Diversity-oriented design of supramolecular dendrimers

Self-assembling dendrons that self-organize into liquid crystalline supramolecular dendrimers enable the study of the principles that underlie how the primary structure determines the formation of the three-dimensional (3-D) structure in macromolecules and what the correlation is between the primary structure and tertiary and quarternary assemblies and their function. By modifying the dendritic architecture, we can assess the control of the diversity of the sizes and shapes of the supramolecular dendrimers. Two dendritic architectures and three libraries of self-assembling dendrons will be discussed. One architecture employs a conformationally-flexible tetrahedral branching point to connect an A functional group to either two B2 or a combination of B 2 and B3 functional groups to create AB4 and AB 5 dendritic building blocks. The structural and retrostructural analysis of supramolecular dendrimers self-assembled from hybrid dendrons based on different combinations of benzyl ether dendrons with the AB4 and AB5 building blocks enabled the discovery of new classes of tapered and conical dendrons generated by the intramolecular back-folding of their repeat units and of their apices. These new classes include pine tree-like helical columns, crown-like pyramidal columns, and hollow spheres. The second dendritic architecture incorporates a flexible propyl group and a rod-like biphenyl moiety to generate propylbiphenyl building blocks. The supramolecular dendrimers synthesized from these repeat units include both hollow and non-hollow structures, which exhibit higher order and larger dimensions than corresponding phenylpropyl and biphenyl dendrons. These new dendritic architectures may provide supramolecular dendrimers with functions that previously have not been encountered.