Browsing by Author "McGlamery, Devin"

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Bulk Phosphorus-Doped Graphitic Carbon
(2018-07) Billeter, Emanuel; McGlamery, Devin; Aebli, Marcel; Piveteau, Laura; Kovalenko, Maksym V.; Stadie, Nicholas P.
A direct synthetic route to a tunable range of phosphorus-doped graphitic carbon materials is demonstrated via the reaction of benzene and phosphorus trichloride in a closed reactor at elevated temperatures (800-1050 degrees C). Graphitic materials of continuously variable composition PC,, up to a limit of approximately x = 5 are accessible, where phosphorus is incorporated both substitutionally within the graphite lattice and as stabilized P-4 molecules. Higher temperatures result in a more ordered graphitic lattice, while the maximum phosphorus content is not observed to diminish. Lower temperatures and higher initial phosphorus content in the reaction mixture are shown to correlate with higher structural disorder. Phosphorus incorporation within directly synthesized PC, as both a substitutional dopant and in the form of interstitial, stabilized molecular P-4,d is demonstrated to occur with little oxygen contamination in the bulk (<4 atom %), motivating promising future applications in fuel cells and alkali metal-ion batteries.
A Divergent Synthesis of Spongistatin
(Montana State University, 2017-04) McGlamery, Devin
Since the dawn of organic chemistry, natural products have long been coveted for their remarkable complexity as well as unmatched bio-activities. Spongistatin is one such natural product possessing activity against human melanoma with a GI50 value of just 25 pM. In addition to medicinal potential, spongistatin is an intriguing synthetic puzzle, containing a multitude of intricate stereocenters as well as two spiroketal subunits that join the A,B and C,D ring systems forming the spitoketal moiety’s of the molecule. Spongistatin’s two spiroketals exist as two stereoisomers, the axial-axial (A,B) and the axial-equatorial (C,D). The axial-axial spiroketal is favored due to stabilization via the double anomeric effect, whereupon the ring system is stabilized by lengthening of the C-O bond by n→σ * donation. However due to poor orbital overlap the axial-equatorial stereoisomer does not benefit from double stabilization. The Cook group has developed a divergent synthesis of highly substituted spiroketals via an ortholactone allylsilane fragment coupling reaction which proceeds through a Sakauri type mechanism. To make this more applicable to spongistatin we aim to develop methodology around less rigid frameworks (scheme 1). We have so far focused on the synthesis of cyclic ortholactones from the C4 unsubstituted dihydropyran, via an oxidative catalytic nucleopalladation reaction. Regretfully the cyclic nature of the molecule provides an increase in stability that prevents the operation of the previously developed spiroketalization conditions (scheme 1). To combat this, recent work has focused on generation of methoxy or ethoxy substituted ortholactones, in order to generate the C4 unsubstituted spiroketals (scheme 2).
Hydrogen-Type Binding Sites in Carbonaceous Electrodes for Rapid Lithium Insertion
(American Chemical Society, 2023-08) McGlamery, Devin; McDaniel, Charles; Xu, Wei; Stadie, Nicholas P.
Direct pyrolysis of coronene at 800 °C produces low-surface-area, nanocrystalline graphitic carbon containing a uniquely high content of a class of lithium binding sites referred to herein as “hydrogen-type” sites. Correspondingly, this material exhibits a distinct redox couple under electrochemical lithiation that is characterized as intermediate-strength, capacitive lithium binding, centered at ∼0.5 V vs Li/Li+. Lithiation of hydrogen-type sites is reversible and electrochemically distinct from capacitive lithium adsorption and from intercalation-type binding between graphitic layers. Hydrogen-type site lithiation can be fully retained even up to ultrafast current rates (e.g., 15 A g–1, ∼40 C) where intercalation is severely hampered by ion desolvation kinetics; at the same time, the bulk nature of these sites does not require a large surface area, and only minimal electrolyte decomposition occurs during the first charge/discharge cycle, making coronene-derived carbon an exceptional candidate for high-energy-density battery applications.