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    ABSTRACT: A rapid and diastereoselective synthesis of highly substituted aminobicyclo[4.3.0]nonanes and bicyclo [4.4.0]decanes from alkyne derived allylic alcohols has been developed using a one-pot multi-bond forming tandem catalytic process. Overman rearrangement of the allylic trichloroacetimidates was followed by a ring closing enyne metathesis/cross metathesis sequence of reactions, in which both steps were catalysed by Grubbs second generation catalyst. The resulting exo-diene was then subjected to a hydrogen bonding directed Diels-Alder reaction forming an endo-adduct as a single diastereomer. Variation of the cross metathesis partner and dienophile allowed examination of the scope of this one-pot process and the preparation of a diverse series of highly substituted polycyclic scaffolds.
    Tetrahedron 10/2014; 70(40):7133–7141. DOI:10.1016/j.tet.2014.06.020
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    ABSTRACT: The hydrogenation of 4-nitroacetophenone (4-NAP) and 4-aminoacetophenone (4-AAP) was examined over rhodium/silica catalysts. The reactions were carried out using isopropanol as the solvent under a range of temperatures (303-333 K) and pressures (1-5 barg). An activation energy of 50 +/- 14 mol(-1) was determined for 4-NAP hydrogenation and 48 +/- 2 kJ mol(-1) for 4-AAP hydrogenation. Orders of reaction were obtained for 4-NAP (zero order) and hydrogen (first order) and a kinetic isotope effect of 3.0 was observed for 4-NAP hydrogenation and similar to 1.4 for 4-AAP hydrogenation when deuterium was used. Under specific conditions high yields (similar to 94%) to 4-aminoacetophenone and 1-(4-aminophenyl) ethanol could be obtained from 4-NAP hydrogenation. An antipathetic metal crystallite particle size effect was observed for both reactants.
    Applied Catalysis A General 08/2014; 484:59–63. DOI:10.1016/j.apcata.2014.07.011
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    ABSTRACT: A two-step process combining percolation-mode ammonia pretreatment of poplar sawdust with mild organosolv purification of the extracted lignin produced high quality, high purity lignin in up to 31% yield and 50% recovery. The uncondensed fraction of the isolated lignin was up to 34%, close to that the native lignin (40%). Less lignin was recovered after pretreatment in batch mode, apparently due to condensation during the longer residence time of the solubilised lignin at elevated temperature. The lignin recovery was directly correlated with its molecular weight and its nitrogen content. Low nitrogen incorporation, observed at high ammonia concentration, may be explained by limited homolytic cleavage of β-O-4 bonds. Ammonia concentrations from 15% to 25% (w/w) gave similar results in terms of lignin structure, yield and recovery.
    Bioresource Technology 01/2014; 162:236–242.
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    ABSTRACT: We explore the concept that the incorporation of polyoxometalates (POMs) into complementary metal oxide semiconductor (CMOS) technologies could offer a fundamentally better way to design and engineer new types of data storage devices, due to the enhanced electronic complementarity with SiO2 , high redox potentials, and multiple redox states accessible to polyoxometalate clusters. To explore this we constructed a custom-built simulation domain bridge. Connecting DFT, for the quantum mechanical modelling part, and mesoscopic device modelling, confirms the theoretical basis for the proposed advantages of POMs in non-volatile molecular memories (NVMM) or flash-RAM.
    Chemistry - A European Journal 12/2013; 19(49):16502-11. DOI:10.1002/chem.201301631

  • Plant physiology 12/2013; 163(4):1485-6. DOI:10.1104/pp.113.231092
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    ABSTRACT: In this article, we describe the synthesis of new biotin-functionalised naphthalene derivatives and and their complexation behaviour with avidin and neutravidin using a range of analytical techniques. We have shown using 2-(4'-hydroxyazobenzene)benzoic acid displacement and ITC experiments, that compounds and have the propensity to form reasonably high-affinity bioconjugates with avidin and neutravidin. We have also demonstrated using (1)H NMR, UV-vis and fluorescence spectroscopy that the naphthalene moiety of and facilitates the formation of pseudorotaxane-like structures with in water. We have then investigated the ability of avidin and neutravidin to modulate the complexation between and or . UV-vis and fluorescence spectroscopy has shown that in both cases the addition of the protein disrupts complexation between the naphthalene moieties of and with .
