The synthesis of calix[6]arene crown ethers 3 and 4 has been accomplished for the first time by selective bridging of the parent macrocycles. The alkylation of 3 with alpha-chloro-N,N-diethyl acetamide produces a compound 6 whose conformational flexibility is strongly reduced and which assumes a cone conformation both in solution and in the solid state. Compound 6 represents a new type of ditopic receptor which binds tetramethylammonium cation in the polar region at the lower rim, showing an association constant K-a=750 M(-1) in CDCl3.
Bridged Calix[6]arenes in the Cone Conformation: New Receptors for Quaternary Ammonium Cations / Casnati, Alessandro; P., Jacopozzi; Pochini, Andrea; Ugozzoli, Franco; R., Cacciapaglia; L., Mandolini; Ungaro, Rocco. - In: TETRAHEDRON. - ISSN 0040-4020. - 51:(1995), pp. 591-598. [10.1016/0040-4020(94)00918-K]
Bridged Calix[6]arenes in the Cone Conformation: New Receptors for Quaternary Ammonium Cations
CASNATI, Alessandro;POCHINI, Andrea;UGOZZOLI, Franco;UNGARO, Rocco
1995-01-01
Abstract
The synthesis of calix[6]arene crown ethers 3 and 4 has been accomplished for the first time by selective bridging of the parent macrocycles. The alkylation of 3 with alpha-chloro-N,N-diethyl acetamide produces a compound 6 whose conformational flexibility is strongly reduced and which assumes a cone conformation both in solution and in the solid state. Compound 6 represents a new type of ditopic receptor which binds tetramethylammonium cation in the polar region at the lower rim, showing an association constant K-a=750 M(-1) in CDCl3.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
