 1, Tb 2, D-H2cam = D-camphoric acid, H3imdc = 4,5-imidazole dicarboxylic acid) have been synthesized via hydro(solvo)thermal reactions. X-ray single crystal structure analysis reveals that they are isomorphic and both crystallize in the orthorhombic space group Pna21. Compound 1 shows good chemical resistance to both acidity and alkalinity solutions with pH ranging from 2 to 13 and is highly stable in several boiling solvents, which make it potentially useful for wide-range pH sensors, especially in the physiological environment with pH = 6.8–8.0. Careful adjusting of the codoping ratio of Eu3+/Tb3+ into the same framework of 1 affords a mixed Ln-MOF, formulated as [Eu0.7Tb0.3(D-cam)(Himdc)2(H2O)2]3, which has demonstrated to be a viable probe for sensing temperature in a wide temperature range from 100 to 450 K.

Thermal synthesis and structural characterization of the orthorhombic Th2(PO4)(P3O10)

Polycrystalline thorium(IV) phosphate-triphosphate, Th2(PO4)(P3O10) (1), was obtained by (NH4)2Th(PO4)2·H2O (2) heating from room temperature to 1,273 K. 1 crystallizes in the orthorhombic space group Pn21 a (a = 11.6846(2) A, b = 7.1746(1) A, c = 12.9320(3) A, Z = 4). Combining powder synchrotron X-ray diffraction data and DFT geometry optimization, a structural model is proposed for 1. The structure is built on ThO8 polyhedral chains along the b-axis. PO4 3− and P3O10 5− groups coexist in the structure and the latter group forms non-linear chains. Cohesion of the structure is made by the linkage of ThO8 chains by PO4 and P3O10 groups. Thermal transformation from 2 to 1 was monitored by thermogravimetric analysis (activation energy as a function of the extent of conversion was obtained from Kissinger–Akahira–Sunose (KAS) isoconversional method) and powder X-ray thermo-diffraction. For 2, the dehydration process takes place in two steps, with the apparition of a layered intermediate phase, (NH4)2Th(PO4)2·nH2O (0 < n < 1, d = 6.42 A), previously to the formation of (NH4)2Th(PO4)2 (d = 6.31 A). The condensation process produces an amorphous material that crystallizes to α-ThP2O7 (3) when the temperature increases. At 1,273 K, 3 slowly transforms to 1.

Doping effect from Ag and Sb in KBiO3 photocatalyst: first principles study

The direct band gap of cubic KBiO3 with space group Pn-3 calculated from the standard density functional theory (DFT) within the Perdew–Burke–Ernzerhof functional is ∼0·54 eV and obviously underestimated in comparison with the experimental value of 2·1 eV. Using the Heyd–Scuseria–Ernzerhof hybrid functional, the band gap can be corrected to ∼1·77 eV. Further, first principles calculations on Ag/Sb doped KBiO3 indicate that a flexible band gap can be obtained by adjusting the amount of Ag and Sb doping in KBiO3. In particular, K0·667Ag0·333Bi0·5Sb0·5O3 has a DFT band gap of 0·61 eV and larger dispersion at the bottom of the conduction band with smaller effective electron masses, which would lead to an enhancement in photocatalytic activity in comparison with pure KBiO3.

Thermo-elastic behavior and P/T phase stability of TlAlSiO4 (ABW)

