Naslov
Chiroptical Redox Switching of Tetra‐Cationic Derivatives of Azoniahelicenes

Autori
Rončević, Igor ; Jirásek, Michael ; Severa, Lukáš ; Reyes‐Gutierrez, Paul Eduardo ; Teplý, Filip ; Bednárová, Lucie ; Hromadová, Magdaléna ; Pospíšil, Lubomír

Izvornik
ChemElectroChem (2196-0216) 00 (2019), 00; 2196-0216, 9

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
helquats ; ECD ; DFT

Sažetak
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 α or γ 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 γ position yields a folded structure, which favours the internal donor‐ acceptor interaction. This explains the spectroelectrochemical differences between both tetra‐cations.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA