Anion binding by a tetradipicolylamine-substituted resorcinarene cavitand.
Inorg Chem
; 44(12): 4295-300, 2005 Jun 13.
Article
em En
| MEDLINE
| ID: mdl-15934759
ABSTRACT
Anion binding has been achieved with a resorcinarene substituted with four 2,2'-dipicolylamine moieties on the upper rim. The four dipicolylamine groups reside in proximity on one rim of the cavitand. The dipicolylamine groups were protonated with triflic acid to provide the cationic ammonium sites for anion binding. This anion receptor binds strongly to anions of different geometries, such as H(2)PO(4)(-), Cl(-), F(-), CH(3)CO(2)(-), HSO(4)(-), and NO(3)(-). The association constants for binding these anions are large, on the order of log K = 5 in CD(3)CN, a solvent of intermediate dielectric constant. These values represent significant binding compared to other cavitands with nitrogen pendant groups. Evidence suggests that the cavitand provides two identical receptor sites formed by two dipicolylamine groups, facilitating the simultaneous binding of two anions. Intramolecular binding of anions between two protonated dipicolylamine groups is indicated on the basis of the comparison to a structurally similar monomeric analogue and by semiempirical PM3 molecular modeling. Titrations with the analogue result in much weaker anion association, even at high concentrations, indicating the importance of proximity and preorganization of sites on the cavitand upper rim.
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Base de dados:
MEDLINE
Assunto principal:
Fenilalanina
/
Picolinas
/
Resorcinóis
/
Modelos Moleculares
/
Éteres Cíclicos
Idioma:
En
Revista:
Inorg Chem
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Estados Unidos