Hypervalent iodine oxidants have been widely applied in organic reactions due to their low toxicity, ready availability, and ease of handling. We produced an oxidant, [phenyliodine(III)bis(trifluoroethoxide)] (PIFE) by anodic oxidation of iodobenzene, which possesses comparable or superior properties to those of commercially available congeners, such as [phenyliodine(III)bis(trifluoroacetate)] (PIFA) and [phenyliodine(III)diacetate] (PIDA). The availability of PIFE was demonstrated by construction of several nitrogen-containing molecular skeletons; construction of quinolinone derivatives by PIFE occurred smoothly in moderate yield. In addition, the carbazole derivatives were synthesized in higher yields than with use of PIFA. Application of this methodology enabled synthesis of the bioactive tetrahydropyrroloiminoquinone-, carbazole-, and pyrroloindole-class natural products, including makaluvamines, damirones, glycozoline, debromofrustraminol B, and CPC-1.

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D-π-A pyridinium dye without carboxylic acid moiety as anchoring group has been used as a photosensitizer for dye-sensitized solar cells (DSSCs). FTIR and absorption spectra of the D-π-A pyridinium dye adsorbed on TiO₂ nanoparticles indicate that the dye is adsorbed on the TiO₂ surface by an electrostatic interaction between pyridinium moiety of the dye and the hydroxyl group of TiO₂ surface. DSSC based on the D-π-A pyridinium dye had a power conversion efficiency (η) of 0.09% with a short-circuit photocurrent density (J_sc) of 0.48 mA cm⁻².

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The electrochemical and photoelectrochemical behaviors of polythiophene nanowires prepared by templated electrodeposition in supercritical fluids were investigated. The polythiophene nanowires prepared showed sharp and strong capacitive redox waves in its cyclic voltammogram and excellent photocurrent responsivity in its cyclic voltammogram under photo-irradiation. These were better results compared to those obtained by the use of polythiophene films deposited on the flat disc electrode. This is mainly due to the fact that surface area of nanowires are much larger than that of flat films.

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Electrocatalytic reactions build targeted molecules with low energy consumption and thus are intriguing both synthetically and mechanistically. We have carried out cyclic voltammetric studies on electrocatalytic intermolecular [2 + 2] cycloaddition reactions between an enol ether and an olefin nucleophile to reveal the electron transfer reactions in detail at the surface of the electrode.

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We have synthesized 3,4-ethylendioxythiophene (EDOT) monomer analogs such as 3,4-ethyleneoxythiathiophene (EOTT), 3,4-ethylenedithiathiophene (EDTT) and 3,4-methylethylenedithiathiophene (MEDTT), and investigated morphological and electrochemical properties of the corresponding polymer films prepared by their electrochemical polymerization. In addition, their properties were compared with those of poly(3,4-ethylendioxythiophene (PEDOT) film electropolymerized.

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In this communication, we report the synthesis of triarylamine-conjugated bis(dipyrrinato)zinc(II) complexes 1 and 2, and disclose their photochemical and electrochemical properties. The structures of 1 and 2 were determined by means of single-crystal X-ray structure analysis. The effect of the triarylamine moieties on the UV-vis spectra of 1 and 2 was not large, although it significantly quenched the fluorescence of 1 and 2. Cyclic voltammetry and differential pulse voltammetry revealed that 1 and 2 underwent oxidation up to four electrons. Since they bear two triarylamine entities and two dipyrrinato ligands, the oxidation is assignable to the one-electron oxidation processes of each of the four moieties. The redox reversibility was much higher in 2 than that in 1. The introduction of ethyl groups on the 2 and 6 positions of dipyrrin moieties contributed to the enhancement of the electrochemical reversibility.

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Electropolymerization of thiophene-3-boroles was successfully carried out in the presence of BF₃-OEt₂ as roles of supporting electrolyte and lowering their oxidation potentials. The obtained polythiophenes having borole moieties showed broadening energy band due to the extended conjugated system via the borole side chain.

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Redox properties of 2,3-diaminophenazine were investigated in acidic aqueous and acetonitrile solutions. In each case, continuous potential cycling generated deposited products, poly(2,3-diaminophenazine) (PDAP) on electrode surfaces. PDAP deposited from aqueous solution showed rather complicated redox response with reduction pre-peak that depended on the initial potential, while PDAP deposited from acetonitrile indicated well-defined adsorption species properties in acidic aqueous solution.

