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| hope college > academic departments > chemistry |
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Gillmore Research Group
There is an opportunity to join a thriving organic photochemistry research group at Hope College, with a primary focus on incorporating undergraduate students into all aspects of the research endeavor. In the process these student collaborators gain familiarity with organic synthesis, photochemistry, electrochemistry, ion radical intermediates, polymers, and materials research. Together, we develop gateable photosensitizers for photoinduced charge transfer (PICT) based on a family of photochromic compounds. Photochromic organic molecules are compounds that undergo a reversible photochemical rearrangement from a short wavelength (SW) form to a long wavelength (LW) form, with reversion occuring thermally, photochemically, or both. The vast majority of organic photochromes have been investigated for applications in ophthalmic lenses (e.g., Transitions® lenses), novelty items, or data storage applications all related to their color change. Studies of the spectral changes, molar absorptivity, reversibility, and fatigue resistance predominate. Exploration of other dynamic properties of photochromic compounds has been far more limited. Extremely little is known regarding the redox properties of these compounds. Very few ground state redox potentials have been measured, and it appears that not a single excited state reduction or oxidation potential has been determined. In many cases, the structural changes that underlie the photchromic transformation are profound and likely to significantly alter the redox properties of the molecules in question. In the Gillmore Research Group at Hope College, the perimidinespirocyclohexadienone family of photochromes are being studied as potential "photochromic photooxidants." Students are synthesizing known and novel compounds in this family of compounds. Students also do all the characterization of structure, photophysical properties, and ground and excited state electrochemical properties, using NMR, UV-Vis, Cyclic Voltammetry, and other techniques. A variety of structures will be synthesized by multiple students in an attempt to tune these properties in a rational manner. Eventually it is hoped that a library or ladder of potential photochromic photooxidants can be developed.
These photochromic photooxidants will ultimately allow sensitivity towards chemical initiation by PICT to be switched on and off. There are several followup cation radical processes of great interest to materials science (polymerization, 3D microlithography, holographic data storage, waveguides) that it would be interesting or advantageous to gate, and as gateable photooxidants are developed they will also eventually be tested in these real applications, or in model reactions thereof. Finally, as this work is beginning to be publicized by Professor Gillmore and his students at conferences nationwide and among seminar speakers (and soon in our first publication), collaborations are beginning to form. For instance, there will soon be the opportunity to study this family of photochromes by solid state NMR with in situ photochemical irradiation, in collaboration with physical chemist Professor Sophia Hayes, at Washington University in St. Louis, MO.
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