Shigeru Takagi

Facile fabrication method for p∕n-type and ambipolar transport polyphenylenevinylene-based thin-film field-effect transistors by blending C60 fullerene

We have demonstrated the solution-processed p- and n-type transports including ambipolar transport organic thin-film transistors (OTFTs), required for complementary thin-film integrated circuit technology, by a facile method of blending the n-type C60 and the p-type [poly(2-methoxy-5-[2’-ethyl-hexyloxy]-1,4-phenylene vinylene] (MEH-PPV). The carrier transport of PPV-based thin-film field-effect transistors with various C60 compositions are investigated by using the field-effect gated structure. One of the important findings is that tunable electronic properties of OTFTs are achieved by controlling C60 composition using a simple and an inexpensive spin-cast technology. The mobility increases with increase in the C60 composition in both n- and p-type OTFTs. Temperature measurements on n-type OTFTs revealed that transport follows a thermally activated hopping transport model with small activation energy.

Synthesis and characterization of tetrakis(2,6-difluorophenyl)porphinato ruthenium(II)(CO)(N-MeIm); oxidation reaction of hydrocarbon catalyzed by the ruthenium porphyrin

Abstract Synthesis, characterization and properties of a new ruthenium porphyrin, tetrakis(2,6-difluorophenyl)porphinato ruthenium(II)(CO)(N-MeIm), Ru2FP(CO)(N-MeIm), are described. The complex catalyzes the oxidation of hydrocarbons by use of t-BuOOH or hypochlorite as oxidant. To styrene and α-methyl- styrene oxidation, Ru2FP(CO)(N-MeIm)-oxidant systems favor the cleavage of the CC double bond over the formation of the epoxide. Cyclooctene epoxidation and cyclohexane hydroxylation are efficiently performed by the use of TBHP oxidant. On the contrary, hypochlorite oxidant demonstrates only a low catalytic ability for cyclooctene and cyclohexene oxidations.

The unexpected synthesis of a tricobalt cluster with ferrocenyl groups: Crystal structure and cyclic voltammetry of Co3(CO)7(μ3-PFc)(μ2-PFc2)(Fc = (C5H5)Fe(C5H4))

Abstract FcPCl2 is reacted with NaCo(CO)4 in THF at room temperature. Crystallization from CH2Cl2—hexane affords dark-green diamagnetic rhombi in low yield. Single crystal X-ray analysis has shown that the structure is [Co3(CO)7(μ3-PFc)(μ2-PFc2)](1). Cyclic voltammetry has shown that three iron atoms in 1 are oxidized at the same potential, but it exhibits two reversible reduction peaks.

Metal-metal bonds extended over a porphyrin ring: III. Syntheses and spectral studies of new metal—metal bonded indium porphyrin complexes, (TBPP)In—ML and (5FP)In—ML☆

Abstract Two new series of metal—metal bonded indium porphyrin complexes, (TBPP)In—ML and (5FP)In—ML, where TBPP is the dianion of 5,10,15,20-tetrakis (3,5-di-t-butylphenyl)porphyrin and 5FP is the dianion of 5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin, ML is Mn(CO)5, Mo(CO)3Cp, and Co(CO)4, have been synthesized in addition to (OEP)In—ML and (TPP)In—ML. These new metal—metal bonded porphyrin complexes have shown higher solubilities to organic solvents or higher photochemical stabilities as compared with (OEP)In—ML and/or (TPP)In—ML. (P)In—Co(CO)4 complexes where P denotes all of these porphyrin ligands have been obtained in almost quantitative yield by the reaction of (P)In—Cl with LiCo3(CO)10. These porphyrin complexes have shown typical UV-vis spectra to the hyper class. Analysis of the absorption spectra has revealed an anomalous character of (5FP)In—ML complexes. 17O and 13C NMR chemical shifts for CO ligands in (P)In—ML complexes have exhibited only small changes with the change of the porphyrin ligand for the same ML. IR data of (P)In—ML complexes in the ν(CO) region have clearly shown higher frequency shifts in inverse proportion to σ-donor ability of these four porphyrin ligands.

CD spectral study of Dnp derivatives of amino acids and peptides for their configurational and conformational analysis

Rules relating the stereochemistry of N‐Dnp (Dnp: 2,4‐dinitrophenyl) derivatives of α‐amino acids and peptides and the sign of the Cotton effects at the longest wavelength band (ca. 400 nm) are surveyed. Some new data and insights concerning the CD spectra of Dnp–α‐amino acids are included: i.e., the spectra of Dnp derivatives as the composite of the corresponding o‐nitrophenyl and p‐nitrophenyl derivatives; the crystal structure of Dnp–I‐phenylalanine and its solid‐state CD spectra; the CD spectra of Dnp–α‐amino acids containing sulfur atom on their side chains; and the theoretical approach to the CD spectra using molecular orbital method‐based calculation. Conformational analyses of cyclic and linear peptides by the CD spectra of their Dnp derivatives are also discussed.

SYNTHESIS OF HIGHER-NUCLEARITY CLUSTERS BY ASSEMBLING THE -CCo3(CO)9 UNITS INTO AROMATIC SPACER MOLECULES

Abstract p-[(CO)9Co3C]2C6H4 (1) has been synthesized by reacting Co2(CO)8 with p-(Cl3C)2C6H4. 4,4′-[(OC)9Co3CC(O)]C6H4-C6H4[C(O)CCo3(CO)9] (2) has been synthesized from p-LiC6H4-C6H4Li and BrCCo3(CO)9. Similarly m-[(OC)9Co3CC(O)CH2]2C6H4 (3) has been synthesized from m-(LiCH2)2C6H4 and BrCCo3(CO)9. X-ray analysis was done for 1 and 2; both compounds exhibit a stacked structure. Cyclic voltammetry and UV spectra revealed usual behavior for 1, that is, two cluster units interact strongly through the benzene spacer, which is not the case for clusters 2 and 3.

Investigation of Pcbm Concentration on Photovoltaic Characteristics of Polymer Solar Cells with Blends of P3Ht and Pcbm

Polymer photovoltaic cells (PVCs) consisting of a blend of p-type poly(3-hexylthiophene) (P3HT) and n-type [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were fabricated and investigated the role of the PCBM concentration. The photocurrent and the power conversion efficiency gradually increased with increase in PCBM concentration up to 50% and decreased with further increase in PCBM concentration. Both the root mean square and average roughnesses measured by atomic force microscopy decrease as the PCBM concentration increases from 0 to approximately 70%. The surface morphology of P3HT/PCBM blended and improved donor-acceptor proximity, leading to electron conductivity, contribute to the increase in power conversion efficiency