纯硅介孔分子筛SBA-15表面的手性移植

Research on Grafting Chiral Compound(+)-Dibenzoyl-L-Tartaric Acid to the Surface of SBA-15 Molecular Sieve

聚环氧乙烯醚-聚环氧丙烯醚-聚环氧乙烯醚(EO20PO70EO20)三嵌段高分子为模板剂制备了SBA-15分子筛.用3-氨丙基-三乙氧基硅烷对SBA-15进行改性,改性后SBA-15表面上的氨基再与(+)O-,O′-二苯甲酰基-L-酒石酸酐(DBTA)进行酰化反应,以酰胺键将该手性羧酸连接在SBA-15表面上.XRD和氮气吸附结果表明,材料经过处理后仍然保持良好的孔性质;13C和29S i魔角旋转核磁共振(MAS NMR)谱图表明,SBA-15与氨丙基化合物的作用是共价成键,表面修饰度达25%;从傅里叶变换红外(FTIR)光谱可见,有部分修饰氨基与DBTA成功地进行了酰化反应,以一个羧基裸露的形式将该二元羧酸化合物连接在表面上;从孔径分布图可知,胺丙基修饰之后孔减小了1.5 nm,与DBTA修饰后孔尺寸又减少0.5 nm,说明胺丙基化合物是头对头垂直连接在S i表面上,而酒石酸分子是采取平行方式侧卧在氨基表面.

A sample of SBA-15 mesoporous silicate was synthesized and characterized by XRD and N2 adsorption. It is confirmed from N2 adsorption and ^13C, ^29Si NMR techniques that the surface of SBA-15 was chemically modified with 3-aminopropyhrimethoxylsilane. According to integration of the curve of the ^29Si MAS （ Magic Angle Spinning） NMR calculation it can be interpreted that about a quarter of the silonol （Si-OH） surface of the mesoporous material was modified. Under gentle conditions the optically active compound, （ ＋ ）-dibenzol-tartaric anhydride, can be easily absorbed onto the surface of modified SBA-15 material. FTIR spectrum confirms that this absorption procedure results in covalently tethering to the silonol surface rather than just physical absorption. Subsequently, pore size distribution experiments reveal that the state of aminopropyl group absorbed onto the surface is in head to head position with a pore size of 4. 00 nm. Whereas, when the （ ＋ ）-dibenzoyl-tartaric acid was attached to the modified SBA-15 surface, it is orientated in a layered format over the SBA-15-（CH2）3NH2 surface, resulting in a pore diameter of 3.50 nm.