with G25, they form quite different nanostructures which differ considerably from
each other observed by TEM and SEM imaging. Free G25 spontaneously assembles
into fine nanofibers with a diameter of 20 nm. When G25 is associated with H5,
rectangular nanosheets with the length ranging from 200 to 700 nm are found by
TEM and SEM experiments. In the case of G25 & CB[7] complex, nanorods with
the length of about 500 nm and width of about 200 nm are observed; this is also
investigated by DLS experiments to show distribution of 672 nm for their hydrodynamic diameter in solution. In contrast, G25 & CB8 forms rarely reported octahedron-like nanostructure, and G25 & WP5A forms left-handed helical nanowires.
1.6
Conclusions and Outlook
In conclusion, we have summarized the binding strengths and properties of watersoluble aromatic crown ethers with various cationic guest molecules, their thermodynamic aspect, inner noncovalent interaction, and applications. Possessing negative
charges, π-electron-rich cavity, and additional binding sites on ethylene glycol chains,
water-soluble aromatic crown ethers can extensively form inclusion complexes with a
variety of cations, showing distinguishable binding characteristic and selectivities.
Furthermore, these pronounced binding properties endow them broad applications
in material fields, including MOFs, supramolecular amphiphilic, and so on. However,
we believe that more structures of water-soluble aromatic crown ethers with powerful
binding ability are still attractive field in the years to come.
References
1. Pedersen CJ (1967) Cyclic polyethers and their complexes with metal salts. J Am Chem Soc
89:7017–7036
2. Jane YS (1994) Crown ether phase-transfer catalysts for polymerization of phenylacetylene. J
Mol Catal 89:29–40
3. (a) Cram DJ, Helgeson RC, Peacock SC, Kaplan LJ, Domeier LA, Moreau P, Koga K,
Mayer JM, Chao Y (1978) Host-guest complexation. 8. Macrocyclic polyethers shaped by
two rigid substituted dinaphthyl or ditetralyl units. J Org Chem 43:1930–1946; (b) Merten C,
Hyun MH, Xu Y (2013) Absolute configuration and predominant conformations of a chiral
crown ether-based colorimetric sensor: a vibrational circular dichroism spectroscopy and DFT
study of chiral recognition. Chirality 25:294–300
4. Gokel GW, Leevy WM, Weber ME (2004) Crown ethers: sensors for ions and molecular
scaffolds for materials and biological models. Chem Rev 104:2723–2750
5. Ashton PR, Campbell PJ, Chrystal EJT, Glink PT, Menzer S, Philp D, Spencer N, Stoddart JF,
Tasker PA, Williams DJ (1995) Dialkylammonium ion/crown ether complexes: the forerunners
of a new family of interlocked molecules. Angew Chem Int Ed 34:1865–1869
6. Barin G, Coskun A, Fouda MMG, Stoddart JF (2012) Mechanically interlocked molecules
assembled by π–π recognition. Chem Plus Chem 77:159–185
7. Kaiser G, Jarrosson T, Otto S, Ng Y-F, Bond AD, Sanders JKM (2004) Lithium-templated
synthesis of a donor–acceptor pseudorotaxane and catenane. Angew Chem Int Ed
43:1959–1962
24
L. Chen and Y. Liu
each other observed by TEM and SEM imaging. Free G25 spontaneously assembles
into fine nanofibers with a diameter of 20 nm. When G25 is associated with H5,
rectangular nanosheets with the length ranging from 200 to 700 nm are found by
TEM and SEM experiments. In the case of G25 & CB[7] complex, nanorods with
the length of about 500 nm and width of about 200 nm are observed; this is also
investigated by DLS experiments to show distribution of 672 nm for their hydrodynamic diameter in solution. In contrast, G25 & CB8 forms rarely reported octahedron-like nanostructure, and G25 & WP5A forms left-handed helical nanowires.
1.6
Conclusions and Outlook
In conclusion, we have summarized the binding strengths and properties of watersoluble aromatic crown ethers with various cationic guest molecules, their thermodynamic aspect, inner noncovalent interaction, and applications. Possessing negative
charges, π-electron-rich cavity, and additional binding sites on ethylene glycol chains,
water-soluble aromatic crown ethers can extensively form inclusion complexes with a
variety of cations, showing distinguishable binding characteristic and selectivities.
Furthermore, these pronounced binding properties endow them broad applications
in material fields, including MOFs, supramolecular amphiphilic, and so on. However,
we believe that more structures of water-soluble aromatic crown ethers with powerful
binding ability are still attractive field in the years to come.
References
1. Pedersen CJ (1967) Cyclic polyethers and their complexes with metal salts. J Am Chem Soc
89:7017–7036
2. Jane YS (1994) Crown ether phase-transfer catalysts for polymerization of phenylacetylene. J
Mol Catal 89:29–40
3. (a) Cram DJ, Helgeson RC, Peacock SC, Kaplan LJ, Domeier LA, Moreau P, Koga K,
Mayer JM, Chao Y (1978) Host-guest complexation. 8. Macrocyclic polyethers shaped by
two rigid substituted dinaphthyl or ditetralyl units. J Org Chem 43:1930–1946; (b) Merten C,
Hyun MH, Xu Y (2013) Absolute configuration and predominant conformations of a chiral
crown ether-based colorimetric sensor: a vibrational circular dichroism spectroscopy and DFT
study of chiral recognition. Chirality 25:294–300
4. Gokel GW, Leevy WM, Weber ME (2004) Crown ethers: sensors for ions and molecular
scaffolds for materials and biological models. Chem Rev 104:2723–2750
5. Ashton PR, Campbell PJ, Chrystal EJT, Glink PT, Menzer S, Philp D, Spencer N, Stoddart JF,
Tasker PA, Williams DJ (1995) Dialkylammonium ion/crown ether complexes: the forerunners
of a new family of interlocked molecules. Angew Chem Int Ed 34:1865–1869
6. Barin G, Coskun A, Fouda MMG, Stoddart JF (2012) Mechanically interlocked molecules
assembled by π–π recognition. Chem Plus Chem 77:159–185
7. Kaiser G, Jarrosson T, Otto S, Ng Y-F, Bond AD, Sanders JKM (2004) Lithium-templated
synthesis of a donor–acceptor pseudorotaxane and catenane. Angew Chem Int Ed
43:1959–1962
24
L. Chen and Y. Liu