Triclinic Crystal Structure Research Articles

Synthesis of a Series of Monophthalocyaninato Cyclen Heavy Lanthanide(III) Complexes with Tetragonal Symmetry.

A series of the new monophthalocyaninato lanthanide complexes, [Ln(Pc)(cyclen)]Cl (Ln = Y, Tb, Dy, Ho, Er, Tm, and Yb; Pc = phthalocyaninato; cyclen = 1,4,7,10-tetraazacyclododecane) was synthesized and characterized. The crystallographic study of monophthalocyaninato complexes with a capping macrocyclic ligand having no π-conjugation while keeping the 4-fold symmetry is presented for the first time. All the six complexes were crystallized in a tetragonal structure of the I4mm space group. In addition to this, the Tb complex exhibited a triclinic crystal structure of the P1̅ space group. All of the complexes are isostructural, where both Pc and cyclen are coordinated to an Ln3+ ion giving an eight-coordinate square-antiprismatic geometry. The skew angle between the Pc and cyclen ligands was 45° in the tetragonal crystals and 41.5° in the triclinic crystal. The metal-nitrogen bond lengths were shorter on the Pc ligand side than cyclen side, presumably due to the difference in the charges of the ligands and the steric factor.

Metastable State during Melting and Solid-Solid Phase Transition of [CnMim][NO3] (n = 4-12) Ionic Liquids by Molecular Dynamics Simulation.

We simulate the heating process of ionic liquids [CnMim][NO3] (n = 4, 6, 8, 10, 12), abbreviated as Cn, by means of molecular dynamics (MD) simulation starting from a manually constructed triclinic crystal structure composed of polar layers containing anions and cationic head groups and nonpolar regions in between containing cationic alkyl side chains. During the heating process starting from 200 K, each system undergoes first a solid-solid phase transition at a lower temperature, and then a melting phase transition at a higher temperature to an isotropic liquid state (C4, C6, and C8) or to a liquid crystal state (C10 and C12). After the solid-solid phase transition, all systems keep the triclinic space symmetry, but have a different set of lattice constants. C4 has a more significant structural change in the nonpolar regions which narrows the layer spacing, while the layer spacings of other systems change little, which can be qualitatively understood by considering that the contribution of the effective van der Waals interaction in the nonpolar regions (abbreviated as EF1) to free energy becomes stronger with increasing side-chain length, and at the same time the contribution of the effective electrostatic interaction in the polar layers (abbreviated as EF2) to free energy remains almost the same. The melting phase transitions of all systems except C6 are found to be a two-step process with an intermediate metastable state appeared during the melting from the crystal state to the liquid or liquid crystal state. Because the contribution of EF2 to the free energy is larger than EF1, the metastable state of C4 has the feature of having higher ordered polar layers and lower ordered side-chain orientation. By contrast, C8-C12 have the feature of having lower ordered polar layers and higher ordered side-chain orientation, because for these systems, the contribution of EF2 to the free energy is smaller than EF1. No metastable state is found for C6 because the free-energy contribution of EF1 is balanced with EF2.

Crystal and Electronic Structure of (Y,Pr) x Sm1−x BO3 Oxide

The effects of Y and Pr substitution on the electronic and crystal structure of triclinic SmBO3 have been investigated using x-ray diffraction (XRD) analysis and x-ray absorption fine-structure spectroscopy. Polycrystalline structure was observed on substitution of Y3+ and Pr4+ ions with Sm3+ coordination. Yttrium-substituted samples were found to contain BO3 ligands around Sm atoms, while the crystal structure of YBO3 presented hexagonal geometry, not preserving the triclinic crystal structure. Also, praseodymium ions (Pr4+) formed isolated Pr2B5 crystal structure by distorting some BO3 ligands. Moreover, electronic structure studies revealed that 4f levels of Sm and Pr were inactive in bonding interaction and did not support strong coupling between neighboring Sm and Y/Pr atoms.