The P/T phase stability and the thermo-elastic behavior of synthetic TlAlSiO4 [ABW framework type, space group Pna21, a=8.2719(2), b=9.4373(2), c=5.4180(1)Å] have been investigated up to 950°C (at room-P) and up to 8GPa (at room-T) by means of in situ synchrotron powder diffraction with a diamond anvil cell and with a high-temperature furnace. The Rietveld structure refinement of TlAlSiO4 at room P/T confirms the general structure model previously reported. Only one independent Tl site, with full site occupancy and close to channel wall, represents the extra-framework population. No phase transition has been observed within the temperature- and pressure-range investigated. P–V data were fitted to a second-order Birch–Murnaghan Equation of State (BM-EoS), giving: V0=420.76(5)Å3, KT0=48.8(2)GPa. The evolution of the lattice parameters with pressure shows a significantly anisotropic compressional pattern. The elastic parameters calculated with a “linearized” second-order BM-EoS are: KT0(a)=21.96(7)GPa for the a-axis; KT0(b)=68(1)GPa for the b-axis, and KT0(c)=112(2)GPa for the c-axis. The volume thermal expansion with T was modeled by the polynomial function: V(T)/V0=1+α0·ΔT+α1·ΔT2=1+4.44(3)·10−5·ΔT−2.3(3)·10−9·ΔT2. The anisotropic thermal scheme is characterized by a negative thermal expansion along [010] (i.e. α0(b)=−8.5(1)·10−6°C−1), almost no expansion along [001] (i.e. α0(c)=0.9(1)·10−6°C−1) and a positive expansion along [100] (i.e. α0(a)=52.4(1)·10−6°C−1). A comparative analysis of the thermo-elastic behavior of the isotypic TlAlSiO4 and CsAlSiO4 is carried out.

Structural Investigation of Na2MnSiO4, a Novel Cathode Material for Rechargeable Sodium Ion Batteries

Lithium ion batteries dominate the world’s requirements of portable power storage due to their superior energy and power capability. However, as the focus of battery applications shifts towards larger scale energy storage, placing pressure on the declining amount of usable lithium, research interests shift towards the development of sodium ion batteries. Recently, various sodium based cathode materials have been based on structures that allow lithium insertion. Mixed-polyanion lithium compounds have been shown to be suitable precursors as they have the structural stability required for the complete exchange of lithium with sodium.1 The silicates Li2 MSiO4, (M = Mn and Fe), fulfil today’s requirements of safe, cheap and sustainable cathode materials especially due to the abundance of iron, manganese and silicon. The relatively higher theoretical capacities for these materials arise due to the possible extraction of two lithium ions accessing the M 2+/M 3+ and M 3+/M 4+ redox couples.2 The clear advantages of Li2 MSiO4, (M = Mn and Fe), over other lithium insertion compounds have made these materials attractive as possible analogues for cathode materials in Na-ion batteries.While the structure of Na2MnSiO4 (monoclinic, space group Pn) has been reported previously employing conventional X-ray diffraction technique,3 the possibility of this compound to be utilised as a cathode material in sodium ion batteries has not been explored. To date, we have been able to synthesise the Na2MnSiO4 and investigated the structural parameters of the compounds through the combination of synchrotron X-ray and neutron powder diffraction studies. This contribution will also address the electrochemical behaviour of this compound, including structural changes which occur in Na2MnSiO4during electrochemical cycling and the connection of these structural changes to the observed properties.

Synthesis and Structure of an Aluminum Bis(3-chloropentanedionate) Isopropoxide: [Al(μ-OiPr)(3-Clacac)2

1A [Al(OiPr)3]4 was reacted at ambient temperature with 3-chloropentanedione (3-ClacacH) in 1 : 1 molar ratio in toluene, to obtain the mono-substituted product. However, the bis-substituted dinuclear tetrakis(3-chloropentanedionato)-di-m-isopropoxy-dialuminum(III) [Al(μ-OiPr)(3-Clacac)2]2 () was isolated in 46% yield upon aging of the reaction mixture at −10 °C. The supernatant upon aging yielded a crop of tris-3-chloroacetylacetonate Al(3-Clacac)3·H2O (1) in 13% yield. Complexes 1A (monoclinic, space group P21/c with Z = 2) and 1(cubic, space group P43n with Z = 8) were characterized by elemental analyses, NMR and IR spectroscopy and single-crystal X-ray crystallography.

2-Phenylethylammonium p-hydroxybenzoate: Growth, structural, spectral, thermal, optical and mechanical characterization

An efficient nonlinear optical single crystal of 2-phenylethylammonium p-hydroxybenzoate (2PPHB) was grown from aqueous solution by slow evaporation solution growth method. Single crystal X-ray diffraction studies confirmed that 2PPHB crystallizes in orthorhombic crystal system with non-centrosymmetric space group of Pna21. The presence of functional groups in the synthesized compound was identified by FTIR spectral analysis. The grown crystals were thermally stable up to 155°C. UV–vis absorption, photoluminescence and birefringence optical properties of grown crystal were explored. The laser induced surface damage threshold and relative second harmonic generation properties of the grown crystal were studied using Q-switched Nd:YAG laser. The variation of dielectric properties of the grown crystal with frequency was investigated for different temperatures. The mechanical response of the crystal was studied by Vicker's microhardness technique.

