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Conformational Features and Recognition Properties of a Conformationally Blocked Calix[7]arene Derivative
Author(s) -
Gaeta Carmine,
Talotta Carmen,
Farina Francesco,
Campi Gaetano,
Camalli Mercedes,
Neri Placido
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201102179
Subject(s) - derivative (finance) , chemistry , calixarene , alkyl , stereochemistry , alkylation , similarity (geometry) , crystallography , molecule , image (mathematics) , organic chemistry , artificial intelligence , computer science , financial economics , economics , catalysis
The shaping of a calix[7]arene macrocycle into cone‐like structure 3 , through exhaustive alkylation of doubly bridged calix[7]arene derivative 2 with bulky groups, has been investigated. Conformational details about the structure adopted by calix[7]arene derivative 3 in solution have been obtained by using chemical shift surface maps, as previously reported by our group. Thus, chemical shift contour plots indicated that 3 adopted a cone‐shaped structure in solution analogous to that adopted by the known p ‐ tert ‐butylcalix[7]arene heptacarboxylic acid derivative 4 . Interestingly, the X‐ray structure of derivative 3 showed a high degree of similarity to the theoretical structure, which confirmed the validity of the contour plots method. The preorganized calix[7]arene host 3 showed interesting recognition abilities toward both organic and alkali cations. In fact, an unprecedented endo ‐cavity complexation of linear and branched alkyl ammonium cations with a larger calix[7]arene host was evidenced. A comparable affinity for branched t BuNH 3 + and linear n BuNH 3 + guests was observed.