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Electrochemical Studies on New Chelating Compounds of the Mono‐ and Bis(imidazolyl)pyridine Type
Author(s) -
Mikysek Tomáš,
Švancara Ivan,
Bartoš Martin,
Vytřas Karel,
Drabina Pavel,
Sedlák Miloš,
Klíma Jiří,
Urban Jiří,
Ludvík Jiří
Publication year - 2007
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200703991
Subject(s) - coulometry , chemistry , pyridine , electrochemistry , chelation , protonation , electrolysis , diastereomer , ring (chemistry) , polarography , cyclic voltammetry , aqueous solution , medicinal chemistry , inorganic chemistry , electrode , organic chemistry , ion , electrolyte
Recently designed and synthetized mono‐imidazolinone (I and III) and bisimidazolinone (II and IV) chelating ligands were electrochemically characterized at mercury and carbon paste electrodes. Based on polarographic, voltammetric and coulometric investigations in buffered aqueous media, the general reduction pathway has been suggested. Reduction of the mono‐imidazolinone derivatives proceeds in acidic and neutral media in two two‐electron steps. In the first step, the 2,3‐CN double bond of the imidazolone ring is reduced yielding a mixture of two diastereoisomers (V and VI). In the second step, the 2,3‐CN single bond (in protonated form) is further reductively split and as the only final product the compound VII was formed. Both intermediates (V and VI) as well as the final product (VII) were prepared using controlled potential electrolysis on the first and second wave, respectively, isolated and identified by means of NMR. The reduction of bis‐derivatives proceeds most probably in an analogical way: in the first step, both imidazoles are reduced simultaneously at the same potential, whereas the following reduction (ring‐opening) proceeds stepwise. In the case of compound III, the covalent hydration of the parent compound takes place in acidic media, partially preventing its reduction. Finally, voltammetric behaviour of mono‐ and bisimidazolinones at carbon paste electrode is also discussed and, in prospect, possible electroanalytical applications outlined.