Anion binding modes in meso-substituted hexapyrrolic calix[4]pyrrole isomers.
J Am Chem Soc
; 136(4): 1520-5, 2014 Jan 29.
Article
em En
| MEDLINE
| ID: mdl-24392650
ABSTRACT
We report on the synthesis of a new receptor for anions, meso-substituted hexapyrrolic calix[4]pyrrole 1. The calix[4]pyrrole's core features two additional pyrrole side-arms suspended above or below the calix[4]pyrrole core. This hexapyrrolic calix[4]pyrrole 1 is formed as cis- and trans-configurational isomers, the structures of which have been determined by single crystal X-ray diffraction. The anion binding experiments revealed interesting difference in the binding mode The cis-1 isomer binds anions in a mixed binding mode featuring a combination of hydrogen bonding and anion-π interactions resulting in an unexpected strong binding. On the other hand, the trans-1 isomer displays only hydrogen bonding and lower affinity for anions. This is unexpected as one would assume both isomers to display the same binding modes. Overall, the titrations of 1 using UV spectrophotometry and NMR titrations by anions reveal that cis-isomer 1 displays higher affinity (10(5)-10(6) M(-1)) and cross-reactivity for anions, while the trans-isomer 1 shows a more selective response to anions. Such differences in binding mode in configurational isomers are so far unexplored and a feature deserving further study.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Porfirinas
/
Calixarenos
Idioma:
En
Revista:
J Am Chem Soc
Ano de publicação:
2014
Tipo de documento:
Article
País de afiliação:
Estados Unidos