Individual and mixed oxides of Zn, Mg, Si, and Ti modified with L-proline during their solgel synthesis have been obtained. The IR spectra of these oxides studied in detail show changes in the vibrational band parameters of the siliconoxygen and metal–oxygen bonds. Enhancement of the amount of basic sites on the SiO₂–TiO₂ mixed oxide was found after removal of L-proline from the surface. The use of SiO₂–Mg(OH)₂^* L-proline composite as a catalyst leads to an enhanced enantiomeric excess of some asymmetric Biginelli reaction products up to 18%.

中文翻译：

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L-脯氨酸改性Si、Ti、Mg、Zn氧化物的合成及光谱研究

已获得在溶胶凝胶合成过程中用 L-脯氨酸改性的 Zn、Mg、Si 和 Ti 的单独和混合氧化物。详细研究的这些氧化物的红外光谱显示了硅氧和金属-氧键的振动带参数的变化。从表面去除L-脯氨酸后，发现SiO ₂ -TiO ₂混合氧化物上碱性位点的数量增加。使用 SiO ₂ –Mg(OH) ₂ ^* L-脯氨酸复合材料作为催化剂导致一些不对称 Biginelli 反应产物的对映体过量增加高达 18%。