Investigation of photo-responsive chiral polyisocyanates

A new class of polyisocyanates incorporating the 8-phenylmethylenebicyclo [ 3.2.1]octan-3-one chromophore through three different linkage patterns to t he polymer backbone was synthesized. Photoresolution and photoracemization experiments were conducted to test its response to circularly polarized lig ht (CPL). Irradiation of the polymers with CPL leads to the partial photore solution of the bicyclicketone chromophore. This enantiomeric excess causes the polyisocyanate chain to favor one helical sense over the other. The ha ndedness of the polymer chain can be switched with the sense of the circula rly polarized light, leading to novel photoresponsive polyisocyanates.