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，为了采用一种可能的化学方法来阐明这类发射的基本结构，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。以1，2-二甲基-1，1，2，2-四乙氧基二硅烷为原料，在酸性条件下进行缩合反应，合成了两种含硅硅键的四聚笼状聚硅氧烷。它们的最大吸收波长分别位于235和229 nm。同时，它们不出所料地在360 nm和351 nm处发射，量子产率分别为0.13和0.11。这些发射性质与二维类似物的发射性质进行了比较，这表明这种同时具有硅-硅和硅-氧-硅键的刚性三维结构应该是观察到的有效发射所必需的。然后，为了考察取代基对发射的影响，我们通过1，2-二异丙基-1，1，2，2-四乙氧基二硅烷在相似的酸性条件下缩合制备了具有异丙基取代甲基的笼状聚硅氧烷。它们分别在2 5 6和2 42 nm处有较长的紫外光吸收，并分别在36 1和35 0 nm处出现发射极大值，量子效率较低，分别为0.067和0.034。以1，2-二苯基-1，1，2，2-四氯二硅烷在丙酮水溶液中的水解为起始原料，合成了苯基衍生物。

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.