Electropolymerized Azines: Part II. In a Search of the Best Electrocatalyst of NADH Oxidation

Abstract

A comparative investigation of catalytic activity of different polyazines in NADH electrooxidation is reported. The structure of azine monomers taken for electropolymerization was varied systematically changing both the second heteroatom and the substituents of aromatic rings. It was found that the monomer structure affects catalytic activity of the resulting polymer in the following way: (i) additional substitution of benzene ring by alkyl group reduced the catalytic activity, (ii) polymerized phenoxazine Brilliant Cresyl Blue was a better electrocatalyst than the corresponding phenothiazine (o-Toluidine Blue), (iii) ring substitution with only tertiary nitrogen atoms as ligands provides higher catalytic activity, (iv) higher redox potential of the polymer also provides higher catalytic activity.

Amperometric Sensor for Detection of the Reduced Form of Nicotinamide Adenine Dinucleotide Using a Poly(pyronin B) Film Modified Electrode

“…. During the first anodic scan, an irreversible oxidation wave was observed at þ 1.0 V (Pa1) which can be assigned to the oxidation of tertiary amino group of PyB monomers [10,51]. In the first cathodic scan a cathodic peak at À 0.2 V (Pc1) was observed.…”

“…As shown in Figure 5 curve b, polymerized PyB film on GCE was performed as an excellent redox mediator for electrocatalytic oxidation of NADH in 0.1 M PBS. PyB monomers were able to form an electroactive polymer by anodic oxidation from acidic aqueous solutions similar to poly(methylene blue) nor poly(methylene green) [10,53]. The structure of poly(PyB) film might similar to the hypothetical structure proposed for poly(methylene blue).…”

“…Moreover, as polymerization occurs, more tertiary amine groups become nitrogen bridges and these bridges become electroactive similar to those in polyaniline and poly(thionine) films [54,55]. PyB monomers were able to form an electroactive polymer by anodic oxidation from acidic aqueous solutions similar to poly(methylene blue) nor poly(methylene green) since its chemical structure resembles with methylene blue and methylene green [10,52,53]. The structure of poly(PyB) film might similar to the hypothetical structure proposed for poly(methylene blue).…”

“…A new group of electroactive polymers known as polyazines have been extensively studied and reported for electrocatalytic oxidation of NADH [8,10]. Redox mediators with tertiary nitrogen atoms such as methylene blue, methylene green, oxazine 170, azure A etc.…”

“…Redox mediators with tertiary nitrogen atoms such as methylene blue, methylene green, oxazine 170, azure A etc. served as efficient electrocatalyst towards oxidation of NADH [10,53]. In the same way, PyB monomer structure resembles with azine monomers (Scheme 1).…”