Redox-Responsive Host–Guest Chemistry of a Flexible Cage with Naphthalene Walls

“Naphthocage”,
a naphthalene-based organic cage,
reveals very strong binding (up to 1010 M–1) to aromatic (di)­cationic guests, i.e., the tetrathiafulvalene mono-
and dication and methyl viologen. Intercalation of the guests between
two naphthalene walls is mediated by C–H···O,
C–H···π, and cation···π
interactions. The guests can be switched into and out of the cage
by redox processes with high binding selectivity. Oxidation of the
flexible cage itself in the absence of a guest leads to a stable radical
cation with the oxidized naphthalene intercalated between and stabilized
by the other two. Encapsulated guest cations are released from the
cavity upon cage oxidation, paving the way to future applications
in redox-controlled guest release or novel stimuli-responsive materials.