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Electro-oxidative Wacker-type reaction has been developed in PEG/CH₃CN thermomorphic biphasic system. The heterogeneous solution was turned into homogeneous solution with heating to 60°C, and electro-oxidative Wacker-type reactions of alkenes bearing long alkyl chains proceeded smoothly to afford methyl ketones in good yields. The recycling of PEG phase containing Pd has also been achieved.

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The addition of methyl viologen (MV²⁺) accelerates the reduction of Na₂SeO₃ not only in 0.1 mol dm⁻³ sodium phosphate buffer (PBS, pH 7) but also in 0.22 mol dm⁻³ sodium acetate buffer (pH 4). Water-insoluble red Se is dispersed in the vicinity of the electrode surface as the reduced product. Michaelis-Menten-type relationship is obtained between the reduction current and the concentration of Na₂SeO₃, suggesting that MV²⁺ molecules mediate the electron transfer from the electrode to HSeO3⁻ or SeO₃²⁻ dissolved in PBS. MV²⁺ is also effective in accelerating the reduction of SeO₄²⁻, which has already been reported to be electrochemically inactive.

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We have demonstrated anodic alkoxylation of lactams followed by reactions with carbon nucleophiles in a one-pot manner using 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as a solvent. In the two-step transformation, HFIP acted as a nucleophile in the presence of solid-supported bases, while it acted as an inert solvent in the absence of solid-supported bases. This enabled us to conduct anodic alkoxylation of lactams and subsequent C-C bond forming reactions without replacing the solvent.

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Electro-reductive homo-coupling of aryl bromides in a double mediatory system involving catalytic amounts of PdCl₂(PPh₃)₂ and N-alkyl-4-alkoxycarbonylpyridinium salts was performed successfully to afford the corresponding biaryls in good to moderate yields.

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Electroreduction of aryl halides loaded on the Pd-immobilized activated carbon and/or activated carbon cloth proceeded smoothly by using a newly designed stacked-type cell to give the corresponding dehalogenated arenes.

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An electro-reductive halogen-deuterium exchange reaction in CD₃CN has been developed. Using 9-fluorenone as a mediator, the electro-reduction of several aryl halides proceeded smoothly to give the deuterated products selectively. A methylation reaction of aryl halides also proceeded under similar conditions.

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The electrochemical oxidation of various organic compounds using inorganic salts like sodium halides and sodium tetrafluoroborate has been accomplished under mild conditions. The long-standing problem of solubility of inorganic salts in aprotic organic solvents in electroorganic synthesis has been overcome by the addition of poly(ethylene glycol) to the electrolytic solutions through cyclic voltammetry analysis and macro-scale electrolysis. By using this method, anodic halogenation, anodic deprotection, and anodic coupling reaction of organic compounds were successfully carried out to provide desired products efficiently.

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Novel carborane-triphenylamine dyad 1 was successfully prepared. The dyad exhibited the aggregation-induced emission (AIE) property in a solution of THF/water [1/99 (v/v)]. The cyclic voltammogram of 1 measured in tetrabutylammonium perchlorate (TBAP)/DMF using glassy carbon (GC) disk working electrode showed redox couples both at anodic side and cathodic side derived from redox responses of the triarylamine and the carborane moieties, respectively. The mediatory behavior of 1 for the anodic oxidation of benzyl alcohol was clearly confirmed by cyclic voltammetry in the presence of 2,6-lutidine. The catalytic current of 1 for the cathodic reduction of 1,2-dibromo-1,2-diphenylethane was also observed.

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We have developed an electrolytic system based on the acid-base reaction between Amberlite IR-120 as a solid-supported acid and water. On the basis of the electrolytic system, electroreduction of activated olefins was carried out to provide the corresponding hydrogenation products in moderate to good yields. Furthermore, the spent Amberlite IR-120 was recyclable for many times by regeneration.

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An environmentally friendly electrochemical process for selective oxidation of 1,2-diols in water using Me₂SnCl₂ catalyst, KBr as a bromide ion source and platinum electrodes has been developed. This method uses “Br⁺” ion, generated at the anode as an oxidant and OH⁻ ion, at the cathode as an electro-generated base. Various cyclic and acyclic 1,2-diols were tolerated affording the corresponding α-hydroxyketones in moderate to high yields.

