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The title compound, C15H10I2O, is a halogenated chalcone formed from two iodine substituted rings, one para-substituted and the other meta-substituted, linked through a prop-2-en-1-one spacer. The crystal structure shows the mol­ecules contain halogen bonds which are always between equivalent iodine atoms, either para–para or meta–meta., The title compound, C15H10I2O, is a halogenated chalcone formed from two iodine substituted rings, one para-substituted and the other meta-substituted, linked through a prop-2-en-1-one spacer. In the mol­ecule, the mean planes of the 3-iodo­phenyl and the 4-iodo­phenyl groups are twisted by 46.51 (15)°. The calculated electrostatic potential surfaces show the presence of σ-holes on both substituted iodines. In the crystal, the mol­ecules are linked through type II halogen bonds, forming a sheet structure parallel to the bc plane. Between the sheets, weak inter­molecular C—H⋯π inter­actions are observed. Hirshfeld surface analysis showed that the most significant contacts in the structure are C⋯H/H⋯C (31.9%), followed by H⋯H (21.4%), I⋯H/H⋯I (18.4%). I⋯I (14.5%) and O⋯H/H⋯O (8.1%).

An organic–inorganic hybrid CuII–ErIII heterometallic arsenotungstate Na3[Cu(en)2(H2O)][Cu(en)2]1.5[H3Er(α-AsW11O39)2]·4H2O (1) (en = ethylenediamine) has been hydrothermally synthesized and structurally characterized by elemental analyses, IR and UV spectra, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry and single-crystal X-ray diffraction. 1 displays an organic–inorganic 2-D sheet structure constructed by sandwich-type [H3Er(α-AsW11O39)2]8− fragments and [Cu(en)2]2+ connectors. From the topological viewpoint, if the [H3Er(α-AsW11O39)2]8− fragments are viewed as 3-connected nodes and [Cu(en)2]2+ connectors are considered as linkers, the 2-D sheet can be simplified into a 2-D (6,3)-network topology. Keywords: Polyoxometalate, Arsenotungstate, CuII–ErIII heterometallic derivative, Spectroscopic characterization

Herein, we report a new polymorph of amodiaquine dihydrochloride dihydrate obtained via heterogeneous crystallisation. This new polymorph exhibits similarity in molecular conformation as well as in its one-dimensional chain structure with a previously known polymorph, however with a difference in its two-dimensional sheet structure. Although crystal DFT-calculations predict the new form to be thermodynamically less stable compared to the previously known polymorph, the preparation method applied opened up the access to its metastable zone.

The title crystals are isomorphous, and form centrically stacked planar sheets formed by CN⋯I and NC⋯I short contacts., The title crystals, C7H2I3N, are isomorphous. Both mol­ecules lie across two crystallographic mirror planes and a twofold axis. The principal supra­molecular inter­action is centric R 2 2(10) CN/NC⋯I short contacts involving both ortho I atoms, with two contacts bis­ecting each cyano and iso­cyano group. These form ribbons along [010] and give rise to a planar sheet structure parallel to (100). All pairs of adjacent sheets have centric stacking, a mode not previously reported for sheets of this type. This study completes the series of homo-2,4,6-trihalobenzo­nitriles, in which I atoms give the strongest CN⋯X and NC⋯X inter­actions (X = F, Cl, Br, I).

Natural enzymes are expected to be used in biomedical fields due to their extensive antibacterial activity, good biocompatibility and resistance to bacteria. Herein, we constructed a multi-enzyme protein assembly with ultrathin single protein sheet structure by the strategy of interface assembly and developed an efficient and intelligent antibacterial system based on the combination of multi-enzymes. The multi-enzyme protein assembly not only displayed extremely high antibacterial activity, but can also be turned on and off through the denaturant induced folding and unfolding of natural enzymes, and this process can be realized for several reversible cycles. Such an intelligent antibacterial material provides the possibility for its application in biomedical and other fields.

The reaction of Ni(mnt)2 (mnt = 1,2-dicyano-1,2-ethylenedithiolate) with CuI in THF results in the formation of a Ni(mnt)2Cu4I4 unit with an eight-membered Cu4I4 crown motif. Coordination polymers with Ni(mnt)2Cu4I4 building units, having doubly bridged 1-D chains, were formed with bulky NBu4 counterions. To pack the bulky NBu4 cations into the crystal structure, no direct interactions between the 1-D chain structures are observed. When the bulky NBu4 cations are exchanged for small sodium cations, direct interactions between the 1-D chain structures dominate. A doubly bridged 2-D sheet structure is formed through the bridging of the cyano groups of the Ni(mnt)2Cu4I4 units of neighboring 1-D chain structures by sodium atoms. The monomeric [Na2(18-crown-16)]2[Ni(mnt)2Cu4I4] complex is formed when the sodium cations of the 2-D sheet structure are captured by 18-crown-6. The configuration of the coordination polymer or the monomer is controlled through the selection of the appropriate countercation to the Ni...

