Chemistry Weekly Seminar - Jake Pushie

Title:Down the Rabbit-hole: Illuminating the Complex Solution Chemistry of Copper-Cuprizone with Theory and Experiment

Cuprizone (oxalic acid bis(cyclohexylidene hydrazide)), first reported nearly 70 years ago, is a highly sensitive colorimetric indicator for various copper salts. Interest in cuprizone grew substantially in the 1970s when it was developed for use in laboratory animals to induce multiple sclerosis-like symptoms, vis-à-vis its efficacy at reproducibly demylenating nerve fibers in the brain. Despite its continued use in research worldwide, characterization of the chemical form of the copper-cuprizone complex has been mired in controversy and misdirection, including conflicting characterizations of the intensely coloured complex and the oxidation state of the copper centre involved. Using a combination of computational chemistry methods as well as an array of experimental techniques, including X-ray absorption spectroscopy, the interactions of cuprizone with copper reveals a rich and unexpectedly complex system. Results reveal two closely-related copper-cuprizone complexes, which are critically important to understanding the complex solution chemistry and the discrepancies in the literature.  In addition to refining our understanding of the structure and oxidation state of the copper-cuprizone complexes, mechanisms for the hydrolysis of cuprizone as well as intermolecular electron transfer will also presented, which have not been addressed in the 70-year history of this interesting system.