Space Group Pna21 Research Articles

Dielectric relaxation and anhydrous proton conduction in [C2H5NH3][Na0.5Fe0.5(HCOO)3] metal-organic frameworks.

Metal-organic frameworks (MOFs), in which metal clusters are coupled by organic moieties, exhibit inherent porosity and crystallinity. Although these systems have been examined for vast potential applications, the elementary proton conduction in anhydrous MOFs still remains elusive. One of the approaches to deal with this problem is the utilization of protic organic molecules, to be accommodated in the porous framework. In this work we report the temperature-dependent crystal structure and proton conduction in [C2H5NH3][Na0.5Fe0.5(HCOO)3] metal-organic frameworks using X-ray diffraction and broadband dielectric spectroscopic techniques. The detailed analysis of the crystal structure reveals disorder of the terminal ethylene groups in the polar phase (space group Pn). The structural phase transition from Pn to P21/n at T ≈ 363 K involves the distortion of the metal formate framework and ordering of EtA+ cations due to the reduction of the cell volume. The dielectric data have been presented in the dynamic window of permittivity formalism to understand the ferroelectric phase transition. The relaxation times have been estimated from the Kramers-Kronig transformation of the dielectric permittivity. A Grotthuss type mechanism of the proton conduction is possible at low temperatures with the activation energy of 0.23 eV. This type of experimental observation is expected to provide new prospective on the fundamental aspect of elementary proton transfer in anhydrous MOFs.

Low-temperature-flux syntheses of ultraviolet-transparent borophosphates Na4MB2P3O13 (M = Rb, Cs) exhibiting a second-harmonic generation response.

The first non-centrosymmetric mixed-alkali-metal borophosphates, Na4MB2P3O13 (M = Rb 1, Cs 2), were obtained using a low-temperature flux method. Single-crystal X-ray diffraction studies of 1 and 2 reveal that the two compounds are isostructural, both crystallizing in the orthorhombic space group Pna21; their structures consist of novel 1D borophosphate chains constructed from B2P3O14 fundamental building units, assembled into a 3D framework by alkali metal cations. Second-harmonic generation (SHG) measurements show that 1 and 2 are type-I phase-matchable, with SHG responses ca. 0.35 and 0.42 times that of KH2PO4, respectively. The cut-off edges of 1 and 2 are ca. 276 and 267 nm, respectively, which suggests that they are potential ultraviolet nonlinear optical materials. Density functional theory calculations were employed to shed light on the band structure and density of states as well as the electron density distribution.

Pyridine and 3-methylpyridine solvates of the triple sulfa drug constitutent sulfamethazine.

Sulfonamides display a wide variety of pharmacological activities. Sulfamethazine [abbreviated as SMZ; systematic name 4-amino-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide], one of the constitutents of the triple sulfa drugs, has wide clinical use. Pharmaceutical solvates are crystalline solids of active pharmaceutical ingredients (APIs) incorporating one or more solvent molecules in the crystal lattice, and these have received special attention, as the solvent molecule can impart characteristic physicochemical properties to APIs and solvates, therefore playing a significant role in drug development. The ability of SMZ to form solvates has been investigated. Both pyridine and 3-methylpyridine form solvates with SMZ in 1:1 molar ratios. The pyridine monosolvate, C12H14N4O2S·C5H5N, crystallizes in the orthorhombic space group Pna21, with Z = 8 and two molecules per assymetric unit, whereas the 3-methylpyridine monosolvate, C12H14N4O2S·C6H7N, crystallizes in the orthorhombic space group P212121, with Z = 4. Crystal structure analysis reveals intramolecular N-H...N hydrogen bonds between the molecules of SMZ and the pyridine solvent molecules. The solvent molecules in both structures play an active part in strong intermolecular interactions, thereby contributing significantly to the stability of both structures. Three-dimensional hydrogen-bonding networks exist in both structures involving at least one sulfonyl O atom and the amine N atom. In the pyridine solvate, there is a short π-π interaction [centroid-centroid distance = 3.926 (3) Å] involving the centroids of the pyridine rings of two solvent molecules and a weak intermolecular C-H...π interaction also contributes to the stability of the crystal packing.

