Photoisomerization of a chiral azobenzene dopant possessing only one asymmetric carbon, (R)-3-(1-methylhexyloxy)-3′-octyloxy-2,2′-dimethylazobenzene, was found to be able to specifically induce a helical twist inversion in liquid crystals having alkenyl terminal substituents, an alkenyl-selective interaction which was not found in conventional para-substituted azobenzenes.