Synthesis and structural analysis of two constitutional isomeric librariesof AB(2)-based monodendrons and supramolecular dendrimers

The synthesis and structural analysis of two constitutional isomeric librar ies of self-assembling AB(2) monodendrons based on 3,4- and 3,5-disubstitut ed benzyl ether internal repeat units containing four different first gener ation monodendrons, i.e., 3,4,5-tris(n-dodecan-1-yloxy)benzyl ether, 3,4-bi s(n-dodecan-1-yloxy)benzyl ether, 3,4,5-tris [p-(n-dodecan-1-yloxy)benzylox y]benzyl ether, and 3,4-bis[p-(n-dodecan-1-yloxy)benzyloxy]benzyl ether, on their periphery are described. Regardless of the repeat unit on their peri phery, the first three or four generations of the 3,4-disubstituted series of monodendrons self-assemble into spherical supramolecular dendrimers that self-organize into a Pm (3) over barn 3-D cubic lattice while the same gen erations of the 3,5-disubstituted series of monodendrons self-assemble into cylindrical supramolecular dendrimers that self-organize into a p6mm hexag onal columnar 2-D lattice. The internal repeat unit of the monodendrons det ermines the shape of the supramolecular dendrimers. However, for a particul ar internal repeat unit, the architecture from its periphery determines the size of the monodendron, the number of monodendrons that self-assemble int o a supramolecular dendrimer, the solid angle of the monodendron, and the d ependence of the size of the supramolecular dendrimer on generation number. Since ultimately all monodendrons must reach the shape of a single sphere, the diameter of cylindrical and spherical supramolecular dendrimers constr ucted from these building blocks is Limited to less than 100 Angstrom. The library of 3,5-disubstituted monodendrons also provided the first five exam ples of supramolecular dendrimers that undergo reversible shape changes ind uced by temperature and functionality at their focal point. In addition, a spherical supramolecular dendrimer based on a 3,5-disubstituted repeat unit that self-assembles in an Im (3) over barm 3-D cubic lattice was discovere d in the same library. The structural information generated by these two AB (2) and the previously reported AB(3) libraries of quasi-equivalent monoden drons provides building blocks that enable the construction of externally r egulated functional supramolecular, macromolecular, and single-molecule-bas ed nanosystems self-organizable in predictable lattices.