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Intramolecular electron transfer is expected to play a key role in anodic [2 + 2] cycloaddition reactions. We synthesized 2-allyl-6-methoxy-1,2,3,4-tetrahydronaphthalene as an olefin nucleophile to study the [2 + 2] reaction, leading to the finding that the intramolecular electron transfer that completes the formation of cyclobutane rings occurs mainly through space rather than through bonds.

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Constant current electrolysis of polyfluoroarenes in DMF containing 0.1 mol dm⁻³ Bu₄NBF₄ in the presence of carbon dioxide by using a one-compartment cell equipped with a Pt cathode and a Mg anode at −40°C resulted in reductive cleavage of a C-F bond of the phenyl ring followed by reaction with carbon dioxide in highly regio- and chemoselective manners to give the corresponding mono-carboxylated products, polyfluorobenzoic acids, in moderate to good yields.

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Thermoresponsive polymers having 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) moieties were fixed on the graphite surface by using the reversible addition-fragmentation chain transfer (RAFT) graft polymerization technique. The surface of graphite has been anodically oxidized by using our original electrochemical method, and then modified with 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoyloxy groups (RAFT reagents) by esterification with the corresponding acid chlorides. From the resulting RAFT reagent-modified graphite, 2,2,6,6-tetramethyl-4-piperidyl methacrylate (TEMPMA) and N-isopropylacrylamide (NIPAAm) monomers were copolymerized stepwise under RAFT polymerization conditions to afford the thermoresponsive block-copolymer-grafted graphite, poly(TEMPMA)-block-PNIPAAm-grafted graphite. N-Oxylation of tetramethylpiperidyl groups on the resulting graphite successfully afforded the corresponding TEMPO-containing thermoresponsive polymer-grafted graphite. Redox behavior of the resulting graphites was observed by cyclic voltammetry. The potential and intensity of the cathodic current peaks were discontinuously changed below and above the lower critical solution temperature (LCST) of the grafted thermoresponsive polymers. These results indicate that the phase transition of the thermoresponsive polymer on the graphite influences the electron transfer between the TEMPO moieties and the graphite surface.

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A π-conjugated polymer having 1,4-bismercapto-substituted 1,3-diene units in the main chain, prepared by the reaction of a polymer possessing titanacyclopentadiene-2,5-diyls units with benzenesulfenyl chloride (PhSCl), was subjected to the oxidation with m-chloroperoxybenzoic acid (mCPBA) to control optoelectronic properties of the resulting materials. That is, polymers possessing sulfoxide- and/or sulfone-substituted 1,3-diene units were obtained by the oxidation reactions of the polymer having phenylmercapto moieties with varied amount of mCPBA. Electrochemical properties of the resulting sulfoxide- and/or sulfone-containing polymers were studied by their cyclic voltammetric analyses, from which their HOMO and LUMO energy levels proved to be tunable by the oxidation states of the sulfur atoms (HOMO = −5.1–−5.7 eV and LUMO = −2.7–−3.1 eV).

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The electrochemical oxidation of ortho- and meta-anisylsilanes in the presence of sodium cyanide facilitated the direct cyanation of the aromatic ring through the exchange of a hydrogen atom and a cyano group to give cyanoanisylsilanes without elimination of the silyl group. The anodic cyanation of anisylsilanes in methanol and electrophilic reactions of the obtained cyanoanisylsilanes largely depended on the substituted position of the silyl group on the aromatic ring and on the bulkiness of the alkyl group on the silicon atom.

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The reactions of thiophene derivatives, bithiophene, and terthiophene with an electrochemically generated diarylcarbenium ion pool afforded multiple alkylation products. Extended diarylcarbenium ion pools afforded dendritic molecules by the multiple alkylation of bithophene and terthiophene.

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We investigated the characteristics of organic thin-film transistors based on 2,8-disubstituted chrysene derivatives with a polymer treated SiO₂ dielectric layer to examine the effect of polymer coating. Field-effect characteristics were strongly influenced by the applied polymer insulators, and the best field-effect mobility (2.8 cm² V⁻¹ s⁻¹) was obtained for the CYTOP-treated device incorporating 2,8-diphenyl chrysene.

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