Structural studies of a green-emitting terbium doped calcium zinc phosphate phosphor

In this study, a new green emitting CaZn2(PO4)2:Tb3+ phosphors were synthesized through solid-state reaction route. The phosphors were characterized structurally by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). All the synthesized phosphors were crystallized in triclinic crystal structure with P1¯ space group. The phosphate groups in the phosphors were confirmed by FTIR analysis. The surface elements O 1s, P 2p, Ca 2p, Zn 2p and Tb 3d were studied by high-resolution XPS spectra. Upon excitation at 378 nm, the dominant green emission of CaZn2(PO4)2:Tb3+ phosphors at 542 nm were noticed in the emission spectra. For various emission wavelengths (at 435 and 489 nm) and constant excitation wavelength (at 378 nm), the decay curves have shown two different decay dynamics of phosphors. The lighting properties such as Commission International de l’Eclairage (x = 0.319, y = 0.398) and color temperature (5995 K) were calculated.

Investigations on FCAM-III (Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36): A new homologue of the aenigmatite structure-type in the system CaO-MgO-Fe2O3-Al2O3

In the course of a systematic study of a part of the quaternary system Fe2O3-CaO-Al2O3-MgO (FCAM) the previously unknown compound Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 (FCAM-III) has been synthesized. By analogy with the so-called SFCA series [1–5], our investigation in the system of FCAM shows the existence of a stoichiometric homologous series M14+6nO20+8n, where M = Fe, Ca, Al, Mg and n = 1 or 2.In air, we can prove the formation of coexisting FCAM-III and FCAM-I solid solutions at 1400°C. By increasing the temperature up to 1425°C FCAM-I disappears completely and FCAM-III co-exists with magnesiumferrite and a variety of calcium iron oxides. At 1450°C FCAM-III breaks down to a mixture of FCAM-I again as well as magnesioferrite and melt. Small single-crystals of FCAM-III up to 35µm in size could be retrieved from the 1425°C experiment and were subsequently characterized using electron microprobe analysis and synchroton X-ray single-crystal diffraction. Finally the Fe2+/Fetot ratio was calculated from the total iron content based on the crystal-chemical formula obtained from EMPA measurements and charge balance considerations. FCAM-III or Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 has a triclinic crystal structure (space group P1̅). The basic crystallographic data are: a = 10.223(22) Å, b = 10.316(21) Å, c = 14.203(15) Å, α = 93.473(50)°, β = 107.418(67)°, γ = 109.646(60)°, V = 1323.85(2) ų, Z = 1.Using Schreinemaker's technique to analyze the phase relations in the system Fe2O3-CaO-Al2O3-MgO it was possible to obtain the semi-quantitative stability relations between the participating phases and construct a topologically correct phase sequence as a function of T and fO2. The analysis shows that Ca2Al0.5Fe1.5O5 (C2A0.25F0.75) and CaAl1.5Fe2.5O7 (CA0.75F1.25) with higher calculated Fe2+ contents are preferably formed at lower oxygen fugacity and react to CaAl0.5Fe1.5O4 (CA0.25F0.75) by increasing fO2. Spinel-type magnesium-aluminium-ferrite (Mg,Fe2+)Fe3+1.25Al0.75O4 or (MA0.375F0.625) is the typical phase which occurs at high temperature (1400°C).

Facile synthesis of hierarchical carpet-like WO3 microflowers for high NO2 gas sensing performance

The hierarchical carpet-like WO3 microflowers were synthesized via a facile one-step hydrothermal method by using oleic acid as a oriented growth reagent. The as-synthesized WO3 microflowers show a triclinic crystal structure and are basically hierarchical assemblies of carpet-like nanosheets made up of the subunit of bundle-like nanowires. Based on the morphology evolution process, a possible crystal growth and nanostructure assembling mechanism were proposed. The prepared WO3 microflower sensor exhibits a gas sensing response of about 228 when exposed to 10ppm of toxic NO2 gas at 200°C.