Synthesis, thermal analysis, and crystal structure of potassium triiodomercurate monohydrate

Single crystals of potassium triiodomercurate monohydrate KHgI3 · H2O are synthesized and studied by X-ray diffraction: space group Pna21; a = 8.57961(11), b = 9.23621(13), and c = 11.38977(16) A, Z = 4; R= 0.0574. Thermal conditions of decomposition of the compound are studied by differential scanning calorimetry.

Synthesis, Crystal Structure and Characterization of (Z)-2-N′-hydroxyisonicotinamidine

The compound (Z)-2-N′-hydroxyisonicotinamidine, (2) was synthesized and characterized by 1H NMR, FT-IR, FAB-Mass, UV-Visible Spectra, and elemental Analysis. Its molecular structure was solved by single crystal X-ray diffraction method. The title molecule, C6H7N3O is crystallized in the orthorhombic crystal system with the space group Pna21 and with unit cell parameters a = 12.5664(8) Å, b = 8.8622(6) Å, c = 5.7953(4) Å, α = 90°, β = 90°, γ = 90°, and Z = 4. The molecular and crystal structure of the title molecule is stabilized by an intramolecular interaction of the type N—H···O, and the intermolecular interactions of types N—H···N and O—H···N.

Trinepheline and fabriesite: two new mineral species from the jadeite deposit of Tawmaw (Myanmar)

Two new mineral species, trinepheline (NaAlSiO 4 ) and fabriesite (Na 3 Al 3 Si 3 O 12 · 2H 2 O), are described from late-stage metamorphic veins of the jadeite deposit of Tawmaw-Hpakant (Myanmar). Both minerals and their names were approved by the IMA Commission on New Minerals and Mineral Names (IMA 2012–024 and IMA 2012–080). The name trinepheline is known in literature for the polymorphs of synthetic NaAlSiO 4 with a value of the c parameter that is three times that of nepheline. Fabriesite is named in memory of Jacques Fabries (1932–2000), former professor of the “Museum National d’Histoire Naturelle” in Paris (France). Fabriesite and trinepheline occur intimately intergrown together with nepheline, more rarely with albite and other feldspar-group phases such as banalsite and stronalsite; other associated minerals are jadeite and secondary products like natrolite and harmotome. All phases have been identified via electron backscatter diffraction (EBSD) patterns. Both fabriesite and trinepheline are pseudomorph after jadeite and occur as skeletal allotriomorphic crystals up to 15–20 μm long and 5–10 μm wide. They are white to yellowish in hand specimen, colourless in thin section; the streak is white and the lustre appears vitreous to greasy; they are non-fluorescent; Mohs’ hardness is 5–5½. Empirical formulae (EMPA analysis) are very close to the ideal compositions with traces of Ca and K for trinepheline, and of Ca, K, Ba, Mg, Fe, and Mn for fabriesite. Calculated densities are 2.642 g cm −3 for trinepheline (space group P 6 1 , a = 9.995 A, c = 24.797 A) and 2.386 g cm −3 for fabriesite (space group Pna 2 1 , a = 16.426 A, b = 15.014 A, c = 5.223 A), respectively. The strongest five lines in the calculated X-ray powder diffraction patterns [ d (A) ( I )( hkl )] are: 3.163(100)(122), 3.834(81)(023), 4.133(49)(006), 3.272(40)(120) and 2.403(31)(127) for trinepheline; 3.41(100)(240), 4.41(77)(201), 2.97(70)(421), 2.61(40)(002) and 8.21(36)(200) for fabriesite.

