The Role of Oligomethylene Linkage on the Photophysics of Alternating Dialkylsilylene-Spaced Donor-Acceptor Copolymers
Date Issued
2011
Date
2011
Author(s)
Liao, Wei-Chih
Abstract
Alternating dialkylsilylene-spaced donor-acceptor copolymers with two substituents (methyl vs isopropyl) on silicon and different oligomethylene linkages, piperazinyl, ethylene, tetramethylene, and 2,2-dimethylpropylene, have been designed and synthesized by Rh-catalyzed hydrosilylations. The donors were selected to be the oligomethylene-connecting bis-aminostyrene moieties, and the acceptors were chosen as the stilbene chromophores with dialkylsilyl substituents at both ends.
Thorpe-Ingold effect is introduced by changing the size of the substituents (methyl vs isopropyl) on silicon. Totally different photophysical properties of SiMe2-spaced (methyl substituents on silicon) copolymers from those of SiiPr2-spaced (isopropyl substituents on silicon) copolymers were observed.
Furthermore, different oligomethylene linkages provide different behaviors of rotations of sigma-bonds. Thus, different polymer folding natures would be exhibited in those polymers with similar degrees of polymerization. The photophysical behaviors in SiMe2- and SiiPr2-spaced copolymers (within a range of degrees of polymerization ca. 5~15) may be perturbed.
To sum up, the photophysics of the copolymers could be affected by the synchronization of the Thorpe-Ingold effect on silicon and the polymer folding nature. Besides, it seems that polymer folding natures may be perturbed via different conformational equilibrium in various oligomethylene moieties within a range of degrees of polymerization.
Subjects
oligomethylene
dialkylsilylene
donor
acceptor
photophysical property
charge transfer
polymer folding
Type
thesis
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