title: Cooperative binding of calix[4]pyrrole-anion complexes and alkylammonium cations in halogenated solvents.
abstract: Calix[4]pyrrole-chloride interactions are affected not only by the choice of countercation in halogenated solvents, but show a specific dependence on the way in which these cations are bound within the electron rich, bowl-like calix[4]pyrrole cavity formed upon chloride anion complexation. In dichloromethane, the affinities of simple meso-octamethylcalix[4]pyrrole (1) for methyl-, ethyl-, and n-butylammonium chlorides are on the order of 10(5), 10(4), and 10(2) M(-1), respectively, as determined from isothermal titration calorimetry (ITC) analyses. These cation-dependent anion affinity effects, while clearly evident, are less pronounced in other halogenated solvents, such as 1,2-dichloroethane. Support for the proposed cation complexation selectivity is provided by solid state X-ray crystallographic analyses.
authors.affiliation: Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Dustin E
authors.initials: DE
authors.lastname: Gross
authors.forename: Franz P
authors.initials: FP
authors.lastname: Schmidtchen
authors.forename: Wiebke
authors.initials: W
authors.lastname: Antonius
authors.forename: Philip A
authors.initials: PA
authors.lastname: Gale
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Lynch
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Sessler
mesh_terms: D000478:Alkylation; D047250:Calixarenes / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D018360:Crystallography, X-Ray; D054879:Halogenation; D008958:Models, Molecular; D015394:Molecular Structure; D011166:Porphyrins / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D017186:Titrimetry
chemical_list: D002412:Cations; D011166:Porphyrins; D000644:Quaternary Ammonium Compounds; D012997:Solvents; C469811:calix(4)pyrrole; D047250:Calixarenes