title: Highly negative homotropic allosteric binding of viologens in a double-cavity porphyrin.
abstract: The synthesis of a double-cavity porphyrin with interesting allosteric binding properties toward viologens (N,N'-disubstituted 4,4'-bipyridines) is described. The porphyrin host forms very strong 1:2 complexes with viologens, displaying a negative allosteric behavior. The first viologen guest binds exceptionally tight (K > 107 M-1), and the second guest binds much more weakly (DeltaDeltaG = 9-15 kJ mol-1). The allosteric effect, one of the highest reported so far, originates in structural changes upon binding the first ligand, closely following the sequential (or induced-fit) theory of allosteric interactions by Koshland, Némethy, and Filmer (the KNF-model).
authors.affiliation: Department of Organic Chemistry, NSRIM, University of Nijmegen, Toernooiveld 1, 6525 ED, Nijmegen, The Netherlands.
authors.forename: Pall
authors.initials: P
authors.lastname: Thordarson
authors.forename: Edward J A
authors.initials: EJ
authors.lastname: Bijsterveld
authors.forename: Johannes A A W
authors.initials: JA
authors.lastname: Elemans
authors.forename: Peter
authors.initials: P
authors.lastname: Kasák
authors.forename: Roeland J M
authors.initials: RJ
authors.lastname: Nolte
authors.forename: Alan E
authors.initials: AE
authors.lastname: Rowan
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011166:Porphyrins / Q000138:chemical synthesis / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D014755:Viologens / Q000737:chemistry*
chemical_list: D011166:Porphyrins; D014755:Viologens