Joel spent the summer with us doing research into rhenium compounds…
Photophysical and Redox Properties of Novel Bipyridine-Rhenium Complexes; Joel Sowders, Nick Mortimer, Amber Prins and Dr. Tom Guarr
The photophysical properties of metal-ligand complexes have been well researched over the past two decades. Due to their unique and wide range of properties, metal-ligand complexes have been investigated in energy and electron transfer research. Rhenium(I) complexes are among these classes of compounds. Rhenium(I) complexes have also been studied for their ability to catalyze both oxidation and reduction events, including the reduction of CO2 to CO. Bimetallic rhenium and ruthenium complexes have also been the topic of many studies on intramolecular energy transfer. In this study we show a rhenium-pyridine ligand complex. The ligand, 4,6-diphenyl-2,2’-bipyridine (BPY) was synthesized according to previous literature. The complex was prepared from the ligand and chloropentacarbonylrhenium (1JMS045). Characterization was done with NMR, LC-MS, cyclic voltammetry, UV-Vis and fluorescent spectroscopy. The mono-rhenium complex was further reacted with 4,4’-bipyridine to bridge the complex to form a bi- or poly-rhenium bipyridine complex. LC-MS of the compound revealed the 4,4’-bipyridine did join a single complex but did not bridge to a second complex (1JMS037).
Joel is a Holland native that comes to us via Seattle Pacific University. Much gratitude to Joel for all his hard work this summer. Enjoy your time back at school.
Nick and Amber collaborated on a poster, which they presented in Chicago at the International Meeting on Lithium Batteries. They are both researchers here at the Organic Energy Storage Laboratory.
Exploiting Steric Factors in the Design of Overcharge Additives; Nicholas Mortimer, Amber J Prins, Robert Polik and Thomas F. Guarr
Lithium ion batteries are very commonly used today, but unsafe conditions can occur if expensive electronics are not used to prevent overcharging. These electronics can double the price of the battery pack, so it is important to find a more economical way to control charging. Redox shuttles are potential additives to batteries to shunt the excess current and allow the battery to be safely used to its full capacity. Numerous organic compounds have been investigated as shuttle candidates, but finding materials that possess both a sufficiently high oxidation potential and adequate durability has proven challenging. Our current approach exploits the change in molecular geometry that often accompanies the oxidation of heterocyclic compounds. By introducing bulky groups to sterically impede this reorganization, computational modeling suggests that oxidation potentials can be shifted to more positive values without sacrificing stability.
Thank you Amber and Nick, your work is appreciated.
Brandon worked with heavy metals to synthesize large, complex structures…
The Synthesis and Metal Complexation of Bis-terpyridine Derivatives; Brandon Wackerle and Dr. Thomas Guarr
Bis-terpyridine derivatives can be used as ligands that bind with metals in solution to form complex structures. These structures can be used in many applications, including medicine, alternative energy, and molecular electronics. By deviating from the terpyridine subunit, new ways for metals to interact with the ligand can be introduced and potentially create larger, more complex structures. Iron(II) has been used to complex with the ligand and complexes between the metal and ligand have been analyzed using electrospray ionization mass spectroscopy (ESI-MS). Currently, europium is being investigated in order to compare the properties of europium and iron complexes. This will also enable us to observe how a transition metal behaves compared to an f-block element when complexed with a bis-terpyridine.
Brandon is working towards a degree in biochemistry from Grand Valley State University. He has one year left to complete his degree and his future is bright. Thanks for a great summer.
Jessica was kept busy synthesizing this summer….
Development of Heterocyclic Catholyte Molecules for Application in Redox Flow Batteries; Jessica D. Scott and Thomas F. Guarr
Accompanying the increased discussion over climate change and global warming in the news, there is a widespread desire to research and design stable and cost-effective methods to store renewable energy on a large scale. One possible answer to the energy crisis may be found in the use of redox flow batteries. Redox flow batteries have the ability to convey chemical energy, generated from electrochemically reversible reactions, into electrical energy which could then be stored for later use. Research suggests that heterocyclic derivatives can be paired with extended viologen systems to produce very desirable electrochemical properties.
Jessie graduated from Hope College this spring with an ACS Certification Chemistry degree, spent her summer with us, and is continuing on to work in the Chicago area. Best wishes for your future, Jessie!
Taylor performed research on electroactive materials for electrode surfaces this summer…
Synthesis of Bispyridine Derivatives for Chemically Modified Electrodes; Taylor Grace, Dr. Thomas Guarr
Attachment of electroactive materials to an electrode surface can result in the formation of modified electrodes suitable for applications in displays, electrocatalytic devices, or organic batteries. Pyridinium compounds are readily and reversibly reduced, and previous work has demonstrated that bispyridine species are especially stable in both their oxidized and reduced states. The objective of this project is to prepare several different bispyridinium compounds that can be electrochemically polymerized or covalently attached to an electrode surface. The resultant chemically modified electrodes will be characterized by spectroscopic and electrochemical methods.
Taylor is pursuing a degree in chemistry with a minor in biology at Western Michigan University. We loved having her energy with us this summer and we wish her all the best when she returns to WMU.
James continued our insights into alternatives to platinum as an oxygen reduction catalyst…
Investigation of Metal(II) Tetradiphenylaminophthalocyanines for Oxygen Reduction Catalysis in Fuel Cells; James A. Wortman, Thomas F. Guarr
Catalytic oxygen reduction (OR) is an important reaction in fuel cell design. Platinum has been used as an OR catalyst, but its high cost has made large-scale applications impractical. The purpose of this study was to investigate metal(II) tetra(diphenylamino)phthalocyanine (MT4(dpa)Pc) complexes as potential cheap alternatives to platinum. The obtained complexes were electropolymerized into thin films using cyclic voltammetry (CV). These polymer films may possess improved OR capabilities due to the nature of the diphenylamine substituent.
James is (another!) Chemical Engineering student from MSU. He is part of the MSU Regional champion Chem-E-Car team and will join Brian and Mark at the Chem-E-Car competition in San Francisco this November. Good luck to them and thank you to James for his hard work.