One electron vs. two electron electrochemical and chemical oxidation of electron-donor substituted diketo-pyrrolo-pyrroles

0394518 - ÚFCH JH 2014 RIV GB eng J - Journal Article
Luňák jr., S. - Eliáš, Z. - Mikysek, T. - Vyňuchal, J. - Ludvík, Jiří
One electron vs. two electron electrochemical and chemical oxidation of electron-donor substituted diketo-pyrrolo-pyrroles.
Electrochimica acta. Roč. 106, SEP 2013 (2013), s. 351-359. ISSN 0013-4686. E-ISSN 1873-3859
Grant - others:GA ČR(CZ) CZ.1.07/2.3.00/30.0021
Institutional support: RVO:61388955
Keywords : Diketo-pyrrolo-pyrroles * electrochemistry * Absorption spectra
Subject RIV: CG - Electrochemistry
Impact factor: 4.086, year: 2013

Electrochemical and chemical (using FeCl3) oxidation reactions of a series of eight N,N -dialkylated soluble diketo-pyrrolo-pyrrole dyes (DPPs) substituted by electron donating and/or electron withdrawing groups were investigated electrochemically and by UV–vis spectrometry and the results were rationalized by DFT calculations. Influence of substituents on HOMO and LUMO energies as well as on the electron transfer mechanism was followed. Destabilization of HOMO by two piperidino-substituents in 3,6-diphenyl-DPP 5 enabled to observe a potential inversion in electrochemical oxidation of this derivative, when a twoelectron oxidation occurs leading directly to a dication, whereas other DPPs are oxidized first in a oneelectron transfer to a radical cation. In chemical oxidation with FeCl3 the radical cation is produced by two mechanisms: either directly (standard reaction) or in the case of 5 by a comproportionation reaction of neutral molecule and its dication. Using mutual comparison of oxidation potentials and HOMO/LUMO energies a quite realistic limit of FeCl3 oxidation ability in acetonitrile was found.
Permanent Link: http://hdl.handle.net/11104/0222746