New GC/MS and Potentiostat and their Application to Photochrome Research
Dr. Jason Gillmore, Hope College
Photoinduced charge transfer (PICT) is a useful means of generating organic ion radicals. Cation radicals generated by PICT have relevance in a variety of applications of materials science interest, including new approaches to volume holographic data storage and 3D microfabrication. However a limitation to the use of PICT-initiated cation radical reactions is the persistence of photooxidant in the material subsequent to completion of the desired reaction. For instance, in data storage, this prohibits the use of the writing laser to read out the data without a “fixing” step that may alter the material. We are therefore attempting to develop a reversible "pro-photooxidant" system to gate sensitivity to PICT, in essence only having a photooxidant present when it is desired. Organic photochromes have long been used to “gate” optical properties, specifically color (absorbance) – in essence Transitions® lenses “gate” the presence of sunglasses. The increase in conjugation that underlies the change in absorbance upon isomerization of a photochrome also has significant impact on electronic properties. This phenomenon has received much less attention. Our group's emphasis continues to be on controlling and utilizing these electrochemical changes which occur concurrently with the photochromic rearrangement's shift in absorbance to create "photochromic photooxidants", in which one isomer of the photochrome is a good photooxidant, while the other isomer is not. An NSF CAREER grant was recently awarded to our group, enabling us to purchase new instrumentation. Two Agilent 6890 GC/FID’s were upgraded, as was an Agilent 6890 GC with a 5973 MSD. A new Agilent 7890 GC with 5975C MSD was also purchased. A new potentiostat system was purchased from BASi as well. Their application to our photochromic photooxidant research program will be discussed. In particular, results indicating differential electrochromic vs. photochromic ring opening of quinazolinespirohexadienones will be described.
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