title: Accurate method to quantify binding in supramolecular chemistry.
abstract: An approach for accurate and comparable measurement of host-guest binding affinities is introduced whereby differences in binding strength (ΔlogKass values) are measured between two host molecules toward a particular guest under identical solvent conditions. Measuring differences instead of absolute values enables obtaining highly accurate results, because many of the uncertainty sources (the solvation/association state of the guest in solution, deviations in solvent composition, etc.) cancel out. As a proof of concept, this method was applied to the measurement of the binding strength of 28 synthetic anion receptors toward acetate in acetonitrile containing 0.5% water. The receptors included differently substituted indolocarbazoles, ureas, thioureas, and some others. Possible deprotonation of more acidic receptors of each compound class by acetate was checked by measuring their acidities (ΔpKa values) relative to acetic acid in the same solvent. A self-consistent (consistency standard deviation 0.04 log units) binding affinity scale ranging for around 2.7 log units was constructed from the results. Absolute logKass values were found by anchoring the scale to the absolute logKass values of two receptor molecules, determined independently by direct measurements. This new approach is expected to find use in accurate quantification of a wide range of binding processes relevant to supramolecular chemistry.
authors.affiliation: Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia.
authors.forename: Kristjan
authors.initials: K
authors.lastname: Haav
authors.forename: Sandip A
authors.initials: SA
authors.lastname: Kadam
authors.forename: Lauri
authors.initials: L
authors.lastname: Toom
authors.forename: Philip A
authors.initials: PA
authors.lastname: Gale
authors.forename: Nathalie
authors.initials: N
authors.lastname: Busschaert
authors.forename: Marco
authors.initials: M
authors.lastname: Wenzel
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Hiscock
authors.forename: Isabelle L
authors.initials: IL
authors.lastname: Kirby
authors.forename: Tõiv
authors.initials: T
authors.lastname: Haljasorg
authors.forename: Märt
authors.initials: M
authors.lastname: Lõkov
authors.forename: Ivo
authors.initials: I
authors.lastname: Leito
mesh_terms: D001665:Binding Sites; D002227:Carbazoles / Q000138:chemical synthesis / Q000737:chemistry*; D007211:Indoles / Q000138:chemical synthesis / Q000737:chemistry*; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry*; D015394:Molecular Structure; D014508:Urea / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D002227:Carbazoles; D007211:Indoles; D046911:Macromolecular Substances; D014508:Urea