Monthly Archives: August 2023

Taylor Opolka

Ferrocene- based donor-acceptor systems

Taylor D. Opolka, Dennis Downing and Dr. Thomas Guarr

Redox Flow Batteries (RFBs) are preferred over traditional lithium-ion cells for grid storage applications based on increased cycle longevity and safety.  However, the cell voltage of RFBs is limited by the low potential window of aqueous solvents and a relatively small library of active materials.  Typical RFB design also requires the use of ion-selective membranes to prevent the mixing of anolyte and catholyte, which in turn increases cost.  Employing non-aqueous solvents allows much higher cell voltages, but ion-selective membranes are highly resistive when employed in aqueous solvents.  Previous work in our lab has focused on the use of bifunctional organic molecules composed of covalently lined anolytes/catholytes that possess three stable oxidation states and can use a simple, inexpensive porous separator rather than an ion-selective membrane.  This work focuses on slight modifications of the aryl-linked ferrocene donor-pyridinium acceptor systems in order to improve solubility in inducing molecular asymmetry.

Taylor returned to the lab this summer after finishing up at Davenport and earning her degree and we were really happy to have her back.  She is starting a PhD program at Notre Dame this fall that we have no doubt she is going to do great at.  Thanks for spending the summer with us again Taylor!

Published in Nature Chemistry

We are excited to announce that Tom Guarr and Charley Hengesbach from the OESLab have been published in Nature Chemistry! This is part of a collaboration with David Hickey from MSU and Jolt Energy Storage. Better solubility of our electrochemical compounds = better batteries!

C–H···π interactions disrupt electrostatic interactions between non-aqueous electrolytes to increase solubility


Grid-scale energy storage applications, such as redox flow batteries, rely on the solubility of redox-active organic molecules. Although redox-active pyridiniums exhibit exceptional persistence in multiple redox states at low potentials (desirable properties for energy storage applications), their solubility in non-aqueous media remains low, and few practical molecular design strategies exist to improve solubility. Here we convey the extent to which discrete, attractive interactions between C–H groups and π electrons of an aromatic ring (C–H···π interactions) can describe the solubility of N-substituted pyridinium salts in a non-aqueous solvent. We find a direct correlation between the number of C–H···π interactions for each pyridinium salt and its solubility in acetonitrile. The correlation presented in this work highlights a consequence of disrupting strong electrostatic interactions with weak dispersion interactions, showing how minimal structural change can dramatically impact pyridinium solubility.

Congrats to Dr. Guarr, Dr. Hickey, Sharmila Samaroo and Charley Hengesbach!

Summer 2023 intern program success!

It has been a while since we updated this website, but the summer is so busy!

Our lab hosted four new summer interns and a returning intern this summer.  I will highlight each one of them in subsequent posting soon.  The summer was a whirlwind as always and I will attempt to document some of it with the few pictures I took.

We had a great summer group!  Everyone was very supportive and a lot of research was completed

Not only did our group spend time in the lab, but we enjoyed tours of a local brewery, power plant and manufacturer.

We found a little time to get out and enjoy the summer together, but it is never enough.

Please stay tuned for more highlights of each intern in the coming weeks.