Selective separation of phenanthrene (PHE) from aromatic isomer mixtures is a big challenge in industry. In this work, a light-responsive water-soluble azobenzene-based macrocycle 1 is synthesized and an aqueous solution of E,E-1 is employed to separate PHE from anthracene via a solid−liquid extraction method under ambient conditions. After five extraction cycles, the average purity for PHE is about 91.1% and macrocycle 1 can be reused at least five times without obvious reduction of separation performance for PHE. This work not only comprises a new and clean way to separate PHE by taking advantage of a macrocyclic host but also promotes the application of host−guest chemistry.
Self‐assembly by imine condensation in aqueous media is a formidable task because of the labile nature of imines in the presence of water. Here, by taking advantage of multivalence and ligand preorganization, basket‐shaped triscationic cage molecules are self‐assembled in high yields in both water and organic solvent, by condensing a hexaformyl and bisamine. These cages, especially the chiral ones, are stable or inert in aqueous solution, that is, no decomposition was observed upon dilution, precipitation, or exposure to competitive amines or aldehydes. Such water‐compatibility allows the hosts to take advantage of the hydrophobic effect to accommodate hydrophobic guests. The chiral cage S‐23+ selectively binds and distinguishes one of two enantiomers, opening up opportunities for applications such as chiral compound separation. Chiral narcissistic self‐sorting and sergeants‐and‐soldiers effects occur during cage formation when two amino precursors are involved in self‐assembly.
Azobenzene (azo)‐based macrocycles are highly fascinating in supramolecular chemistry because of their light‐responsiveness. In this work, a series of azo‐based macrocyclic arenes 1, 2, 3, and 4, distinguished by the substituted positions of azo groups, is rationally designed and synthesized via a fragment‐cyclization method. From the crystal and computed structures of 1, 2, and 3, we observe that the cavity size of these azo‐macrocycles decreases gradually upon E→Z photoisomerization. Moreover, light‐controlled host–guest complexations between azo‐macrocycle 1 and guest molecules (7,7,8,8‐tetracyanoquinodimethane, terephthalonitrile) are successfully achieved. This work provides a simple and effective method to prepare azo‐macrocycles, and the light‐responsive molecular‐encapsulation systems in this work may further advance the design and applications of novel photo‐responsive host–guest systems.
We report the preparation of a chiral 3D polymer network endowed with ability of heterogeneous asymmetric catalysis and good recyclability based on pillar[5]arene and (R,R)-tetraaryl-1,3-dioxolane-4,5-dimethanol derivatives.
The
construction of smart nanomaterials from host macrocycles that
are responsive to specific stimuli has gained significant attention
in recent years. The application of pillar[n]arenes
has been of particular interest given their ease of functionalization
and tunability of the intrinsic cavity electronic properties that
allows them to encapsulate a great variety of guests and complex with
metal ions with high selectivity via noncovalent interactions, endowing
them with captivating properties and functions. Herein, we present
the most recent advances in the design and functionalization of pillar[n]arene-based smart nanomaterials, and their applications
for sensing, catalysis, drug delivery, and artificial transmembrane
channels.
The host–guest properties
of [15]paracyclophane
([15]PCPs) are engendered by π-metalation, which
exhibits fantastic regioselectivity toward a macrocyclic molecule.
The synthesis and characterization of mono-, di-, and trimetalated
[15]PCPs are discussed in this article, and the anion binding
behavior of 3Ru-[1
5
]PCP-II
6+, one of the trimetalated [15]PCPs, driven
by anion−π interactions, is comprehensively demonstrated
in both solution and the solid state. The anion binding properties
of 3Ru-[1
5
]PCP-II
6+ in solution are investigated by 1H NMR titrations,
showing selectivity toward ReO4
– in both
organic and aqueous solutions. The binding mode is unexpected; the
anionic guest stacks over the host rather than threads it. This selectivity
for ReO4
– is also supported by water–nitromethane
extraction experiments, which demonstrate that its partition from
water into the organic phase by 3Ru-[1
5
]PCP-II·6OTf is maintained to some extent
in the presence of excess Cl–, SO4
2–, H2PO4
–,
NO3
–, and ClO4
–.
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