Electrochemical polymerization of azure A and properties of poly(azure A)

Abstract

ABSTRACT:The electrochemical polymerization of azure A has been carried out using repeated potential cycling. The scan potential is set between Ϫ0.2 and 1.3 V (vs. Ag/AgCl). The electrolytic solution consisted of 5 mmol dm Ϫ3 azure A and 0.5 mol dm Ϫ3 Na 2 SO 4 with pH 6.0. The temperature for polymerization was controlled at 50°C. An anodic peak and a cathodic peak appear at 0.38 and 0.23 V, respectively, on the cyclic voltammogram of poly(azure A) in 0.5 mol dm Ϫ3Na 2 SO 4 solution of pH 1.0. Their peak potentials shift toward the negative direction as pH value increases from 1.0 to 4.0. Poly(azure A) has good electrochemical activity and stability in the aqueous solution at the above pH range. The UV-visible spectrum and FTIR spectrum of poly(azure A) are different from those of azure A. The FTIR spectrum of poly(azure A) indicates that no anions were doped into the oxidation form of poly(azure A).

Chronoamperometric and morphological investigation of nucleation and growth mechanism of poly(azure A) thin films

“…By reversing the potential into positive direction, an oxidative peak is obtained at À150 mV. This pair of redox peaks corresponds to the reduction and oxidation of AA monomer species in the solution, respectively [22,24,27]. If potential of the working electrode is scanned through more positive region, current density starts to increase after approximately +750 mV and is attributed to oxidation of AA.…”

“…If potential of the working electrode is scanned through more positive region, current density starts to increase after approximately +750 mV and is attributed to oxidation of AA. At the potential values more positive than +750 mV, radical cations of AA molecules are formed and electropolymerization of AA occurs on the electrode surface [22,24,27]. As a result of electropolymerization process and formation of poly(AA) film, a new anodic peak arises after the first scan at about +50 mV and the current density of this new peak gradually increases with increasing number of potential scan.…”

“…Schlereth et al also reported that poly(AA) film is one of the best catalysts among 10 dye polymers [10]. Mu et al found that poly(AA) films have a good electrochemical activity in the pH range of 1.0-4.0 [24]. Yang et al studied the poly(AA) films for NADH sensor system and determined that detection limit of poly(AA) films for NADH is about 2 Â 10 À7 M [22].…”

Nucleation and Growth Mechanism of Electropolymerization of Methylene Blue: The Effect of Preparation Potential on Poly(methylene blue) Structure

“…Polymer thin films of different phenothiazine derivatives, e.g. azure A [7][8][9]18], azure B [10,11], and thionine [12,13,15], have been prepared by using the electropolymerization technique until now. Electropolymerization of MB has been under study [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] and poly(MB) thin films have been investigated for glucose [14,20], oxygen [27], NADH [16,20,22], and haemoglobin [24] sensors.…”

Poly(neutral red): Electrosynthesis, Characterization, and Application as a Redox Mediator

“…1), is used for a variety of purposes such as biological staining [2], for medical purposes to investigate viruses [3], as a pH indicator in biochemical systems [4], in the determination of DNA using optical and electrochemical methods [5,6], for the evaluation of naturally-derived and synthetic biomaterials [7,8], for the development of optical sensors [9], etc. Like other phenazine derivatives, in particular azur A [10], azur B [11], toluidine blue O [12], methylene blue [13], methylene green [14], phenosafranin [15], NR can be polymerized electrochemically and form a conductive polymer [16 -21]. Recently, polymerized NR or poly(neutral red) (PNR) has been used as a redox mediator for sensors and biosensors [21 -24].…”