“…Stable radical–chromophore open-shell hybrids have emerged as a versatile class of molecules for light emission, − chemical sensing, information storage, and studying the fundamental photophysics of processes such as spin catalysis. , In particular, the ability to spin polarize radicals by optical pumping of the coupled chromophore has allowed one to considerably increase the sensitivity of select electron spin resonance experiments. − In the last few decades there has been considerable progress in the understanding of optically induced spin polarization transfer and charge transfer mechanisms in photoactive molecules , using model systems such as C 60 –TEMPO, ,, naphthalene–TEMPO, NDI–TEMPO, , ZnTPP–BDPA, NDI–BDPA, and pentacene–TEMPO . In parallel, an increasing number of these studies have focused on closed- and open-shell pentacene derivatives with the goal of increasing their stability, solubility, and triplet yield. − An increased triplet yield has, for example, implications for improving charge carrier mobilities in pentacene-doped solar cell devices and applications in molecular spintronics, artificial photosynthesis, and signal enhancement methods for magnetic resonance. − The triplet yield can be enhanced by increasing the intersystem crossing rate, which may be accomplished by addition of free-radical substituents …”