Photoswitchable Intramolecular Through-Space Magnetic Interaction

The interaction between two TEMPO spin centers connected to a photoswitchable overcrowded alkene changes from noncoupled (three-line EPR spectrum) in the trans state, where the two spin centers are separated by similar to 22 angstrom, to strongly coupled (five-line EPR spectrum) in the cis state, where the separation is similar to 7 angstrom, upon photoswitching. Importantly, the performance of the alkene switching unit is essentially unaffected by the spin centers.