1 research outputs found
Stable π‑Extended Thio[7]helicene-Based Diradical with Predominant Through-Space Spin–Spin Coupling
In this work, a novel π-extended thio[7]helicene
scaffold
was synthesized, where the α-position of the thiophene unit
could be functionalized with bulky phenoxy radicals after considerable
synthetic attempts. This open-shell helical diradical, ET7H-R, possesses high stability in the air, nontrivial π conjugation,
persistent chirality, and a high diradical character (y0 of 0.998). The key feature is a predominant through-space
spin–spin coupling (TSC) between two radicals at the helical
terminals. Variable-temperature continuous-wave electron spin resonance
(cw-ESR) and superconducting quantum interference device (SQUID) magnetometry
in the solid state reveal a singlet ground state with a nearly degenerate
triplet state of ET7H-R. These results highlight the
significance of a stable helical diradicaloid as a promising platform
for investigating intramolecular TSCs