This lab has a history of keeping summer interns around through the year and then the next summer they prove invaluable by serving as mentors to the new interns.  Madison Shaffer did this for us and she has proven to be one of the best!  We are so happy she stuck around!  If you ask any of the summer 2023 interns about Madison they will tell you she is the best lab mate to have, and if you ask any of the summer 2024 interns about Madison they will tell you they couldn’t have survived the summer without her!

She has made countless contributions and she will continue to help us out.  Madison started full-time at Jolt Energy Storage this September.  We were not going to let her go, so she agreed to transfer over to Jolt.  Congratulations Madison!  Here’s to a bright future!

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Examining the Stability of Sterically Hindered 4-arylpyridinium Compounds

Avery Reimink, Madison Shaffer, Thomas Guarr

With growing concern over the dwindling supply of fossil fuels along with the humanitarian concerns involved in mining and producing lithium batteries, there has been a continuous effort to look for sustainable and scalable battery alternatives.  Redox Flow Batteries (RFBs) have emerged as a promising alternative, as they provide grid-scale energy storage.  Previous research has been done on the synthesis of different redox-active organic material (ROM) with the same criteria: a low reduction potential, high solubility, and a stable reduced state.  Previous lab members have successfully synthesized several different classes of pyridinium compounds which act as the ROM.  However, previous pyridiniums were determined to have varying stability, hypothesized to be due to the alpha hydrogens near the nitrogen atom.  This work focuses on the stability and looks at synthesizing pyridiniums that have a reduced number or no alpha hydrogens, such as tert-butyl or phenyl groups.  This class of pyridiniums has been synthesized and characterized using cyclic voltammetry and mass spectroscopy.

Avery attends Hope College and chose to spend her summer doing chemistry synthesis with us.  Her smile and her positive attitude are infectious and have made everyone’s summer better.  She did some great work on her summer project and a lot of work advancing our knowledge of electrochemical compounds.  She liked it so much she is back for more and will continue working with us through the fall!

Photophysical Characterization of Pyrylium Salts

Sophia Jaeger, Thomas Guarr

Pyrylium salts are cationic species distinguished by a trivalent oxygen within a six membered conjugated ring.  Pyryliums can be utilitzed as precursors for heterocyclic benzene analogs, photocatalysts, fluorescent cellular probes, organic light emitting diodes, and in photodynamic therapies.  Their photophysical characteristics lend them to these applications.  To better understand the impact of structure on the photophysical properites of pyryliums, ten unique pyrylium salts were synthesized from four synthetic pathways.  The resulting pyryliums were then characterized using NMR and mass spectrometry.  Once their structures were confirmed, their photophysical characteristics were examined via UV-Visible spectroscopy and fluorescence spectroscopy.  In comparing the structure and unique spectrum of each pyrylium the impact of substituents on the central pyrylium ring on the fluorescent wavelenegth and lifetime were examined.

Sophia was a pleasure to work with this summer!  She just graduated from Michigan Tech University and is returning in the fall for her MS.  She impressed us with her knowledge but mostly with her infectious “chemistry is fun” attitude!  Her project was kind of narrow, but her contributions to the lab this summer were outsized and her hard work provided a lot of valuable info.  Thanks for spending the summer with us!

Optimizing Solubility and Stability of 2,6-Diethyl-4-(4-Methoxyphenyl)pyridinium Compounds for Redox Flow Batteries

Margaret Cooper, Madison Shaffer, Thomas Guarr

As the demand for renewable energy grows, the need for long duration energy storage has become critical.  Redox flow batteries (RFBs) have emerged as a potential alternative for grid-scale energy storage as they are both safe and environmentally friendly.  RFBs employ two electrolyte solutions (an anolyte and catholyte) and achieving commercially viable energy density in such systems requires that the anolyte displays a low reduction potential and high solubility.  Previous research has shown that pyridinium compounds offer low reduction potentials, but varying solubilities and stability in their reduced states.  This work focuses on 2,6-diethyl-4-(4-methoxyphenyl)pyridinium compounds with various 1-aryl substituents in an attempt to improve solubility and stability while maintaining a low reduction potential.  These compounds are prepared via condensation of 2,6-diethyl-4-(4-methoxyphenyl)pyrylium with the desired aryl amine.  Solubilities were measured by UV-visible spectroscopy, while radical stability was measure by cyclic voltammetry.

Maggie attends Montana State University and we were lucky to have her join us at the OESLab in Holland this summer.  She is a lot of fun to have around and she is up for anything, including a lot of synthesis projects and analysis. Thanks for being a trooper!  Enjoy the rest of your summer and enjoy returning to Big Sky country!