SHG-active LnIII–[MoI(CN)5(NO)]3−(Ln = Gd, Eu) magnetic coordination chains: a new route towards non-centrosymmetric molecule-based magnets

The rare heteroligand pentacyanidonitrosylmolybdate(I) anion was employed in the construction of d–f bimetallic cyanido-bridged {[LnIII(dmf)6][MoI(CN)5(NO)]} (Ln = Gd, 1; Eu, 2) chains crystallizing in the non-centrosymmetric Pna21 space group. 1 exhibits Gd–Mo antiferromagnetic coupling giving rise to the ferrimagnetic spin chain behaviour with the onset of magnetic ordering below 2 K, and shows high second harmonic generation (SHG) activity with SH susceptibility of 1.2 × 10−10 esu, opening a novel family of non-centrosymmetric molecule-based magnets.

Crystal structure, Hirshfeld surface and spectroscopic studies of the noncentrosymmetric Bi(III) halide complex: [C8H12N]3BiCl6

A new organic–inorganic hybrid material with the formula [C8H12N]3BiCl6 has been synthesized and characterized by spectroscopic techniques and single crystal X-ray structure determination. This compound crystallizes in the non-centrosymmetric space group Pna21 of the orthorhombic system with crystallographic parameters a=25.5620(2), b=16.7170(5), c=7.8840(4)Å, V=3369.0(2)Å3 and Z=4. Its structure consists of discrete [BiCl6]3− anions, showing the distorted octahedral geometry, surrounded by three crystallographically independent 2-phenylethylammonium cations. The crystal packing is governed by the formation of a number of N–H⋯Cl hydrogen bonds arranged in a three-dimensional network. Crystal structure analysis supported with the Hirshfeld surface and fingerprint plots enabled the identification of the significant intermolecular interactions. The 13C and 15N CP-MAS NMR spectra are in agreement with the X-ray structure. The optical properties of [C8H12N]3BiCl6 were investigated by UV–Vis and luminescence spectroscopy. The differential scanning calorimetry (DSC) revealed that the title compound is stable up to 210°C.

The chemical behavior of the silaoxine C22H34OSi3and silaazetidine C25H43NSi4towards CO2

AbstractWhen 4,4a-dihydro-3,3-dimethyl-1-phenyl-4,4-bis(trimethylsilyl)-3H-2-oxa-3-sila-naphthaline (silaoxine C22H34OSi3(3); orthorhombic, space groupPna21,Z=4) was thermolized in a CO2atmosphere, the corresponding oxasilacyclobutane (silaoxetane)5was quantitatively formed. The [2+2] cycloreversion of the silaoxetane5occurred at temperatures higher than 120°C to give exclusively Ph2C=C(SiMe3)2and (Me2SiO)n. Single crystals of Ph2C=C(SiMe3)2(6; monoclinic, space groupC2/c,Z=8) were isolated from this reaction. When the azasilacyclobutane (silaazetidine) C25H43NSi4(4; monoclinic, space groupP21/n,Z=4) was reacted with an excess of CO2at 100°C an unknown intermediate was formed along with the benzophenonimine Ph2C=N(SiMe3). The NMR resonances of this intermediate indicates the formation of theβ-silalactone (silaoxetanone) C10H24O2Si3(7). At temperatures higher than 120°C the silaoxetanone7decomposed to give (Me3Si)2C=C=O and (Me2SiO)n, respectively.

A strategic approach to physico-chemical analysis of bis (thiourea) lead chloride – A reliable semi-organic nonlinear optical crystal

