Block-shaped Crystals Research Articles

Salts of 2-amino-5-iodopyridinium

Reaction of 2-amino-5-iodopyridine (5IAP) with concentrated HBr at room temperature yielded 2-amino-5-iodopyridinium bromide, C5H6IN2 +·Br− or (5IAPH)Br. The complex formed pale-yellow crystals, which exhibit significant hydrogen bonding between the amino and pyridinium N—H donors and bromide ion acceptors. Halogen bonding is also observed. Similarly, reaction of 5IAP with cobalt(II) chloride in mixed HCl/HBr in 1-propanol yielded 2-amino-5-iodopyridinium (2-amino-5-iodopyridine-κN 1)bromido/chlorido(0.51/2.48)cobalt(II), (C5H6IN2)[CoBr0.51Cl2.48(C5H5IN2)] or (5-IAPH)[(5IAP)CoCl2.48Br0.51], as blue block-shaped crystals. Two of the three halide positions exhibit mixed occupancy [Cl/Br = 0.797 (5):0.203 (5) and 0.689 (6):0.311 (6)], while the third position is occupied solely by a chloride ion. Extensive hydrogen and halogen bonding is observed.

Influence of temperature and flow rate on alteration layer structure and leaching properties of simulated sulfur-containing borosilicate HLW glass under multi-field coupling effects

During long-term deep geological disposal process, high-level liquid waste (HLW) glass may be exposed to “Thermodynamics-Hydrodynamics-Mechanics-Chemistry” (THMC)multi-field coupling effects. The leaching properties of sulfur-containing borosilicate HLW glass at different temperatures (40–150 °C) and different flow rates (0.01–0.10 mL/min) under THMC coupling effects were studied in this work. The alteration layer structure of waste glass surface was also characterized. The results show that honeycomb-shaped phyllosilicate alteration layer forms after leaching in simulated groundwater and white block-shaped BaSO4 crystals appear on the glass surface at 90 °C after 28 d. The amount of BaSO4 crystals increases obviously at 150 °C. The leaching rates of B, Si, Cs and U elements increase with increasing temperature and flow rate. Particularly, the leaching rates of B, Si, Cs, and U under THMC coupling effects (90 °C, 0.01 mL/min, 10 MPa, pH=8.05) after 28 d in the simulated groundwater are 1.10 × 10–1, 1.73 × 10–1, 2.91 × 10–1, 3.79 × 10–1 g·m-2·d-1, respectively.

3-[(Benzo-1,3-dioxol-5-yl)amino]-4-methoxycyclobut-3-ene-1,2-dione: polymorphism and twinning of a precursor to an antimycobacterial squaramide.

The title compound, 3-[(benzo-1,3-dioxol-5-yl)amino]-4-methoxycyclobut-3-ene-1,2-dione, C12H9NO5 (3), is a precursor to an antimycobacterial squaramide. Block-shaped crystals of a monoclinic form (3-I, space group P21/c, Z = 8, Z' = 2) and needle-shaped crystals of a triclinic form (3-II, space group P-1, Z = 4, Z' = 2) were found to crystallize concomitantly. In both crystal forms, R22(10) dimers assemble through N-H...O=C hydrogen bonds. These dimers are formed from crystallographically unique molecules in 3-I, but exhibit crystallographic Ci symmetry in 3-II. Twinning by pseudomerohedry was encountered in the crystals of 3-II. The conformations of 3 in the solid forms 3-I and 3-II are different from one another but are similar for the unique molecules in each polymorph. Density functional theory (DFT) calculations on the free molecule of 3 indicate that a nearly planar conformation is preferred.