By introduction of 2-methyl-1,5-diaminopentane (DAP) and 1,4-diaminobutane (DAB) as templated ions, three new amine-templated organophosphonate open-framework compounds [H2DAP][Zn6(Hhedp)2(hedp)2]·4H2O, I, [H2DAB][Zn6(Hhedp)2(hedp)2]·4H2O, II, and [H2DAB][Zn3(hedp)2]·2H2O, III, have been synthesized, structurally analyzed, and characterized for the first time. Both compounds I and II have analogous 2-D sheet structure connecting through metal and diphosphonates (1-hydroxyethane-1,1-diphosphonic acid), while the templated amines are different in the framework. Compound III consists of Zn ions and diphosphonate ligands with templated DAB, forming three-dimensional framework with interconnected 4-T, 8-T, and 12-T ring channels. To the best of our knowledge, such structural modifications with coordination variation of metal ions applying the same amine have never been reported in the organophosphonate family. The presence of mixed metal as well as different aliphatic amines plays a crucial role for the struct...

In the title compound, the 1,3-dioxane ring has an envelope conformation. In the crystal, classical O—H⋯O and N—H⋯O hydrogen bonds link mol­ecules into a sheet structure, and a weak inter­molecular C—H⋯Cl inter­action extends the sheet structure into a three-dimensional network., In the title compound, C10H14Cl3NO5, the five-membered dioxolane ring adopts an envelope conformation with the C atom bonded to the butenoate side chain as the flap. It deviates from the mean plane of the other atoms in the ring by 0.446 (6) Å. In the crystal, mol­ecules are connected by O—H⋯O hydrogen bonds into helical chains running along the b-axis direction. The chains are linked into a sheet structure parallel to (001) by an N—H⋯O hydrogen bond. These classical hydrogen bonds enclose an R 4 4(24) graph-set motif in the sheet structure. Furthermore, a weak inter­molecular C—H⋯Cl inter­action expands the sheet structures into a three-dimensional network.

In the title dimedone derivative, the 4-hy­droxy-3-meth­oxy­benzyl substituent adopts a sofa conformation. In the crystal, mol­ecules are assembled into a sheet structure parallel to the ab plane via O—H⋯O hydrogen bonds., In the title compound, C16H20O4, a new starting compound for the synthesis of various heterocycles, the partially saturated six-membered ring adopts a sofa conformation. An intra­molecular O—H⋯O hydrogen bond is observed in the guaiacol residue. In the crystal, mol­ecules are assembled into a sheet structure parallel to the ab plane via O—H⋯O hydrogen bonds. The hydrogen-bond pattern is described by an R 4 4(28) graph-set motif. The sheets are further linked by C—H⋯O hydrogen bonds into a three-dimensional network.

The fabrication of so-called ghost-leg sheets and their electronic properties is reported. This unique sheet structure is composed of one-dimensional mixed-valence nickel chains, which are linked with one another by bis(azamacrocycle) ligands. They are also topologically unique NiII/NiIII mixed-valence complexes, as confirmed by X-ray and optical measurements. Moreover, their magnetic susceptibilities indicated two-dimensional antiferromagnetic behavior following the Fisher 1D chain model with interchain interactions, where spins on NiIII sites mutually interact antiferromagnetically in the sheets.

In the crystal of the title compound, a supra­molecular sheet structure is formed through N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds., In the title compound, C19H19NO5, the amide carbonyl O atom is positioned anti to the other two carbonyl O atoms. The 4-hy­droxy­hydro­cinnamate fragment is disordered over two positions with an occupancy ratio of 0.729 (12):0.271 (12). The N—(C=O)—C plane of the acetamide group and the acetate O—(C=O)—C plane are almost co-planar; the acetamide plane makes dihedral angles of 1.9 (6) and 16.0 (19)°, respectively, with the acetate planes of the major and minor occupancy components. In the crystal, N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into a supra­molecular sheet structure parallel to (102).

