Self-complementary Tetracationic Cyclophanes Containing 4,4′-Bipyridinium and 2,5-Dimethoxy-1,4-xylyl Subunits

Abstract

4,4′-Bipyridinium-based tetracationic cyclophanes containing a 2,5-dimethoxy-1,4-xylyl unit were synthesized by using either m-terphenyl building blocks or incorporating a 4-hydroxy benzyl spacer between the complementary subunits. The cyclophanes show weak intramolecular charge-transfer (CT) bands in the visible region and one of the cyclophanes formed a green-coloured CT complex with ferrocene with an association constant (K _a) of 6.3 M⁻¹. The electrochemical parameters obtained for the cyclophanes indicate that all the redox processes are reversible.

Keywords:

• Self-complementary cyclophanes
• 4,4′-Bipyridine
• 2,5-Dimethoxy-1,4-xylyl
• m-Terphenyl
• Redox potentials

Acknowledgements

K.S. thanks CSIR, India, for financial support. The authors thank SAIF, Madras, for NMR spectra and MALDI-TOF MS, and RSIC, Lucknow, for FAB-MS.