Square-planar nickel/copper(II) complexes of (E)-2-(((2-ethylphenyl)imino)(phenyl)methyl)phenol: Supramolecular analysis, keto-enol tautomerism, polymorphism and antibacterial activities

A new Schiff base proligand, (E)-2-(((2-ethylphenyl)imino)(phenyl)methyl)phenol (HL), was synthesized from 2-hydroxybenzophenone and 2-ethylaniline and its coordination chemistry with nickel(II) and copper(II) acetate explored. In solution, the proligand HL undergoes ketoimine-enolimine tautomerism which settles exclusively into an enolimine form in the solid-state. Interestingly, while a single crystalline habit was obtained for the nickel complex 1 (block-shaped single crystals), the copper species 2 was found to solidify in two detectable polymorphs: block-shaped crystals (2a, monoclinic space group P21/c) and rhombic crystals (2b, triclinic space group P-1). Single-crystal X-ray diffraction studies reveal that the N,O Schiff base ligand chelates the divalent metal ions with square-planar geometry in the isostructural 1 and 2a and in a distorted square-planar geometry with a dihedral chelate-plane angle of 27.9° in 2b. The copper complex 2 exhibits significant antibacterial activity against the E. coli and medium activity against S. aureus bacteria. The physical properties of the complexes were further probed using thermal techniques, while their electronic structure was investigated by electrochemistry and electronic absorption spectroscopy.

Uncovering the mechanism of Tenofovir amibufenamide fumarate punch sticking by combining direct compression experiment and computational simulation

Punch sticking during tablet manufacturing is a prevalent issue for many active pharmaceutical ingredients (APIs) encountered by the pharmaceutical industry. Tenofovir amibufenamide fumarate (TMF), a heavyweight drug for the treatment of hepatitis B, was selected as a model drug due to its tendency to punch sticking during tablet compression. In this study, the cause of sticking was explored by investigating crystal habits, excipients and structure characteristics. The difference in sticking of three crystal habits can be visually represented through direct compression experiments on powdered samples and analysis of crystal surfaces. The excipients play a direct role in decreasing the probability of sticking, and the extent of sticking can be assessed by measuring the tensile strength of the tablet. Additionally, the plasticity index was utilized to theoretically analyze the potential enhancements of four excipients. These experimental results indicate that the block-shaped crystals have superior ability of anti-sticking and that suitable excipients can significantly improve the sticking situation of TMF. Ultimately, the phenomenon of punch sticking was additionally examined through computational calculations, focusing on the mechanical characteristics of TMF molecules and intermolecular interactions. The strategy of combining experiments and simulation calculations has broader significance for the study of drug production.

Crystal structures of polymerized lithium chloride and dimethyl sulfoxide in the form of {2LiCl·3DMSO} n and {LiCl·DMSO} n.

Two novel LiCl·DMSO polymer structures were created by combining dry LiCl salt with dimethyl sulfoxide (DMSO), namely, catena-poly[[chlorido-lithium(I)]-μ-(dimethyl sulfoxide)-κ2 O:O-[chlorido-lithium(I)]-di-μ-(dimethyl sulfoxide)-κ4 O:O], [Li2Cl2(C2H6OS)3] n , and catena-poly[lithium(I)-μ-chlorido-μ-(dimethyl sulfoxide)-κ2 O:O], [LiCl(C2H6OS)] n . The initial synthesized phase had very small block-shaped crystals (<0.08 mm) with monoclinic symmetry and a 2 LiCl: 3 DMSO ratio. As the solution evaporated, a second phase formed with a plate-shaped crystal morphology. After about 20 minutes, large (>0.20 mm) octa-hedron-shaped crystals formed. The plate crystals and the octa-hedron crystals are the same tetra-gonal structure with a 1 LiCl: 1 DMSO ratio. These structures are reported and compared to other known LiCl·solvent compounds.

Crystal structure of potassium orthoselenate(IV), K2SeO3.

Crystal structure data for potassium orthoselenate(IV), K2SeO3, are reported for the first time. Colorless, block-shaped crystals were grown in a potassium hydro-flux, i.e. under ultra-alkaline conditions, within 10 h. K2SeO3 crystallizes isostructural with Na2SO3 and K2TeO3 in the trigonal space group P with lattice parameters a = 6.1063 (4) Å and c = 6.9242 (4) Å at 100 (1) K. In the trigonal-pyramidal, C 3v-symmetric [SeO3]2- anion, the bond length is 1.687 (1) Å, and the bond angle is 103.0 (1)°. Two of the three unique potassium cations exhibit a coordination number of six, and the third a coordination number of nine.

