The Characteristics of the Mixed Crystals of the K2SO4-(NH4)2SO4-H2O System at 298 K

Equilibrium studies of the K₂SO₄-(NH₄)₂SO₄-H₂O system at 298 K have been conducted. The isotherm of solubility and the curve of distribution have been mathematically described. The parameters of the crystal lattice and the enthalpy of crystallization of the [K_x(NH₄)_1-x]₂SO₄ solid solutions as a function of their composition have been presented.     

Crystal structure of 2-amino-3-methylpyridinium ortho-phthalate

A new crystal of 2-amino-3-methylpyridinium ortho-phthalate has been prepared and characterized by X-ray crystallography. The salt crystallizes in the monoclinic space group P2₁/c with a = 11.015(2) Å, b = 11.057(2) Å, c = 15.767(2) Å, = 90.00°, = 96.220(10)°, = 90.00°, V = 1909.0(5) ų, Z = 4. In the cell unit, the phthalate anion is linked with two pyridinium cations by NHO hydrogen bond on both sites of annular and exocyclic nitrogen atoms. The two pyridinium cations are arranged in a face-to-face pattern with a dihedral angle of 7.3° and a shortest aspectant distance of 3.4(1) Å between them, indicating the existence of – interaction. The C(5) atom is an electron donating center. The exocyclic N atom is an electron receiving center, which is consistent with features of imino resonance evidenced by bond lengths and angles. In the cell unit, two entities of pyridinium cation are aligned with each other in a face-to-face manner of electron receiving to donating center.     

The Characteristics of the Mixed Crystals of the KCl-KBr-H2O System at 298 K

The equilibrium studies of the KCl-KBr-H₂O system at 298 K have been conducted. The isotherm of solubility and the curve of distribution have been mathematically described. The parameters of the crystal lattice and the enthalpy of crystallization of the K[Cl_xBr_1-x] solid solutions as a function of their composition have been presented.     

Growth and characterization of 2-amino-5-chlorobenzophenone (2A-5CB) single crystals

Organic nonlinear optical single crystals of 2-amino-5-chlorobenzophenone (2A-5CB) were grown in ethanol by slow solvent evaporation technique. The grown crystals were characterized by single-crystal XRD, FTIR, FT-Raman and UV–vis–NIR techniques. The UV–vis–NIR spectrum ascertains the cut-off wavelength of the sample as 390 nm. The powder second harmonic generation (SHG) technique reveals that 2A-5CB crystal has its SHG efficiency nearly three times that of KDP. The dielectric response of the sample was studied in the frequency region of 50 Hz–1 MHz at varying temperatures. The photoconductivity studies indicate that the 2A-5CB crystal exhibits negative photoconductivity. TGA–DTA studies confirm the melting point of the sample as 101.5 °C.     

Structure of bis(2-pyridine-N-oxide) diselenide and its formation from tetraphenylantimony(V)selenopyridine-N-oxide

The structure of bis(2-pyridine-N-oxide) diselenide was determined by single crystal X-ray diffraction. The compound crystallized in the triclinic system and the structure was solved in the space group . The lattice constants were determined to bea=7.174(2),b=7.176(2),c=11.070(2) , =87.67(2)°, =73.68(2)°, and =89.57(2)°;Z=2,D _x=1.906 Mg m^–3. The final least squares refinement based on 1942 independent observed reflections yieldedR=0.033,wR=0.044. The Se–Se bond length is 2.326(1) and each Se is coordinated to the O atom of the corresponding N-oxide moiety at a distance of about 2.6 .     

Structure of ethyl(3-amino-5-nitrobenzo[b]thiophen)-2-carboxylate

The title compound was obtained as main product by the reaction of 3-chloro-5-nitro-1,2-benzisothiazole with diethyl malonate in sodium ethoxide. It crystallizes in the monoclinic space groupP2₁/n witha=12.143(5),b=11.172(4),c=8.567(3) Å,=95.51(2)°,Z=4. The structure was solved by direct methods and refined by full-matrix least-squares to a finalR value of 0.035 for 1217 reflections. The entire molecule is substantially planar except for the terminal methyl group. The amino group is involved in intra- and intermolecular hydrogen bonding.     

