Electrosynthesis of poly(o-phenylenediamine) in ionic liquid and its properties

Abstract

Ionic liquid 1-ethyl-3-methylimidazolium bromide ([EMIM]Br) and N-methylimidazolium tetrafluoroborate ([HMIM]BF 4 ) have been used as solvent and electrolyte for the electropolymerization ofo-phenylenediamine at glassy carbon electrode by cyclic voltammetry. It was found that monomer was more easily oxidized in ionic liquid than acidic aqueous solution, and oxidative potential was reduced by 0.725 and 0.455 V, respectively. Electrode modified with poly(o-phenylenediamine) (PPD) has obvious electrochemical activity in acid solution (pH 1-4). The apparent diffusion coefficient (D app ) of PPD film is measured by chronocoulometry and chronoamperometry. The polymer structure is measured by UV and IR. IR spectrometry reveals that poly(o-phenylenediamine) has phenazine ring structure. The heat stability of polymer is observed from thermogravimetry. ionic liquid, electropolymerization, poly(o-phenylenediamine)Ionic liquids have been the focus of many recent scientific investigations because of their physical and chemical properties. They are nonvolatile and non-flammable, and have high thermal stability. From electrochemical point of view, ionic liquids have excellent properties such as high-ionic conductivity and wide potential windows [1][2][3] . Nowadays, ionic liquids also have been applied to peculiar media for electroorganic synthesis and electropolymerizations. The electrochemical synthesis of conductive polymers such as polypyrrole [4] , poly(3,4-ethylenedioxythiophene) [5] , and thio-phene [6] in ionic liquid media have been reported in some research papers. Furthermore studies on the electrooxidative polymerization of aromatic organic compounds were reported [7,8] .Poly(o-phenylenediamine) (PPD) has drawn much attention in recent years owing to its attractive applications such as pH response, electrochemical diode properties, electron-transfer mediation, and photovoltatic properties, permselectivity for a dissolved species [9] . In general, PPD is currently prepared in acidic solution. The direct electropolymerization of o-phenylenediamine was firstly carried out in ionic liquid [EMIM]Br [10] . On the basis of fore-research, we detailedly discussed electrochemical polymerization of o-phenylenediamine in ionic liquid [EMIM] Br and N-methylimidazolium tetrafluoroborate [HMIM] BF 4 . Compared with acidic aqueous solution, the monomer was more easily oxidized in ionic liquids. Electrode modified with poly(o-phenylenediamine) has obvious electrochemical properties in acid solution. The charge transport within electroactive PPD film was measured by chronocoulometry and chronoamperometry. The rates of the charge-transport within PPD film in acidic aqueous solution have been estimated as apparent diffusion coefficients for the diffusion-like charge transport within the film. The polymer structure was measured by UV，IR and thermogravimetry.

Electropreparation of (±)‐10‐camphorsulfonate‐doped poly(o‐phenylenediamine) in acetonitrile and its use in determination of glucose

“…The band observed at 1626 cm −1 can be assigned to the CN stretching vibrations in phenazine ring . The band located at 1530 cm −1 can be attributed to the CC stretching vibrations in phenazine ring . The band at 1373 cm −1 is related to the CN stretching vibrations in quinoid rings .…”

“…In the spectrum of P o PD–CSA film, the bands at 3368 and 3196 cm −1 are due to the N–H stretching vibrations of the NH 2 and NH groups in polymer chain . The band observed at 1626 cm −1 can be assigned to the CN stretching vibrations in phenazine ring . The band located at 1530 cm −1 can be attributed to the CC stretching vibrations in phenazine ring .…”

“…The CH in‐plane bending vibration of the substituent benzene rings is observed at 1150 cm −1 , while the CH out‐of‐plane bending vibrations of the substituent benzene rings are observed at 854 cm −1 and 758 cm −1 . The bands at around 2957 cm −1 and 2887 cm −1 can be assigned to both CH stretching vibrations in aromatic rings and CH stretching vibrations of the CH 2 and CH 3 groups of CSA − , respectively . In addition, the bands at nearly 1734 cm −1 and 1036 cm −1 are assigned to the CO and the SO groups, respectively .…”

Electrochemical routes for industrial synthesis

“…Other electropolymerisations described in the open literature are the electrosynthesis of polyphenylenediamine in 1-ethyl-3-methylimidazolium bromide and N-methylimidazolium tetrafluoroborate, 201 the electrosynthesis of poly(o-phenylenediamine) in N-butyl-N-methylpyrrolidinium (nonafluorobutane-sulphonyl)-(trifluoromethanesulphonyl) imide, 202 and the electrosynthesis of polyaniline in 1-butyl-3-methyl-imidazolium. 203 Deng and co-workers 204 found that CO 2 was reduced at a copper cathode at -2.4 V vs. Ag/AgCl.…”

Reference Systems for Voltammetric Measurements in Ionic Liquids

“…Lordermeyer et al also used an acetonitrile-based reference electrode to study the electroplating of dysprosium from an ionic liquid [36]. Other studies have described the use of the saturated calomel electrode (aqueous based) in electrochemical investigations in ionic liquids [37][38][39][40]. However, a problem with these and related approaches is that large junction potentials may exist between the two very different media (molecular solvent in the reference compartment and IL in the working solution compartment) and a contamination of the IL with the molecular solvent part of the reference system is unavoidable [20].…”