Self-assembly of a cobalt(II)-based metal-organic framework as an effective water-splitting heterogeneous catalyst for light-driven hydrogen production.

The solar photocatalysis of water splitting represents a significant branch of enzymatic simulation by efficient chemical conversion and the generation of hydrogen as green energy provides a feasible way for the replacement of fossil fuels to solve energy and environmental issues. We report herein the self-assembly of a CoII-based metal-organic framework (MOF) constructed from 4,4',4'',4'''-(ethene-1,1,2,2-tetrayl)tetrabenzoic acid [or tetrakis(4-carboxyphenyl)ethylene, H4TCPE] and 4,4'-bipyridyl (bpy) as four-point- and two-point-connected nodes, respectively. This material, namely, poly[(μ-4,4'-bipyridyl)[μ8-4,4',4'',4'''-(ethene-1,1,2,2-tetrayl)tetrabenzoato]cobalt(II)], [Co(C30H16O8)(C10H8N2)]n, crystallized as dark-red block-shaped crystals with high crystallinity and was fully characterized by single-crystal X-ray diffraction, PXRD, IR, solid-state UV-Vis and cyclic voltammetry (CV) measurements. The redox-active CoII atoms in the structure could be used as the catalytic sites for hydrogen production via water splitting. The application of this new MOF as a heterogeneous catalyst for light-driven H2 production has been explored in a three-component system with fluorescein as photosensitizer and trimethylamine as the sacrificial electron donor, and the initial volume of H2 production is about 360 µmol after 12 h irradiation.

Guanine and 7,8-Dihydroxanthopterin Reflecting Crystals in the Zander Fish Eye: Crystal Locations, Compositions, and Structures.

The eyes of many fish contain a reflecting layer of organic crystals partially surrounding the photoreceptors of the retina, which are commonly believed to be composed of guanine. Here we study an unusual fish eye from Stizostedion lucioperca that contains two layers of organic crystals. The crystals in the outer layer are thin plates, whereas the crystals in the inner tapetum layer are block-shaped. We show that the outer layer indeed contains guanine crystals. Analyses of solutions of crystals from the inner layer indicated that the block-shaped crystals are composed of xanthopterin. A model of the structure of the block-shaped crystals was produced using symmetry arguments based on electron diffraction data followed by dispersion-augmented DFT calculations. The resulting crystal structure of xanthopterin included, however, a problematic repulsive interaction between C═O and N of two adjacent molecules. Knowing that dissolved 7,8-dihydroxanthopterin can oxidize to xanthopterin, we replaced xanthopterin with 7,8-dihydroxanthopterin in the model. An excellent fit was obtained with the powder X-ray diffraction pattern of the biogenic crystals. We then analyzed the biogenic block-shaped crystals in their solid state, using MALDI-TOF and Raman spectroscopy. All three methods unequivocally prove that the block-shaped crystals in the eye of S. lucioperca are crystals of 7,8-dihydroxanthopterin. On the basis of the eye anatomy, we deduce that the guanine crystals form a reflective layer producing the silvery color present on part of the eye surface, whereas the block-shaped crystals backscatter light into the retina in order to increase the light sensitivity of the eye.

Polymorphic crystals of oxacalix[4]arene with 1,3-alternate conformations of S4 and C2 symmetry.

Calix[4]arene and oxacalix[4]arene derivatives have eight possible conformations in the up and down directions of their four aromatic rings from the mean plane of a bridged central ring, the conformations of which determine the functionality of the host frameworks. Despite being a known compound for five decades, oxacalix[4]arene, C24H16O4, has not been characterized previously by crystallographic methods. It crystallizes from hexane/CH2Cl2 solution to give two polymorphs, i.e. prismatic and block-shaped crystals as twisted 1,3-alternate structures with S4 and C2 symmetry, respectively. These were previously suggested as the prefered stable conformations by density functional theory (DFT) calculations.