Crystal Structure of 5,5'-(Furan-2-ylmethylene)bis(6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione)

Crystallography Reports - The crystal structure of the title compound is determined by single crystal X-ray structure analysis. The compound C17H20N6O5, crystallizes in the monoclinic crystal...     

Crystal growth and characterization of Au3+ ion irradiated 2-amino-5-nitropyridinium hydrogen oxalate (2A5NPHO)

2-amino-5-nitropyridinium hydrogen oxalate (2A5NPHO) was grown using slow evaporation and bulk crystal of 2A5NPHO was harvested from Assembled Temperature Reduction (ATR) method. Cut and polished crystal was irradiated using Au³⁺ ion with various fluences. Electronic loss, nuclear energy loss and penetration depth were calculated using SRIM software. It was observed in X- ray pattern that intensity of peak was reduced. Intensity of peak decreased with increase of ion fluencies from 10¹³ ions/cm² to 10¹⁴ ions/cm². Optical properties were measured using UV-Vis spectrometer. The increase of absorption was due to excited electrons which were formed by vacancies and formation of additional defects centres. Energy band gap of irradiated crystals increased with increase of ion fluence. Energy band gap of irradiated crystals were 3.39 eV, 3.42 eV, and 3.4 eV for 10¹³ ions/cm², 5 × 10¹³ ions/cm² and 10¹⁴ ions/cm² respectively and increase of band gap was due to the increase of forbidden gap. Microhardness was calculated using Vicker's Hardness tester. Increase of microhardness in irradiation crystal was due to increase of high density lattice defects produced by Au³⁺ of 10.8 MeV. Electrical property was calculated using dielectric constant. Increase of dielectric constant was due to large polarization which caused by disorderness and rich defects in the crystalline surface. Decrease of intensity peak in fluorescence was due to transition of excited electron to intermediated energy levels from excited state which converted into vibrational energy of lattice atoms (phonon). Morphology of irradiated crystal was seen using scanning electron microscope (SEM). It was observed from the SEM image that surface of crystal was heavily damaged. It was also noticed that the thermal stability of the irradiated single crystal increased with increase of ion fluences. Impedance of irradiated crystal was measured. The bulk resistance and grain boundary resistance also were calculated.     

Structure, thermal behavior, and IR investigation of bis(3-amino-1,2,4-triazolium)monohydrogen monophosphate

Chemical preparation, calorimetric studies, crystal structure, and IR spectrometric investigation of (C₂H₅N₄)₂HPO₄, denoted ATZP, are described. The compound crystallizes in the monoclinic system with C2/c space group. Its unit cell dimensions are a = 13.589(2) Å b = 11.105(2) Å c = 15.734(3) Å = 104.68(2)°, V = 2296.8(7) ų, and Z = 8. The structure of the title compound consists of a three dimensional network of H-bonds connecting all its components. The IR spectrum of ATZP is reported and discussed on the basis of group theoretical analysis.     

Synthesis and crystal structures of 5-amino-1-(2-hydroxyethyl)imidazole-4-carboxamide and 5-amino-1-(2-chloroethyl)-4-cyanoimidazole

Both 5-amino-1-(2-hydroxyethyl)imidazole-4-carboxamide (AHIC) and 5-amino-1-(2-chloroethyl)-4-cyanoimidazole (ACCI) have been synthesized and crystallized in the monoclinic space group P2₁/c, Z = 4, with a = 8.420(2), b = 9.759(2), c = 10.583(2) Å, = 111.80(2)° for AHIC and a = 6.139(1), b = 8.522(2), c = 15.156(3) Å, = 96.71(2)° for ACCI. Differences in the molecular geometries of the two compounds are attributed to the differences in the substituents at the 1- and 4-positions of the imidazole ring. The molecular conformation of AHIC is stabilized by intramolecular hydrogen bonding between the 5-amino and the vicinal carboxamide moiety, resulting in an extended planar structural pattern. The presence of the cyano group in the 4-position of ACCI prevents the formation of such an intramolecular hydrogen bond. Both the crystal structures are stabilized by networks of intermolecular hydrogen bonds.     

