Tetra-CMPO-Derivatives of Calix[4]arenes fixed in the 1,3-Alternate Conformation
Résumé
Calix[4]arene derivatives fixed in the 1,3-alternate conformation and substituted at one end by four carbamoylmethylphosphine oxide residues (=CMPO) were synthesized. Two CMPO groups are directly attached to the wide rim while the second pair is bound to the narrow rim via a tri- or tetramethylene spacer. Similar compounds, in which two CMPO groups at the wide rim are combined with two picolinamide groups or two ionisable carboxylic groups at the narrow rim were also prepared. Some of these calixarene derivatives were studied as extractants for lanthanides (La3+, Eu3+, Yb3+) and thorium (Th4+) from acidic solution to methylenechloride. For selected samples stability constants in methanol were determined by spectrophotometric titrations. Three compounds (1b', 13, 17) in the 1,3-alternate conformation were confirmed by a crystal structure. Two further crystal structures of similar intermediates in the cone conformation (18, 19) are also reported.
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