title: Quantum-Chemical Design of Cryptand-like Ditopic Salt Binders.
abstract: Hartree-Fock, density functional, and MP2 methods are applied to the problem of designing neutral, bicyclic C3-symmetric cages incorporating interacting anion- and cation-binding sites which strongly bind NaCl as an ion contact pair. A large number of trial ligands L and their complexes L:NaCl are tested, with the focus on maximizing binding by (i) optimizing the cavity size and shape and (ii) varying the nature of the anion- and cation-binding functionalities. The corresponding complexes L:Cl(-) and L:Na(+) are also studied in some detail. An analysis of their structures and charge distributions helps to build a consistent picture of the requirements for a successful NaCl binding. The 'best' candidate ligand utilizes a tripodal triether-substituted amine N(CH2CH2OR-)3 to bind the sodium cation; three thiourea groups in a tripodal arrangement with a 1,3,5-trisubstituted benzyl spacer group {C6H3(CH2NHC [Formula: see text] XNH-)3 X=O,S} to bind chloride; and a -CH2CH2- spacer linking the two binding sites. A simple Quantitative Structure-Property analysis suggests that the binding cavity shape and size is near to the optimal one for this system.
authors.affiliation: School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia 5000, Australia, Faculty of Pharmacy, University of Sydney, Camperdown, New South Wales 2006, Australia, and Department of Chemistry, Cardiff University, Cardiff CF10 3TB, Wales, U.K.
authors.forename: Siân T
authors.initials: ST
authors.lastname: Howard
authors.affiliation: School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia 5000, Australia, Faculty of Pharmacy, University of Sydney, Camperdown, New South Wales 2006, Australia, and Department of Chemistry, Cardiff University, Cardiff CF10 3TB, Wales, U.K.
authors.forename: David E
authors.initials: DE
authors.lastname: Hibbs
authors.affiliation: School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia 5000, Australia, Faculty of Pharmacy, University of Sydney, Camperdown, New South Wales 2006, Australia, and Department of Chemistry, Cardiff University, Cardiff CF10 3TB, Wales, U.K.
authors.forename: Angelo J
authors.initials: AJ
authors.lastname: Amoroso
authors.affiliation: School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia 5000, Australia, Faculty of Pharmacy, University of Sydney, Camperdown, New South Wales 2006, Australia, and Department of Chemistry, Cardiff University, Cardiff CF10 3TB, Wales, U.K.
authors.forename: James A
authors.initials: JA
authors.lastname: Platts