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1,3‐Dialkoxycalix[4]arenecrowns‐6 in 1,3‐Alternate Conformation: Cesium‐Selective Ligands that Exploit Cation‐Arene Interactions
Author(s) -
Ungaro Rocco,
Casnati Alessandro,
Ugozzoli Franco,
Pochini Andrea,
Dozol JeanFrançois,
Hill Clement,
Rouquette Hélène
Publication year - 1994
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199415061
Subject(s) - caesium , chemistry , selectivity , ring (chemistry) , ether , crystallography , crown ether , crystal structure , ion , stereochemistry , inorganic chemistry , organic chemistry , catalysis
Exceptionally high selectivity for cesium ions (α(Cs/Na) > 33000) is displayed by calix[4]arenecrowns‐6 in the 1,3‐alternate conformation. They also remove 137 Cs quantitatively (>96%) from radioactive waste that is 1 M in HNO 3 . The complexation properties result from the simultaneous operation of several effects: the size of the crown ether ring, the polarity of the calix conformation, and the strength of the cation/π‐electron interactions. The latter interaction was evident in the X‐ray crystal structure of the cesium complex (shown on the right).