Light-controlled cooperative catalysis of asymmetric sulfoxidation based on azobenzene-bridged chiral salen TiIV catalysts.

Incorporation of azobenzene into the linker of bimetallic chiral salen TiIV catalysts allowed the photoswitchable arrangement of the two Ti(salen) units through cis/trans photoisomerization of azobenzene. The differently arranged Ti(salen) units changed their cooperative function to reflect the positional relationships, as a result, their efficiency as cooperative catalysts in asymmetric sulfoxidation could be readily controlled by light stimuli.