Optical behavior and surface morphology of the azobenzene functionalized dendrimer in Langmuir and Langmuir–Blodgett monolayers

Abstract We synthesized a dendrimer containing light switchable azobenzene group. The chemical structure was verified by using NMR and UV spectroscopy. We firstly investigated the monolayer behavior by using π–A isotherm with light irradiation at the air/water interface. As a result, the monolayer of dendrimer with azobenzene group showed the reversible photoswitching behavior by the isomerization of azobenzene group in the periphery. From the absorbance spectrum by UV irradiation and heat treatment, we can see that the absorbance in the UV region decreases with the increases of the UV irradiation time, but LB monolayers not absorbance shift. The results indicate that the azobenzene dendrimer could be photoisomerized reactions. In the surface morphology by AFM, the introduction of azobenzene group coagulates G4-48 Azo dendrimer and forms network dendrimers. This result strongly suggests that a dendrimer with azobenzene group can be applied to high efficient photoreaction device of molecular level.