Synthesis and Characterization of Some Three Dimensional Cyclic Organosilanes

多孔硅的发射还没有完全解释清楚。在这里，为了采取一种可能的化学方法来阐明这种发射的基本结构，我们计划合成并表征一些既具有硅-硅键又具有硅-氧-硅键的笼状固体有机硅烷。通过1,2-二甲基-1,1,2,2-四乙氧基二硅烷在酸性条件下缩合制备了两种含硅-硅键的四聚笼型聚硅氧烷。它们分别在235 nm和229 nm处表现出最大的紫外吸收。同时，它们在360 nm和351nm处发射，量子产率分别为0.13和0.11。这些发射特性与二维类似物的发射特性进行了比较，这表明这种具有硅-硅和硅-氧-硅键的刚性三维结构对于观察到的有效发射是必不可少的。然后，为了考察取代基对发射的影响，我们在类似的酸性条件下，用1,2-二异丙基-1,1,2,2-四乙氧基二硅烷缩合制备了相同类型的异丙基代替甲基的笼型聚硅氧烷。它们的紫外吸收波长较长，分别为256 nm和242 nm，最大发射波长分别为361 nm和350 nm，量子效率较差，分别为0.067和0.034。从1,2-二苯基-1,1,2,2-四氯二硅烷在丙酮水溶液中水解开始，也制备了苯基衍生物。

The emission from the porous silicon has not fully explained yet. Here, in order to take one of possible chemical approaches to clarify the essential structure of the emission of this kind, we have planned to synthesize and characterize some caged solid organosilanes having both silicon-silicon and silicon-oxygen-silicon bonds. Tow types of tetrameric caged polysiloxanes containing silicon-silicon bonds have been prepared by condensation of 1,2- dimethyl-1,1,2,2-tetraethoxy disilane under acidic conditions. They show UV absorption maxima at 235 and 229 nm, respectively. At the same time, they emit as expected at 360 and 351 nm with quantum yields of 0.13 and O.11 respectively. These emissive properties are comp ared with those of two-dimensional analogues and this indicates that such a rigid three-dimensional structure having both silicon-silicon and silicon-oxy gen-silicon bonds should be essential for the efficient emission observed. Then, to examine the substituent effect on the emission, we have prepared the same types of caged polysiloxane with isopropyl groups instead of methyl groups by condensation of 1,2-diisopropyl-1,1,2,2- tetraethoxy disilane under similar acidic conditions. They show UV absorptions at longer wavelength, 256 and 242 nm, respectively, and give the emission maxima at 361 and 350 nm, respectively, with poor quantum efficiency, namely, 0.067 and 0.034, respectively. Phenyl derivatives have been also prepared starting from hydrolysis of 1,2-diphenyl-1,1,2,2- tetrachlorodisilane in aqueous acetone.