Nanospaces are ubiquitous in the realm of biological systems and are of significant interest among supramolecular chemists. Understanding chemical behavior within nanospaces offers new perspectives on biological phenomena in nature and opens the way to highly unusual and selective forms of catalysis. Supramolecular chemistry exploits weak, yet effective, intermolecular interactions such as hydrogen bonding, metal‐ligand coordination, and the hydrophobic effect to assemble nano‐sized molecular architectures, providing reactions with remarkable rate acceleration, substrate specificity, and product selectivity. In this minireview, the focus is on the strategies that supramolecular chemists use to emulate the efficiency of biological processes, and elucidating how chemical reactivity is efficiently controlled within well‐defined nanospaces. Approaches such as orientation and proximity of substrate, transition‐state stabilization, and active‐site incorporation will be discussed.
The
intrinsic structural complexity of proteins makes it hard to
identify the contributions of each noncovalent interaction behind
the remarkable rate accelerations of enzymes. Coulombic forces are
evidently primary, but despite developments in artificial nanoreactor
design, a picture of the extent to which these can contribute has
not been forthcoming. Here we report on two supramolecular capsules
that possess structurally identical inner-spaces that differ in the
electrostatic potential (EP) field that envelops them: one positive
and one negative. This architecture means that only changes in the
EP field influence the chemical properties of encapsulated species.
We quantify these influences via acidity and rates of cyclization
measurements for encapsulated guests, and we confirm the primary role
of Coulombic forces with a simple mathematical model approximating
the capsules as Born spheres within a continuum dielectric. These
results reveal the reaction rate accelerations possible under Coulombic
control and highlight important design criteria for nanoreactors.
The many useful features possessed by pillararenes (PAs; e.g. rigid, capacious, and hydrophobic cavities, as well as exposed functional groups) have led to a tremendous increase in their popularity since their first discovery in 2008. In this Minireview, we emphasize the use of functionalized PAs and their assembled supramolecular materials in the field of catalysis. We aim to provide a fundamental understanding and mechanism of the role PAs play in catalytic process. The topics are subdivided into catalysis promoted by the PA rim/cavity, PA‐based nanomaterials, and PA‐based polymeric materials. To the best of our knowledge, this is the first overview on PA‐based catalysis. This Minireview not only summarizes the fabrications and applications of PAs in catalysis but also anticipates future research efforts in applying supramolecular hosts in catalysis.
An orthogonal strategy was utilized
for synthesizing a novel water-soluble
pillar[5]arene (
m-TPEWP5) with tetraphenylethene-functionalized
on the bridged methylene group (meso-position) of
the pillararene skeleton. The obtained macrocycle exhibit both the
aggregation-induced emission (AIE) effect and interesting host–guest
property. Moreover, it can be made to bind with a tailor-made camptothecin-based
prodrug guest (DNS-G) to form AIE-nanoparticles based
on host–guest interaction and the fluorescence resonance energy
transfer process for fabricating a drug delivery system. This novel
type of water-soluble AIE-active macrocycle can serve as a potential
fluorescent material for cancer diagnosis and therapy. In addition,
the present orthogonal strategy for designing meso-functionalized aromatic macrocycles may pave a new avenue for creating
novel supramolecular structures and functional materials.
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