 | Diarylpolysilanes:
Helicity and Switchable Enantiomorphism
|
| | Julian R. Koe1)3), Masao Motonaga3) and Michiya Fujiki2)3) |
| 1) Department of Chemistry, International Christian University
2) NTT Basic Research Laboratories
3) CREST-JST |
| | Polysilanes comprise an inorganic polymer backbone of linearly catenating, conjugating silicon atoms, the unique spectroscopic feature of which is a UV absorption due to the Si σ-σ* transition at wavelengths between 300 and 400 nm, dependent on substituent effects, both electronic and steric. We recently showed that the sign and magnitude of the dissymmetry ratio, gabs (ratio of CD to UV absorption intensity, Δε/ε), for poly(diarylsilylene)s containing enatiopure chiral aryl substituents in dilute solution, has a marked dependence on aryl ring substitution, chiral content, comonomer and temperature.1,2 In one case, a temperature-dependent helix-helix transition is observed.3 We now report our results concerning the optical activity of enantiopure chiral containing poly(diarylsilylene) aggregates formed upon mixing a poor solvent (eg. methanol) with a poly(diarylsilylene) solution (eg. toluene or THF), as exemplified in Figure 1. |
| | | |
