Synthesis of Thiapillar[6]arenes Bearing Redox-Active (Hydro)quinone Groups. Electrochemical and XRD Study

Pillar[n]arenes are among the newest
members of
the macrocyclic family. Nevertheless, their conformational behavior
and binding properties as well as redox properties of dealkylated
pillar[n]arenes are well-studied. At the same time,
introducing a heteroatom into a cyclophane macrocycle is already known
to alter all the above properties drastically. This study presents
a simple synthetic approach based on thia-Michael addition cyclization
that readily resulted into hexathiapillar[6]arene with four phenylene
units alternated by two redox-active hydroquinone moieties. The straightforward
synthesis of the macrocycle enabled a systematic study of its conformation
and redox behavior. The modification of hexathiapillar[6]arene afforded
five functionalized derivatives, which were studied structurally in
detail. The findings revealed interesting redox and structural properties
of the macrocycle and its derivatives including the formation of crystal
lattices with continuous channels and empty voids.