Formation and proof of stable bi-, tri- and tetraradical polyanions during the electrochemical reduction of cone-polynitrocalix[4]arenes. An ESR-UV-vis spectroelectrochemical study

0431769 - ÚFCH JH 2015 RIV GB eng J - Journal Article
Liška, Alan - Rosenkranz, M. - Klíma, Jiří - Dunsch, L. - Lhoták, P. - Ludvík, Jiří
Formation and proof of stable bi-, tri- and tetraradical polyanions during the electrochemical reduction of cone-polynitrocalix[4]arenes. An ESR-UV-vis spectroelectrochemical study.
Electrochimica acta. Roč. 140, SEP 2014 (2014), s. 572-578. ISSN 0013-4686. E-ISSN 1873-3859
R&D Projects: GA ČR GA13-21704S
Institutional support: RVO:61388955
Keywords : cone-calix[4]arenes * electrochemical reduction * in-situ UV-vis and ESR spectroelectrochemistry
Subject RIV: CG - Electrochemistry
Impact factor: 4.504, year: 2014

The first intermediates of electrochemical reduction of nitro compounds in nonaqueous DMF are stable radical anions. In the series of mono-, di-, tri- and tetranitro calix[4]arenes each nitro group represents a reduction center, therefore the question about the spin state of intermediary anions arises. In this communication, the voltammetric and coulometric investigation of these compounds is performed together with the spectral measurements (ESR and UV-vis). The in-situ spectroelectrochemical approach proved that during reduction, in all polynitro radicalic intermediates the electrons remain unpaired and thus relatively stable mono-, di-, tri- and tetraradical mono-, di-, tri- and tetraanions, respectively, can be electrochemically generated in aprotic DMF from polynitrocalix[4]arenes. This finding confirms that the nitrophenyl units in polynitrocalix[4]arenes are completely independent and no mutual electronic communication takes place among them.
Permanent Link: http://hdl.handle.net/11104/0236336