Effect of Si/Al ratio in the framework on the pervaporation properties of hollow fiber CHA zeolite membranes

Abstract Hollow fiber supported CHA zeolite membranes with different Si/Al ratios in the framework were successfully synthesized by changing precursor compositions. The influence of precursor composition on the membrane composition, microstructure evolution and dehydration performances of CHA zeolite membranes, were extensively investigated. Pervaporation (PV) results indicated that the membrane separation performances were strongly influenced by both the framework Si/Al ratio and the microstructure of the membranes. The membranes with Si/Al ratio of ca. 2.7–2.8 composed of flake-like grains showed higher flux with relatively low selectivity, while the membrane with Si/Al ratio of >2.9 composed of block-shaped crystals exhibited higher separation factor of >10000. Both hydrothermal and acid stability of the membranes were dependent on the framework Si/Al ratio of CHA zeolite membranes.

A cadmium(II) coordination polymer with both polyrotaxane and polycatenane features constructed by a V-shaped semi-rigid ligand: synthesis and fluorescence properties.

One of the most interesting phenomena in coordination polymers (CPs) is the co-existence of different interlaced motifs. However, CPs having two different interlaced motifs at the same time are still rare. Colourless block-shaped crystals of the two-dimensional polymer poly[[aqua(μ2-naphthalene-2,6-dicarboxylato){μ2-4,4'-[oxybis(4,1-phenylene)]dipyridine}cadmium(II)] monohydrate], {[Cd(C12H6O4)(C22H16N2O)(H2O)]·H2O}n, (I), was synthesized under hydrothermal conditions by the self-assembly of 4,4'-[oxybis(4,1-phenylene)]dipyridine (OPY) with CdII in the presence of naphthalene-2,6-dicarboxylic acid (H2ndc). Each CdII ion is six-coordinated by two N atoms from the pyridine rings of two OPY ligands and by four O atoms, three of which are from two ndc2- ligands and one of which is from a water molecule. In (I), every two identical two-dimensional (2D) 63 layers are interpenetrated in a parallel fashion, resulting in an interesting 2D→2D framework with both polyrotaxane and polycatenane characteristics. The extension of these sheets into a three-dimensional supramolecular net is via O-H...O hydrogen bonds. The solid-state photoluminescence properties of (I) are also discussed.

Cadmium(II)-Triazole Framework as a Luminescent Probe for Ca(2+) and Cyano Complexes.

A bidentate ligand, 1-{4-[4-(1H-1,2,4-triazol-1-yl)phenoxy]phenyl}-1H-1,2,4-triazole (TPPT), has been designed and synthesized. By using TPPT as a building block for self-assembly with Cd(NO3 )2 ⋅4 H2 O and CdCl2 ⋅10.5 H2 O, novel 1D double-chain {[Cd(TPPT)(NO3 )2 ]⋅3 H2 O}n (1) and 2D (4,4) layer [Cd(TPPT)Cl2 (H2 O)]n (2) have been constructed. When 1 was employed as a precursor and exposed to DMF or N,N'-dimethylacetamide (DMAC), the crystals of 1 dissolved and reassembled into two types of brown block-shaped crystals of 1D double chains: {[Cd(TPPT)2 (NO3 )2 ]⋅DMF}n (1 a) and {[Cd(TPPT)2 (NO3 )2 ]⋅DMAC}n (1 b). The anion-exchange reactions of complex 2 have also been investigated. After gently stirring crystals of 2 in CHCl3 /C2 H5 OH/H2 O containing NaBr, NaI⋅2 H2 O, or NaOAc⋅3 H2 O, the crystals retained their crystalline appearances. A remarkable single crystal to single crystal transformation was observed and 1D double chains of {[Cd(TPPT)Br2 ]⋅C2 H5 OH}n (2 a) and {[Cd(TPPT)2 I2 ]⋅CHCl3 }n (2 b), and 1D single chains of [Cd(TPPT)(H2 O)2 (CH3 COO)2 ]n (2 c), can be obtained. Luminescent properties indicate that 1 shows excellent selectivity for Ca(2+) and cyano complexes. To the best of our knowledge, this is the first example of a luminescent probe for Ca(2+) based on triazole derivatives.

