Inclusion of methylviologen in cucurbit[7]uril.
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].
Kim
Hee-Joon
HJ
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.
Jeon
Woo Sung
WS
Ko
Young Ho
YH
Kim
Kimoon
K
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
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