Strategy for Stimuli-Induced Spin Control Using a Liquescent Radical Cation

A liquescent
salt based on an N-pentylphenothiazine
radical cation (1•+·NTf2–) exhibited a unique crystal–crystal phase transition
from a paramagnetic orange solid to a diamagnetic green solid induced
by brief, weak, and pinpoint mechanostress. Electron spin resonance
and electronic spectroscopies revealed that this unprecedented solid-state
spin controllability was attributable to mechanostress-triggered sequential
association of the highly mobile radical species occurring under neat
conditions.