Current approaches exploit equilibrium-based strategies to construct superstructures in which molecular interaction and macroscopic organization are neither structurally nor electronically configured for maximum function efficiency. Consequently, electronic materials derived from supramolecular chemistry are virtually inoperable at low voltages drastically hampering the use of these promising semiconductors. Because structures define functions, the (opto)electronic properties of π-conjugated superstructures are intimately correlated with the conformation of molecular building blocks.

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By using redox chemistry to perturb the electrostatic interactions that regulate the conformation of subunits in non-covalent assemblies, we delineate a new set of tools to navigate the aggregation free-energy landscape and create energetically trapped architectures equipped with structure-function properties unattainable at thermodynamic equilibrium. From solution-phase studies that exploit spectroscopy and electrochemistry, our goal is to understand how reconfigured superstructures promote exciton delocalization and transport.

Liu, K.; Paulino, V.; Mukhopadhyay, A.; Bernard, B.; Kumbhar, A.; Liu, C.; Olivier, J. -H* “How to Reprogram the Excitonic Properties and Solid-State Morphologies of π-Conjugated Supramolecular Polymers” Phys. Chem. Chem. Phys.  2021, 23, 2703-2714

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Liu, K.; Mukhopadhyay, A.; Ashcraft, A.; Liu, C.; Levy, A.; Blackwelder, P. Olivier, J.-H.* “Reconfiguration of π-conjugated superstructures enabled by redox-assisted assembly” Chem. Commun., 2019, 55, 5603-5606​

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Liu, K.; Levy, A.; Liu, C; Olivier, J.-H.* “Tuning Structure–Function Properties of π-Conjugated Superstructures by Redox-Assisted Self-Assembly” Chem. Mater. 2018, 30, 2143-2150

Post-Assembly Modification Strategies to Create Structurally and Electronically Robust Nanoscale Materials:

Because structure defines the functions of supramolecular architectures, non-covalent assemblies are fragile compositions where minor changes in temperature, solvent dielectric, and building block concentration can alter the conformation of superstructures, consequently compromising the emergent functions evidenced by this class of materials. Consequently, the development of molecular strategies to covalently capture superstructures at equilibrium and far-from-equilibrium can deliver entirely new nanoscale platforms with which to elucidate structure-function properties that remain elusive by current supramolecular methodologies.

To achieve this goal, our group works on delineating new strategies to lock-in the conformation of initially prepared supramolecular polymers and create nanomaterials that are electronically and structurally robust. Exploiting a combination of microscopy, electrochemistry and spectroscopy methods, we investigate the novel electronic properties that emerges from these new classes of nanomaterials.

Ashcraft, A.; Liu, K.; Mukhopadhyay, A.; Paulino, V.; Liu, C.; Bernard, B.; Husainy, D.; Phan, T.; Olivier Olivier, J.-H. “A Molecular Strategy to Lock-in the Conformation of a Perylene Bisimide-Derived Supramolecular Polymer” Angew. Chem., Int. Ed. 2020, 59,7487–7493

Electrode Functionalization: Towards Organic Piezoelectric Materials

Despite the significant potential of organic piezoelectric materials for mechanical energy harvesting and electronic skin applications, progress in this area has been limited due to the lack of soft mesoscale structures that feature substantial macroscopic polarizabilities. To this end, strategies to build non-centrosymmetric molecular architectures featuring a strong piezoelectric effect are necessary.

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By exploiting surface chemistry, our group explore new methodologies to anchor redox-active units on atomically flat electrodes and form 2D nanoscale objects equipped with emergent electronic properties.  Our long-term vision is to develop templating strategies that aim at producing mesoscale non-centrosymmetric materials.

Mukhopadhyay, A.; Paulino, V.; Liu, K.; Donley, C. L.;  Bernard, B.; Shomar, A.; Olivier, J. -H* “Leveraging the Assembly of a Rylene Dye to Tune the Semiconducting Properties of Functionalized n-Type, Hybrid Si Interfaces” ACS Appl. Mater. Interfaces, 2021, 13, 4665–4675

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Mukhopadhyay, A.; Bernard, B.; Liu, K.; Paulino, V.; Liu, C.; Donley, C.; Olivier, J. -H. “Molecular Strategies to Modulate the Electrochemical Properties of P-Type Si(111) Surfaces Covalently Functionalized with Ferrocene and Naphthalene Diimide” J. Phys. Chem. B. 2019, 123, 11026-11041 

Chemical Funtionalization of Microelectrode Arrays:

Maintaining a stable neural interface and recording high quality neuronal signals for long periods of time are key challenges that limit clinical applications for neuroprosthetics. While neural probe development has enabled us to sample signals from large populations of neurons, the available technology does not allow us to access these signals for more than several years due to gradual decrease in signal quality. While passive delivery of drugs at the site of injury has been exploited to minimize neuro-inflammation, this strategy has all but failed to increase long-term recordings as a bolus of anti-inflammatory drugs is released at pre-determined times that often are not consistent with the ongoing innate inflammatory process. 

In collaboration with the laboratory of Prof. Abhishek Prasad (UM, Biomedical engineering departments), our laboratory is engineering hybrid microelectrode arrays platforms that feature smart coatings capable of releasing encapsulated anti-inflammatory drugs under specific chemical and electrical stimuli

Liu, C.; Nguyen, M. S.; Alvarez-Ciara, A.; Franklin, M.; Bennet, C.; Domena, J. B.; Kleinhenz, K. G.; Blanco Colmenares, G. A.; Duque, S.; Chebbi, A. F.; Bernard, B.; Prasad, A.;* Olivier, J. -H* “Surface Modifications of an Organic Polymer-Based Microwire Platform for Sustained Release of an Anti-Inlflammatory Drug” ACS Appl. Bio Mater., 2020, 3, 4613−4625