Refereed journal article or data article (A1)

Charged states in diphenylamino endcapped thiophenes with a 1,4-phenylene core – In situ electron spin resonance/ultraviolet-visible-near infrared and nuclear magnetic resonance spectroelectrochemistry and quantum chemical study




Subtitle: In situ electron spin resonance/ultraviolet-visible-near infrared and nuclear magnetic resonance spectroelectrochemistry and quantum chemical study

List of Authors: Peter Rapta, Kinga Haubner, Peter Machata, Vladimír Lukes, Marco Rosenkranz, Sandra Schiemenz, Sabrina Klod, Henri Kivelä, Carita Kvarnström, Horst Hartmann, Lothar Dunsch

Publisher: PERGAMON-ELSEVIER SCIENCE LTD

Publication year: 2013

Journal: Electrochimica Acta

Journal name in source: ELECTROCHIMICA ACTA

Journal acronym: ELECTROCHIM ACTA

Volume number: 110

Number of pages: 11

ISSN: 0013-4686

DOI: http://dx.doi.org/10.1016/j.electacta.2013.02.006


Abstract
The three diphenylamino-endcapped thiophene compounds 1,4-bis-(2-diphenylaminothiophen-5-y1)-benzene (A), 1,4-bis-[2-(phenothiazin-10-yl)-thiophen-5-yl]-benzene (B), and 1,4-bis-(5-diphenylamino-[2,2']bithiophen-5'-yl)-benzene (C) with a central phenylene core were investigated by in situ ESR/UV-vis-NIR and in situ NMR spectroelectrochemistry and quantum chemical studies. The computed vertical ionization potentials are 4.85 eV for A, 5.39 eV for B and 4.80 eV for C while the adiabatic ionization potentials are slightly lower 4.45 eV (for A), 4.96 eV (for B) and 4.47 eV (for C). The minimal difference between computed ionization potentials of A and C and the lower oxidation ability of B are in good agreement with the experimental electrochemical findings with the first half-wave anodic potentials 0.69V (for A), 0.81 V (for B) and 0.67 V (for C), all vs. decamethylferrocene (DmFc(+)/DmFc). For the radical monocations A(center dot+) and C center dot+ the spin delocalisation on the central phenylene moiety was confirmed both experimentally and by theoretical calculations. For the radical cation B center dot+, the presence of a phenothiazinyl moiety is responsible for the delocalization of unpaired electron in the lateral part of this molecule. The stability of the charged states was increased substantially by the incorporation of two further 2,5-thienylene moieties between the central moiety and the side groups in C. Detailed spectroelectrochemical studies of the cation radical, dication, trication and tetracation of C are in good agreement with the calculated electronic transitions and experimental values for all redox states. In situ NMR spectroelectrochemical studies at different temperatures indicate dirnerisation reactions of charged 1,4-bis-(5-diphenylamino-[2,2']bithiophen-5'-yl)-benzenes.


Last updated on 2021-24-06 at 11:55