Narrow Results

A series of dendritic 2,3,4,5-tetraphenylsiloles (1–8) are prepared. Polymerizations of 4-8 are effected by transition-metal catalysts, giving linear (9-12) and hyperbranched polymers (14) in high yields. Whereas the silole polymers are practically nonluminescent when molecularly dissolved, they become emissive when aggregated in poor solvents or cooled to low temperatures. The light-emitting diodes using linear poly(silolylacetylene)s as active layers emit blue and green lights with current efficiency up to 1.45 cd/A. The hyperbranched poly(silolenearylene)s are nonlinear optically active and strongly attenuate the optical power of intense laser pulses, whose optical limiting performances are superior to that of C₆₀, a well-known optical limiter.

Poly(phenylacetylene)s bearing monosaccharide pendant groups are synthesized in high yields by [Rh(nbd)Cl]₂ catalyst. The polymers have high molecular weights and give satisfactory spectroscopic data corresponding to their molecular structures. They are thermally quite stable (≥ 300°C) and show strong circular dichroism signals in the visible spectral region owing to the helicity of the polyene backbone. The monosaccharide-containing polyacetylenes are cytophilic and can stimulate the growth of living cells.