Cucurbiturile

Models from CB [5], CB [6] and CB [7]; Above: view into the cavity; Below: side view

Cucurbiturils are macrocyclic molecules that are composed of several glycoluril units and have the ability to bind other molecules in their chemically extremely inert cavity. The name is derived from Cucurbita , the botanical name of the pumpkin , based on the similarity of the shape of the molecules with a pumpkin. The cavity of the cucurbit [6] uril, a twelve-fold methylene- bridged "hexamer", has a volume in the nm ³ range, with a height of about 9.1 Å , an outside diameter of about 5.8 Å and an inside diameter of approx 3.9 Å.

Cucurbiturils were first synthesized in 1905 by R. Behrend. However, its structure was not clarified until 1981. Currently, cucurbiturils consisting of 5, 6, 7, 8 or 10 repeating units have been isolated. These have a corresponding volume of 82, 164, 279, 479 and 870 Å ³ . A cucurbituril made up of 9 units has not yet been isolated. Other known molecules with a similar molecular shape are the cyclodextrins and the calixarenes .

nomenclature

Cucurbiturils are commonly referred to as cucurbit [#] uril , with the number of repeating units in brackets. A common abbreviation is CB [#] or CB #.

synthesis

Cucurbiturils are aminals that are made from two molecules of urea ( 1 ) and an α- dicarbonyl compound such as an α- diketone or usually glyoxal ( 2 ) through a nucleophilic addition , whereby glycoluril ( 3 ) is formed as an intermediate . The intermediate is condensed with formaldehyde ( 4 ) , whereby the hexamer cucurbit [6] uril ( 5 ) is formed at a temperature above 110 ° C.

literature

Jeon YJ, Kim SY, Ko YH, Sakamoto S, Yamaguchi K, Kim K: Novel molecular drug carrier: encapsulation of oxaliplatin in cucurbit [7] uril and its effects on stability and reactivity of the drug . (PDF) In: Org. Biomol. Chem. . 3, No. 11, June 2005, pp. 2122-5. doi : 10.1039 / b504487a . PMID 15917899 .

Individual evidence

↑ Jason Lagona, Pritam Mukhopadhyay, Sriparna Chakrabarti, Lyle Isaacs: The Cucurbit [n] uril Family. In: Angewandte Chemie International Edition. 44, 2005, p. 4844, doi : 10.1002 / anie.200460675 .
↑ R. Behrend, E. Meyer and F. Rusche (1905): “About Condensationsproducte from Glycoluril and Formaldehyde.” Liebigs Ann. Chem. 339 , 1-40.
↑ Cucurbituril WA Freeman, WL Mock, and N.-Y. Shih J. Am. Chem. Soc. , 1981 , 103, 7367.

[1] Jason Lagona, Pritam Mukhopadhyay, Sriparna Chakrabarti, Lyle Isaacs: The Cucurbit [n] uril Family. In: Angewandte Chemie International Edition. 44, 2005, p. 4844, doi : 10.1002 / anie.200460675 .

[2] R. Behrend, E. Meyer and F. Rusche (1905): “About Condensationsproducte from Glycoluril and Formaldehyde.” Liebigs Ann. Chem. 339 , 1-40.

[3] Cucurbituril WA Freeman, WL Mock, and N.-Y. Shih J. Am. Chem. Soc. , 1981 , 103, 7367.