Photogenerated Quartet State Formation in a Compact Ring-Fused Perylene-Nitroxide

We report on a novel small organic molecule comprising a perylene chromophore fused to a six-membered ring containing a persistent nitroxide radical to give a perylene-nitroxide, or PerNO(center dot). This molecule is a robust, compact molecule in which the radical is closely bound to the chromophore but separated by saturated carbon atoms, thus limiting the electronic coupling between the chromophore and radical. We present both ultrafast transient absorption experiments and time-resolved EPR (TREPR) studies to probe the spin dynamics of photoexcited PerNO(center dot). and utilize X-ray crystallography to probe the molecular structure and stacking motifs of PerNO(center dot) in the solid state. The ability to control both the structure and electronic properties of molecules having multiple spins as well as the possibility of assembling ordered solid state materials from them is important for implementing effective molecule-based spintronics.