Synthesis of a stimuli-responsive P-chiral polymer with chiral phosphorus atoms and azobenzene moieties in the main chain.

A reaction of the P-chiral compound (S,S)-1,2-bis(boranato(tert-butyl)methylphosphino)ethane with an azobenzene derivative gave stimuli-responsive polymers with P-chiral phosphines in the main chain. This is the first example of a stimuli-responsive P-chiral polymer. The polymer isomerized from the trans to the cis form upon UV irradiation and reverted to the trans form reversibly. The polymer was able to coordinate to platinum, and the resulting polymer complex exhibited the Cotton effect owing to the chirality of the phosphorus atoms. The structure of the P-chiral polymer obtained could be changed reversibly by light and thermal stimuli, and the polymer chain was induced to rotate helically when complexed with transition metals through the chiral phosphorus atoms.