title: Aza-Bambusurils En Route to Anion Transporters.
abstract: Previous calculations of anion binding with various bambusuril analogs predicted that the replacement of oxygen by nitrogen atoms to produce semiaza-bambus[6]urils would award these new cavitands with multiple anion binding properties. This study validates the hypothesis by efficient synthesis, crystallography, thermogravimetric analysis and calorimetry. These unique host molecules are easily accessible from the corresponding semithio-bambusurils in a one-pot reaction, which converts a single anion receptor into a potential anion channel. Solid-state structures exhibit simultaneous accommodation of three anions, linearly positioned within the cavity along the main symmetry axis. The ability to hold anions at a short distance of about 4 Å is reminiscent of natural chloride channels in E. coli, which exhibit similar distances between their adjacent anion binding sites. The calculated transition-state energy for double-anion movement through the channel suggests that although these host-guest complexes are thermodynamically stable they enjoy high kinetic flexibility to render them efficient anion channels.
authors.affiliation: Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ra'anana, 43107, Israel.
authors.forename: Mandeep
authors.initials: M
authors.lastname: Singh
authors.affiliation: The Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Technion City, Haifa, 32000, Israel.
authors.forename: Ephrath
authors.initials: E
authors.lastname: Solel
authors.affiliation: The Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Technion City, Haifa, 32000, Israel. keinan@technion.ac.il.|Guangdong Technion Israel Institute of Technology and Department of Chemistry, Shantou University, Guangdong, 515063, P. R. China. keinan@technion.ac.il.
authors.forename: Ehud
authors.initials: E
authors.lastname: Keinan
authors.affiliation: Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ra'anana, 43107, Israel. oferre@openu.ac.il.
authors.forename: Ofer
authors.identifier: http://orcid.org/0000-0003-1048-1947
authors.initials: O
authors.lastname: Reany
mesh_terms: D000480:Alkynes / Q000737:chemistry; D000838:Anions / Q000737:chemistry; D001372:Aza Compounds / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D002151:Calorimetry; D018118:Chloride Channels / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D004055:Differential Thermal Analysis; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D004988:Ethers, Cyclic / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D047028:Macrocyclic Compounds / Q000737:chemistry* / Q000378:metabolism; D008968:Molecular Conformation; D012118:Resorcinols / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics; D013818:Thermogravimetry; D006574:Heterocyclic Compounds, 2-Ring; D048289:Imidazolidines
chemical_list: D000480:Alkynes; D000838:Anions; D001372:Aza Compounds; D018118:Chloride Channels; D029968:Escherichia coli Proteins; D004988:Ethers, Cyclic; D007093:Imidazoles; D047028:Macrocyclic Compounds; D012118:Resorcinols; C569684:bambus(6)uril; C442939:cavitand; C092018:glycoluril; D006574:Heterocyclic Compounds, 2-Ring; D048289:Imidazolidines
keywords: anion transporters; bambusuril; cavitands; glycoluril; host-guest interactions