    Organic & Biomolecular Chemistry 11/2013; 12(3). DOI:10.1039/c3ob41612g
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    ABSTRACT: The significant advances in the area of solid-state microwave (MW) synthesis are studied. MWs are broadly regarded as those electromagnetic waves which are situated between infrared and radio wavelengths in the electromagnetic spectrum, with wavelengths between 0.01 and 1 m, corresponding to frequencies between 0.3 and 300 GHz. MW radiation interacts directly with the reaction components, so the sample alone is heated with minimal need for energy to be expended in heating furnaces, containment materials, and the sample environment. While absorption of MWs in solid and liquid samples is frequency dependent, it is, in effect, nonquantized. Instead, the material behaves as though reacting to a high-frequency electric field. Manipulating MW penetration depth will be vital to develop the flow processes that underpin manufacturing and mass production.
    Chemical Reviews 11/2013; 114(2). DOI:10.1021/cr4002353
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    ABSTRACT: Polynuclear manganese complexes are used as precursors for the synthesis of manganese oxide nanoparticles (MnO NPs). Altering the thermal decomposition conditions can shift the nanoparticle product from spherical, thermodynamically-driven NPs to unusual, kinetically-controlled octapod structures. The resulting increased surface area profoundly alters the NP's surface-dependent magnetism and may have applications in nanomedicine.
    Nanoscale 11/2013; 6(1). DOI:10.1039/c3nr04832b
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    ABSTRACT: A range of Organosolv pretreatments, using ethanol:water mixtures with dilute sulphuric acid, were applied to Sitka spruce sawdust with the aim of generating useful co-products as well as improving saccharification yield. The most efficient of the pretreatment conditions, resulting in subsequent saccharification yields of up to 86%, converted a large part of the hemicellulose sugars to their ethyl glycosides as identified by GC/MS. These conditions also reduced conversion of pentoses to furfural, the ethyl glycosides being more stable to dehydration than the parent pentoses. Through comparison with the behaviour of model compounds under the same reaction conditions it was shown that the anomeric composition of the products was consistent with a predominant transglycosylation reaction mechanism, rather than hydrolysis followed by glycosylation. The ethyl glycosides have potential as intermediates in the sustainable production of high-value chemicals.
    Bioresource Technology 11/2013; 151. DOI:10.1016/j.biortech.2013.10.105
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    ABSTRACT: We demonstrate that engineered artificial gold chiral nanostructures display significant levels of non-linear optical activity even without plasmonic enhancement. Our work suggests that although plasmonic excitation enhances the intensity of second harmonic emission it is not a prerequisite for significant non-linear (second harmonic) optical activity. It is also shown that the non-linear optical activities of both the chiral nanostructures and simple chiral molecules on surfaces have a common origin, namely pure electric dipole excitation. This is a surprising observation given the significant difference in length scales, three orders of magnitude, between the nanostructures and simple chiral molecules. Intuitively, given that the dimensions of the nanostructures are comparable to the wavelength of visible light, one would expect non-localised higher multipole excitation (e.g. electric quadrupole and magnetic dipole) to make the dominant contribution to non-linear optical activity. This study provides experimental evidence that the electric dipole origin of non-linear optical activity is a generic phenomenon which is not limited to sub-wavelength molecules and assemblies. Our work suggests that viewing non-plasmonic nanostructures as "meta-molecules" could be useful for rationally designing substrates for optimal non-linear optical activity.
    Nanoscale 11/2013; 5(24). DOI:10.1039/c3nr04746f
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