Electronic Structure and Optical Properties of α-CH3NH3PbBr3 Perovskite Single Crystal

The electronic structure and related optical properties of an emerging thin-film photovoltaic material CH3NH3PbBr3 are studied. A block-shaped α-phase CH3NH3PbBr3 single crystal with the natural ⟨100⟩ surface is synthesized solvothermally. The room-temperature dielectric function ε = ε1 + iε2 spectrum of CH3NH3PbBr3 is determined by spectroscopic ellipsometry from 0.73 to 6.45 eV. Data are modeled with a series of Tauc-Lorentz oscillators, which show the absorption edge with a strong excitonic transition at ∼2.3 eV and several above-bandgap optical structures associated with the electronic interband transitions. The energy band structure and ε data of CH3NH3PbBr3 for the CH3NH3(+) molecules oriented in the ⟨111⟩ and ⟨100⟩ directions are obtained from first-principles calculations. The overall shape of ε data shows a qualitatively good agreement with experimental results. Electronic origins of major optical structures are discussed.

Crystal structure of catena-poly[bis(formato-κO)bis-[μ2-1,1'-(1,4-phenyl-ene)bis-(1H-imidazole)-κ(2) N (3):N (3')]cobalt(II)

A red block-shaped crystal of the title compound, [Co(HCOO)2(C12H10N4)2]n, was obtained by the reaction of cobalt(II) nitrate hexa­hydrate, formic acid and 1,1′-(1,4-phenyl­ene)bis­(1H-imidazole) (bib) mol­ecules. The asymmetric unit consists of one CoII cation, one formate ligand and two halves of a bib ligand. The central CoII cation, located on an inversion centre, is coordinated by two carboxyl­ate O atoms and four N atoms from bib ligands, completing an octa­hedral coordination geometry. The CoII centres are bridged by bib ligands, giving a two-dimensional net. Topologically, taking the CoII atoms as nodes and the bib ligands as linkers, the two-dimensional structure can be simplified as a typical sql/Shubnikov tetra­gonal plane network. The structure features C—H⋯O hydrogen-bonding inter­actions between formate and bib ligands, resulting in a three-dimensional supra­molecular network.

Structural characterization of 2,3,5,6-tetramethyl-p-phenylenediamine radical cation and its dimer in molecular crystals

Reaction between 2,3,5,6-tetramethyl-p-phenylenediamine (DDA) and bromanil (BA) gave two different crystalline products, needle-like and block-shaped crystals. The former was an alternate-stack 1:1 charge-transfer complex between DDA and BA with an electron-transfer ratio of about 0.7. The latter was a bromide salt of DDA, which was crystallized simultaneously with the decomposition of BA anions. The DDA molecules in the salt were dimerized even at room temperature. The similar products were obtained by a reaction between DDA and chloranil. The molecular and electronic structures are discussed with the calculation results of the density functional theory. This report has two additional meanings on the synthesis of charge-transfer complexes with using haloanils, which are commonly used as electron acceptors: (1) special attention must be paid for contaminating halide ions in characterizing reaction products and in discussing their properties, and (2) a new moderate synthetic root of halide complexes becomes available when using haloanils.

