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Dr. Matthew Asplund is a Professor of Physical Chemistry in the Department of Chemistry and Biochemistry at Brigham Young University, Provo. He received a Bachelor's in Science at BYU in 1992, then completed his Ph.D. at the University of California at Berkely in 1998. From 1998 to 2000 he worked as a postdoctoral fellow at the University of Pennsylvania.
The Asplund Lab researches chemical reactions with an emphasis on spectroscopy as a means of analysis.
The development of short-pulsed lasers has allowed Asplund researchers to directly probe chemical reactions in real time. Typically, one laser pulse is used to initiate a chemical reaction, and a second pulse is used to probe the intermediates or products some time later. Chemical reactions in condensed phases are especially well suited to these techniques, since the steps in the reactions occur very fast, usually on a time scale shorter than a nanosecond. Asplund Lab research focuses on the use of time-resolved techniques, both on the femtosecond/picosecond time scale, and on the longer nanosecond/microsecond time scale. Of particular importance is the use of infrared spectroscopy for probing chemical species, since it is easier to correlate with molecular structure than electronic spectroscopy.
Model Ring Formation Reactions: One area of particular interest in the Asplund Lab Group is reactions involving organometallic species involved in the formation of new carbon-carbon bonds and the formation of rings. An interesting class of reactions is labeled Pauson-Khand reactions. In its most general form, it is the reaction of an alkene, and alkyne a carbonyl to form a 5-membered cyclopenteneone ring.
The reaction proceeds thermally, and a variant of the reactant that combines the alkene and alkyne in the same molecule is used to follow the reaction with time-resolved spectroscopic methods.
The reaction mechanism shows that the first step is the removal of a CO from the Mo(CO)6, followed by formation of a complex between the Mo(CO)5 and the complex, followed by formation of the ring. The Asplund Lab is trying to establish which part of the ligand attaches to the metal first.
Bi-metal catalyst systems: One of the difficulties in current catalytic systems is that they usually require use of a rare and expensive metal atom. There is tremendous interest in using bimetallic systems where the two atoms act cooperatively to give reactions that are similar to rare metals. While there are many catalytic reaction studies that have established the viability of this approach, there is little known about the details of the reactions. The Asplund Lab is applying our transient infrared spectroscopy to these bi-metallic systems to try to understand how these cooperative systems drive chemistry.
C-F bond activation reactions: One are of particular interest in the Asplund Lab is reactions involving organometallic species involved in catalytic bond breaking processes. Previous work on molecules which break C—H bonds in alkanes shows that the first photon dissociates a ligand from the metal center, and then this metal atom reacts with the surrounding alkane solvent molecule to form a alkyl hydride product, having broken a C—H bond in the alkane. Currently the Lab is studying a related molecule that is able to break C—F bonds in perfluoro-benzene. This tungsten containing organometallic has a reaction between the W atom, and a tethered perfluorobenzene ring. The Asplund Lab's recently published work showed that the rate of the reaction is limited by the formation of a weak complex with the solvent. The Asplund Lab Group is to measure the spectrum of this solvent complex on a nanosecond time-scale, and compare the spectrum directly with calculations.
Laser surface patterning: In the Asplund Lab, members put time into researching novel methods for using lasers to functionalize surfaces. Working with Dr. Matt Linford, the Lab uses high intensity laser pulses to ablate, or remove, atoms from the surface of silicon wafers. The newly exposed Si atoms react rapidly with molecules in liquid placed on the surface. Using an array of micro-lenses, the Lab Group has shown rapid functionalization and patterning of surfaces with alkyl halides, epoxides, amines and other chemically important groups. The lab's current setup allows for the creation of 2500 spots each with a diameter of 2-3 microns. These spots can be functionalized with DNA, proteins or other chemical or biochemical sensors.