Date of Award
Doctor of Philosophy (PhD)
Function in complex biological and non-biological supramolecular assemblies is determined by structure. Nature programs a primary structure, such as an amino acid sequence, with all necessary information to undergo hierarchical self-assembly to generate functional constructs such as proteins. Self-assembling benzyl ether dendrons provide a similar platform to program hierarchical self-assembly in synthetic soft matter and self-organize into a variety of functional periodic arrays, including columnar hexagonal phases and 3D phases generated from spheres such as body-centered cubic and Pm3n cubic, known also as Frank-Kasper A15. Understanding the structure of these supramolecular objects and their assembly is critical for the design of additional functional assemblies and materials with technological applications. This work examines the synthesis and structural aspects of the self-assembly of various dendronized building blocks, including perylene bisimides (PBIs), naphthalene bisimides, cyclotriveratrylenes (CTV), cyclotetraveratrylenes (CTTV), and Janus glycodendrimers. Structural and retrostructural analysis by combination of techniques including differential scanning calorimetry, oriented fiber X-ray diffraction (XRD), molecular modeling, reconstruction of electron density, simulation of XRD, circular dichroism spectroscopy, and solid state NMR reveals: (1) decreasing molecular order provides increased supramolecular order in assemblies of tetrachlorinated PBIs; (2) a supramolecular double helix assembled from chiral PBIs displays identical single crystal-like order irrespective of molecular chirality, rationalized by the cogwheel model; (3) defining the sequence and composition of dendrons modulates the cogwheel assembly of dendronized PBIs; (4) dendronized PBI and CTV assemble according to an unprecedented columns-from-spheres model; (5) supramolecular spheres of dendronized CTTV are chiral; (6) the transition between a columnar array and a cubic array can provide supramolecular orientational memory in which columnar domains are reoriented according to the directions of the preceding cubic phase; (7) sugar moieties on the surface of synthetic cell membrane mimics segregate to generate lamellar and hexagonal nanomorphologies. In summary, the structural aspects underpinning multiple events in supramolecular self-assembly have been elaborated and are expected to inform the design of additional functional assemblies and materials.
Partridge, Benjamin Edward, "Structural Aspects Of The Supramolecular Helical Polymerization Of Self-Assembling Benzyl Ether Dendrons" (2018). Publicly Accessible Penn Dissertations. 3169.