Waterproof-breathable (WB) materials with outstanding waterproofness, breathability, and mechanical performance are critical in diverse consumer applications. Electrospun nanofibrous membranes with thin fiber diameters, small pore sizes, and high porosity have attracted significant attention in the WB fabric field. Hot-press treatment technology can induce the formation of inter-fiber fusion structures and hence improve the waterproofness and mechanical performance. By combining electrospinning and hot-press treatment technology, polyurethane/fluorinated polyurethane/thermoplastic polyurethane/alkylsilane-functionalized graphene (PU/FPU/TPU/FG) nanofiber WB fabric was fabricated. Subsequently, the morphologies, porous structure, hydrostatic pressure, water vapor transmission rate (WVTR), and stress&ndash, strain behavior of the nanofiber WB fabric were systematically investigated. The introduction of the hydrophobic FG sheet structure and the formation of the inter-fiber fusion structure greatly improved not only the waterproofness but also the mechanical performance of the nanofiber WB fabric. The optimized PU/FPU/TPU-50/FG-1.5 WB fabric exhibited an excellent comprehensive performance: a high hydrostatic pressure of 80.4 kPa, a modest WVTR of 7.6 kg m&minus, 2 d&minus, 1, and a robust tensile stress of 127.59 MPa, which could be used to achieve various applications. This work not only highlights the preparation of materials, but also provides a high-performance nanofiber WB fabric with huge potential application prospects in various fields.

Designed as an anode material for sodium ion batteries, nitrogen-doped carbon sheets (NCSs) were successfully synthesized using graphene and dopamine as template and carbon precursor, respectively. The NCSs demonstrate high reversible capacity and excellent rate performance, delivering a high reversible capacity of 382 mAh g−1 at 50 mA g−1 after 55 cycles. Even up to 10 A g−1, a rate capacity of 75 mAh g−1 can be obtained. Furthermore, NCSs also have remarkable cycling stability with specific capacity of 165 mAh g−1 after 600 cycles (under 200 mA g−1). The excellent performance of NCSs can be ascribed to the nitrogen-doped two-dimension sheet structure.

Five novel copper(II) coordination polymers containing cyanoacetate (cna) anion with various N,N′-ditopic spacers [Cu(cna)2(pyz)]n (1), [Cu(cna)2(bpy)(H2O)2]n (2), [Cu(cna)2(dpe)]n (3), [Cu(cna)2(dpe)]n(H2O)n (4), and [Cu(cna)2(bpa)]n (5) (when pyz = pyrazine, bpy = 4,4′-bipyridyl, dpe = 1,2-di(4-pyridyl)ethylene, and bpa = 1,2-di(4-pyridyl)ethane) were structurally and spectroscopically characterized. Compound 1 shows a two-dimensional (2D) sheet structure constructed from μ2-1,3(syn,anti) coordinative mode of cyanoacetate and μ2-pyz linking adjacent Cu(II) centers. Compound 2 exhibits a one-dimensional (1D) polymeric chain which is formed by μ2-bpy bridging between [Cu(cna)2(H2O)2] units, whereas compounds 3–5 reveal 1D ladder-like structures which are built from double-μ2-dpe/bpa spacers connecting neighboring Cu(II) cyanoacetate dimers. Weak interactions such as hydrogen bonding and N···π and/or C–H···π interactions join the adjacent layers of 1 or polymeric chains of 2–5 to stabilize overall supramol...

Two uranyl tungstates, Cs4[(UO2)4(WO5)(W2O8)O2] (CsUW-1) and Cs4[(UO2)7(WO5)3O3] (CsUW-2), were obtained via the high-temperature solid-state synthesis method by reacting uranyl nitrate with WO3 in the presence of cesium nitrate. CsUW-1 crystallizes in space group P21/n, adopting a two-dimensional (2D) sheet structure. CsUW-2 forms a three-dimensional (3D) framework constructed by complex 2D sheets linked by cation–cation interactions of UO22+ groups. The cation–cation interactions fragment presented in CsUW-2 involves the 2D → 3D transformation of the uranyl tungstate network and acts as an intermediate part by bridging the structures of CsUW-1 and CsUW-2. We demonstrate that the chemical and structural transformation from CsUW-1 to CsUW-2 is possible via adding a suitable amount of UO3 oxide. In addition, the differential scanning calorimetry-thermogravimetric technique was carried out to gain insight into the thermal behavior of the synthesized compounds. Raman spectra of titled compounds were obtained...

