Increasing the diameter of cylindrical and spherical supramolecular dendrimers by decreasing the solid angle of their monodendrons via periphery functionalization

The synthesis of three generations of self-assembling monodendrons based on an internal AB(3) 3,4,5-trisubstituted benzyl ether repeat unit containing an AB(2) 3,4-bis[p-(n-dodecan-1-yloxy)benzyloxyl]benzyl ether monodendron [(4-3,4)12G1-X] attached on the periphery and the structural analysis of the corresponding supramolecular dendrimers by X-ray diffraction (XRD) experiments are described. The results from these experiments are compared with data reported previously from our laboratory on three generations of monodendrons based on the same internal AB(3) repeat unit containing an AB(3) 3,4,5-tris[p-(n-dodecan-1-yloxy)benzyloxy]benzyl ether monodendron [(4-3,4,5)12G1-X] on the periphery (Percec, V.; Cho, W.-D.; Mosier, P. E.; Ungar, G.; Yeardley, D. J. P. J. Am. Chem. Soc. 1998, 120, 11061). In both series of monodendrons, the solid angle of the monodendron increases with the increase of the generation number. As a result, the increase in the diameter of the cylindrical and spherical supramolecular dendrimers is smaller than the one expected from the fully extended monodendritic repeat unit. For the same internal repeat unit, the solid angle of the monodendron is determined by the solid angle of the unit attached to its periphery. The (4-3,4)12G1-X AB2 group attached to the periphery of the monodendrons decreases their solid angle by comparison with the series containing the (4-3,4,5)12G1-X AB(3) group on their periphery, and subsequently, the AB(2) group increases the diameter of the supramolecular dendrimers. The elucidation of this architectural effect clarifies some of the current limitations and provides new strategies for the design of functional nanosystems from dendritic building blocks.