The structure of cellulose microfibrils in wood is not known detail, despite the abundance woody biomass and its importance for biology, energy, engineering. spruce was investigated using a range spectroscopic methods coupled to small-angle neutron wide-angle X-ray scattering. scattering data were consistent with 24-chain favored “rectangular” model both hydrophobic hydrophilic surfaces exposed. Disorder chain packing hydrogen bonding shown increase outwards from microfibril center. extent...

In the primary walls of growing plant cells, glucose polymer cellulose is assembled into long microfibrils a few nanometers in diameter. The rigidity and orientation these control cell expansion; therefore, synthesis key factor growth morphogenesis plants. Celery (Apium graveolens) collenchyma useful model system for study wall microfibril structure because its are oriented with unusual uniformity, facilitating spectroscopic diffraction experiments. Using combination x-ray neutron scattering...

Cellulose is the most familiar and abundant strong biopolymer, but reasons for its outstanding mechanical performance are not well understood. Each glucose unit in a cellulose chain joined to next by covalent C-O-C linkage flanked two hydrogen bonds. This geometry suggests some form of cooperativity between bonding. Using infrared spectroscopy X-ray diffraction, we show that tension straightens out zigzag conformation chain, with each pivoting around fulcrum at either end. Straightening...

We report a series of Zr(<sc>iv</sc>) 2,2′-bipyrrolidine–salan derived complexes and their exploitation for the ROP <italic>rac</italic>-lactide to afford highly isotactically enriched PLA.

A series complexes based on 2,2′-bipyrrolidine salan ligands have been prepared and either isotactic or heterotactic PLA prepared.

A simple route to crystallization of the pharmaceutically important paracetamol form II is reported. The method based around multicomponent techniques, involving various second components containing carboxylic acid groups and a range solvents. These experiments do not produce molecular complexes, but instead they provide conditions in which metastable reliably produced 100% yields with stability greater than one year. To date, batches have been easily on 100 mg scale clear potential for bulk...

New {TbCu3} and {DyCu3} single-molecule magnets (SMMs) containing a low-symmetry Ln(III) center (shape measurements relative to trigonal dodecahedron biaugmented prism are 2.2-2.3) surrounded by three Cu(II) metalloligands reported. SMM behavior is confirmed frequency-dependent out-of-phase ac susceptibility signals single-crystal temperature sweep rate dependent hysteresis loops. The ferromagnetic exchange interactions between the central ion ions could be accurately measured inelastic...

Abstract We report a series of 3d–4f complexes {Ln 2 Cu 3 (H L) X n } (X=OAc − , Ln=Gd, Tb or X=NO Tb, Dy, Ho, Er) using the 2,2′‐(propane‐1,3‐diyldiimino)bis[2‐(hydroxylmethyl)propane‐1,3‐diol] 6 pro‐ligand. All complexes, except that in which show slow magnetic relaxation zero applied dc field. A remarkable improvement energy barrier to reorientation magnetisation {Tb is seen by changing auxiliary ligands for NO ). This leads largest reported field Tb/Cu‐based single‐molecule magnet. Ab...

High resolution X-ray diffraction data on forms I-IV of sulfathiazole and neutron II-IV have been collected at 100 K analyzed using the Atoms in Molecules topological approach. The molecular thermal motion as judged by anisotropic displacement parameters (adp's) is very similar all four forms. adp thiazole sulfur atom had greatest amplitude perpendicular to five-membered ring, analysis temperature dependence adps indicates that this due genuine rather than a concealed disorder. A minor...

Cellulose from grasses and cereals makes up much of the potential raw material for biofuel production. It is not clear if cellulose microfibrils differ in structure those other plants. The structures highly oriented cell walls internodes bamboo Pseudosasa amabilis are reported. Strong orientation facilitated use a range scattering techniques. Small-angle neutron provided evidence extensive aggregation by hydrogen bonding through hydrophilic edges sheets chains. had mean centre-to-centre...

Abstract Cellulose microfibrils in conifers, as other woody materials, are aggregated into loose bundles called macrofibrils. The centre-to-centre spacing of the within these macrofibrils can be estimated from position a broad diffraction peak small-angle neutron scattering (SANS) after deuteration. A known 3.0 nm, increasing with moisture content, is consistent direct microfibril to contact. However recent evidence indicates that conifer partially coated bound xylan chains, and possibly...

