亞甲基-二乙炔苯共聚物光物理性質之取代基效應：比較亞甲基及矽代亞甲基連接基團對對高分子摺疊之影響

Abstract

Alternating tert-butyl- and methyl- substituted alkoxymethylene-diethynylbenzene copolymers 11 with different degree of polymerization and the corresponding dimers 15 were synthesized. The tert-butyl substituted polymers 11b show strong emissions around 350-400 due to ground state interactions between adjacent chromophores while copolymer 11a with less bulkily methyl-substituted tether exhibits emission around 400-450 nm due to through-space interactions between nonadjacent diethynylbenzene chromophores. Such substituent effect on photophysical properties was attributed to the Thorpe-Ingold effect exerted by the bulky tert-butyl group, compressing the bond angle at the methylene tether and therefore altering the overall folding behavior of the polymer chain. As the polymer chains fold in different manner, difference in intrachain chromophore-chromophore interaction modes were expected and corresponding photophysical property differences were observed.

These methylene tethered polymers have photophysical properties similar to those of the related silylene-tethered copolymers 1, albeit the relative intensity in the blue light emission is significantly smaller in methylene-bridged copolymers than in silylene-linked copolymers. Comparison between these two series of polymers suggests that folding behaviors of such polymers may depend on the tetrahedral tethers (methylene versus silylene).