New (TMTSF)2X Derivatives: A Change in the Selenium Network Dimensionality Derived From the Molecular and Crystal Structures of (TMTSF)2(Fso3) [T=298K, 123K] and (TMTSF)2(Bro4) T=298K

Abstract

We report the first crystallographic analysis, as a function of temperature, of a TMTSF derivative. Both (TMTSF)₂(FSO₃) and (TMTSF)₂(BrO₄) are isostructural (triclinic, with space group PI) with superconducting (TMTSF)₂(ClO₄). (TMTSF)₂(FSO₃) undergoes a metal-to-insulator transition at 86-90K as observed by microwave conductivity, D.C. conductivity, and magnetic susceptibility. The crystal structure contains 2-dimensional sheets of short Se-Se contacts in the molecular stacking direction and perpendicular to the stacking direction. The temperature dependent variations in these contact distances appear to be of special importance in determining the conduction properties of these materials, and are observed to change in a surprising manner when (TMTSF)₂(FSO₃) is cooled (298 → 123K). The homoatomic Se separations within each TMTSF molecule appear to increase slightly, but not significantly. At the same time the entire 2-dimensional sheet of intermolecular (intra- and interstack) Se-Se contacts between TMTSF molecules contract quite anisotropically, which results in an increase in “dimensionality” of the Se-Se network. Hence, an increase in electrical conduction, in the absence of insulating phenomena, over the temperature range 298 → 123K is not surprising. The intermolecular Se-Se contact distances in (TMTSF)₂(BrO₄) are significantly longer than in (TMTSF)₂(FSO₃) which suggests that the room temperature electrical conductivity of the (BrO₄)^? salt may be diminished compared to the (FSO₃)^? analogue.     

Synthesis, growth of organic nonlinear optical crystal: Semicarbazone of 2-amino-5-chloro-benzophenone (S2A5CB) and its characterisation

A new organic crystal of semicarbazone of 2–amino–5–chloro–benzophenone has been grown as a single crystal by slow evaporation solution growth technique for the first time in the literature. The grown crystal has been characterised by proton nuclear magnetic resonance spectral analysis and single crystal and powder X-ray diffraction studies. Functional groups of the crystallised molecules were confirmed by FT-IR and FT-Raman analyses. Mechanical strength of the crystals was studied by microhardness test. Optical transparency of the grown crystals has been studied by UV-Visible spectra. The second harmonic generation property of the compound was analysed.     

Structure of a C2-symmetric bis(benzyloxy)trishomocubanone

The structure of a bis(benzyloxy)trishomocubanone with molecular C₂ symmetry reveals that substitution of benzyloxy groups has little effect on the trishomocubane cage.     

Synthesis and crystal structure of bis(2-methylbenzimidazolium) tetrahalocuprate(II)

The crystal structures of 2-methylbenzimidazolium tetrahalocuprates (H2-mebz)₂[CuX₄] (X = Cl and Br) have been detemined. The chloride salt is monoclinic, P2₁/c, with a = 8.540(2) Å, b = 16.591(2) Å, c = 14.303(3) Å, and = 98.69(2)°. The bromide salt is also monoclinic, P2₁/c, with a = 8.316(3) Å, b = 17.436(3) Å, c = 14.747(3) Å, and = 98.82(3)°. Both the compounds contain discrete distorted tetrahedral CuX₄ ^2– anions and almost planar 2-methylbenzimidazolium cations. In the chloride salt, three chloride ions are involved in hydrogen bonding instead of two bromide ions in the bromide salt.     

