(6jg) Supramolecular Mesochemistry: Engineering Materials from the Bottom Up

One of the most inspiring aspects about the chemistry of life is the hierarchical organization by which biomolecules self-organize into complex structures across vast length scales. The grand vision of ‘supramolecular mesochemistry’ is to emulate Nature’s capacity to build intricate structures of virtually any size using bottom-up self-assembly. Toward this ultimate goal I propose three projects aimed at engineering well-defined mesoscale aggregates and functional materials from colloidal particles and reversible supramolecular crosslinks.

 Project I. Retrosynthetic Self-Assembly of Functionalized Colloids. Retrosynthetic thinking will be applied to the rational self-assembly of mesoscale objects, guided by noncovalent interactions between complementary molecular recognition motifs mounted on the surfaces of shape-defined colloidal particles. Initial target mesostructures include sequence-defined colloidal polymers and 3D colloidal networks. These assemblies may be observed directly by microscopy and reconfigured by manipulating the reversible, stimulus-responsive crosslinking interactions.

Project II. Competition Driven Evolution of Dissipative Self-Organizing Aggregates. Surface-functionalized, shape-defined microparticles displaying various supramolecular elements will be passed through iterations of an evolutionary algorithm (manual or automated) involving (i) competition among particles for noncovalent crosslinks, which induce aggregation via interfacial supramolecular interactions, (ii) selection of aggregates that dissipate energy according to imposed fitness criteria, (iii) mutation involving the introduction of new microparticle geometries, materials, stoichiometries, surface motifs, etc., and (iv) reproduction, i.e., repeated cycles of competition, selection, and mutation. The evolution of aggregates exhibiting ‘life-like’ behaviors such as stimulus response, adaptation, templation, and autocatalysis will be prioritized.

 Project III. Host-Guest Organic Semiconductors. Supramolecular design motifs are numerous and diverse, yet few of them are suited for applications involving organic semiconductors because of unfavorable optoelectronic properties. Novel semiconducting host-guest complexes based on fully π-conjugated hosts (e.g., cycloparaphenylenes) and guests (e.g., polycyclic aromatic hydrocarbons) could be of use for mediating charge transfer in self-assembling organic electronics and organic photovoltaics. If substituted appropriately, these design motifs could also help establish electronic communication between functionalized colloidal particles when implemented in Projects I–II.