The effects of annealing temperature on the structural properties and optical constants of a novel DPEA-MR-Zn organic crystalline semiconductor nanostructure thin films

The dependence of structural properties and optical constants on annealing temperature of a 2-((1,2-bis (diphenylphosphino)ethyl)amino) acetic acid-methyl red-monochloro zinc dihydride (DPEA-MR-Zn) as a novel organic semiconductor thin film was studied. The DPEA-MR-Zn thin film was deposited on silicon substrates using the spin coating technique. The as-deposited film was annealed in air for 1 h at 150, 175 and 205 °C. The XRD study of DPEA-MR-Zn in its powder form showed that this complex is mere a triclinic crystal structure with a space group P-1. In addition, the XRD patterns showed that the as-deposited thin films were crystallized according to the preferential orientation [(214), (121), (02¯6), (3¯02), (122) and (114¯)]. Moreover, two additional peaks (2¯2¯1 and 24¯7) were shown at 2θ nearly 30°, and 69°, where, the more annealing temperature, the more the intensity of the two peaks. In addition, it was noticed that the grain size had a remarkable change with an annealing temperature of the DPEA-MR-Zn thin films. The optical measurements showed that the thin film has a relatively high absorption region where the photon energy ranges from 2 to 3.25 eV. Both of Wemple–DiDomenico and single Sellmeier oscillator models were applied on the DPEA-MR-Zn to analyze the dispersion of the refractive index and the optical and dielectric constants. The outcome of the study of the structural and optical properties reported here of the DPEA-MR-Zn organic semiconductor crystalline nanostructure thin film had shown various applications in many advanced technologies such as photovoltaic solar cells.

Rubidium chalcogenido diferrates(III) containing dimers [Fe2 Q 6]6− of edge-sharing tetrahedra (Q=O, S, Se)

Abstract The two isotypic rubidium chalcogenido diferrates Rb12[Fe2 Q 6](Q 2)3 (Q=S/Se), which both form needles with green-metallic lustre, were synthesized from Rb2S, elemental iron, rubidium and sulfur (Q=S) or from the pure elements (Q=Se) at maximum temperatures of 500–800°C. Their triclinic crystal structures were determined by means of X-ray single crystal data (space group P1̅, a=863.960(10)/903.2(3), b=942.790(10)/982.1(3), c=1182.70(2)/1227.4(4) pm, α=77.4740(10)/77.262(6), β=71.5250(10)/71.462(6), γ=63.7560(10)/63.462(5)°, Z=1, R1=0.0308/0.0658 for Q=S/Se). The structures contain isolated dinuclear anions [FeIII 2 Q 6]6− composed of two edge-sharing [FeQ 4] tetrahedra (dFe −Q =223.4–232.3/236.2–244.8 pm), which are also found in the two polymorphs of the pure alkali diferrates Rb6[Fe2 Q 6]. The diferrate ions are arranged in layers running in the a/b plane around z=0. Inbetween (around z ≈ 1 2 $z \approx {1 \over 2}$ ), two crystallographically different disulfide/diselenide ions Q 2 2 − $Q_2^{2 - }$ (dQ −Q =211.1–213.4/237.9–241.1 pm), which are arranged in slightly puckered 36 nets, are intercalated. The intra-anionic distances and angles, the Rb coordination numbers and the molar volumes of these two ‘double-salts’ are in accordance with their corresponding reference compounds, Rb6[Fe2 Q 6] and Rb2 Q 2. In addition, the two polymorphs of Rb6[Fe2Se6], which are both isotypic with the sulfido analogous (Cs6[Ga2Se6]-type, monoclinic, space group P21 /c, a=827.84(5), b=1329.51(7), c=1074.10(6) pm, β=127.130(5)°, R1=0.0443 and Ba6[Al2Sb6]-type, orthorhombic, space group Cmce, a=1963.70(3), b=718.98(3), c=1348.40(7) pm, R1=0.0264) were prepared and characterized to complete the series of alkali diferrates(III) with oxido, sulfido and selenido ligands. The electronic band structures of the three Rb salts Rb6[Fe2 Q 6], which have been calculated within the GGA+U approach applying an AFM spin ordering in the dimers and appropriate Hubbard parameters, allow a comparison of the chemical bonding characteristics (e.g. covalency) and the magnetic properties (magnetic moments) within the series of chalcogenido ligands. An analysis of the spin densities enables a comparative consideration of the mechanisms crucial for the magnetic ordering in chalcogenido ferrates. Ultimately, the electronic structure of the new compound Rb12[Fe2S6](S2)3 nicely compares with those of the S2-free reference compound Rb6[Fe2S6].

