Modulation of Reduction Potentials of Bis(pyridinium)alkane Dications through Encapsulation within Cucurbit[7]uril.

Supramolecular modulation of reduction potentials of two series of bis(pyridinium)alkane salts is described. Study of the encapsulation of bis(pyridinium)alkane guests within the CB[7] cavity revealed the critical influence of the linker length and the position of the heteroatom on the reduction potentials of encapsulated guests. CB[7] complexation of pyridinium salts induced reduction potential changes ranging between +50 and -430 mV. Noncovalent modulation of the electron-accepting ability of organic cations can be utilized in electron-transfer-initiated reactions.