Self-Assembled Monolayers of Arylazoisoxazole Photoswitches: Reversible Photochemical Isomerization and Modulation of Surface Wettability

Arylazoisoxazole (AIZ) photoswitches exhibit interesting interfacial behavior including photoresponsive surface patterning, phase transitions, and adhesion. However, in contrast to other members of the azo-family, the formation of self-assembled monolayers (SAMs) of AIZ, their reversible photoisomerization, or the modulation of surface wettability upon alternating exposure to UV and green light have not been reported. In this article, we expand the scope of azo-photoswitches capable of reversibly changing the surface wettability and introduce an AIZ organosilane with the rather polar isoxazole moiety pointing to the outermost surface layer, forming SAMs on quartz glass and silicon oxide substrates. We characterize the SAMs formed and further compare the wettability range that can be targeted using different azo-photoswitches rather than using complex molecular substitution or polymerization.