Synthesis and Self‐Assembly of Supramolecular Dendritic “Bow‐Ties”: Effect of Peripheral Functionality on Association Constants.

Self-assembled polyester dendritic bow-ties with various peripheral groups were prepared, and\ntheir association constants were measured by <sup>1</sup>H NMR in CDCl<sub>3</sub>. The two complementary dendrons\nwere prepared by attachment of either a bis(adamantylurea) or a glycinylurea to the focal point of\nthe dendron. The parent self-assembled system with benzylidene acetals on one periphery and\nisopropylidene acetals on the other had an association constant of 520 M<sup>-1</sup>. Upon deprotection of\none dendron, the association constant is increased by more than an order of magnitude as the\nsolubility of the hydroxyl-terminated dendron in CDCl<sub>3</sub> is decreased. In contrast, attachment of\ntri(ethylene oxide) units to the periphery of one dendron lowers the association constant by almost\nan order of magnitude. The causes of these relatively large changes in complex strength are\ndiscussed in terms of solubility, steric effects, competitive hydrogen bonding, and the structure of\nthe dendritic scaffold.