posted on 2021-09-21, 22:13authored byAnni I. Taponen, Awatef Ayadi, Manu K. Lahtinen, Itziar Oyarzabal, Sébastien Bonhommeau, Mathieu Rouzières, Corine Mathonière, Heikki M. Tuononen, Rodolphe Clérac, Aaron Mailman
Cocrystallization
of 7,7′,8,8′-tetracyanoquinodimethane
radical anion (TCNQ–•) and 3-methylpyridinium-1,2,3,5-dithiadiazolyl
radical cation (3-MepyDTDA+•) afforded isostructural
acetonitrile (MeCN) or propionitrile (EtCN) solvates containing cofacial
π dimers of homologous components. Loss of lattice solvent from
the diamagnetic solvates above 366 K affords a high-temperature paramagnetic
phase containing discrete TCNQ–• and weakly
bound π dimers of 3-MepyDTDA+•, as evidenced
by X-ray diffraction methods and magnetic susceptibility measurements.
Below 268 K, a first-order phase transition occurs, leading to a low-temperature
diamagnetic phase with TCNQ–• σ dimer
and π dimers of 3-MepyDTDA+•. This study reveals
the first example of cooperative interactions between two different
organic radical ions leading to magnetic bistability, and these results
are central to the future design of multicomponent functional molecular
materials.