| Abstract
| - Control over the preferred helical sense of a poly(n-hexyl isocyanate) (PHIC) by using a singlelight-driven molecular motor, covalently attached at the polymer's terminus, has been accomplished insolution via a combination of photochemical and thermal isomerizations. Here, we report that afterredesigning the photochromic unit to a chiroptical molecular switch, of which the two states are thermallystable but photochemically bistable, the chiral induction to the polymer's backbone is significantly improvedand the handedness of the helical polymer is addressable by irradiation with two different wavelengths oflight. Moreover, we show that the chiral information is transmitted, via the macromolecular level of thepolyisocyanate, to the supramolecular level of a lyotropic cholesteric liquid crystalline phase consisting ofthese stiff, rodlike polymers. This allows the magnitude and sign of the supramolecular helical pitch of theliquid crystal film to be fully controlled by light.
|
