Duygu Ekinci

Electrochemical synthesis and characterization of 2-amino-3-cyano-4-phenylthiophene dimer and oligomers

Abstract The electrochemical dimerization of 2-amino-3-cyano-4-phenylthiophene (ACPT) has been studied in acetonitrile solutions by using Pt electrodes. The resulting dimer obtained after a preparative electrolysis was characterized by using FAB mass, 13 C and 1 H nuclear magnetic resonance ( 13 C -NMR and 1 H -NMR) and fourier transform infrared spectroscopic techniques. Voltammetric measurements showed that the dimer formed by the coupling of two cation radicals (CR–CR) is stable and has a reversible electrochemical behavior. The fast scan voltammetric experiments using microelectrodes revealed that the dimer formed by the coupling of a cation radical with a parent molecule (CR–PM) has a quasi-reversible electrochemistry and undergoes to further couplings resulting in oligomers. On the basis of voltammetric and spectroscopic data, it was found that dimerization of ACPT occurs mainly by the coupling of a neutral ACPT molecule with the cation radicals, which is very important in the formation of regioregular oligomers and polymers.

The electrochemical oxidation of 2-amino-3-cyano-4-phenylthiophene: evidence for a new class of photoluminescent material

Abstract The electrooxidation of 2-amino-3-cyano-4-phenylthiophene on platinum electrodes was investigated for the first time in acetonitrile by cyclic voltammetry, controlled potential electrolysis, and spectrometric methods. The voltammetric responses were similar to those of common aromatic amino compounds. Two types of dimers were observed as intermediates in the early stages of oxidation. Ethlyamine and phenol were added to an electrolytic solution in order to determine the electrochemical behavior of 2-amino-3-cyano-4-phenylthiophene under basic and acidic conditions. We propose an E(CE) n mechanism to account for this electrochemistry. 2-Amino-3-cyano-4-phenylthiophene is first oxidized to a cation radical, followed by chemical coupling to form dimers, which are electroactive. Controlled potential electrolysis gave a new class of π-conjugated oligoaminothiophenes exhibiting an absorbance at 432 nm and photoluminescence at 538 nm.

Synthesis of Graphene-like Films by Electrochemical Reduction of Polyhalogenated Aromatic Compounds and their Electrochemical Capacitor Applications

Graphene is a promising two-dimensional nanomaterial for many applications due to its exciting properties. In the past decade, a variety of techniques-each with its own set of advantages and disadvantages-have been developed to prepare graphene, and there are ongoing efforts to improve these techniques and to reveal new approaches. Here, we describe a simple and low-cost process for the bottom-up synthesis of graphene-like films. This new methodology involves a two-step procedure: (i) formation of polyaromatic ring structures by the repeated covalent coupling of aryl radicals generated from electrochemical reduction of polyhalogenated aromatic compounds in aprotic solvent, and (ii) production of carbon networks by heating of polyaromatic surface films. Accordingly, polymeric films were prepared on the electrodes by electrochemical reduction of polyhalogenated compounds such as hexafluorobenzene (HFB), hexachlorobenzene (HCB), and hexabromobenzene (HBB), and then polymer films were annealed at 400 °C for 30 min. The structure and surface characteristics of electrodeposited carbon films under self- and thermal-annealing conditions were studied by spectroscopic and morphological techniques. Also, the capacitance performance of the films was evaluated by means of cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. Results indicate that graphene-like carbon films can be achieved by use of the electrochemical approach under mild conditions without expensive equipment, and also that these carbon materials are very promising for low-cost energy-storage devices.