The title compound shows two packing polymorphs, in which the mol­ecular structures are planar and essentially similar. One crystal shows inter­molecular C—H⋯O and π–π inter­actions, while the other crystal exhibits several modes of inter­molecular C—H⋯O inter­actions., The title compound, C11H13NO6, shows two polymorphs, orange and yellow forms, both of which crystallize in the space group P21/c. The mol­ecular structures in the two polymorphs are essentially similar and adopt a planar structure, the maximum deviations for the non-H atoms being 0.1836 (13) and 0.1276 (13) Å, respectively, for the orange and yellow forms. In the orange crystal, mol­ecules are linked by an inter­molecular C—H⋯O inter­action into a helical chain along the b-axis direction. The chains are stacked along the c axis through a π–π inter­action [centroid–centroid distance = 3.6087 (11) Å], forming a layer parallel to the bc plane. In the yellow crystal, mol­ecules are connected through C—H⋯O inter­actions into a sheet structure parallel to (-302). No significant π–π inter­action is observed. The unit-cell volume of the orange crystal is larger than that of the yellow one, and this accounts for the predominant growth of the yellow crystal.

Eight compounds of Co, Ni, and Cu with mellitate ligands display a wide variety of structures with metal–mellitate coordination polymer dimensionality 0–3. Usually mellitate is fully deprotonated (mel6–), but there is one example of Hmel5– and one of H2mel4–. [M3(mel)(OH2)12]·6H2O (M = Co or Ni) are chain polymers with octahedral M, while [Cu7(OH2)19(OH)2(mel)2]·9H2O has a 2D polymer sheet structure with square-based pyramidal Cu. Addition of KOH produces different compounds. Two incorporate K+ in the structures: K+2(OH2)5[{Ni(OH2)5}2(mel)]2–·2H2O contains discrete nickel–mellitate anionic units, and K+2(OH2)6[{Cu(OH2)3}2(mel)]2–·H2O has a copper–mellitate two-dimensional (2D) polymeric anion. For Co the product is [Co(OH2)6]2+[{Co(OH2)4}5(mel)2]2–·4H2O, with a 2D polymeric anion and discrete cations. A gel-supported synthesis leads to [Cu3(OH2)10(Hmel)][Cu2(OH2)6(Hmel)]·7H2O, with two different copper–mellitate polymeric sheets arranged alternately in a stack. [{Cu(OH2)(EtOH)(4,4′-bipy)}2(H2mel)] contain...

FTIR microspectroscopy was applied for studying macromolecular changes in human serum samples from patients with healthy livers, and those diagnosed with liver cirrhosis or hepatocellular carcinoma (HCC). Our study demonstrated that the serum samples from HCC and cirrhotic patients could readily be discriminated from those from healthy controls based on macromolecular differences related to their lipid and protein structure. Spectral changes appeared to indicate that the secondary structure of protein from HCC sample groups contained a more distinctive β -sheet structure and a lower lipid content compared to samples from the healthy and cirrhosis group. This was correlated with measurements of large decreases in albumin levels in serum from diseased patients. We argue that this technique shows potential as a simple, rapid, inexpensive, and non-subjective methodology for the screening patients suspected of liver disease. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Three new supramolecular coordination polymers, namely [Zn(1,3-BDC)(HL)]n (Polymer 1), [Zn3(1,3,5-BTC)2(HL)2(H2O)2]n (Polymer 2), and [Zn9(5-SO3-1,3-BDC)2(L)8(OH)4]n (Polymer 3), were synthesized under solvothermal conditions, based on 1H-pyrazolo[3,4-b]pyridin-3-amine (HL) along with 1,3-benzenedicarboxylate (1,3-BDC) and its derivatives, such as 1,3,5-benzenetricarboxylate (1,3,5-BTC) and 5-sulfo-1,3-benzenedicarboxylate (5-SO3-1,3-BDC). Polymers 1–3 were characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction (PXRD), and single crystal X-ray diffraction analysis. Polymer 1 exhibited a two-dimensional (2D) 4-connected sql net. The neighboring 2D nets were further linked into a 3D supramolecular network by hydrogen-bonding interactions. Polymer 2 displayed a 3D (4, 4, 4)-connected network, which was further stabilized by R 2 2 (14) and S(9) hydrogen-bonding rings along with π–π interactions. The 2D sheet structure of Polymer 3 was constructed by novel quasi-linear nonanuclear Zn(II) units, which further extended into a 3D supramolecular structure by hydrogen-bonding interactions. The solid-state photoluminescence properties of Polymers 1–3 were also investigated.

A 2D Strandberg-type phosphomolybdate hybrid [Cu(En)(EnH)]2[P2Mo5O23] · 3H2O (I) (En = ethylenediamine) has been successfully synthesized under hydrothermal conditions and structurally characterized by elemental analyses, IR spectrum, UV spectrum and single-crystal X-ray diffraction. The molecular structural unit of I consists of one Strandberg-type [P2Mo5O23]6− subunit, two [Cu(En)(EnH)]3+ cations and three lattice water molecules. The most remarkable feature of I is that each molecular structural unit is connected with adjacent four same units by four [Cu(En)(EnH)]3+ bridges constructing the 2D organic-inorganic hybrid sheet structure with a 4-connected topology. As far as we know, such 2D hybrid sheet structure constructed from Strandberg-type phosphomolybdate units and copper-organic cation bridges is very rare.

