Conspectus
Pillar[n]arenes (pillarenes for short) are a
relatively new generation of macrocyclic host compounds with rigid
cylinder architectures containing several hydroquinone units that
are bridged by methylene (−CH2−) at their
para positions. The investigation of pillarenes has expanded from
the sole domain of supramolecular chemistry to invoke immense interest
among scientists striving to exploit intelligent materials or functional
systems, with regard to their fascinating attributes such as symmetric
structures, tailorable functionalization, and unique host–guest
properties. Over the past few years, researchers have focused on the
construction of prominent supramolecular architectures such as supramolecular
switches, supramolecular polymers, and self-assembled amphiphilic
systems on the basis of host–guest chemistry in collaboration
with other noncovalent interactions. One of the most attractive characteristics
of these supramolecular assemblies relies on the tunable mechanical
motions via switching of the most conformationally and thermally stable
structures in a dynamic and reversible manner, which could be affected
by the external conditions and enable the reciprocal effect with surrounding
environments. Consequently, macrocyclic arenes are the key components
of stimuli-responsive supramolecular assemblies, serving as important
candidates in the construction of advanced supramolecular materials,
including organic functional systems and organic–inorganic
hybrid systems. In this Account, we present a relatively elaborate
summary of the significant and typical intelligent systems containing
pillarenes and their extended versions with a focus on our own contributions
to this field during the past decade. Finally, in the last section
of the review, challenges and perspectives are given.
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