Trapping of metastable paramagnetic states generated by photoexcitation is one of the most fascinating phenomena in the study of photoresponsive molecular materials. The magnetic state switching holds potential for being used in memory devices, sensors, or radiation detectors. Although this phenomenon has been studied extensively in transition metal complexes, such as spin crossover coordination compounds, no examples of long-lived (on the order of days) paramagnetic states have been reported in solid state organic materials. Herein, we demonstrate our first observations of such switching in hypervalent 4-center 6-electron S���S-S���S bridged s-dimers of a bisdithiazolyl radicals. The results are very encouraging, as the photogenerated paramagnetic state exhibits an unusually high relaxation temperature, remaining stable to nearly room temperature before converting back to the diamagnetic dimer form. The radical-dimer interconversion under irradiation has been monitored by magnetic susceptibility measurements, optical absorption spectroscopy, and single crystal X-ray diffraction.

Light-induced radical trapping (LIRT): Toward photomagnetic switching at room temperature

247th National Meeting (2014)

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