Four new silver(I) coordination polymers (CPs) based on 3-nitrophthalic acid (H2npt), [Ag2(NH3)2(npt)]n (1), [Ag2(NH3)(npt)]n (2), {(NH4)[Ag(npt)·H2O]}n (3) and [Ag4(NH3)4(npt)2·H2O]n (4), have been synthesized and structurally characterized. Compound 1 shows a 1D chain based on a binuclear Ag(I) SBU (secondary building unit). The [Ag(NH3)2] units are bound on the two sides of the 1D chain through the ligand-unsupported argentophilic interactions. Compound 2 is a 2D 44-sql net constructed from npt ligand-bridged centrosymmetric Ag4 rhombus SBUs. Compound 3 exhibits an anionic 2D sheet, in which the infinite chain-like [Ag2(COO)2]n SBUs are observed along the b axis. In compound 4, infinite silver nets are fabricated by ligand-unsupported argentophilic interactions and the npt ligands are anchored on the net to form the 2D sheet structure. Four CPs exhibit unprecedentedly high structural diversity dependent on the solvent and induction agent. In detail, 1, 2 and 3, 4 are mainly controlled by the induction agent, but 1, 3 and 2, 4 are controlled by the solvent systems. The thermal stabilities and photoluminescence behaviours of the compounds were also discussed.

The arsenic(III) and antimony(III) cyanides M(CN)3 (M=As, Sb) have been prepared in quantitative yields from the corresponding trifluorides through fluoride-cyanide exchange with Me3 SiCN in acetonitrile. When the reaction was carried out in the presence of one equivalent of 2,2'-bipyridine, the adducts [M(CN)3 ⋅(2,2'-bipy)] were obtained. The crystal structures of As(CN)3 , [As(CN)3 ⋅(2,2'-bipy)] and [Sb(CN)3 ⋅(2,2'-bipy)] were determined and are surprisingly different. As(CN)3 possesses a polymeric three-dimensional structure, [As(CN)3 ⋅(2,2'-bipy)] exhibits a two-dimensional sheet structure, and [Sb(CN)3 ⋅(2,2'-bipy)] has a chain structure, and none of the structures resembles those found for the corresponding arsenic and antimony triazides.

In this paper, tubular structure has been obtained by self-assembly of cholesterol derivative via sol–gel process. The tube structure and the formation mechanism have been studied and certified by scanning electron microscopy, infrared, ultraviolet-visible spectroscopy (UV–vis) and x-ray diffraction (XRD) data. It is predicated that the tube has been formed by the curl of sheet structure, and the aggregates are composed of two molecules of 1 with H aggregate in laminar structure at micro level.

(Chemical Equation Presented) A twist of fate: Parallel-turn linkers comprising an amino acid derived alcohol conjoined with an aromatic amide through a flexible linkage adopt reverseturn conformations. Cyclopropane tetra-and hexapeptide analogues form a C-H⋯O hydrogen-bond-stabilized parallel-sheet conformation (see scheme). NMR studies confirm the presence of hydrogen bonds in these structures. © 2008 Wiley-VCH Verlag GmbH and Co. KGaA.

Two-dimensional (2D) magnetic pyrrhotite (Fe7S8) and greigite (Fe3S4) nanosheets were synthesized by pyrolyzing, respectively, single-source precursors such as Fe(Ddtc)2(Phen) (Phen = 1,10-phenanthroline; Ddtc = diethyldithiocarbamate) and Fe(Ddtc)3 in oleylamine. Under optimized reaction temperature of 280 °C, both monoclinic Fe7S8 and cubic Fe3S4 obtained presented hexagonal sheet structure with sizes of 500–800 nm and 100–500 nm, respectively. AFM measurements revealed that both of these two types of nanosheets had a nearly identical thickness of 50 nm. Further XRD measurements revealed that the reaction temperature played a critical role in determining the crystalline structure as well as the chemical composition of the resultant nanosheets. In the reaction temperature range of 240−320 °C, a higher reaction temperature generally favored the transformations of monoclinic Fe7S8 to hexagonal FeS, and cubic Fe3S4 to hexagonal Fe7S8, respectively. The magnetic properties of the resultant nanosheets were ac...