Thermal characterization and non-isothermal kinetics of 4-fluorobenzyltriphenylphosphonium chloride crystal

4-Fluorobenzyltriphenylphosphonium chloride (4-FBTC), a quaternary phosphonium salt, was synthesized, a single crystal was grown by slow evaporation method, and the structure was confirmed by single crystal XRD and spectral analyses. The single crystal XRD analysis showed the triclinic crystal structure with molecular formula, C50H48P2F2Cl2O3. Thermal studies were carried out at three different heating rates (5, 10 and 15 °C min−1) under N2 atmosphere, which shows the single-stage decomposition at all heating rates. The conventional, non-isothermal decomposition kinetic studies using model-free method were carried out to calculate the kinetic parameters like activation energy, pre-exponential factor, half-life and rate constant at various conversion percentages (1, 2.5, 5, 10 and 20%). Lifetime of 4-FBTC at room temperature for different conversion percentages was calculated to estimate the stability of the compound. Specific heat capacity and change in enthalpy were calculated using DSC analysis at 10 °C min−1 heating rate under N2 atmosphere.

Investigations on the Crystal Structure and the Stability Field of FCAM-I (Ca3MgAl6Fe10O28), an Iso-structure to SFCA-I

In a study on parts of the system Fe2O3-CaO-Al2O3-MgO, the previously unknown compound Ca3MgAl6Fe10O28 or FCAM-I (iso-structural with SFCA-I) has been synthesized. The two principal aims of our investigations have been (i) analysis of the stability field of the new phase as a function of T and fO2 and (ii) determination of its crystal structure. Two experimental series in air and under controlled oxygen fugacity via the hematite-magnetite buffer were conducted. Pure polycrystalline FCAM-I has been obtained at 1463.15 K (1190 °C) in air. While increasing the temperature from 1573.15 K to 1673.15 K (1300 °C to 1400 °C), the FCAM-I phase breaks down forming a variety of new compounds depending on T and fO2. Ca3MgAl6Fe10O28 has a triclinic crystal structure (space group P overline{1} ). Basic crystallographic data are as follows: a = 10.2980(4) Å, b = 10.4677(4) Å, c = 11.6399(4) Å, α = 94.363(3)°, β = 111.498(3)°, γ = 109.744(3)°, V = 1069.81(7) Å3, Z = 2.

Crystal and molecular structures, temperature dependence of the IR and Raman spectra and vibrational dynamics of aquo 4,6-dimethyl-5H-[1,2,3]triazolo[4,5-c]pyridine in a new zwitterionic form

The crystal and molecular structures of aquo 4,6-dimethyl-5H-[1,2,3]triazolo[4,5-c]pyridine in a zwitterionic form have been determined by X-ray diffraction and DFT quantum chemical calculations. The compound adopts a triclinic crystal structure, space group P-1 = Ci1 (No. 2) with Z = 2 and the unit cell parameters: a = 6.7452 Å, b = 9.5292 Å, c = 9.5554 Å and α = 69.279°, β = 73.951°, γ = 74.242°. The temperature dependence of its IR and Raman spectra have been measured and discussed in terms of proton transfer dynamics. The molecular structure and simulated vibrational spectra of the studied compound have been determined using the DFT B3LYP/6-311G(2d,2p) approach. Vibrational characteristics of a triazolo-pyridinium system in the studied compound has been proposed. A role of water molecules in stabilization of the compound space structure has been considered.

