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Selective Complexation and Membrane Transport of Guanidinium Salts by Calix[6]arene Amides
Author(s) -
Casnati Alessandro,
Minari Patrizia,
Pochini Andrea,
Ungaro Rocco,
Nijenhuis Wilma F.,
De Jong Feike,
Reinhoudt David N.
Publication year - 1992
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.199200011
Subject(s) - chemistry , picrate , calixarene , membrane , alkali metal , ether , nuclear magnetic resonance spectroscopy , medicinal chemistry , stereochemistry , organic chemistry , molecule , ion , biochemistry
The p‐tert ‐butylcalix[6]arene hexamide 2 and syn ‐1,3,5–trimethoxy‐2,4,6‐triamide 4 were synthesized by reaction of α‐chloro‐ N,N ‐diethylacetamide and the corresponding calix[6]arenes 1 and 3 , respectively. 1 H NMR spectroscopy shows that 2 is a mixture of different conformations whereas 4 is fixed in a cone conformation. Extraction experiments, (S‐L) and (H 2 O–CDCl 3 ) with picrate salts, indicate that 2 complexes both alkali metal (1:2 complex) and guanidinium salts (1:1 complex) but 4 complexes only guanidinium (1:1 complex). Incorporated in supported liquid membranes (Accurel ® / o ‐nitrophenyl n ‐octyl ether) the calixarenes 2 and 4 transport guanidinium salts. The hexamide 2 is a more efficient carrier of guanidinium but the syn ‐1,3,5‐trimethoxy‐2,4,6‐triamide 4 is much more selective. Both 2 and 4 are sufficiently lipophilic to give membranes that are stable over longer periods (weeks).