An increasing number of diseases, including Alzheimer's, have been found to be a result of the formation of amyloid aggregates that are practically independent of the original primary sequence of the protein(s). (Eakin, C. M.; Berman, A. J.; Miranker, A. D. Nat. Struct. Mol. Biol. 2006, 13, 202-208.) Consequently, the driving force of the transformation from original to disordered amyloid fold is expected to lie in the protein backbone, which is common to all proteins. (Nelson, R.; Sawaya, M. R.; Balbirnie, M.; Madsen, A. O.; Riekel, C.; Grothe, R.; Eisenberg, D. Nature 2005, 435, 773-778. Wright, C. F.; Teichmann, S. A.; Clarke, J.; Dobson, C. M. Nature 2005, 438, 878-881.) However, the exact explanation for the existence of such a "dead-end" structure is still unknown. Using systematic first principle calculations on carefully selected but large enough systems modeling the protein backbone we show that the beta-pleated sheet structure, the building block of amyloid fibers, is the thermodynamically most stable supramolecular arrangement of all the possible peptide dimers and oligomers both in vacuum and in aqueous environments. Even in a crystalline state (periodical, tight peptide attechment), the beta-pleated sheet assembly remains the most stable superstructure. The present theoretical study provides a quantum-level explanation for why proteins can take the amyloid state when local structural preferences jeopardize the functional native global fold and why it is a beta-pleated sheetlike structure they prefer.

The heat-induced denaturation and the molecular basis for aggregation in β -lactoglobulin has been investigated using a combination of molecular dynamics simulation and bioinformatics analysis. Molecular dynamics has been used to simulate the temperature induced unfolding of a single β -lactoglobulin molecule. Although the study is carried out at an elevated temperature to speed up the simulation, it confirms the experimental observation that the β -sheet structure in the protein is more stable to heat than the α-helical regions. We have also used bioinformatics analysis to search the β -lactoglobulin primary sequence for potential minimal sequences that may act as initiators for fibril formation in fine-stranded gels. Two potential candidate sequences were identified, and one GDLEIL was shown by molecular dynamics simulation to be able to form anti-parallel β -sheet with copies of itself. The potential significance of the minimal sequences to fine-stranded gel formation is discussed by way of analogy with the postulated mechanisms for amyloid fibril formation.

Crystal structures of morpholinium hydrogen bromanilate have been determined at 130, 145 and 180 K. The asymmetric unit comprises one morpholinium cation and two halves of crystallographically independent bromanilate monoanions. The conformations of the two independent bromanilate anions are different from each other with respect to the O—H orientation. The two different anions are linked alternately into a chain though a short O—H⋯O hydrogen bond, in which the H atom is disordered over two positions., Crystal structures of the title compound (systematic name: morpholin-4-ium 2,5-di­bromo-4-hy­droxy-3,6-dioxo­cyclo­hexa-1,4-dien-1-olate), C4H10NO+·C6HBr2O4 −, were determined at three temperatures, viz. 130, 145 and 180 K. The asymmetric unit comprises one morpholinium cation and two halves of crystallographically independent bromanilate monoanions, which are located on inversion centres. The conformations of the two independent bromanilate anions are different from each other with respect to the O—H orientation. In the crystal, the two different anions are linked alternately into a chain along [211] through a short O—H⋯O hydrogen bond, in which the H atom is disordered over two positions. The refined site-occupancy ratios, which are almost constant in the temperature range studied, are 0.49 (3):0.51 (3), 0.52 (3):0.48 (3) and 0.50 (3):0.50 (3), respectively, at 130, 145 and 180 K, and no significant difference in the mol­ecular geometry and the mol­ecular packing is observed at the three temperatures. The morpholinium cation links adjacent chains of anions via N—H⋯O hydrogen bonds, forming a sheet structure parallel to (-111).

In the title complex, [Co(μ-NCS)2(μ-C6H7NO)]n, both the thio­cyanate and 4-methyl­pyridine N-oxide ligands coordinate to the CoII atom as bridging ligands, forming a two-dimensional sheet structure. There is a non-classical C—H⋯S hydrogen bond in the sheet.