Good quality crystals of bis thiourea lead chloride (BTLC) have been grown by slow evaporation method from aqueous solution. Orthorhombic structure and Pna21 space group of the crystals have been identified by single crystal X-ray diffraction. Studies on nucleation kinetics of grown BTLC has been carried out from which meta-stable zone width, induction period, free energy change, critical radius, critical number and growth rate have been calculated. The experimental values of interfacial surface energy for the crystal growth process have been compared with theoretical models. Ultra violet transmittance studies resulted in a high transmittance and wide band gap energy suggested the required optical transparency of the crystal. The second harmonic generation (SHG) and phase matching nature of the crystal have been justified by Kurtz-Perry method. The SHG nature of the crystal has been further attested by the higher values of theoretical hyper polarizability. The dielectric nature of the crystals at different temperatures with varying frequencies has been thoroughly studied. The activation energy values of the electrical process have been calculated from ac conductivity study. Solid state parameters including valence electron plasma energy, Penn gap, Fermi energy and polarisability have been unveiled by theoretical approach and correlated with the crystal's SHG efficiency. The values of hardness number, elastic stiffness constant, Meyer's Index, minimum level of indentation load, load dependent constant, fracture toughness, brittleness index and corrected hardness obtained from Vicker's hardness test clearly showed that the BTLC crystal has good mechanical stability required for NLO device fabrication.

Synthesis and Structure Determination of the Quaternary Zinc Nitride Halides Zn2NX1−yX′y (X, X′ = Cl, Br, I; 0 < y < 1)

The quaternary series Zn2NCl1−yBry and Zn2NBr1−yIy were synthesized from solid-liquid reactions between zinc nitride and the respective zinc halides in closed ampoules, and the evolution of their crystal structures was investigated by single-crystal and powder X-ray diffraction. Zn2NX1−yX′y (X, X′ = Cl, Br, I) adopts the anti-β-NaFeO2 motif in which each nitride ion is tetrahedrally coordinated by four zinc cations, and the halide anions are located in the voids of the skeleton formed by corner-sharing [NZn4] tetrahedra. While Zn2NCl1−yBry crystallizes in the acentric orthorhombic space group Pna21 (No. 33), isotypic to Zn2NX (X = Cl, Br), the structure of Zn2NBr1−yIy is a function of the iodide concentration, namely, Zn2NBr (Pna21) for low iodine content and Zn2NI (Pnma) for higher (y ≥ 0.38).

Bis (thiourea) strontium chloride as promising NLO material: An experimental and theoretical study

Single crystals of pure bis (thiourea) strontium chloride (BTSC) have been grown from aqueous solution by slow evaporation method. The results from single crystal X-ray diffraction studies indicated the orthorhombic structure and Pna21 space group of the crystals. 77% transmittance measured by the Ultra violet transmittance studies and a band gap of 4.7 eV indicated the high optical transparency. From Kurtz and Perry powder method, the second Harmonic Generation (SHG) efficiency of the BTSC has been found to be 1.54 times as that of KDP and the phase matching nature of the crystal has been confirmed. Hyper polarizability studies showed that the synthesized BTSC crystal has higher polarisability and dipole values and hence can be used as potential NLO material. The frontier orbital HOMO-LUMO gap has been determined to understand the chemical reactivity and kinetic stability of the title crystal. The values of various global chemical molecular reactivity descriptors like chemical hardness (η) and electrophilicity index (ω) have been calculated. Natural bond orbital (NBO) analysis has been carried out to study the charge distribution and to understand various donor–acceptor interactions taking place in the BTSC crystal.

Spectroscopic, structural, electrochemical and antimicrobiological studies of Cu(II)-sulfathiazole complex with diethylenetriamine ligand

The present study describes the synthesis, spectroscopic and electrochemical characterization of Cu(II)-sulfathiazole (Hstz:4-amino-N-(1,3-thiazol-2-yl) benzene sulfonamide) complexes with dien (diethylenetriamine). The techniques used for the characterization have been single crystal X-ray diffraction, IR and EPR. The structural study indicated that the [Cu(stz)2dien] complex crystallizes in the monoclinic space group Pna21 with Z=4. Two sulfathiazole anions were coordinated to the metal ion through N atom of the deprotonated sulfonamido group. Almost square-bipyramidal geometry with value of τ parameter≈0.048hasbeen completed with three nitrogen atoms of dien molecule. The most important spectral features of the complex with its structural properties were compared and discussed. The electrochemical study indicated the formation and the irreversibility of the mixed ligand metal complex. Biological study of the [Cu(stz)2dien]·3H2O against Gram-positive and Gram-negative bacterial and fungal strains complex showed very strong antibacterial activity with MIC values ranging from 1 to 4μg/mL.