Synthesis and antimicrobial activities of copper(II) complexes of N(4),N(11)-dimethyl (LBZ & LCZ) and N(4)-monomethyl (LCZ1)-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane. Crystal and molecular structure of [CuLCZ1](ClO4)2

Naturally occurring azamacrocyclic metal complexes such as haems, chlorophyll, vitamin B12, and the factor F430 carry pendent ring substituemts and axial co-ligands that act as functional components in these important biological systems. Design of related systems with structural features related to their natural counterparts is thus a multifarious challenge. With this in mind, we have recently reported on the characterization and antimicrobial activities of tetraazacyclotetradecanes and their Ni2+ complexes. Here, we present results on modified N-pendent ligands and their Cu2+ complexes: The interaction of two isomers of 3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane, LB and LC (differing in the orientation of the CH3 groups on the chiral C atoms), with CH3I resulted in the substitution of the N(4) and N(11) protons by CH3, forming the dimethyl derivatives LBZ and LCZ, when reacted with CH3I in the ratio 1:2, yielded the N(4) monomethyl derivative LCZ1. On reaction with Cu(ClO4)2·6H2O, the square-planar complexes [CuL](ClO4)2 (L=LBZ, LCZ, or LCZ1).) were obtained. The complex cations [CuLBZ]+ and [CuLCZ]+ undergo axial ligand addition with the anions X=NCS−, NO2−, NO3− Cl−, Br− and I− to form six-coordinate trans-[CuL′X2] (L′=LBZ or LCZ). The compounds have been characterized on the basis of analytical, spectroscopic, conductometric and magnetochemical data. The structure of [CuLCZ1](ClO4)2 {space group Pn, No. 2, a=10.3581(12), b=8.8335(10), c=14.2584(16)Å; β=99.917(3) (2)°} has been determined by X-ray crystallography. The copper centre is coordinated to an N4 donor set of LCZ1 in a square planar geometry. The antifungal and antibacterial activities of the compounds have been studied against some phyto-pathogenic fungi and bacteria. Generally, the complexes exhibit a more pronounced antimicrobial activity than the parent ligands.

(1S*,3R*,5S*,7S*)-4,4,8,8-Tetra-chloro-1-isopropyl-5-methyl-tri-cyclo-[5.1.0.0(3,5)]octa-ne.

The title compound, C12H16Cl4, is a derivative of the natural product 1-isopropyl-4-methyl­cyclo­hexa-1,4-diene, and represents a diastereomer with two trans-fused cyclo­propane rings. Both enanti­omers are present in the non-centrosymmetric polar space group Pna21. The central cyclo­hexane ring is planar within 0.02 (1) Å. The C atoms of di­chloro­methyl­ene groups deviate from this plane by 1.19 (1) and −1.26 (1) Å, whereas the isopropyl and methyl groups are oriented more equatorially, deviating by 0.71 (1) and −0.87 (1) Å, respectively.

Crystal Structure and NMR Study of Tetrakis(acetonitrile)silver(I) Fluorosulfonate [Ag(CH3CN)4]+[SO3F]–

The title compound [Ag(CH3CN)4]+[SO3F]- crystallizes in the orthorhombic space group Pna21, a = 24:383(24), b = 8:632(11), c = 20:755(17) Å, V = 4368(6) Å3, Z = 12, with three independent formula units in the unit cell. A comparison with the isostructural compound [Ag(CH3CN)4]+ [ClO4]- is given. The salt has also been characterized by solution 1H and 19F NMR spectroscopy and the data compared to that of fluorosulfonic acid

Syntheses, Weak Interactions, and Crystal Structures of Two Tetrabromocuprate(II) Complexes Containing Benzyl Substituted Alkyl Pyridinium

Two tetrabromocuprate(II) complexes containing substituted benzyl alkyl pyridinium, [Bz-4-MePy]2[CuBr4] (1) and [Bz-4-EtPy]2[CuBr4] (2) ([Bz-4MePy]+ = (1-benzyl-4′-methylpyridinium) [Bz-4-EtPy]+ = 1-benzyl-4′-ethylpyridinium), were crystallized from methanol and dilute HBr solutions, and were determined by single crystal X-ray diffraction. Two complexes crystallize in the orthorhombic system with space group Pna21, and comprise two tortuous cations and one tetrahedral [CuBr4]2– anion. The [CuBr4]2– anions in two complexes form a linear chain by Br···Br interaction with the distance of 4.001 Å for 1 and 4.062 Å for 2, while the combination of C‒H···Br and C‒H···N weak hydrogen bonds, p···π and π···π, interactions consolidate the crystal packing and results in a 3D network structure.