Influences of Molecular Structure on Supramolecular Selection during Cocrystallization of Polypyridyl Metal Complexes

Heteroleptic complexes of the type [RuL2L′](PF6)2 (L, L′ = combinations of 1,10-phenanthroline (phen) and 2,2′-bipyridine (bipy)) were found to cocrystallize with [Ni(phen)3](PF6)2 to produce cocrystals of [Ni(phen)3]x[RuL2L′]1–x(PF6)2. In this report we show that the ability of the complexes to cocrystallize is influenced by the number of common ligands between complexes in solution. Supramolecular selection is a phenomenon caused by molecular recognition through which cocrystals can grow from the same solution but contain different ratios of the molecular components. It was found that systems where L = phen displayed less supramolecular selection than systems where L = bipy. With increasing supramolecular selection, the composition of cocrystals was found to vary significantly from the initial relative concentration in the cocrystallizing solution, and therefore it was increasingly difficult to control the final composition of the resultant cocrystals. Consequently, modulation of concentration-dependent properties such as phase was also found to be less predictable with increasing supramolecular selection. Notwithstanding the complication afforded by the presence of supramolecular selection, our results reaffirm the robustness of the [M(phen)3](PF6)2 structure because it was maintained even when ca. 90% of the complexes in the cocrystals were [Ru(phen)(bipy)2](PF6)2, which in its pure form is not isomorphous with [M(phen)3](PF6)2. Experiments between complexes without common ligands, i.e., [Ru(bipy)3](PF6)2 cocrystallized with [Ni(phen)3](PF6)2, were found to approach the limit to which molecular recognition processes can be confused into cocrystallizing different molecules to form single cocrystals. For these systems the result was the formation of block-shaped crystals skewered by a needle-shaped crystals.

Structural Diversity of Hydrogen-Bonded Networks of [Co(NH3)6]3+ Complex Cations and Acetylenedicarboxylic Acid Anions

2011 The crystal structure of [Co(NH3)6](ADC)(HADC) · 2H2O (1) (ADC2- =acetylenedicarboxylate) (P21=n, Z = 4) was mistakenly described as containing the [Co(H2O)6]3+ ion [I. Stein, U. Ruschewitz, Z. Naturforsch. , 66b, 471 - 478]. A revision is reported. While attempting to reproduce 1, we isolated phase-pure crystalline material of [Co(NH3)6]Cl2(HADC) · H2O (2), the crystal structure of which was also reported in the article above. Upon standing in the aqueous mother liquor at room temperature for several days, the needle-shaped crystals of 2disappear, while blockshaped crystals of the formerly unknown compound [Co(NH3)6](ADC)(HADC) (3) grow. Satellite peaks in the X-ray diffraction frames indicate that the crystal structure is incommensurately modulated. Dissolving crystals of 3 in water at elevated temperature leads to plate-shaped crystals of the new compound [Co(NH3)6]2(ADC)3 · 3H2O (4) upon slow cooling to room temperature. Compounds 2- 4 were investigated by elemental analysis, powder X-ray diffraction and infrared spectroscopy. Structural characterization of 4 by single-crystal X-ray analysis was also achieved (P1̅ , Z = 2). Complex 1, however, could not be reproduced

Investigation into the Cooling Crystallization and Transformations of Carbamazepine Using in Situ FBRM and PVM

The cooling crystallization of carbamazepine (CBZ) from 1-propyl alcohol has been investigated experimentally using in situ FBRM and PVM to study crystal growth and transformations. The effects of seeding strategies and cooling profiles on nucleation, growth, and polymorphism were investigated. The trigonal form II of CBZ, which has a needle-like morphology, was obtained in 72% yield from an unseeded crystallization process. Block-shaped crystals of CBZ form III were obtained in 86% yield from a crystallization process that was seeded with form III. Both product CSD and crystal form were influenced significantly by cooling profiles. As the cooling rate in the seeded process increased, the levels of form II in the product decreased. The transformation from form II to form III during crystallization was studied using online tools and offline measurements by optical microscopy, X-ray powder diffraction (XRPD), and differential scanning calorimetry (DSC).

ChemInform Abstract: Nona‐Copper(II)‐Containing 18‐Tungsto‐8‐arsenate(III) Exhibits Antitumor Activity.

AbstractDark‐brown, block‐shaped crystals of Na8 [H4{Cu9As6O15 (H2O)6} (α‐AsW9O33)2]·41H2O are obtained from aqueous mixtures of NaAsO2, Na2WO4, CuCl2, and AcOH (room temperature, 14 d, 11% yield).