Chiroptical Redox Switching of Tetra-Cationic Derivatives of Azoniahelicenes

0511906 - ÚFCH JH 2020 RIV DE eng J - Článek v odborném periodiku
Rončević, I. - Jirásek, M. - Severa, L. - Reyes-Gutierrez, P. E. - Teplý, F. - Bednárová, L. - Hromadová, Magdaléna - Pospíšil, Lubomír
Chiroptical Redox Switching of Tetra-Cationic Derivatives of Azoniahelicenes.
ChemElectroChem. Roč. 6, č. 12 (2019), s. 3002-3008. ISSN 2196-0216. E-ISSN 2196-0216
Grant CEP: GA ČR(CZ) GA18-04682S
Grant ostatní: GA MŠk(CZ) LM2015042
Institucionální podpora: RVO:61388955
Klíčová slova: electronic circular-dichroism * polarized luminescence * complex-formation * viologen * helquats * recognition * reduction * spectra * helquats
Obor OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis)
Impakt faktor: 4.154, rok: 2019
Způsob publikování: Omezený přístup

New tetra- and di-cationic azoniahelicenes provide electrochemical, spectroelectrochemical and electronic circular dichroism (ECD) data reflecting their differences in electron transfer (ET) kinetics. Di-cationic helquats containing two seven-membered rings are irreversibly reduced in two ET steps. Substitution by redox-active ethenylpyridinium in the alpha or gamma position with respect to nitrogen atoms of the helquat core yields tetra-cationic derivatives with reversible ET steps and communicating redox centres. Redox-inactive substituents in di-cationic azoniahelicenes retain ET irreversibility. Redox switching of ECD of tetra-cationic enantiomers was observed. Unlike fully aromatic helquat, the ECD response of tetra-cationic helquats to periodic reduction-oxidation cycles is slower, owing to a strong adsorption on electrodes. Quantum chemical calculations (DFT) indicate that the first ET step of tetra-cationic derivative substituted in the gamma position yields a folded structure, which favours the internal donor-acceptor interaction. This explains the spectroelectrochemical differences between both tetra-cations.
Trvalý link: http://hdl.handle.net/11104/0302143