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Gold Electrodes Modified with 16H,18H-Dibenzo[c,l]-7,9-Dithia-16,18-Diazapentacene for Electrocatalytic Oxydation of NADH

Domenii publicaţii > Chimie + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: V. Rosca, L. Muresan, I. C. Popescu, C. Cristea and I. A. Silberg.

Editorial: Elsevier, Electrochemistry Communications, 3, p.439-445, 2001.

Rezumat:

16H, 18H-Dibenzo[c,l]-7,9-ditia-16,18-diazapentacenul (DDDP), un nou derivat de fenotiazina continand doua inele fenotiazinice condensate, se adsoarbe puternic pe aurul poliorientat ducand la un electrod modificat cu activitate electrocatalitica pentru oxidarea beta-nicotinamid adenin dinucleotidei (NADH). Masuratori de voltametrie ciclica, efectuate in solutii tampon apoase la diferite valori ale pH-ului, au permis sa se: (i) estimeze constantele heterogene standard de viteza (ks aprox. 1/s la pH 7.0) in domeniul de pH cuprins intre 4 si 8; (ii) demonstreze activitatea catalitica pentru oxidarea NADH a compusului supus cercetarilor. Constanta de viteza electrocatalitica de ordinul doi, ki, a fost evaluata cu ajutorul tehnicii electrodului disc rotitor (ki /[NADH]=0 5.0x10exp3/Ms la pH 7.0). Comportarea electrochimica si activitatea electrocatalitica a DDDP sunt influentate in chip marcant de interactia intramoleculara a celor doua inele fenotiazinice conjugate. Activitatea electrocatalitica a DDDP (acceptor de 1 electron si 1 proton) a fost atribuita capacitatii sale de a extrage rapid din NADH cel dintai electron si protonul. 16H, 18H-Dibenzo[c,l]-7,9-dithia-16,18-diazapentacene (DDDP), a new phenothiazine derivative containing two linearly condensed phenothiazine rings, strongly adsorbs on polyoriented gold resulting in a modified electrode with electrocatalytic activity for beta-nicotinamide adenine dinucleotide (NADH) oxidation. Cyclic voltammetry measurements, performed in aqueous buffer solutions at different pH values, allowed to: (i) estimate the standard heterogeneous rate constants (ks approx. 1/s at pH 7.0) in the pH range between 4 and 8; (ii) demonstrate the electrocatalytic activity of the investigated compound for NADH oxidation. The second-order electrocatalytic rate constant, ki, was evaluated from the rotating disk electrode technique (ki /[NADH]=0 5.0x10exp3/Ms at pH 7.0). The electrochemical behaviour and electrocatalytic activity of DDDP are markedly influenced by the intramolecular interaction between the two conjugate phenothiazine rings. The electrocatalytic activity of DDDP (1 electron, 1 proton acceptor) was assigned to its ability to extract rapidly from NADH the first electron and the proton.

Cuvinte cheie: electrozi modificati, derivat de fenotiazina, radicali liberi, oxidarea electrocatalitica a NADH // modified electrodes, phenothiazine derivative, free radicals, NADH electrocatalytic oxidation