Talk:Calixarene

I'm going to have a go at putting in a structure from chemdraw, showing the basket shape.Rob82 19:41, 25 September 2007 (UTC)

Thanks a lot for excellent paper. But there is some unclear information concerning calixarene`s conformational chemistry. It is known that the mobility of calixarene`s framework is important supramolecular characteristic. Some comments.. «The 4 hydroxyl groups interact by hydrogen bonding and stabilize the cone conformation. This conformation is in dynamic equilibrium with the other conformations. Conformations can be locked in place with proper substituents replacing the hydroxyl groups which increase the rotational barrier. Alternatively placing a bulky substituent on the upper rim also locks a conformation.» First of all the calixarene with hydroxyl group have the rigid conformation because of the very strong intramolecular hydrogen bond. Only pinched cone-pinched cone conventional observed. After alkylation of lower rim two different mode of rotation may be possible. (para substituent through the annulus and oxygen through the annulus). For calix[4]arenes there is contradictory information. Referring to (Ikeda A., Shinkai S., Novel Cavity Design Using Calix[n]arene Skeletons: Toward Molecular Recognition and Metal Binding, Chem. Rev. 1997, 97, 1713-1734. (12(3))) Calix[4]arenes have two possible mode of rotation. But referring to.. Jan Lang, Jiri Vlach, Hana Dvorakova, Pavel Lhotak, Michal Himl, Richard Hrabal, Ivan Stibor, Thermal isomerisation of 25,26,27,28-tetrapropoxy-2,8,14,20-tetrathiacalix[4]arene: isolation of all four conformers, Journal of the Chemical Society, Perkin Transactions 2 (Physical Organic Chemistry), 1 (2001), 4 ( 07), 576-580. Calix[4]arenes have only one mode of rotation (oxygen through the annulus). Consequently calix[4]arene (-O-Pr in lower rim) is conformational rigid irrespective of para-substituent referring to Jan Lang. The calix[4]arene is conformational mobile when H is para-substituent reffering to Shinkai S. Haw many inversion for calix[4]arene skelleton are possible for calix[4]arene two or one?

With best regards Vasiliy M. (support the Russian wiki-paper devoted to calixarene).

Metal [1] 13:15, 12 February 2007 (UTC)

I think this:

"In calix[4]arenes the internal volume is around 10 cubic nanometers. " is wrong and should be cubic _Angstroms_ but that's just from looking at the structure...note that 10nm^3 is about the volume of one turn of a DNA helix...which wouldn't fit...by a large margin. The source ought to be double checked. —Preceding unsigned comment added by 68.121.23.3 (talk) 11:46, 28 July 2009 (UTC)

Discussion moved from article

The above account of the “History” is badly flawed. It is misleading, includes unnecessary facts while omitting other important ones, and is totally wrong in several of its statements. A more accurate and informative account is provided below:

==Revised History==

In 1872 Adolf von Baeyer, a famous German chemist, mixed various aldehydes, including formaldehyde, with phenols in the presence of a strong acid. The resulting tars defied characterization but represented the opening chapter of what was to become the field of phenol/formaldehyde chemistry. Leo Baekeland, Belgian by birth and a naturalized American citizen, discovered that these tars could be transformed to a hard, brittle substance which he marketed as “Bakelite”, the first commercial synthetic plastic. The success of Bakelite spurred serious investigations into the chemistry of the phenol/formaldeyde reaction, one result of which was the discovery in 1942 by the Austrian chemist Alois Zinke that p-alkyl phenols and formaldehyde in the presence of a strong base yield mixtures containing, inter alia, cyclic tetramers. Concomitantly, the American chemists Joseph Niederl and H. J. Vogel obtained similar cyclic tetramers from the acid-catalyzed reaction of resorcinol and aldehydes such as benzaldehyde. A number of years later the British chemist John Cornforth showed that the product from p-tert-butylphenol and formaldehyde is a mixture of the cyclic tetramer and another ill-defined cyclomer. His interest in these compounds was in the tuberculostatic properties of their oxyethylated derivatives. In the early 1970s the American chemist C. David Gutsche, recognizing the basket-like shape of the cyclic tetramer and the possibility that it might furnish the framework for building an enzyme mimic, initiated a study that extended for three decades. His attention to these compounds came from acquaintance with the Petrolite company’s commercial demulsifiers made by oxyethylation of the still ill-defined products from p-alkylphenols and formaldehyde. He introduced the name “calixarene” (“calix” the Greek name for a vase-like pottery; “arene” for the presence of aryl groups in the cyclic array) and established the structures for the cyclic tetramer, hexamer and octamer; worked out procedures for obtaining these materials in good to excellent yields; established procedures for attaching functional groups to both the upper and lower rims; and explored the conformational properties of these flexible molecules showing that the cyclic tetramer can be frozen into its basket shape (the “cone” conformation) by the introduction of sufficiently large substituents on the lower rim. Concomitant with Gutsche’s work was that of the German chemists Hermann Kämmerer and Voker Böhmer who developed methods for the stepwise synthesis of calixarenes and the Italian chemists Giovanni Andreetti, Rocco Ungaro and Andrea Pochini who were the first to obtain definitive x-ray crystallographic pictures of some of the calixarenes. In the mid 1980s other groups of investigators entered the field of calixarene chemistry which has become an important facet of supramolecular chemistry and which commands the attention of hundreds of scientists around the world. The Niederl cyclic tetramers from resorcinol and aldehydes were studied in detail by the American chemist Donald J. Cram who called the derived compounds “cavitands” and “carcerands”. An accurate and detailed history of the calixarenes along with extensive discussion of calixarene chemistry can be found in the 1989 publication (ref 1) as well as the second edition in 2008 - User:C.David Gutsche 16:54, 31 December 2012

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Note:    [Modified:~E:74.60.29.141 (talk) 23:55, 1 January 2013 (UTC)

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