Altering the Polymorphic Accessibility of Polycyclic Aromatic Hydrocarbons with Fluorination

Substituting hydrogen with fluorine is an extensively employed strategy to improve the macroscopic properties of compounds for use in fields as diverse as pharmaceutics and optoelectronics. The role fluorine substitution plays on polymorphism—the ability of a compound to adopt more than one crystal structure—has not been previously studied. Yet, this understanding is important as different polymorphs of the same compound can result in drastically different bulk properties (e.g., solubility, absorptivity, and conductivity). Strategies to either promote or suppress the crystallization of particular polymorphs are thus desired. Here, we show that substituting hydrogen with fluorine affects the polymorphic behavior of contorted hexabenzocoronene (cHBC). A polycyclic aromatic hydrocarbon and molecular semiconductor, cHBC exhibits two polymorphs (i.e., P21/c crystal structure which we refer to as polymorph I and a triclinic crystal structure which we refer to as polymorph II) that are accessible through postdep...

Structures and optical spectroscopy of lanthanide trifluoroacetates obtained from hexafluoroacetylacetone

Several lanthanide trifluoroacetate complexes with 2,2′-bipyridine (Bpy) and 1,10-phenanthroline (Phen) prepared in an unusual method from hexafluoroacetylacetone (H-hfa) have been investigated using single crystal X-ray analysis, photoluminescence and IR spectroscopy. The triclinic crystal structures of [Ln(CF3CO2)3·Bpy·(H2O)3]·Bpy (Ln=Eu (1), Tb (2)) contain outersphere Bpy molecules. The structure of the compound [Eu(CF3CO2)3·Phen·(H2O)3]·Phen (3) is identical to 1 and 2 ones. A distorted square antiprismatic coordination geometry of the Ln3+ luminescence center, lifetimes of the 5D0 (Eu3+) and 5D4 (Tb3+) emitting states, luminescence efficiencies and energy transfer processes are discussed. Analysis of the relative energies of the lowest excited singlet and triplet states of the ligands and the electronic states of the Ln3+ ions showed that the most efficient luminescence excitation in the trifluoroacetates is realized through the auxiliary ligand. The results obtained were compared with available data for lanthanide acetates and β-diketonates. This study can be useful in the identification of lanthanide products synthesized from H-hfa, when the formation of mixtures of hexafluoroacetylacetonate and trifluoroacetate or the complete “replacement” of the final compound is a real problem.

Synthesis, Crystal Structure and Luminescence Property on Cabazoly-Based Zinc Metal Organic Frameworks

A novel zinc metal organic frameworks, named ZnL(2,2′-bpy), has been successfully synthesized, serving 3,6-dicarboxylic-9-ethylcarbazole acid (H2L) as ligand. This kind of ZnMOFs was characterized by FI-IR, elemental analysis, SEM, powder X-ray diffraction and single crystal X-ray diffraction to illustrate the structures. TG analysis was applied to investigate the thermostability. Structural analysis demonstrates that ZnMOFs possess triclinic crystal structure which is a 1D chain that occurs distorted-octahedral coordination geometry. Furthermore, the luminescent performance of ZnMOFs is performed and discussed in detail. The results show that ZnMOFs can emit blue luminescence originating, which is assigned to the ligand-to-metal charge transfer (LMCT).

Novel Gd2Mo4O15: Eu3+ red-emitting phosphor for UV, NUV and blue LED applications

Novel Eu3+ activated Gd2Mo4O15 phosphors were synthesized at the comparatively low temperature of 700°C via solid-state reaction. X-ray powder diffraction results demonstrate that the phosphors crystallize in the triclinic crystal structure, the space group PI¯. The photoluminescence spectra and ultraviolet-visible (UV–vis) reflectance and transmittance spectra indicate that Eu3+ doped Gd2Mo4O15 phosphors show a broad and strong absorption band covering ultraviolet (UV) and near ultraviolet (NUV) regions and the crystals emit red light with peak maximum at about 618nm under excitation of UV, NUV or blue light. The optimal doping concentration of Eu3+ ions in Gd2Mo4O15 phosphors is around 50mol% and the main concentration quenching mechanism is determined to be the exchange interaction.

