Polysilane with aromatic substitutents

Examination of the absorption spectra of the new polysilane materials reveals a number of interesting features (14). As shown in Table III, simple alkyl substituted polymers show absorption maxima around 300-310 nm. Aryl substitution directly on the silicon backbone, however, results in a strong bathochromic shift to 335-345 nm. It is noteworthy that 4, which has a pendant aromatic side group that is buffered from the backbone by a saturated spacer atom, absorbs in the same region as the peralkyl derivatives. This red shift for the silane polymers with aromatic substituents directly bonded to the backbone is reminiscent of a similar observation for phenyl substituted and terminate silicon catenates relative to the corresponding permethyl derivatives... 

Anionic polymerization of masked disilenes proceeds via a living condition to give polymers having controlled molecular weight (33). Head-to-tail pol5uners can selectively obtained and polysilanes with fimctional groups such as diethylamino groups are prepared. However, the masked disilene method is only applicable to the synthesis of non-aromatic-substituted polysilanes. 

The cyclic polysilanes can be reduced to radical anions either electrolytically or by reaction with alkali metals quite similar to aromatic rings. Numerous substituted... 

We have found that a certain number of polyhalogenated aromatic derivatives such as compounds 1-3 greatly accelerate the rate of bleaching of a number of poly silane derivatives in the solid state (33). This effect is dramatically demonstrated in Figure 5 for a PM PS film doped with —20% by weight of l,4-bis(trichloromethyl)benzene, 1. Similar results were obtained with substituted triazine sensitizers such as 2. In these cases, the polysilane is the primary absorber of the incident radiation. Interestingly, when compound 3, which absorbs at —400 nm, was incorporated into a PM PS film and the sample was irradiated at 404 nm, where only the sen-... 

Irie et al (7, 8) have reported that the radical cation of phenyl-substituted polysilanes exhibit a similar band in the IR region and assigned it to the CR band between two phenyl groups. They also reported that no IR absorption was observed for the radical anion. In the present study, however, we observed this IR band also for PMPrS(+) and for two polysilane radical anions. Since PMPrS has no aromatic groups, the optical transition should be related with the delocalized positive charge on the a-conjugated polymer main chain. 

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