Collect. Czech. Chem. Commun.
2004, 69, 1345-1361
https://doi.org/10.1135/cccc20041345
Doubly Bridged Calix[8]crowns
Corrada Geracia,*, Grazia M. L. Consolia, Mario Piattellia and Placido Nerib,*
a Istituto di Chimica Biomolecolare, Sezione di Catania, C.N.R., Via del Santuario 110, I-95028 Valverde (CT), Italy
b Dipartimento di Chimica, Università di Salerno, Via S. Allende, I-84081 Baronissi (SA), Italy
Abstract
Biscrowned calix[8]arenes were obtained by alkylation of p-tert-butylcalix[8]arene or calix[8]monocrowns with triethylene glycol ditosylate, in the presence of various bases. Of the 22 possible isomers, 1,4:2,5-, 1,3:2,5-, 1,4:2,3-, 1,4:5,8-, and 1,2:3,4-calix[8]biscrown-4 (3-7) were isolated in 7-30% yields. The presence of two crown bridges in 1,3:2,5- and 1,4:2,5-biscrown-4 (4, 5) leads to a significant rigidness of the calix[8]arene macrocycle and implies inherent chirality. The increased preorganization of calix[8]biscrowns, with respect to monocrowns, leads to significant complexing abilities for alkali cations with a marked preference for Cs+ over Na+.
Keywords: Calixarenes; Calix[8]arenes; Conformation analysis; Complexation; Crown ethers; Host-guest chemistry; Inherent chirality; Intramolecular bridging.
References: 62 live references.
