Colin Rix

A simple and rapid colorimetric method for the determination of amylose in starch products

A method for the determination of the amylose content in starch has been developed which is based on the colorimetric measurement of the iodine complexes formed with amylose and amylopectin. The method requires measurement at only one wavelength and avoids the use of harsh dispersants for the starch. Dimethyl sulphoxide is used as the dispersant and a wavelength of 600 nm can be used for measurement of the amylose content of starches from different botanical sources. A linear relationship was obtained between absorbance and amylose concentration for mixtures of amylose and amylopectin standards, and this forms the basis of the determination. The method is rapid, simple, accurate and does not require the use of multi-component analysis of spectra, since a wavelength is chosen that suits the particular starch being analysed. It can be adapted to a micro-scale method if necessary.

High-peroformance liquid chromatographic procedure for direct determination of the compound class composition of diesel and kerosine fuels using refractive index detection

Abstract A High-performance liquid chromatography method utilizing a bonded aminosilane stationary phase, n -heptane mobile phase and refractive index detection is described for quantification of the compound class composition (saturates, single-ring aromatics, double-ring aromatics, polynuclear aromatics and polars) of olefin free kerosine and diesel fuels. Refractive index response factors for each of the compound classes have been determined using fractions obtained from preparative scale column chromatographic separation for a range of fuel samples. Variations in response factors for fractions derving from different fuel sources are described and are considered sufficiently small to allow acceptable analytical accuracy for refractive index detection.

Novel copper materials based on the self-assembly of organophosphonic acids and bidentate amines

The hydrothermal synthesis and crystal structure of seven new supramolecular, heterocyclic adducts of copper organophosphonates are presented. Compounds 1–4, [CuX(D)2][C6H5P(O)(OH)2] [C6H5P(O)2(OH)], where D = 1,10-phenanthroline (phen) and X = Cl (1), Br (2), I (3), and NCS (4), are ionic in nature and possess a monoclinic structure, with the copper(II)-halide bond lying along a two-fold crystallographic axis. The crystals exhibit an alternating, lamellar structure in which 1-D ‘ribbons’ of [CuX(phen)2]+ cations are interleaved with 2-D ‘sheets’ of anionic [C6H5P(O)(OH)2][C6H5P(O)2(OH)]− dimers. The ribbons are associated through π–π bonding of the heterocyclic rings, and the acid sheets through a combination of π–π bonding of the aromatic rings, and hydrogen-bonding between the PO and P–OH of neighbouring acid dimers. Analogous derivatives have also been prepared by the reaction of [Cu(phen)2]Br with benzylphosphonic acid (5), [Cu(2,2′-bipy)2]I with phenylphosphonic acid (6) and [Cu(phen)2]I with phenylsulfonic acid (7). These complexes did not produce crystals suitable for single-crystal analysis. However, compounds (5) and (7) are thought to have similar structures to 1–4, whilst compound (6) has a different (2 : 2 : 3) ratio of copper : phosphonate : amine. Thus the supramolecular structure is robust for phenyl- and benzyl-phosphonic acids, with Cl, Br, I and NCS copper(II)phen complexes, and slightly varied by the presence of phenylsulfonic acid, but is not observed in the presence of 2,2′-bipy.

Supramolecular bidentate amine derivatives of copper(ii) organophosphonatesElectronic Supplementary Information (ESI) available: 3D images for compound 1 and compound 2. See http://www.rsc.org/suppdata/ce/b4/b400064a/

Four novel complexes of copper(II) with organophosphonic acids and bidentate amines: [CuDn((OH)O2PR)][(OH)O2PR)]·(H2O)x, where D = 1,10-phenanthroline (C12H8N2 or phen) or 2,2′-bipyridyl (C10H8N2 or 2,2′-bipy), n = 1 or 2, R = C6H5 or CH2C6H5, and x = 0, 1, 4 or 7, have been synthesised by hydrothermal reactions at 160 °C. A combination of structural studies and various analytical techniques indicate that for species where D = phen and R = C6H5 (1), and where D = phen and R = CH2C6H5 (2), the compounds are crystalline ionic materials possessing triclinic and monoclinic structures, respectively. The crystal structures of (1) and (2) are supramolecular and contain ribbons of [Cu(phen)2((OH)O2PR)]+ cations, interleaved between H-bonded sheets of organophosphonate anions and water molecules. The data compiled for the 2,2′-bipy derivatives (3–4) are somewhat different from the phen species, indicating there is only one amine ligand for each copper atom. Powder XRD, FTIR, TGA, UV-Vis, and XPS data consistent with the formulations are presented.

Synthesis and characterisation of a series of lamellar gallium and indium phosphonates and related compounds

A series of new layered gallium(III) and indium(III) phosphonates, phenylarsonates and phenylphosphinates have been prepared and characterised. The methylphosphonate, phenylphosphonate and phenylarsonate derivatives of gallium(III) possess a metal to ligand ratio of 1 ∶ 1 and properties consistent with the formulation Ga(OH)(O3XR) (where X = P or As for R = C6H5, and where X = P for R = CH3), whereas the benzylphosphonate derivative forms the monohydrate Ga(OH)(O3XCH2C6H5)·H2O. The corresponding phosphinate derivative of gallium(III) has a metal to ligand ratio of 1 ∶ 2 with the formulation Ga(OH)(O2P(H)C6H5)2. The gallium compounds all contain a hydroxo group bonded to the metal, unlike the corresponding indium(III) compounds. The phenylphosphonate and phenylarsonate derivatives of indium(III) have a 1 ∶ 2 metal to ligand ratio and formula In(O3XR)(O2X(OH)R)·H2O (where R = C6H5 or CH2C6H5 when X = P and R = C6H5 when X = As), where the ligand is present as both a mono- and di-anion. The methylphosphonate of indium(III) has the unexpected formulation In2(O3PCH3)3·2H2O whereas the indium(III) phenylphosphinate compound is In(O2P(H)C6H5)3. These compounds were characterized by elemental analysis, thermal gravimetry, X-ray powder diffraction (XRD) and solid state 31P/13C MAS NMR spectroscopy. Powder XRD measurements indicate these compounds contain layered solid state structures.