Erratum to:Crystal Structure of 5,5'-(Furan-2-ylmethylene)bis(6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione)

Crystallography Reports - An Erratum to this paper has been published: https://doi.org/10.1134/S1063774521220016     

Synthesis,Crystal Growth,Structural and Physical Properties of bis(thallium) bis(nitrilotriacetato) zirconate dihydrate,Tl2Zr(N[CH2COO]3)2 · 2H2O

Single crystals of Tl₂Zr(N[CH₂COO]₃)₂ · 2H₂O having optical quality and dimensions up to 30 × 25 × 12 mm have been grown from aqueous solutions by controlled lowering of temperature. The raw material was synthesized as the first fraction of crystallization during evaporation of an aqueous solution of (CH₃NH₃)₂Zr(N[CH₂COO]₃)₂ · 2H₂O and TlNH₂SO₃. A crystal structure analysis revealed an isotypy to the K₂Zr(N[CH₂COO]₃)₂ · 2H₂O family, space group Ccc2, a₁ = 14.780(2)Å, a₂ = 14.933(2)Å, a₃ = 8.901(1)Å, Z = 4, ρ_calc. = 3.145 gcm^‐3. Thermal stability, thermal expansion and pyroelectric, dielectric, piezoelectric, elastic and thermoelastic properties have been determined. All properties are closely related to those of Rb₂Zr(N[CH₂COO]₃)₂ · 2H₂O.     

Br···HN, N···HC, Br···HC, and Br···Br intermolecular interactions as supramolecular synthons: Synthesis and crystal structure of bis(2-amino-5-methylpyridinium) tetrabromomercurate(II)

The bis(2-amino-5-methylpyridinium) tetrabromomercurate(II) (C₆H₉N₂)₂[HgBr₄] salt is triclinic, P1, with the following cell parameters: a=8.060(8) ?, b=9.035(9) ?, c=14.964(10) ?, α=96.032(19)°, β=90.317(15)°, γ=113.32(2)°, V=993.8(15) ?³, with Z=2 formula units. The crystal structure consists of alternating stacks of inorganic HgBr₄ ²⁻ anions and organic layers of 2-amino-5-methylpyridinium cations parallel to c-axis. The cohesion forces that connect molecules in the organic layers are N···HC hydrogen bonding and π–π stacking. The HgBr₄ ²⁻ units in the inorganic stacks are attracted via Br···Br intermolecular interactions.Supplementary material CCDC 270395 contains the supplementary crystallographic data. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by e-mailing at data_request@ccdc.cam.ac.uk, or by contacting the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: + 44(0)1223-336033.     

Preparative and structural studies of halodimolybdates (II), III. Crystal and molecular structure of bis(4-methylpyridinium)hexaiododiaquo-dimolybdate(II)

The title compound (C₆H₈N)₂Mo₂I₆(H₂O)₂ crystallizes in theP¯1 space group, witha = 8.127(3),b = 8.337(3),c = 10.415(4) Å, = 73.99(2), = 84.35(2), = 73.91(2) ° andZ = 1. The structure was solved by direct methods and refined to the unweighted and weighted residuals of 0.044 and 0.052. The structure is characterized by the eclipsed configuration of the iodide ions and water molecules within Mo₂I₆(H₂O) ₂ ^2– ion and very short Mo-Mo bond distance 2.115(1) Å. Three independent Mo-I distances are 2.784(1), 2.760(2) and 2.797(1) Å. 4-Methylpyridinium ion is planar within 0.02° Å. The compound is isostructural with (C₆H₈N)₂Mo₂Br₆(H₂O)₂.Part II, Breni, J. V., Leban, I., and egedin, P. (1976).Z. Anorg. Allg. Chem. 427, 85.     

The Characteristics of the Mixed Crystals of the KNO3‐NH4NO3‐H2O System at 298 K

The equilibrium studies of the KNO₃‐NH₄NO₃‐H₂O system at 298 K have been conducted. The isotherm of solubility and the curve of distribution have been mathematically described. The parameters of the crystal lattice and the enthalpy of crystallization of the [K_x(NH₄)_1‐x]NO₃ solid solutions as a function of their composition have been presented. The structure of salts KNO₃�xNH₄NO₃ with different x values have been solved and refined.