Rotaxanes with chiral stoppers and photoresponsive central unit

Two new chiral and photoisomerizable rotaxanes (9m, 9p) have been prepared, bearing the longest non-polymeric axle known so far: the axles (6m, 6p) ar e polyether chains made of alternating triethyleneglycol/hydroquinone units , bearing a central meta- or para-azobenzoyl moiety and terminal tetraacety lglucoside stopper groups, while the wheel is the cyclobis(p-xylylene)bis(4 ,4'-bipyridinium) salt. Temperature dependent H-1 NMR measurements reveal t hat the translational process of the wheel across the azobenzene unit. in t he E-configuration is favoured for the para-rotaxane 9p compared to the met a isomer 9m. The azobenzene core of the free axles (6m, 6p) and rotaxanes ( 9m, 9p) undergo photochemical E/Z-isomerisation: from (E) to (Z) by irradia tion at low wavelength and back from (Z) to (E) at, high wavelength. Comple te (Z) to (E) conversion was achieved by thermal isomerization.