Synthesis, growth, optical and DFT calculation of 2-naphthol derived Mannich base organic non linear optical single crystal for frequency conversion applications

2-naphthol derived Mannich base 1-((4-methylpiperazin-1-yl) (phenyl) methyl) naphthalen-2-ol (MPN) – a nonlinear optical single crystal was synthesized and successfully grown by slow evaporation technique at room temperature. The molecular structure was confirmed by single crystal XRD, FT-IR, 1H NMR and 13C NMR spectral studies. The single crystal X-ray diffraction analysis reveals that the crystal belongs to orthorhombic crystal system with non-centrosymmetric space group Pna21. The chemical shift of 5.34ppm (singlet methine CH proton) in 1H NMR and signal for the CH carbon around δ70.169ppm in 13C NMR confirms the formation of the title compound. The crystal growth pattern and dislocations of crystal are analyzed using chemical etching technique. UV cut off wavelength of the material was found to be 212nm. The second harmonic generation (SHG) of MPN was determined from Kurtz Perry powder technique and the efficiency is almost equal to that of standard KDP crystal. The laser damage threshold was measured by passing Nd: YAG laser beam through the sample and it was found to be 1.1974GW/cm2. The material was thermally stable up to 142°C. The relationship between the molecular structure and the optical properties was also studied from quantum chemical calculations using Density Functional Theory (DFT) and reported for the first time.

Synthesis, structure and properties of a 3D acentric coordination polymer with noninterpenetrated (10,3)-d topology

A new coordination polymer, {[Mn(HPIDC)(H2O)]·2H2O}n (1) (H3PIDC = 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid), has been obtained by hydrothermal method and structurally characterized by X-ray single crystal diffraction, elemental analysis and thermogravimetric analysis (TGA). X-ray single crystal diffraction reveals that compound 1 crystallizing in acentric Pna21 space group, exhibits an ultimate racemic three-dimension framework with rare noninterpenetrated (10,3)-d (or utp) topology due to the alternate array of left- and right-handed helixes. Moreover, compound 1 also features ferroelectric, nonlinear optical (NLO) and antiferromagnetic behaviors.

DFT(B3LYP/LanL2DZ), non-linear optical and electrical studies of a new hybrid compound: [C6H10(NH3)2]CoCl4·H2O

A new organic-inorganic material [C6H10(NH3)2]CoCl4·H2O was reported. The title compound was synthesized at room temperature by slow evaporation and then characterized by a single X-ray diffraction, spectroscopic measurements, thermal analysis and dielectric technique. It crystallizes in the non-centrosymmetric space group Pna21 with the following unit cell parameters: a=12.5328(1) Å, b=9.0908(1) Å, c=11.7440(1) and α=β=γ=90°. The structure can be described by the alternation of two different cationic-anionic layers. It consists of isolated H2O, isolated [CoCl4]2− tetrahedral anions and diammoniumcyclohexane [C6H10(NH3)2]2+ cations, which are connected via N–H…Cl, N–H…O and O–H…N hydrogen bonds. The Hirshfeld surface analysis was conducted to investigate intermolecular interactions and associated 2D fingerprint plots, revealing the relative contribution of these interactions in the crystal structure quantitatively. Theoretical calculations were performed using DFT/B3LYP/LanL2DZ method for studying the molecular structure and vibrational spectra and especially to examine the non-linear optical behavior of the compound. Solid state 13C NMR spectrum shows three signals correspond to three different carbon environments. Thermal analysis discloses a phase transition at the temperature 315K and the evaporation of water molecule at 327K. A detailed dielectric study was reported and shows a good agreement with thermal measurements.

