We are working to develop a new class of photooxidants based on organic photochromes to add an additional level of gating to the process of photoinduced charge transfer initiation of cation radical reactions of materials relevance.  Perimidinespirohexadienone meets the requirements of photochemical coloration, thermal fade, and more positive excited state reduction potential (E*red) for long wavelength (LW) vs. short wavelength (SW) isomers.  However ?E*red is very modest, and LW is only a weak photoxidant. To understand and improve these redox properties, several analogs have been prepared.  Electrochemical, photochemical and photophysical measurements help us understand these compounds' photochromic and electrochromic rearrangements. NOE experiments on quinazolinespirohexadienones prove an unexpected structure for LW, and indicate differential spirocyclic ring opening depending on whether this occurs photochromically, electrochromically, or thermally. This newfound structural data explains our interesting electrochemical results, and renders these in agreement with ground-state reduction potentials we are able to predict computationally.

Photochemical, electrochemical, and computational investigations of perimidinespirohexadienone photochromes, toward photochromic photooxidants

243rd National Meeting (2012)

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