ADVERTISEMENT RETURN TO ISSUEPREVLetterNEXTRegiocontrolled Rearrangement of IsobenzofuransBen A. Egan†, Michael Paradowski‡, Lynne H. Thomas§, and Rodolfo Marquez†∥View Author Information WestCHEM, University Glasgow, Joseph Black Building, Avenue, Glasgow G12 8QQ, United Kingdom, Pfizer Global R&D, Sandwich, Kent CT13 9NJ, Department Chemistry, Bath, Bath BA2 7AY, Kingdom[email protected]†University Glasgow.‡Pfizer R&D.§University Bath.∥Ian Sword Reader Organic Chemistry EPSRC Leadership...

The short intramolecular hydrogen bond in dibenzoylmethane has been studied by variable temperature neutron and X-ray single-crystal diffraction. Fourier difference maps have used to image both the nuclear electronic density of bond, addition determination refined positions obtained from maxima these densities. diffraction data shows an asymmetric position atom which is invariant as a function temperature. imaged measurements, on other hand, migration bonding at low temperatures almost centred room

The thermochromic behaviour of the haloaniline – 3,5-dinotrobenzoic acid cocrystals over temperature range from 30–108 °C.

A transferable, simple, method for producing previously elusive and novel polymorphic forms of important active pharmaceutical ingredients (APIs; paracetamol (acetaminophen), piroxicam piracetam) is demonstrated. Nitrogen heterocyclic co-molecules are employed to influence the self-assembly crystallisation process in a multi-component environment. Previously unknown solvates have also been synthesised by this method.

The enantioselective total syntheses of 10 cladiellin natural products have been completed, starting from the known allylic alcohol (+)-14, which can be prepared in large quantities. bridged tricyclic core cladiellins has constructed via three ring-forming reactions: (i) an intramolecular reductive cyclization between aldehyde and unsaturated ester, mediated by samarium(II) iodide, to form a tetrahydropyranol; (ii) reaction metal carbenoid, generated diazo ketone, with ether produce...

The persistence of the acid⋯amide heterodimer and effect methyl substitution on short strong O–H⋯O hydrogen bond is investigated in urea methylurea di-carboxylic acid molecular complexes. Temperature dependent structural changes are also reported utilising X-ray neutron diffraction tandem.

A new functionalized bis-pyrazol-pyridine ligand has been prepared by reaction with hydrazine of the corresponding bis-β-diketone precursor, also unprecedented. The aerobic this ferrous thiocyanate in presence ascorbic or oxalic acid affords dinuclear complex seven-coordinate Fe(III), [Fe₂(H₄L2)₂(ox)(NCS)₄] (1), as revealed single crystal X-ray diffraction. This may represent an entry into a family [Fe₂] compounds heptacoordinate metal centres. capacity unusual chromophore to undergo...

The multicomponent ternary complex of 4-dimethylaminobenzoic acid (4-DABA), 3,5-dinitrobenzoic (3,5-DNBA), and 4,4′-bipyridine (BIPY) has been studied by variable temperature X-ray neutron diffraction. Proton disorder is observed within the 4-DABA homodimers present quantitatively evaluated from data. effect crystal environment in particular pyramidalization nitrogen atom molecule consequential on presence hydrogen are discussed with reference to previously determined pure structure binary...

The carboxylic acid dimer is a frequently observed intermolecular association used in crystal engineering and design, which can show proton disorder across its hydrogen bonds. Proton benzoic dimers dynamic, temperature-dependent process whose reported occurrence still relatively rare. A combination of variable temperature X-ray neutron diffraction has been applied to demonstrate the effect local crystalline environment on both degree onset 3,5-dinitrobenzoic dimers. Dimers have significantly...

A series of monometallic and bimetallic Al(III) complexes with substituted naphthyl based Schiff base ligands have been prepared characterised. When 1-aminonaphthalene were reacted AlMe3 isolated, however, 1,5 1,8-diaminonaphthalene formed. In all cases 4-coordinate tetrahedral centres observed in the solid state solution. There was little difference rate polymerisation rac-lactide between on 1,5-diaminonaphthalene. However, for complex an order magnitude faster than analogous 1,5-system....

A series of new ligands based on a 2-(aminomethyl)piperidine motif have been prepared. An interesting diversity in structure is observed, all complexes trialled for the polymerisation <italic>rac</italic>-lactide.

Analysis of neutron and high-resolution X-ray diffraction data on form (III) carbamazepine at 100 K using the atoms in molecules (AIM) topological approach afforded excellent agreement between experimental results theoretical densities from optimized gas-phase structure multipole modelling static factors. The charge density analysis provides confirmation partially localized π-bonding suggested by conventional structural formula, but evidence for any significant C-N π bonding is not strong....