- Resorcinarene
A resorcinarene (also resorcarene or calix [4] resorcinarene) is a
macrocycle , or a cyclicoligomer , based on the condensation ofresorcinol (1,3-dihydroxybenzene) and analdehyde . Resorcinarenes are a type ofcalixarene .ynthesis
The resorcinarene macrocycle is typically prepared by condensation of
resorcinol and analdehyde in concentratedacid solution. [1] [2] Recrystallization typically gives the desired isomer in quite pure form. However, for certain aldehydes, the reaction conditions lead to significantby-product s. Therefore, alternative condensation conditions have been developed, including the use ofLewis acid catalysts.[
A
green chemistry procedure was recently developed using solvent-free conditions: resorcinol, an aldehyde, and "p"-toluenesulfonic acid are ground together in amortar and pestle at low temperature. [3] A paste-like solid forms upon sitting for several minutes, which can be washed with water and crystallized to give the desired resorcinarene.Under each of these conditions,
aromatic aldehydes react much faster, but less stereoselectively thanaliphatic aldehydes, and the reaction frequently leads to a mixture of desired and undesired products.tructure
Resorcinarenes can be characterized by a wide upper rim and a narrow lower rim. The upper rim includes eight
hydroxyl groups that can participate inhydrogen bonding interactions. Depending on the aldehyde starting material, the lower rim includes four appending groups, usually chosen to give optimal soubility. The resorcin [n] arene nomenclature is analogous to that of calix [n] arenes, in which 'n' represents the number of repeating units in the ring.Pyrogallolarenes are related macrocycles derived from the condensation ofpyrogallol (1,2,3-trihydroxybenzene) with an aldehyde.History
During the late 19th century,
Adolf von Baeyer noted that the condensation reaction ofresorcinol andbenzaldehyde gave a mixture of products that was beyond the characterization methods of that time. Over the following century, the product mixture was more fully characterized byX-ray crystallography andNuclear Magnetic Resonance and found to include general structure shown above and several otherstereoisomers .upramolecular Chemistry
Yasuhiro Aoyama's research group at
Kyoto University first noted the potential for resorcinarenes to interact with other molecules as ahost-guest complex . [4] It was later found that resorcinarenes and pyrogallolarenes self-assemble into to larger supramolecular structures. Both in the crystalline state and inorganic solvent s, six resorcinarene molecules are known to form hexamers with an internal volume of around one cubicnanometer (nanocapsules) and shapes similar to theArchimedean solid s. [5]Hydrogen bonds appear to hold the assembly together. A number of solvent or other molecules reside inside. [6]The resorcinarene is also the basic structural unit for other molecular recognition scaffolds. A number of chemists, including Nobel-laureate
Donald J. Cram , constructed novel molecular structures based on this macrocycle, namelycavitand s andcarcerand s.External links
* [http://www.chem.missouri.edu/faculty/Atwood/research.html Jerry Atwood Research Group]
* [http://www.scripps.edu/skaggs/rebek/ Julius Rebek, Jr. Research Group]References
* [1] cite journal | author=Högberg AGS | title=| journal=Journal of Organic Chemistry | volume=45. | issue= | year=1980 | pages=4498–4500 | doi=10.1021/jo01310a046
* [2] cite journal | author=Högberg AGS | title=| journal=Journal of the American Chemical Society | volume=102. | issue= | year=1980 | pages=6046–6050 | doi=10.1021/ja00539a012
* [3] cite journal | author=Antesberger J, Cave GW, Ferrarelli MC, Heaven MW, Raston CL, Atwood JL | title=Solvent-free, direct synthesis of supramolecular nano-capsules | journal=Chemical Communications (Cambridge, England) | volume=. | issue=7 | year=2005 | pages=892–894 | pmid=15700072 | doi=10.1039/b412251h
* [4] cite journal | author=Aoyama Y, Tanaka Y, Toi H, Ogoshi H | title= | journal=Journal of the American Chemical Society | volume=110 | issue= | year=1988 | pages=634–635 | doi= 10.1021/ja00210a073
* [5] cite journal | author=Atwood JL, Barbour LJ, Jerga A | title=Organization of the interior of molecular capsules by hydrogen bonding | journal=Proceedings of the National Academy of Sciences | volume=99 | issue=8 | year=2002 | pages=4837–4841 | pmid=11943875 | doi=10.1073/pnas.082659799
* [6] cite journal | author=Shivanyuk A, Rebek J | title=Reversible encapsulation by self-assembling resorcinarene subunits | journal=Proceedings of the National Academy of Sciences | volume=98 | issue= | year=2001 | pages=7662–7665 | doi=10.1073/pnas.141226898 | pmid=11427733
* [7] cite journal | author=Palmer LC, Shivanyuk A, Yamanaka M, Rebek J | title=Resorcinarene assemblies as synthetic receptors | journal=Chemical Communications (Cambridge, England) | volume= | issue=7 | year=2005 | pages=857–858 | doi=10.1039/b414252g
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