Suit[3]ane

Suitanes are a class of mechanically
interlocked molecules (MIMs)
that consist of two components: a body with limbs protruding outward
and a suit that fits appropriately around it, so that there is no
easy way for the suit to be removed from the body. Herein, we report
the synthesis and characterization of a suit[3]­ane, which contains
a benzotrithiophene derivative (THBTT) with three protruding
hexyl chains as the body and a 3-fold symmetric, extended pyridinium-based
cage, namely, HexaCage6+, as the suit. Central
to its realization is effective templation, provided by THBTT during cage formation, an observation that has been supported by
the strong binding constant between benzotrithiophene (BTT) and the empty cage. The solid-state structure of the suit[3]­ane
reveals that the body is confined within the suit’s cavity
with its alkyl chains protruding outward through the orifices in the
cage. Notably, such a seemingly unstable molecule, having three flexible
alkyl chains as its only protruding limbs, does not dissociate after
prolonged heating in CD3CN at 100 °C under pressure
for 7 days. No evidence for guest exchange with the host was observed
at this temperature in a 2:1 mixture of THBTT and HexaCage6+ in CD3CN. The results indicate
that flexible protruding limbs are sufficient for a suit[3]­ane to
remain mechanically stable even at high temperatures in solution.