title: Inclusion of methylviologen in cucurbit[7]uril.
abstract: The inclusion behavior of methylviologen (N,N'-dimethyl-4,4'-bipyridinium, MV) dication in cucurbit[7]uril (CB[7]) has been studied by using various spectroscopic and electrochemical methods. The inclusion complex of MV dication in CB[7] is stable thermodynamically and kinetically. The electrochemical study reveals that unlike beta-cyclodextrin, CB[7] prefers the charged species, MV dication (MV(2+)), and cation radical (MV(+)*) to the fully reduced neutral (MV(0) species as guests. Dimerization of MV(+)* is suppressed effectively by forming a stable complex with CB[7] in aqueous solution as confirmed by spectroelectrochemical experiments. Furthermore, the first redox process (MV(2+)/MV(+)*) of the MV(2+)-CB[7] complex occurs predominantly via the direct electron transfer pathway, whereas the second redox process (MV(+)*/MV(0)) occurs via both the direct and indirect pathway because of the low affinity of the fully reduced species MV(0) to CB[7].
authors.affiliation: National Creative Research Initiative Center for Smart Supramolecules, and Department of Chemistry, Division of Molecular and Life Sciences, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784, Republic of Korea.
authors.forename: Hee-Joon
authors.initials: HJ
authors.lastname: Kim
authors.forename: Woo Sung
authors.initials: WS
authors.lastname: Jeon
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Ko
authors.forename: Kimoon
authors.initials: K
authors.lastname: Kim
mesh_terms: D001952:Bridged-Ring Compounds / Q000737:chemistry*; D002151:Calorimetry; D002412:Cations; D002942:Circular Dichroism; D003505:Cyclodextrins / Q000494:pharmacology; D004563:Electrochemistry; D004583:Electrons; D006540:Herbicides / Q000494:pharmacology; D007093:Imidazoles / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010269:Paraquat / Q000494:pharmacology*; D013053:Spectrophotometry; D013816:Thermodynamics; D047392:beta-Cyclodextrins; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D001952:Bridged-Ring Compounds; D002412:Cations; D003505:Cyclodextrins; D006540:Herbicides; D007093:Imidazoles; D010269:Paraquat; D047392:beta-Cyclodextrins; C456276:cucurbit(7)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils; C031215:betadex