Thorpe-Ingold效應對於亞矽基雙乙烯基芳香環聚合物的構型影響
Thorpe-Ingold Effect on the Conformation of alt-Dialkylsilylene-divinylarene Copolymers
Date Issued
2007
Date
2007
Author(s)
Yeh, Mei-Yu
DOI
zh-TW
Abstract
A series of regioregular silylene-spaced alternating donor-acceptor arene copolymers [(donor)-SiR2-(acceptor)-SiR2-]n was synthesized by rhodium catalyzed hydrosilylation of bis-alkynes with bis-silylhydride. Methyl-substituted vinylsilylhydrides were prepared by nickel-catalyzed olefination of the corresponding aryl dithioacetals with Grignard reagent followed by LAH reduction. In addition, isopropyl-substituted vinylsilylhydrides were obtained from the displacement of (iPr)2HSiCl with aryl-vinyllithium. Unlike most copolymers, our strategy has furnished a powerful arsenal for the construction of copolymers with precise regiochemistry and repetitive units. The silylene group serves as an insulating building block between chromophores.
We carried out the first example using the concept of Thorpe-Ingold effect to direct the conformation and may be the softness of silylene-spaced divinylarene copolymers. The results from the STM images are consistent with the outcome of photophysical studies of these polymers. Copolymers with bulky isopropyl substituents are more folded to bring the chromophores in closer proximity, and therefore intrachain interactions between these chromophores will become more prominent leading to enhancement in aggregation emission. Since distance is known to play an important role in photo-induced electron transfer (PET) processes, the present investigation suggested that bulkier substituents on silicon would bring the chromophores in closer proximity. Copolymers with bulky isopropyl substituent are more folded so that intrachain PET between these chromophores become more dominant to result in more efficient fluorescence quenching. The results from the STM images are also consistent with the photophysical data of these polymers.
In addition, the polymer composed of three different chromophores have been synthesized, the sequential energy and electron transfer along the polymeric chain was also observed.
Subjects
構型
聚合物
光物理
conformation
polymer
photophysics
Type
thesis
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