Calix[4]pyrrole dimers bearing rigid spacers: towards the synthesis of cooperative anion binding agents
Calix[4]pyrrole dimers ( 2, 5, and 6), potential hosts for anionic guests, were synthesized by a procedure involving a palladium(0) catalyzed C–C bond formation process. In the case of 2, a dimer linked via a rigid di-ethynyl spacer, a detailed study of carboxylate anion binding was carried out usin...
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Published in | Tetrahedron letters Vol. 41; no. 35; pp. 6731 - 6736 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
OXFORD
Elsevier Ltd
26.08.2000
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | Calix[4]pyrrole dimers (
2,
5, and
6), potential hosts for anionic guests, were synthesized by a procedure involving a palladium(0) catalyzed C–C bond formation process. In the case of
2, a dimer linked via a rigid di-ethynyl spacer, a detailed study of carboxylate anion binding was carried out using
1H NMR spectroscopy. For isophthalate anion, a 1:1 binding stoichometry was observed with this receptor and a much higher association constant was found than for the control monomer, octamethylcalix[4]pyrrole. These findings are ascribed to cooperative binding. Consistent with this conclusion was the finding that, for phthalate and benzoate anions, 1:2 (host:guest) binding stoichometries and lower association constants were recorded than with isophthalate anion. The control compound, octamethylcalix[4]pyrrole, showed a 1:1 binding stoichometry and a much lower association constant than dimer
2, not just with isophthalate but also phthalate and benzoate anions. |
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ISSN: | 0040-4039 1873-3581 |
DOI: | 10.1016/S0040-4039(00)01105-9 |