OSE Seminar by Prof. Jean-Hubert Olivier on Molecular Tools to Tune the Electronic Properties of Semiconducting Nanoscale Objects

Departmental News

Prof. Jean-Hubert Olivier

Posted: August 28, 2024

Date: Thursday, August 29, 2024

Time:  12:00 PM - 1:00 PM MST

Location: CHTM, Room 101 & Zoom.  Zoom link announced tomorrow

Speaker:

Prof. Jean-Hubert Olivier

UNM Chemistry Department and Chemical Biology

Abstract：

As a product of the dynamic equilibrium between solubilized building blocks and self-assembled structures, supramolecular architectures are fragile compositions where minor changes in temperature, solvent dielectric, and building-block concentration can trigger the dismantlement of superstructures and concomitant loss of their emergent properties. Developing molecular strategies to covalently polymerize non-covalent assemblies can provide entirely new nanoscale platforms with which to “dial-in” structure-function properties that remain elusive by current supramolecular methodologies. This seminar will introduce design principles to staple 1-dimensional supramolecular polymers in solution and on Silicon electrodes. The extent to which this novel approach can be leveraged to modulate the semiconducting properties and light-harvesting capabilities of nanoscale objects will be shown. Exploiting ultrafast transient absorption spectroscopy and spectroelectrochemistry, we will discuss the properties of the excited state products formed following photoexcitation and correlate them to the structural properties of the molecular tethers with which π-conjugated aggregates are stapled. We will also introduce novel design principles to regulate excitonic coupling as a function of tethering strategies and new avenues to capture out-of-equilibrium intermediates to form semiconducting monolayers. These studies demonstrate that the ability to modulate the electronic structures of nanoscale objects, used in conjunction with facile hierarchical organization, offers exceptional promises for the development of optoelectronic materials.

Biography:

At the intersection of supramolecular chemistry, physical organic chemistry, and materials science, the Olivier Laboratory develops supramolecular tools to engineer organic compositions equipped with structure-function properties not achievable by contemporary approaches. Specifically, we aim to modulate the excitonic and potentiometric properties of non-covalent assemblies. Our long-term goal is to establish rules and principles to optimize light-matter interactions, control the flow of energy across mesoscale dimensions, and delineate platforms enabling mechanical energy transduction.

It remains a long-standing goal for chemists to manipulate non-covalent interactions between π-conjugated building blocks that dictate the structure-function properties of nanoscale objects. Current technology relies on structures at thermodynamic equilibrium that are neither structurally nor electronically optimized to, for example, efficiently migrate charges and excitons. In addition, supramolecular assemblies are notoriously fragile material compositions where transient structure-function properties are contingent upon temperature, solvent, and pressure conditions. Consequently, the elucidation of structure-function properties that characterize transient states with shallow potential wells (metastable and out-of-equilibrium states) has all but failed due to the lack of strategies to capture these conformations adopted by superstructures. To tackle these modern roadblocks, we are pioneering strategies to: 1) navigate the assembly-free energy landscape by perturbing the electrostatic interactions that regulate superstructure conformation, and 2) capture the conformation of supramolecular polymers in solution and at the solid-liquid interface. By exploiting a suite of analytical techniques, we investigate the structural and electronic properties of the materials we are engineering to quantify the validity of our approaches. Besides this effort, we are delineating new organic materials to functionalize neural interfaces with the goal of reducing foreign body responses, specifically neuroinflammation and oxidative stress due to implanted electrodes