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首页> 外文学位 >Glycans, polyglycans, and cross-linked polyglycans: An analytical study using solid state nuclear magnetic resonance, x-ray powder diffraction and other solid phase methods.
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Glycans, polyglycans, and cross-linked polyglycans: An analytical study using solid state nuclear magnetic resonance, x-ray powder diffraction and other solid phase methods.

机译：聚糖，多糖和交联多糖：使用固态核磁共振，X射线粉末衍射和其他固相方法的分析研究。

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Two polyglycans, chitin (CT) and chitosan (CS), were compared with their corresponding monomers, N-acetyl-D-glucosamine (GlcNAc) and D-glucosamine (GlcN) using solid state nuclear magnetic resonance (SSNMR) spectroscopy and x-ray powder diffraction (XRPD) in order to better understand structural changes during the commercial degradation of the natural polyglycans. A downfield 13C isotropic shift for the ring carbons in both polyglycans confirms structural differences from their monoglycans. Monoglycans were characterized according to their solution chemical shifts and the solid shifts were inadvertently misassigned in earlier literatures. The correct peak assignments for these monoglycans are proposed using shape factors from spinning sideband patterns for the first time.; Cross-linking chitosan with glutaraldehyde (CSGA) was thought to increase metal adsorption by increasing the surface area of CS, a highly desirable chemical engineering goal in the chelation industry to maximize chemical uptake. Experimental results indicate an increase of surface area to >200 m 2/g, but metal uptake is shown to be more likely due to absorption within the polymer lattice rather than adsorption on the surface. Seven metals (Cr, Mn, Fe, Co, Ni, Cu, and Zn) were selected to complex with CS and CSGA to allow for structural comparisons and understanding of the metal uptake properties of CS and CSGA. Cationic binding was found at the C2 position of each monomeric unit of the secondary amine in CS and at the imino linker in CSGA. Two portions of the amorphous XRPD pattern that were ignored in the past are demonstrated for the first time to have structural importance and to interact differently with different metals based on oxidation/electronic spin state, paramagnetic properties, and ligand configuration inside the hydrophilic pockets of the polymers. The former region was confirmed to correspond with the amine in CS by far-FTIR (far-Fourier transform infrared) spectrometry, whereas the latter region was proven to be stacking of intermolecular hydrogen bonding in a unique system between each helical turn. The imino linker in CSGA was calculated to have less negative charges than the amine in CS, which is unusual. Metal interaction in the amino-imino region was studied in detail. Torsion angles at C4 in the beta(1→4)glycosidic bond of several metal complexes were observed for the first time in SSNMR.
机译：使用固态核磁共振（SSNMR）光谱和x-射线光谱法比较了两种多糖，几丁质（CT）和壳聚糖（CS）及其相应的单体N-乙酰基-D-葡萄糖胺（GlcNAc）和D-葡萄糖胺（GlcN）。射线粉末衍射（XRPD），以更好地了解天然多糖的商业降解过程中的结构变化。两个聚聚糖中环碳的低场13C各向同性位移证实了其单聚糖的结构差异。根据单糖的溶液化学位移对其特征进行了表征，而固相位移在早期文献中被误认为是错误的。首次使用旋转边带模式的形状因子提出了这些单聚糖的正确峰分配。壳聚糖与戊二醛（CSGA）的交联被认为可以通过增加CS的表面积来增加金属的吸附，这是螯合工业中最大限度提高化学吸收率的化学工程目标。实验结果表明，表面积增加到> 200 m 2 / g，但是由于聚合物晶格中的吸收而不是表面上的吸附，金属吸收的可能性更高。选择了七种金属（Cr，Mn，Fe，Co，Ni，Cu和Zn）与CS和CSGA络合，以便进行结构比较和了解CS和CSGA的金属吸收特性。在CS中仲胺的每个单体单元的C2位置和CSGA中的亚氨基接头处发现了阳离子结合。首次展示了过去被忽略的无定形XRPD图案的两个部分，它们具有结构上的重要性，并基于氧化/电子自旋态，顺磁性和配体构型在其亲水腔内与不同金属发生不同的相互作用。聚合物。通过远FTIR（远傅立叶变换红外）光谱法确认前一个区域与CS中的胺相对应，而后一个区域被证明是分子间氢键堆叠在每个螺旋圈之间的独特系统中。计算出CSGA中的亚氨基接头比CS中的胺具有更少的负电荷，这是不寻常的。详细研究了氨基亚氨基区域的金属相互作用。在SSNMR中首次观察到几种金属配合物的β（1→4）糖苷键在C4处的扭转角。

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