Chemical synthesis, crystal structure, vibrational spectroscopy, non-linear optical properties and DFT calculation of bis (2,6-diaminopyridinium) sulfate monohydrate

Single crystals of a new organic inorganic hybrid compound “bis (2,6-diaminopyridinium) sulfate monohydrate [C5H8N3]2SO4·H2O ([2,6-HDAP]2SO4·H2O)” was synthesized by slow evaporation method at room temperature and characterized by X-ray single crystal diffraction, infrared spectroscopy and DFT calculation. The new hybrid compound crystallizes in the orthorhombic system with the non-centro symmetric space group Pna21 and the following parameters a = 14.759(2) Å, b = 7.076 (2) Å and c = 28.159 (2) Å.The atomic arrangement can be described as inorganic chains following the b axis connected with the organic groups by means of NH⋯O hydrogen bonds to form 3D network. Antiparallelly π–π stacked 2,6-HDAP cations form molecular columns in the spaces between the chains. The optimized molecular structure, vibrational spectra and the optical properties were calculated by the density functional theory (DFT) method using the B3LYP function with the LanL2DV basis set. The wavenumber calculated are in good agreement with the observed frequency values. The calculated hyperpolarizability βtot is about 4.5 times more than that of the reference crystal KDP. Hence, the large β value shows that the title compound is an attractive object for future studies of nonlinear optical properties.

Benzotriazole p-hydroxybenzoic acid: physicochemical and biological evaluation of an organic cocrystal

A 1:1 molecular complex of benzotriazole p-hydroxybenzoic acid (BPHB) single crystal was grown by slow evaporation solution growth method at ambient temperature. The formation of title compound was confirmed through single-crystal X-ray diffraction analysis and it is found that the compound crystallises in orthorhombic system with Pna21 space group. The modern spectroscopic studies such as Fourier transform infrared, FT-NMR and UV–vis–NIR characteristics were carried out to reveal the molecular structure and optical window of the compound. TG/DTA analysis was performed and found that the compound is stable up to 170.8 °C. The mechanical strength of the BPHB was examined using Vicker’s microhardness tester. Kurtz and Perry powder technique was used to assess the second harmonic generation of the grown crystal and its efficiency it is found to be 1.02 times greater than that of potassium dihydrogen orthophosphate. Antimicrobial and anticancer evaluations were made on the title compound using novel resazurin reduction assay and MTT assay methods which results superior biological activities comparable to available drug products.

Polarized IR and Raman spectra of the novel metal-organic framework [CH3CH2NH3][Cd(HCOO)3

The novel formate-based framework [CH3CH2NH3][Cd(HCOO)3] has been prepared under solvothermal conditions. The X-ray diffraction data reveals that this compound crystallizes in the polar Pna21 space group and is isostructural with the compounds [CH3CH2NH3][M(HCOO)3], where MII=Mg, Mn and Cu, reported previously. The ethylammonium cations located in the cavities of the metal-formate framework are ordered at room temperature. Polarized infrared and Raman spectra of [CH3CH2NH3][Cd(HCOO)3] single crystal have been measured at room temperature and the assignments of the observed bands to the respective external and internal vibrations are proposed. Additionally, the previously reported [CH3CH2NH3][Mn(HCOO)3] has also been synthesized and polycrystalline IR and Raman spectra of both metal-formate frameworks have been compared in order to better understand the aspects of their structures.

New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. V. Katiarsite, KTiO(AsO4)

AbstractA new mineral katiarsite, ideally KTiO(AsO4), occurs in sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with hatertite, bradaczekite, johillerite, yurmarinite, tilasite, arsmirandite, hematite, tenorite, As-bearing orthoclase, fluorophlogopite and aphthitalite. Katiarsite occurs as long prismatic to acicular, typically sword-like, crystals up to 3 μm×10μm×50 μm in size, and rarely up to 0.15 mm long. Crystal forms are {011}, {201}, {100} and {001}. Katiarsite is transparent, colourless, with a vitreous lustre. The mineral is brittle. Cleavage was not observed, the fracture is uneven. Dcalc is 3.49 g cm–3. Katiarsite is optically biaxial (+), α = 1.784(3), β = 1.792(3), γ = 1.870(5); 2Vobs is small. Orientation is X = b, Y = a, Z = c. The Raman spectrum is reported. The chemical composition (wt.%, electron-microprobe data) is K2O 18.98, Fe2O3 5.07, TiO2 27.49, As2O5 47.48, total 99.02. The empirical formula, calculated based on 5 O apfu, is K1.00 (Ti0.85Fe3+0.16)∑1.01 As1.02O5. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are 5.91(17)(110), 5.62(74)(011), 4.18(19)(202), 3.157(66) (013), 2.826(100)(221), 2.809(96)(022) and 2.704(19)(004). Katiarsite is orthorhombic, a = 13.174(4), b = 6.5635(10), c = 10.805(2) Å, V = 934.3(3) Å3, Z = 8, space group Pna21, by analogy with KTA, synthetic KTiO(AsO4), a notable non-linear optical crystalline material. The name of the mineral reflects its chemical composition, kalium titanyl arsenate.

