dc.contributor.author |
Molina-Muriel, Ricardo |
dc.contributor.author |
Aragay, Gemma |
dc.contributor.author |
Escudero-Adán, Eduardo C. |
dc.contributor.author |
Ballester, Pablo |
dc.date.accessioned |
2019-04-02T11:31:07Z |
dc.date.available |
2019-10-16T02:45:06Z |
dc.date.issued |
2018-10-16 |
dc.identifier.uri |
http://hdl.handle.net/2072/352739 |
dc.format.extent |
13507 p. |
dc.language.iso |
eng |
dc.rights |
L'accés als continguts d'aquest document queda condicionat a l'acceptació de les condicions d'ús establertes per la següent llicència Creative Commons:http://creativecommons.org/licenses/by-nc-nd/4.0/ |
dc.source |
RECERCAT (Dipòsit de la Recerca de Catalunya) |
dc.subject.other |
54 |
dc.title |
Switching from Negative-Cooperativity to No-Cooperativity in the Binding of Ion-Pair Dimers by a Bis(calix[4]pyrrole) Macrocycle |
dc.type |
info:eu-repo/semantics/article |
dc.type |
info:eu-repo/semantics/acceptedVersion |
dc.embargo.terms |
12 mesos |
dc.identifier.doi |
10.1021/acs.joc.8b02449 |
dc.rights.accessLevel |
info:eu-repo/semantics/openAccess |
dc.description.abstract |
We report the synthesis of a macrocyclic receptor containing two di-meso-phenylcalix[4]pyrrole units linked by two triazole spacers. The 1,4-substitution of the 1,2,3-triazole spacers conveys different binding affinities to the two heteroditopic binding sites. These features make the receptor an ideal candidate to investigate allosteric cooperativity in the binding of ion-pair dimers. We probed the interaction of tetraalkylammonium salts (TBA·Cl, TBA·OCN, and MTOA·Cl) with the tetra-heterotopic macrocyclic receptor in chloroform solution using 1H NMR spectroscopic titration experiments. The results obtained show that, at millimolar concentration, the addition of 2 equiv of the salt to the receptor’s solution induced the quantitative pairwise binding of the ion-pairs. The 2:1 (ion-pair:receptor) complexes feature different binding geometries and binding cooperativities depending on the nature of the alkylammonium cation. The binding geometries assigned to the complexes of the ion-pair dimers in solution are fully supported by X-ray diffraction analyses of single crystals. The thermodynamic features of the binding processes (separate or concomitant formation of 1:1 and 2:1 complexes), derived from isothermal titration calorimetry (ITC) experiments, are rationalized by combining the different ion-pair binding modes of the salt dimers with the dissimilar electronic properties of the two nearby heteroditopic binding sites of the receptor. |