Clathrate directed assembly of tetrapyridyl-tetraphenylethylene metal–organic frameworks

This work focuses on three 2-D MOFs based on the ligand tetrapyridyltetraphenylethylene (tppe) with the metal ions manganese(II), nickel(II) and copper(II). These networks are all highly microporous with rhomboid channels measuring ∼14 × 17 A giving approximately 49% solvent accessible void space. These voids are filled with ordered tetrachloroethylene (TCE) molecules that act as structure directing agents, and the structures remain porous even after removal of TEC molecules. The networks were characterised via single crystal X-ray diffraction, powder XRD, TGA, FTIR, fluorescence spectroscopy, and elemental analysis. Gas absorption measurements on the desolvated networks indicate that the networks are moderately selective, and their behaviour was typical of similar MOF networks. The Ni2+ based tppe-MOF exhibited greater capacity to absorb polar gases despite structural similarities to the other networks.

Alternative procedure for the analysis of coal-derived materials for oil, asphaltene and pre-asphaltene content

Abstract An alternative method for the analysis of coal-derived materials for oil, asphaltene and pre-asphaltene content, is described. The test sample is coated as a thin layer on the fine mesh glass beads and the relevant fractions are extracted sequentially with hexane, toluene and pyridine. The efficiencies of the extractions are satisfactory. Solvents are removed subsequently from the extracts by evaporation at low pressure, and the residues are weighed. The method has been tested on a range of samples, and its sensitivity to sample loading and to co-solvent effects has been investigated.

Preparation and characterisation of some new Mo/O/XR (X = P or As) heteropoly blue complexes

A new series of molybdenum organophosphonates with a Mo∶P ratio of 1∶1 have been isolated. The proposed formulation for these compounds is (MoV2MoVI4O12)(O3XR)4[O2(OH)XR]2(EtOH)x [when X = P, R = C6H5, C6H5CH2, CH3 or C2H5; when X = As, R = C6H5; x = 5 (for R = C6H5 or CH2C6H5) or 4 (for R = CH3 or C2H5)]. These compounds are intensely blue in colour, as expected for compounds of the heteropoly blue category. XPS data indicate a Mo(V)∶Mo(VI) ratio of 1∶2 in these compounds, and the FTIR, solid-state and solution NMR, TGA, UV/Vis, magnetic and electrochemical data are consistent with the proposed formulations.

Aqueous extraction of oxalate and other anions from coal

A suite of six coals, including three of low-rank, were subjected to aqueous soxhlet extraction and the extract analysed for both cations and anions. In nearly all cases the extracts contained the anions fluoride, chloride and sulphate as well as the organic based anions acetate, carbonate, and oxalate. The oxalate anion was the most prevalent of the extracted organic anions. The extent of oxalate extraction appears to be dependent on coal rank, with substantially more oxalate extracted from the low-rank coals. This is reflected in the cation:anion ratio for the major inorganic ions extracted. The rate of oxalate extraction suggests most, if not all, of the oxalate extracted is due to oxidative breakdown of oxygen containing functional groups in the coals, rather than the intrinsic presence of oxalate itself. The extracts also contained some or all of the cations Na+, K+, Mg2+, Ca2+, Al3+ and Fe3+. In most cases only minor proportions of the total amounts of the inorganic elements present in the coals were extracted, with the extent of extraction depending on the total element content. For low-rank coals the mole ratio of total extracted cations to the sum of the chloride plus sulphate anions was greater than unity, consistent with the presence of carbon based anions in the extract.

Synthetic and Structural Studies on Copper 1 H‐[1,10]‐Phenanthrolin‐2‐one Coordination Complexes: Isolation of a Novel Intermediate During 1,10‐Phenanthroline Hydroxylation

The synthesis and crystal structure elucidation of a novel dinuclear heteroleptic copper(II) complex has led to an alternative mechanism in the formation of covalent hydrates. During further studies on the synthesis and properties of [Cu(2)(ophen)(2)] (1), a dinuclear complex of copper(I) with 1 H-[1,10]-phenanthrolin-2-one (Hophen), two intermediates/alternative products 2 and 3 were isolated. The dinuclear, antiferromagnetic complex [Cu(2)(ophen)(2)(phen)(2)](NO(3))(2)9H(2)O (3, phen=1,10-phenanthroline) contains two five-coordinate copper(II) ions, both with trigonal-bipyramidal coordination, which are bridged together through deprotonated hydroxyl groups with a Cu--Cu non-bonding distance of 3.100 A. Complex [Cu(phen)(2)(H(2)O)](NO(3))(2) (2) is a polymorph of a previously reported material. The occurrence of 2 and 3 has led us to propose a variation to the Gillard mechanism for the formation of covalent hydrates in bidentate N-heterocycles in which the attacking nucleophile may be the deprotonated form of 2, [Cu(phen)(2)(OH)](-), rather than free OH(-).