Supramolecular effects in dendritic systems containing photoactive groups

In this article are described dendritic structures containing photoactive g roups at the surface or in the core. The observed supramolecular effects ca n be attributed to the nature of the photoactive group and their location i n the dendritic architecture. The peripheric azobenzene groups in these den drimeric compounds can be regarded as single residues that retain the spect roscopic and photochemical properties of free azobenzene moiety. The E and Z forms of higher generation dendrimer, functionalized with azobenzene grou ps, show different host ability towards eosin dye, suggesting the possibili ty of using such dendrimer in photocontrolled host-guest systems. The photo physical properties of many dendritic-bipyridine ruthenium complexes have b een investigated. Particularly in aerated medium more intense emission and a longer excited-state lifetime are observed as compared to the parent unsu bstituted bipyridine ruthenium complexes. These differences can be attribut ed to a shielding effect towards dioxygen quenching originated by the dendr itic branches.