Crystals of [Me4N]2[HgI4] (1) and [Me4N][Hg2I5] (2), were obtained from solutions of stoichiometric amounts of HgI2 and Me4NI in EtOH or acetone, resp., while crystals of [Li(12-crown- 4)2]2[Hg4I10] (3) formed upon interdiffusion of methanolic solutions of HgI2, LiI and of the auxiliary ligand. The crystal structures of the compounds were determined. The [Hg2I5]− ion in (2) has a polymeric sheet structure, built up from [Hg2I6] units bridged by [HgI4] groups sharing common apices. The [Hg4I10]2− ion in 3 consists of four [HgI4] tetrahedra sharing common edges. A short survey on the iodomercurate(II) anions known up to now is given and a classification is proposed

A family of lamellar mesostructured aluminophosphates, denoted Mu-4-Ln (L stands for lamellar, n = 4, 8, 12, 16, the number of carbon atoms for n-alkyl chain) has been prepared through intercalating n-alkylamines into the layered aluminophosphate [(C2H5)2NH2]4[Al8P10O40H2]·[H2O]2.5 (Mu-4) using an ultrasonic method. The intercalation compounds are characterized by XRD, IR, TG, NMR, as well as compositional analyses. The results show that the intact sheet structure of Mu-4 retains while the n-alkylamines are intercalated into the layers. A linear relationship is observed between the interlayer distance and the number of carbon atoms in n-alkyl chains. A possible arrangement of the n-alkylamines in the interlayer space has been proposed using computer simulations.

Self-assembly of 5,10,15,20-tetra(4-pyridyl)porphyrin and trans-[Cu(hfacac)2(H2O)2] (hfacac = 1,1,1,5,5,5-hexafluoroacetylacetonate) including in situ Cu2+ metalation of the porphyrin core afforded a rhomboidally distorted (4,4)-net based polymeric 2D layer structure.

The structure of the title compound, C7H9NO2S, forms a supra­molecular network. The planar sheet structure displays both intra- and inter­molecular N—H⋯O hydrogen bonding. The asymmetric unit consists of two molecules.

In the title compound, $C_9H_6N_2O$, two independent and almost identical molecules, pseudosymmetrically related by twofold rotation, form the asymmetric unit. The molecules adopt an overall L-shaped structure in which the cyanomethoxy residue is approximately perpendicular to the benzonitrile plane. The molecules assemble into dimers via $C-H...N$ and $C-H...O$ interactions, forming a sheet structure approximately in the (404) plane. Noteworthy $\pi-\pi$ interactions result in two distinct types of offset $\pi$-stacking arrangements.

In the title compound, C12H12N2O2, the dihedral angle between the planes of the two pyridine rings is 5.8 (1)°. Neighbouring molecules are linkedviaC(Me)—H...N interactions, generating a two-dimensional sheet structure; C—H...π interactions further link the molecules into a three-dimensional network. An overlapped arrangement of parallel pyridine rings in neighbouring molecules [centroid-to-centroid distance = 3.6655 (15) Å] is observed in the crystal structure.

The crystal structure of the title compound, magnesium penta­oxoditellurate(IV), has been redetermined from a crystal grown from the melt and confirms the previous study [Tromel (1975). Z. Anorg. Allg. Chem. 418, 141–144], but with improved precision. It is isotypic with β-MnTe2O5 and contains MgO6 octa­hedra and TeO3+1 units, with the latter forming an extended sheet structure. Mg and one O atom occupy special positions with site symmetry 2.

The cation interacts with the anion in the title compound, [Mn(C12H8N2)2(H2O)2](C7H4O6S)·4H2O, through hydrogen bonding with the coordinated water mol­ecules in a hydrogen-bonded sheet structure. The Mn atom is in an octahedral environment in which the two water mol­ecules occupy cis positions.

Modeling the mechanisms of protofibril twisting: Molecular-dynamics simulations of simian viral peptide aggregates show that β sheets of 10 to 30 chains form left-handed helical ribbons with saddlelike curvature (see picture). These structures are highly dynamic, with oscillations around an average twist angle of 9-10°, and a pitch of 15-20 nm, depending on β-sheet length. The peptides studied are key to viral entry into host cells.

The title compound, C10H9N2+·C8H4NO6−·C8H5NO6·2H2O, consists of singly protonated 2,2′-bipyridinium cations, 5-nitroisophthalate anions, 5-nitroisophthalic acid and water mol­ecules of crystallization, linked by N—H⋯O and O—H⋯O hydrogen bonds. The moieties are linked by multiple hydrogen bonds into an undulating sheet structure.

A solvate of 5-fluoro­uracil with di­methylform­amide (DMF), 2C4H3FN2O2·C3H7NO, is reported. It crystallizes in the monoclinic space group P21/n, with two mol­ecules of 5-fluoro­uracil and one mol­ecule of DMF in the asymmetric unit. This solvate exhibits a sheet structure, with the DMF mol­ecules present on both surfaces of the sheet and 5-fluoro­uracil mol­ecules within the sheath of DMF mol­ecules.

