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The structural parameters for the cyclobutanoQ[5–8] family were determined through single crystal X-ray diffraction. It was found that the electropositive cyclobutano methylene protons (CH2) are important in forming interlinking crystal packing arrangements driven by the dipole–dipole interactions between these protons and the portal carbonyl O of a near neighbor. This type of interaction was observed across the whole family. Electrostatic potential maps also confirmed the electropositive nature of the cyclobutano CH2 but, more importantly, it was established that the cavities are electronegative in contrast to classical Q[5–8], which are near neutral. 相似文献
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Florence Guéguen Hélène Isnard Karsten Kossert Carole Bresson Céline Caussignac Guillaume Stadelmann Anthony Nonell Sébastien Mialle Frédéric Chartier 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(1):289-295
A methodology to purify a 166mHo solution has been developed by a combination of activity and mass concentration measurements in order to further determine the 166mHo half-life. The isobaric interference at m/q ? 166 requires Ho purification from non-natural Er with a high purification degree due to the large amount of Ho as opposed to Er. The Ho/Er separation was achieved using high-performance liquid chromatography on a semi-preparative column followed by purification on gravitational chromatography. The efficiency of the separation was evaluated after precise determination of the Er isotopic composition. The purification methodology enabled to separate Ho from Er. 相似文献
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Chiral Amine Synthesis Using ω‐Transaminases: An Amine Donor that Displaces Equilibria and Enables High‐Throughput Screening 下载免费PDF全文
Dr. Anthony P. Green Prof. Nicholas J. Turner Dr. Elaine O'Reilly 《Angewandte Chemie (International ed. in English)》2014,53(40):10714-10717
The widespread application of ω‐transaminases as biocatalysts for chiral amine synthesis has been hampered by fundamental challenges, including unfavorable equilibrium positions and product inhibition. Herein, an efficient process that allows reactions to proceed in high conversion in the absence of by‐product removal using only one equivalent of a diamine donor (ortho‐xylylenediamine) is reported. This operationally simple method is compatible with the most widely used (R)‐ and (S)‐selective ω‐TAs and is particularly suitable for the conversion of substrates with unfavorable equilibrium positions (e.g., 1‐indanone). Significantly, spontaneous polymerization of the isoindole by‐product generates colored derivatives, providing a high‐throughput screening platform to identify desired ω‐TA activity. 相似文献
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This study investigated the possibility of substituting petroleum-based polymers with biopolymers for films and paper coatings. Arabinoxylan (AX) was extracted from distillers’ grains, a low-value corn ethanol byproduct, and modified through crosslinking with glutaraldehyde (GA) which was made into films and paper coatings. The effects of degree of substitution (DS) on film and coating properties of GA cross-linked AX, referred to as GAX, were investigated. The GAX films had markedly higher tensile strength, approximately 3 times higher than the unmodified AX films at low DS, with higher DS causing a negative effect on the film tensile strength. Compared to unmodified AX coating, paper coated with GAX also had significantly higher tensile index, presumably due to high adhesion between the coating and paper interface. When used as a coating binder with calcium carbonate pigments, GAX showed comparable performance to polyvinyl alcohol, a common industrial binder, demonstrating the potential to be substituted for the petroleum-based paper coating binder. 相似文献