Molecular aspects on the amino acid-mediated sol–gel process of tetramethoxysilane in water
Molecular aspects on the amino acid-mediated sol–gel process of tetramethoxysilane in water
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DOI：
10.1007/s10971-019-04930-7
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发表时间：
2019-02
影响因子：
2.5
通讯作者：
L. Kaßner;Julia Kronawitt;Daniela Klimm;A. Seifert;S. Spange
中科院分区：
文献类型：
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作者：
L. Kaßner;Julia Kronawitt;Daniela Klimm;A. Seifert;S. Spange
摘要（TMOS）的水溶胶-凝胶工艺与几种天然氨基酸（AA）结合用于合成氨基酸/二氧化硅杂化材料。这些杂化材料含有物理键合在基质内的氨基酸。溶胶-凝胶过程很容易在未缓冲的氨基酸水溶液中发生。加工过程中的pH值仅由溶解的氨基酸决定。作为 AA 等电点 (IEP) 的函数，其 pH 范围为 3-11。系统研究氨基酸L-丙氨酸、ε-氨基己酸、L-精氨酸、L-天冬酰胺、L-天冬氨酸、L-谷氨酸、L-谷氨酰胺、甘氨酸、L-组氨酸、L-羟脯氨酸、L-亮氨酸、L-赖氨酸、L-蛋氨酸、L-苯丙氨酸、L-脯氨酸、L-丝氨酸、L-苏氨酸、讨论了L-色氨酸和L-缬氨酸对TMOS在水中的凝胶时间和溶解行为的影响。 AA 的 IEP 决定了 TMOS 在水中的溶解和凝胶化。使用甘氨酸作为模型化合物来研究浓度如何影响 TMOS 的溶解和胶凝时间以及所得二氧化硅的孔隙率。结果，TMOS在水中的水解速率和溶解速率减慢，并且通过增加甘氨酸浓度加速凝胶化过程。甘氨酸介导的 TMOS 溶胶-凝胶过程还通过 1 H NMR 光谱、动态光散射和 ATR-FTIR 光谱作为反应时间的函数进行了检查，以支持视觉观察结果。此外，还使用各种甘氨酸衍生物，如N-乙酰甘氨酸、N-苯甲酰甘氨酸、甘氨酸乙酯、甘氨酸乙酯·HCl、N-甲基甘氨酸、N,N-二甲基甘氨酸、N,N-二甲基甘氨酸甲酯和N-苯基甘氨酸来研究氨基酸结构官能团对TMOS溶解和胶凝时间的影响。 27 种不同的 AA（衍生物）。 TMOS 的水解和 AA/二氧化硅杂化材料的缩合反应受到氨基酸结构和浓度的不同影响。研究了分子结构对生产 A 型整体氨基酸/二氧化硅杂化材料的反应速率的影响。
AbstractThe aqueous sol–gel process of (TMOS) in conjunction with several natural amino acids (AAs) is employed for synthesis of amino acid/silica hybrid materials. These hybrid materials contain the amino acid physically bonded within the matrix. The sol–gel process occurs readily in unbuffered aqueous amino acid solution. The pH value during the processing is only determined by the dissolved amino acid. It ranges between pH 3–11 as function of the isoelectrical point (IEP) of the AAs. Systematic study of the influence of molecular structure of the AAs L-alanine,ε-aminocaproic acid, L-arginine, L-asparagine, L-aspartic acid, L-glutamic acid, L-glutamine, glycine, L-histidine, L-hydroxyproline, L-leucine, L-lysine, L-methionine, L-phenylalanine, L-proline, L-serine, L-threonine, L-tryptophan, and L-valine on the gelation time and dissolution behavior of TMOS in water is discussed. The IEP of the AA determines both dissolution and gelation of TMOS in water. Glycine was used as a model compound to investigate how concentration affects dissolution and gelation time of TMOS as well as porosity of resulting silica. As a result, the hydrolysis rate of TMOS in water and therewith dissolution is decelerated and gelation process is accelerated by increasing glycine concentration. Glycine-mediated sol–gel processes of TMOS were additionally examined by1H NMR spectroscopy, dynamic light scattering, and ATR-FTIR spectroscopy as a function of reaction time to support the visual observed results. Furthermore, various glycine derivatives such asN-acetylglycine,N-benzoylglycine, glycine ethylester, glycine ethylester·HCl, N-methylglycine,N,N-dimethylglycine,N,N-dimethylglycine methylester, andN-phenylglycine are used for studying the influence of amino acid structure functionalities on dissolution and gelation time of TMOS.The amino acid-mediated sol–gel process of tetramethoxysilane in aqueous solution is presented using 27 various AAs (derivatives). Hydrolysis of TMOS and condensation reactions to AA/silica hybrid materials are influenced in different ways by structure and concentration of the amino acid. The impact of molecular structure is examined with regard to reaction rate to produce monolithic amino acid/silica hybrid materials of type A.