A&P Seminar - Jean-Hubert Olivier

The Analytical and Physical Seminar Series presents: Jean-Hubert Olivier

University of New Mexico

Host: Sean Roberts

Title: From Static to Dissipative Semiconducting Assemblies: New Ways to Control the Electronic Functions of π-Conjugated Nanostructures

WEL 2.122

Refreshments served at 3:15pm

As a product of the dynamic equilibrium between solubilized building blocks and self-assembled structures, supramolecular architectures are inherently fragile, where minor changes in temperature, solvent dielectric, or building-block concentration can trigger the dismantlement of superstructures and the concomitant loss of their emergent properties. Developing molecular strategies to functionalize non-covalent assemblies at equilibrium and far from equilibrium using chemical fuels can provide entirely new nanoscale platforms to ‘dial in’ structure–function properties that remain vastly elusive with current supramolecular methodologies. 

This seminar will introduce design principles for stapling one-dimensional supramolecular polymers in solution. We will demonstrate how this novel approach can be leveraged to modulate the semiconducting properties and light-harvesting capabilities of nanoscale objects. Using ultrafast transient absorption spectroscopy and spectroelectrochemistry, we will discuss the excited-state products formed upon photoexcitation and correlate them with the structural properties of the molecular tethers that staple the π-conjugated aggregates. These studies demonstrate that the ability to modulate the electronic structures of nanoscale objects, combined with their facile hierarchical organization, offers exceptional promise for the development of optoelectronic materials.

In the last part of the seminar, we will showcase the molecular engineering of far-from-equilibrium semiconducting superstructures, built from water-soluble π-conjugated building blocks. We harness a simple chemical reaction network to drive dynamic morphological transformations in redox-active supramolecular polymers, where electrical function is directly regulated by the controlled consumption of chemical fuels. Our work expands the scope of fuel-driven complex systems beyond small, solvated building blocks by showing that chemical reaction cycles can be executed directly on non-covalent assemblies, using them as reactive precursors.