4-(Phenylazo)benzoic acid (PABA), an azobenzene derivative, is a photo-isomerisable molecule. It can be synthesized by reacting p-aminobenzoic acid with nitrosobenzene. The interaction of PABA with TiO2 and ZnO electrodes has been investigated. A photoreversible switch has been developed using dimethylamino calix[4]arene and PABA. The post functionalization of poly(hydroxyethyl acrylate) core cross-linked star polymers with PABA induces an ability to complex with α-cyclodextrin.