Addressing the Barrelene Core of Triptycene with Muon Spin Resonance Spectroscopy

Understanding the degrees of freedom of movement of molecules
in
the condensed phase is critical for informing the design of new molecular
materials. Here we have applied muon spin resonance spectroscopy (μSR)
to study the three-dimensional (3D) polycyclic aromatic hydrocarbon
triptycene in the solid phase. This was inspired by the rotational
dynamics observed in previous μSR studies of the archetypical
3D molecular electronic materials, the fullerenes. We identified that
there is only limited motion of triptycene in its crystals. We also
make the intriguing observation that muonium adds to the barrelene
core of the molecules which may provide a powerful new method to examine
through-space interactions between aromatic rings.