Crystal Morphology and Growth in Annealed Rubrene Thin Films

While controlled crystallization of organic thin films holds great potential for enhancing the performance of electronic devices, quantitative understanding of the processes involved is limited. Here, we characterize the thin film crystal growth of the organic semiconductor rubrene during annealing using polarized optical microscopy with a heated stage for in situ measurements, followed by atomic force microscopy and X-ray diffraction. During annealing, the film undergoes transitions from predominant growth of a polycrystalline triclinic crystal structure to single crystal orthorhombic, followed by polycrystalline growth of the orthorhombic polymorph. Observation of crystal morphology with time allows determination of the crystal orientation, which is used in conjunction with crystal size measurements to determine the crystallization activation energies for the observed growth phases and crystal planes.

Design of Mixed-Metal Silver Decamolybdate Nanostructures for High Specific Energies at High Power Density.

Mixed-metal molybdates are interesting host materials for ion-insertion electrodes due to their versatile crystal chemistry, which confers a highway for the conduction of electrons as well as ions. Silver decamolybdate in triclinic crystal structure (T-Ag6 Mo10 O33 ) consists of layers of MoO6 octahedra separated by arrays of silver ions that are able to store a high amount of charges.

Comment on "Structural dynamics of cisplatin binding to histidine in a protein" [Struct. Dyn. 1, 034701 (2014)

Comment on "Structural dynamics of cisplatin binding to histidine in a protein" [Struct. Dyn. 1, 034701 (2014)

Crystal growth, structural and optical properties of a novel benzophenone derivative: 2-Chloro 5-nitro benzophenone

Benzophenone derivatives are promising material for various optical applications. In the present work, bulk crystals of a novel benzophenone derivative, 2-chloro 5-nitro benzophenone (2C5NBP) were grown by solution growth. The growth process was discussed based on solute-solvent interaction in two different growth media. The crystal structure of the material was analysed by single crystal X-ray diffraction method and found that the material belongs to triclinic crystal structure with the space group of P​1. Moreover, the functional groups of the 2C5NBP were identified by FTIR analysis. The material melts at the temperature of 90.3°C and it has wide gap between melting and vapourization process. Moreover, the hardness of the material is comparable with other benzophenone derivatives. The optical absorption studies show that the material has wide transparence window in the visible region and thus it can be useful for optical filters.

Synthesis of triclinic and hexagonal SmBO3 powders by mechanically activated annealing of Sm2O3 and B2O3 blends

Samarium borate (SmBO3) powders were fabricated from oxide raw materials by a two-step solid-state synthesis method including mechanical activation and annealing. Blends containing stoichiometric amounts of samarium oxide (Sm2O3) and boron oxide (B2O3) were mechanically activated in a high-energy ball mill and subsequently annealed in air. Afterwards, mechanically activated and annealed powders were washed with distilled water in order to remove probable unreacted B2O3 phase. The effects of mechanical activation duration (15min, 1h, 3h and 9h) and annealing temperature (700–1250°C) on the resultant powders were investigated. Compositional, microstructural, physical, thermal and optical properties of the powders obtained throughout the different process steps were characterized by using an X-ray diffractometry (XRD), particle size analysis (PSA), stereomicroscopy (SM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), gas pycnometry, differential scanning calorimetry (DSC), heating stage microscopy (HSM), atomic absorption spectrometry (AAS), Fourier transform infrared (FTIR) spectrometry and ultraviolet-visible spectrophotometry (UV–vis) techniques. Fine-grained and pure SmBO3 powders were successfully synthesized via a simple, feasible and scalable route, yielding both triclinic and hexagonal crystal structures. Triclinic SmBO3 powders were synthesized after mechanical activation for 1h and annealing at 700°C for 2h. The polymorphic transformation temperature of SmBO3 powders from triclinic to hexagonal is about 1080°C. Due to the effect of mechanical activation, the synthesis of triclinic SmBO3 phase and its transformation to hexagonal form were found to take place at ∼50–100°C lower temperatures than those reported in other methods. Mainly hexagonal SmBO3 powders were obtained after annealing at 1150°C in the presence of a very small amount of triclinic SmBO3. The resultant powders showed intense UV absorptions in the range between 1025 and 1150nm with minimum reflectivity of 0.57% (triclinic SmBO3 phase) and 0.68% (hexagonal SmBO3 phase) depending on their crystal structures.