Cryptophane
Cryptophanesare a class oforganicsupramolecular compoundsstudied and synthesized primarily formolecular encapsulationand recognition. One possible noteworthy application of cryptophanes is encapsulation and storage ofhydrogengas for potential use infuel cellautomobiles. Cryptophanes can also serve as containers in which organic chemists can carry outreactionsthat would otherwise be difficult to run under normal conditions. Due to their uniquemolecular recognitionproperties, cryptophanes also hold great promise as a potentially new way to study the binding of organic molecules with substrates, particularly as pertaining to biological andbiochemicalapplications.[1]
Discovery
[edit]Cryptophanes were discovered byAndré Colletand Jacqueline Gabard in 1981[2]when these researchers created, using template-directed synthesis, the first cryptophane, now known as cryptophane-A.
Structure
[edit]Cryptophane cages are formed by two cup-shaped [1.1.1]–orthocyclophaneunits (seecyclotriveratrylene),[3]connected by three bridges (denotedY). There are also choices of the peripheral substitutesR1andR2attached to the aromatic rings of the units. Most cryptophanes exhibit twodiastereomericforms (synandanti), distinguished by theirsymmetrytype. This general scheme offers a variety of choices (Y,R1,R2,and symmetry type) by which the shape, volume and chemical properties of the generally hydrophobic pocket inside the cage can be modified, making cryptophanes suitable for encapsulating many types of small molecules and even chemical reactions.
General classification
[edit]Depending on their structure, cryptophane cages are classified according to the following table.[3]
| Structure | Name | ||||
|---|---|---|---|---|---|
| BridgesY | R1 | R2 | anti | syn | described in |
| 3 × O(CX2)2O, where X isHorD | OCX3 | OCX3 | A | Brotinet al.[4] | |
| 3 × O(CX2)2O | OCH2CO2H | OCH2CO2H | A3 | ||
| 3 × O(CX2)2O | OCH3 | H | C | D | |
| 3 × O(CH2)3O | OCH3 | OCH3 | E | F | |
| 3 × O(CH2)3O | OCH2CO2H | OCH2CO2H | E3 | ||
| 3 × O(CH2)5O | OCH3 | OCH3 | O | P | |
| 3 × O(CH2)5O | OCH2CO2H | OCH2CO2H | O3 | ||
| 3 × OCH2C≡CC≡CH2O | CH3 | CH3 | γ(gamma) | δ(delta) | |
| 2 × O(CH2)2O, 1 × O(CH2)3O | OCH3 | OCH3 | 223 | ||
| 2 × O(CH2)3O, 1 × O(CH2)2O | OCH3 | OCH3 | 233 | ||
| 2 × O(CH2)2O, 1 × O(CH2)4O | OCH3 | OCH3 | 224 | ||
Symmetry
[edit]The anti cryptophane isomer belongs to the D3point group and the syn cryptophane isomer belongs to the C3hpoint group.[5]Both molecules therefore do not exhibit a dipole moment.
References
[edit]- ^Palaniappan, K. K.; Francis, M. B.; Pines, A.; Wemmer, D. E. Molecular sensing using hyperpolarized xenon NMR spectroscopy. Isr. J. Chem. 2014, 54, 104−112.
- ^Gabard, J.; Collet, A. (1981). "Synthesis of a (D3)-bis(cyclotriveratrylenyl) macrocage by stereospecific replication of a (C3)-subunit ".Journal of the Chemical Society, Chemical Communications(21).Royal Society of Chemistry:1137–1139.doi:10.1039/C39810001137.
- ^abHolman, K. Travis (2004). "Cryptophanes: Molecular Containers". In Atwood, J. L.; Steed, J. W. (eds.).Encyclopedia of Supramolecular Chemistry.CRC Press.pp. 340–348.doi:10.1081/E-ESMC(inactive 2024-07-16).ISBN0-8247-4723-2.
{{cite book}}:CS1 maint: DOI inactive as of July 2024 (link) - ^Brotin, Thierry; Devic, Thomas;Lesage, Anne;Emsley, Lyndon;Collet, André (March 2001). "Synthesis of deuterium-labeled cryptophane-A and investigation of Xe@Cryptophane complexation dynamics by 1D-EXSY NMR experiments".Chemistry: A European Journal.7(7): 1561–1573.doi:10.1002/1521-3765(20010401)7:7<1561::AID-CHEM1561>3.0.CO;2-9.PMID11330913.
- ^Peter Atkins, J. D. P.,Atkins' Physical Chemistry.Oxford: 2010.