Size Dependence of [n]Cycloparaphenylenes (n=5-12) in Electrochemical Oxidation

Eiichi Kayahara; Kei Fukayama; Tohru Nishinaga; Shigeru Yamago

doi:10.1002/asia.201600582

Size Dependence of [n]Cycloparaphenylenes (n=5-12) in Electrochemical Oxidation

Chem Asian J. 2016 Jun 21;11(12):1793-7. doi: 10.1002/asia.201600582. Epub 2016 Jun 2.

Authors

Eiichi Kayahara^{1

2}, Kei Fukayama¹, Tohru Nishinaga³, Shigeru Yamago^{4

5}

Affiliations

¹ Institute for Chemical Research, Kyoto University, Kyoto, 611 0011, Japan.
² Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo, Japan.
³ Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan.
⁴ Institute for Chemical Research, Kyoto University, Kyoto, 611 0011, Japan. yamago@scl.kyoto-u.ac.jp.
⁵ Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo, Japan. yamago@scl.kyoto-u.ac.jp.

PMID: 27137132
DOI: 10.1002/asia.201600582

Abstract

The oxidation processes of [n]cycloparaphenylenes ([n]CPPs) (n=5-12) were systematically investigated by cyclic and rotating disk electrode voltammetry. All CPPs underwent pseudo-reversible two-electron oxidation irrespective of ring size, forming the corresponding radical cations and then dications. The results were in sharp contrast to those observed for linear oligoparaphenylenes, which only undergo one-electron oxidation. The difference in the first and second oxidation potentials in the CPP oxidation was affected by the ring size and became more significant as the decrease of CPP size. In other words, while the first oxidation from neutral CPP to the radical cation occurred faster as the size of CPP becomes smaller, the second oxidation from the radical cation to dication exhibited opposite size dependence.

Keywords: cyclic voltammetry; cycloparaphenylenes; electrochemistry; oxidation; rotating disk electrode.