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Endo-Complexation of Alkylammonium Ions by Calixarene Cavity: Facilitating Cation−π Interactions through the Weakly Coordinating Anion Approach
- Talotta, Carmen, Gaeta, Carmine, Neri, Placido
- Journal of organic chemistry 2014 v.79 no.20 pp. 9842-9846
- aromatic hydrocarbons, borates, hydrogen bonding, organic chemistry, receptors
- Notwithstanding its small dimensions, the narrow cavity of p-tert-butylcalixarene macrocycle is still able to host alkylammonium guests in the presence of the tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (TFPB–) weakly coordinating (or “superweak”) anion. As an artificial analogue of biological receptors, cone-shaped calixarene 1d is able to recognize a n-BuNH₃⁺ guest mainly through a 4-fold cation−π interaction aided by a weak H-bonding interaction. This recognition motif can be used to assembly a 2:1 capsular architecture with a linear diammonium axle.