Electron Transfer Mechanism of Substituted Benzimidazoles: Dimer Switching, Oscillations, and Search for Singlet Fission Properties

• Published in: Journal of physical chemistry. C Vol. 121; no. 18; pp. 9963 - 9969
• Main Authors: Plutnar, Jan, Hromadová, Magdaléna, Fanelli, Nicolangelo, Ramešová, Šárka, Havlas, Zdeněk, Pospíšil, Lubomír
• Format: Journal Article
• Language: English
• Published: American Chemical Society 11.05.2017
• Subjects: benzimidazoles; cations; dimerization; electrochemistry; electron transfer; oxidation; physical chemistry
• ISSN: 1932-7447; 1932-7455; 1932-7455
• DOI: 10.1021/acs.jpcc.7b02028

Reduction and oxidation of 4,7-dimethyl-1,3-dimethoxybenzimidazolium cation (1) and the related dihydroxy analogue (2) were investigated by electrochemical and in situ spectroelectrochemical methods. Quantum chemical methods were applied to UV–vis spectra in native, reduced, and oxidized forms. Compounds were searched for possible formation of a cation radical and a dication radical suitable for the singlet fission effect. Indeed 1 yields by oxidation the target quinoidal structure. However, the reduction step for both compounds is coupled with very fast dimerization and prevents obtaining a stable target form. The complex mechanism of the reduction process yields electrochemical current oscillation. Estimation of the maximum Ljapunov exponent proves characteristics of the deterministic chaos.