Revealing structural distortion and dielectric relaxation in Ga1−xScxFeO3 (0≤x≤0.3)

Polycrystalline samples of Ga1−xScxFeO3 (x=0, 0.1, 0.2, and 0.3) were prepared by solid state reaction method. The monophasic compounds were found to crystallize in the orthorhombic space group Pna21, confirmed from Rietveld refinement of the XRD patterns. The lattice constants were found to increase with increasing Sc content. Mössbauer measurements carried out at room temperature (RT) showed four paramagnetic doublets. Isomer shift values show that iron is in Fe3+ high spin state for all four Fe sites in all the compositions. Quadrupole splitting increases with Sc content which means that there is an increase in local structural distortion with Sc substitution. That Sc resides in the Ga2/Fe site was confirmed by Mössbauer spectroscopy. Low temperature Mössbauer study also shows a similar trend. Hyperfine magnetic field decreases with increasing Sc content. Sc substitution causes a reduction of magnetic ordering. The dielectric constant was found to decrease with increasing Sc content. The activation energies, obtained by the temperature dependence of dielectric relaxation as well as the conductivity, showed almost equal values around 0.3eV.

Pressure-induced phase transformation in β-eucryptite: An X-ray diffraction and density functional theory study

Certain alumino-silicates display exotic properties enabled by their framework structure made of corner-sharing tetrahedral rigid units. Using in situ diamond-anvil cell x-ray diffraction (XRD), we study the pressure-induced transformation of β eucryptite, a prototypical alumino-silicate that undergoes a phase transformation at moderate pressures. The atomic structure and symmetry group of the new pressure-stabilized phase has not yet been reported. Based on density functional theory studies and Rietveld analysis of XRD patterns, we find that the new phase belongs to the Pna21 space group and report its atomic structure. Furthermore, we discover two other possible pressure-stabilized polymorphs, P1c1 and Pca21.

Synthesis, Crystal Structure, and Antimicrobial Activity of Manganese(III) and Iron(III) Complexes Derived from Similar bis-Schiff Bases

A new manganese(III) complex, [Mn(L1)(CH3OH)(dca)] 1, and a new iron(III) complex, [Fe(L2)(CH3OH)(NCS)] 2, for which dca is dicyanoamide anion, and L1 and L2 are the dianionic form of N,N′-3,4-methylphenylenebis(5-methylsalicylaldimine) and N,N′-bis(5-methylsalicylidene)-o-phenylenediamine, respectively, have been prepared and characterized by elemental analyses, IR, and single-crystal X-ray crystallographic determination. The crystal of complex 1 is orthorhombic: space group Pna21, a = 14.6557(6), b = 10.8906(5), c = 15.0536(7) Å, V = 2402.7(2) Å3, Z = 4, R1 = 0.0321, wR2 = 0.0715. The crystal of complex 2 is monoclinic: space group C2/c, a = 14.6798(9), b = 11.1306(7), c = 27.831(1) Å, β = 93.782(2)°, V = 4537.6(5) Å3, Z = 8, R1 = 0.0423, wR2 = 0.1027. The bis-Schiff base ligands coordinate to the metal center through phenolate O and imine N atoms. Both the Mn and Fe atoms in the complexes are in octahedral coordination, with the equatorial donor atoms come from the Schiff base ligands, and with the axial donor atoms come from a methanol O atom and a pseudohalide N atom. The effects of the complexes on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans were studied.