Chapter 7: Cucurbituril Complexes of Redox Active Guests
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Published:05 Nov 2019
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Special Collection: 2019 ebook collection
A. E. Kaifer, in Cucurbiturils and Related Macrocycles, ed. K. Kim, The Royal Society of Chemistry, 2019, ch. 7, pp. 150-174.
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This chapter focuses on non-covalent complexes formed by cucurbituril hosts with redox active guests, defined as molecules containing a residue capable of reversible electron transfer at accessible potentials. Primarily, we will be concerned with cobaltocenium, ferrocene and viologen derivatives as guests, and cucurbit[7]uril (CB[7]) and cucurbit[8]uril (CB[8]) as the hosts. In general terms, all the resulting complexes are quite stable, with binding affinities from micromolar to femtomolar levels. The elevated thermodynamic stability of these complexes makes it hard to develop redox switchable supramolecular systems based on these complexation phenomena, but we have designed and characterized several systems in which effective redox switching is possible, either on its own or coupled to proton transfer. Considerable attention will be paid to the complexation-induced changes in electrochemical potentials and kinetics in these supramolecular systems.