The title compound, C5H4N2O4·H2O, a uracil derivative, contains several important functional groups, which give rise to its use in biomedical applications. The crystal structure consists of mol­ecules held together by extensive intermolec­ular hydrogen bonding between neighbouring pyrimidine rings and between the acid groups and water mol­ecules, resulting in a layered sheet structure. The asymmetric unit contains two molecules of the carboxylic acid and two water molecules.

New large, up to 45-membered macrocycles were synthesised from piperazine and m- and p-2,6-bis(bromomethyl)xylene under high dilution conditions. X-ray structures of compounds 3a, 4a, 5a, and 8b were determined. Surprisingly, none of the macrocycles prepared showed any inclusion properties towards small guest molecules. Instead, the compounds were found to self-organize during the packing process into larger structures due to the complementary of the molecular skeletons. In the crystalline state 3a forms nets, where the macrocycles are bound by HCH…N interactions to each other. 4a exits in a dimeric structure, which, in turn, further extends to a sheet structure. The positively charged phane 8b (di-dihydrochloride salt) adopts a chair-chair conformation, confirming that protonation of the N atoms does not change the conformation.

Polymeric di­chloro(N,N-di­methyl­ethyl­enedi­amine)­cad­mium­(II), [CdCl2(C4H12N2)]n, has been synthesized and characterized by single-crystal X-ray diffraction. The two-dimensional polymeric sheet structure involves 12-membered zigzag rings formed by chloro bridges.

The title compound, C5H6ClN3O, is essentially planar with a maximum deviation of 0.0256 (11) Å for all non-H atoms. In the crystal, adjacent molecules are linked by a pair of N—H...N hydrogen bonds, forming an inversion dimer with an R22(8) ring motif. The dimers are further linked via N—H...O hydrogen bonds into an undulating sheet structure parallel to the bc plane.

The reactivity of aqueous Fe(II) with aluminum oxide in anoxic solutions was investigated with batch kinetic experiments combined with Fe K edge X-ray absorption spectroscopy measurements to characterize Fe(II) sorption products. Formation of Fe(II)-Al(III)-layered double hydroxides with an octahedral sheet structure similar to nikischerite (NaFe(II)(6) Al(3)(SO(4))(2)(OH)(18) (H(2)O)(12)) was observed within a few hours during sorption at pH 7.5 and aqueous Fe(II) concentrations of 1-3 mM. These Fe(II) phases are composed of brucite-like Fe(II)(OH)(2) sheets with partial substitution of Al(III) for Fe(II), charge balanced by anions coordinated along the basal planes. Their fast rate of formation suggests that these previously unrecognized Fe(II) phases, which are structurally and compositionally similar to green rust, may be an important sink of Fe(II) in suboxic and anoxic geochemical environments, and impact the fate of structurally compatible trace metals, such as Co(II), Ni(II), and Zn(II), as well as redox-reactive species including Cr(VI) and U(VI). Further studies are required to assess the thermodynamics, formation kinetics, and stability of these Fe(II) minerals under field conditions.

The bis(benzimidazol-1-yl)methane molecule of the title compound, C15H12N4·2H2O, displays a trans conformation with a twofold axis running through the methylene C atom. Two adjacent water molecules are bonded to this molecule through O—H...N hydrogen bonds, forming a trimer. Adjacent trimers are connected together via C—H...O interactions, forming a chain running along the b-axis direction. Two such chains are joined together via π–π interactions [centroid–centroid distance = 3.556 (2) Å], forming double chains, which are connected via the water molecules through C—H...O associations, forming a sheet structure. The sheets are stacked on top of each other along the a-axis direction and connected through O—H...O and C—H...O interactions, forming a three-dimensional ABAB layer network structure.

In the crystal structure of the title compound, C6H13N2O+·C7H4NO5−, the isonipecotamide cations and the 5-nitrosalicylate anions form hydrogen-bonded chain substructures through head-to-tail piperidinium–carboxylate N—H...O hydrogen bonds and through centrosymmetric cyclic head-to-head amide–amide hydrogen-bonding associations [graph set R22(8)]. These chains are cross-linked by amide–carboxylate N—H...O and piperidinium–nitro N—H...O associations, giving a sheet structure.

The reaction of silver(I) perchlorate with the semi-rigid ligand 1,4-bis((3,5-dimethylisoxazol-4-yl)methyl) benzene (bisox) in methanol gives a triply-interpenetrated sheet structure, but a structure containing both interpenetrated sheets and Ag-2(bisox)(3) cages is formed on recrystallisation from acetonitrile-diethyl ether. Rearrangement of the cages into sheets occurs on heating under vacuum, a process which involves a solid state change in conformation of the bisox ligands.