We are working to develop a new class of photooxidants based on organic photochromes that would add an additional level of gating to the process of photoinduced charge transfer (PICT) initiation of cation radical reactions with relevance to a variety of materials applications. Photochromes with long wavelength isomers (LW) capable of acting as photooxidants but with short wavelength isomers (SW) less capable of doing so are sought. This necessitates photochromes that revert only thermally and that have excited state reduction potentials that are more positive for LW than for SW. (As the difference in excitation energies is in the opposite direction, this requires a very large difference in ground state reduction potentials!)The parent perimidinespirohexadienone (PSHD) photochrome meets these basic requirements, but with a very modest difference in excited state reduction potential between SW and LW, thus with minimal capacity for gating, and very modest photooxidizing power. Replacing the naphthalene moiety of the PSHD's with a quinoline moiety gives the quinazolinespirohexadienone (QSHD) family of photochromes we have recently reported.  In this presentation we describe recent efforts to develop even more electron deficient QSHD analogs capable of gating PICT and photooxidizing less reducible monomers of interest to materials applications.

Next generation quinazolinespirohexadienone photochromes for application as photochromic photooxidants

248th National Meeting (2014)

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