Calixarene hosts, complexation with, positive

Fig. 4 Positive heterotropic allosteric regulation of complexation with calixarene hosts. Entry 12 Reprinted from Ref. [23]. Copyright 1998. with permission from Elsevier Entry 13 Reprinted with permission from Ref. [5]. Copyright 2001 by American Chemical Society Entry 14 Reprinted from Ref. [24]. Copyright 2000, with permission from Elsevier.

The positive charge on the cobaltocenium ion makes it an excellent guest for water-soluble, anionic cahx[6]arene hosts. Specifically, the hexasulfonatocalix[6]arene (1 ), with its structure given in Scheme 3, was shown to bind two Cob" ions on the equivalent binding sites indicated by the arrows. Therefore, one can think of an aqueous solution containing cobaltocenium, and the two hosts, P-CD and calixarene as a redox-switchable system in which, initially, two Cob" ions form a 2 1 complex with... 

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