Shinsuke Inagi

Gradient Doping of Conducting Polymer Films by Means of Bipolar Electrochemistry

In this paper, we report a novel electrochemical doping method for conducting polymer films based on bipolar electrochemistry. The electrochemical doping of conducting polymers such as poly(3-methylthiophene) (PMT), poly(3,4-ethylenedioxythiophene) (PEDOT), and poly(aniline) (PANI) on a bipolar electrode having a potential gradient on its surface successfully created gradually doped materials. In the case of PEDOT film, the color change at the anodic side was also observed to be gradually transparent. PANI film treated by the bipolar doping gave a multicolored gradation across the film. The results of UV-vis and energy dispersive X-ray analyses for the doped films supported the distribution of dopants in the polymer films reflecting the potential gradient on the bipolar electrode. Furthermore, the reversibility of the bipolar doping of the PMT film was demonstrated by a spectroelectrochemical investigation.

Selective electrochemical fluorination of organic molecules and macromolecules in ionic liquids

This article provides an outline of recent studies on selective electrochemical fluorination in ionic liquid fluoride salts toward green sustainable chemistry. First, a brief historical background of electrochemical fluorination in organic solvents is provided, and some particular problems and unique solvent effects associated with this technique are briefly mentioned. Second, recent progress in selective fluorination and fluorodesulfurization of organic molecules and macromolecules in ionic liquids using direct and indirect electrolysis with recyclable mediators is reviewed.

Electrochemically mediated atom transfer radical polymerization from a substrate surface manipulated by bipolar electrolysis: fabrication of gradient and patterned polymer brushes.

We report the first ever use of electrochemically mediated atom transfer radical polymerization (eATRP) employing a bipolar electrochemical method for the fabrication of both gradient and patterned polymer brushes. A potential gradient generated on a bipolar electrode allowed the formation of a concentration gradient of a Cu(I) polymerization catalyst through the one-electron reduction of Cu(II) , resulting in the gradient growth of poly(NIPAM) brushes from an initiator-modified substrate surface set close to a bipolar electrode. These polymer brushes could be fabricated in three-dimensional gradient shapes with control over thickness, steepness, and modified area by varying the electrolytic conditions. Moreover, by site-selective application of potential during bipolar electrolysis, a polymer brush with a circular pattern was successfully formed. Polymerization was achieved using both a polar monomer (NIPAM) and a nonpolar monomer (MMA) with the eATRP system.

Use of Task-Specific Ionic Liquid for Selective Electrocatalytic Fluorination

Highly selective indirect anodic fluorination of organic compounds was successfully carried out for the first time by using a task-specific ionic liquid of iodoarene as a mediator in ionic liquid hydrogen fluoride salts.

Functional polymers based on electron-donating TTF and derivatives

This review highlights the recent progress of electron-donating polymers containing thio-cyclic units (tetrathiafulvalene, dithiafulvene, thioketene dimers). These polymers with TTF derivatives in the main chain and side chain have been studied with the aim of improving processability of their charge transfer complexes and increasing the dimensionality of their conducting paths in the solid state. This review also highlights a novel synthetic methodology of the electroactive polymers, i.e., cycloaddition polymerization of bisthioketene to produce poly(dithiafulvene) and oxidative polymerization of bisdithiafulvenyl monomers and thioketene dimers. In the application of poly(dithiafulvene)s to the polymer–metal hybrid systems, they act as not only the reducing agent but also the stabilizer for the formed metal nanoparticles.

Site-Controlled Application of Electric Potential on a Conducting Polymer “Canvas”

A novel patterning method for conducting polymer films was successfully demonstrated using the concept of bipolar electrochemistry. The local application of an anodic potential to poly(3-methylthiophene) (PMT) and poly(3,4-ethylenedioxythiophene) (PEDOT) on a bipolar electrode (BPE) realized local electrochemical doping and reaction depending on the supporting salt used. The potential applied on the BPE was measured and corresponded well to the patterns. The array-type driving electrode system was able to draw complex patterns in a site-controlled manner.

Highly efficient and selective electrochemical fluorination of organosulfur compounds in Et3N·3HF ionic liquid under ultrasonication

We found that ultrasonication is highly effective for increase of the yields, current efficiency, and selectivity in anodic fluorination in Et(3)N.3HF ionic liquid.

Electrochemical polymer reaction: selective fluorination of a poly(fluorene) derivative

Anodic fluorodesulfurization of a poly(fluorene) derivative coated on a Pt electrode was successfully carried out in an ionic liquid hydrogen fluoride salt, yielding a alternating copolymer containing a difluorofluorene moiety.

Arsole-Containing π-Conjugated Polymer by the Post-Element-Transformation Technique

A synthetic method to obtain an arsole-containing π-conjugated polymer by the post-transformation of the organotitanium polymer titanacyclopentadiene-2,5-diyl unit with an arsenic-containing building block is described. The UV/Vis absorption maximum and onset of the polymer were observed at 517 nm and 612 nm, respectively. The polymer exhibits orange photoluminescence with an emission maximum (Emax ) of 600 nm and the quantum yield (Φ) of 0.05. The polymer proved to exhibit a quasi-reversible redox behavior in its cyclic voltammetric (CV) analysis. The energy levels of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were estimated to be -5.43 and -3.24 eV, respectively, from the onsets for oxidation and reduction signals in the CV analysis. Further chemical modification of the arsole unit in the π-conjugated polymer by complexation of gold(I) chloride occurred smoothly resulting in the bathochromic shift of the UV/Vis absorption and lowering of the LUMO energy level.

Practical Synthesis and Properties of 2,5-Diarylarsoles

2,5-Diarylarsoles were easily synthesized from nonvolatile arsenic precursors. Diiodoarsine was generated in situ and reacted with titanacyclopentadienes to give 2,5-diarylarsoles. The structures and optical properties were studied in comparison with those of 2,5-diarylphosphole. It was found that the arsoles were much more stable in the air than the phosphole. Single crystal X-ray diffraction revealed the arsenic atoms adopted a trigonal pyramidal structure, reflecting on the s-character of the lone pair. The obtained 2,5-diarylarsoles and 2,5-diarylphosphole showed intense emission in solutions and solid state. In addition, the optical properties were controlled by transition-metal coordination.