Synthesis of π‐conjugated copolymers composed of benzo[2,1,3]thiadiazole and thiophene units bearing various alkyl groups and their application to photovoltaic cells

π‐Conjugated polymers, PTOTBT , PTEHTBT , and PTt‐BTBT , composed of benzothiadiazole as an electron accepting unit and terthiophene as an electron donating unit in the backbone were prepared. PTOTBT , PTEHTBT , and PTt‐BTBT contained side chain groups of n‐octyl, 2‐ethylhexyl, and t‐butyl groups, respectively. Solubility, optical and thermal properties of the polymers showed strong dependences on their side chain groups. PTEHTBT having 2‐ethylhexyl groups in the side chain exhibited absorption maximum (λ_max) at longer wavelength (565 nm) than PTOTBT (534 nm) and PTt‐BTBT (495 nm). PTOTBT showed higher thermal stability than the others. The prepared polymers were employed to polymer solar cells (PSCs) with a configuration of ITO/PEDOT‐PSS/polymer: PC₆₁BH/LiF/Al. Power conversion efficiency of the PSC‐based on PTEHTBT was 1.32%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Polythiophenes bearing electron‐withdrawing groups in the side chain and their application to bulk heterojunction solar cells

Soluble polythiophenes bearing strong electron withdrawing groups, dicyanoethenyl [? CH?C(CN)₂] (PTDCN) and cyano‐methoxycarbonylethenyl [? CH?C(CO₂Me)CN] (PTCNME), in the side chains have been prepared. Optical band gaps calculated from onset absorption were 1.70 eV and 1.73 eV for PTDCN and PTCNME, respectively. Highest occupied molecular orbital energy levels measured with a surface analyzer (AC‐2) were ?5.53 eV and ?5.29 eV for PTDCN and PTCNME, respectively, which were much lower than that of poly(3‐hexylthiophene) (?4.81 eV). To investigate photovoltaic properties, bulk heterojunction polymer solar cells based on PTDCN and PTCNME were fabricated with a structure of ITO/PEDOT:PSS/active layer/LiF/Al, where the active layer was a blend film of polymer and [6,6]‐phenyl C₆₁ butyric acid hexyl ester (PC₆₁BH). Solar cell parameters were estimated from current density–voltage (J–V) characteristics under the illumination of AM1.5 at 100 mW/cm². The solar cell based on the blend film of PTCNME:PC₆₁BH (1:1) showed power conversion efficiency (PCE) of 0.72% together with the open current voltage (V_oc) of 0.61 V, the short current density (J_sc) of 3.90 mA/cm², and the fill factor of 30.3%. The PCE of a solar cell fabricated from PTDCN in a similar way was 0.56%. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Anisotropic magnetotransport near the quantum Hall state

We report experimental results on an anisotropic magnetotransport of a bilayer electron system at the Landau level filling factor under tilted magnetic fields. We find that the magnetoresistance changes when the direction of applied in-plane field B is changed with respect to the direction of the current while keeping the strength of B fixed. This anisotropy only appears at the ground state where interlayer electron tunneling is permitted. Therefore, this phenomenon indicates that bilayer systems at with interlayer tunneling inherently have a dissipation mechanism related to the direction of the in-plane field.     

Electronic spectra and electrochemical properties of bis(dimethylglyoximato)iron(II) complexes containing axialN-heterocyclic ligands

Gaussian analysis of the electronic spectra of 25 bis(dimethylglyoximato)iron(II) complexes containing axialN-heterocyclic ligands are discussed and comparisons made with the spectra of the corresponding [Fe(CN)₅L]^3– complexes. The energies of the metal-to-axial and metal-to-equatorial ligand charge-transfer transitions exhibit opposite trends, correlating with the electronic properties of the axial ligands, and with the redox potentials of the Fe^II/Fe^III couple.     

Hyperfine interactions in the gas-phase E.P.R. spectra of 35ClO (2Π3/2) in the J = 5/2 and J = 3/2 levels

Gas-phase E.P.R. spectra of ³⁵ClO have been measured accurately both in the J=5/2 and J=3/2 rotational levels, using C-band (4·4 GHz) and X-band (9·4 GHz) microwaves, respectively. Special attention has been paid to separate the spectral lines of ³⁵ClO from those of ³⁷ClO. Analysis of the spectra has resulted in the simultaneous determination of the hyperfine parameters h and b and, when combined with a-(b+c)/2 obtained by microwave spectroscopy, the hyperfine parameters a, b and c are all determined. Molecular constants which describe the distribution of the unpaired electron around the chlorine nucleus are derived from them. The molecular g values of the rotational levels indicate the mixing of the ²Π state both with the ²Σ+ and with the ²Δ electronic excited states.     

Synthesis of bicyclic bis(γ‐butyrolactone) derivatives bearing sulfide moieties and their alternating copolymers with epoxide

A series of bicyclic bis(γ‐butyrolactone)s (BBL) bearing sulfide moiety 2 were readily synthesized from a precursor BBL bearing isopropenyl group 1. This efficient and versatile synthesis of 2 was achieved by a highly reliable radical addition reaction of thiols to the C‐C double bond in the isopropenyl group 2 underwent anionic copolymerization with glycidyl phenyl ether in a 1:1 alternating manner to give a series of the corresponding polyester 3, of which side chains inherited the sulfide group from 2. The glass transition temperatures (T_g) of 3 showed clear dependence on the flexibility of the sulfide side chains. The scope of this copolymerization system was further expanded by synthesizing a bifunctional BBL 4 from 1 with using hexanedithiol and performing its copolymerization with bisphenol A diglycidyl ether 5. The copolymerization gave the corresponding networked polymer in high yield. During the copolymerization, the volume expanding nature of the double ring‐opening reaction of 4 contributed to the efficient compensation of the intrinsic volume shrinkage of the ring‐opening of epoxide to achieve a shrinkage‐free curing system. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Generation in singularity categories of hypersurfaces of countable representation type

The Orlov spectrum and Rouquier dimension are invariants of a triangulated category to measure how big the category is, and they have been studied actively. In this paper, we investigate the singularity category $$\textsf {D} _{\textsf {sg} }(R)$$ of a hypersurface R of countable representation type. For a thick subcategory $${\mathcal {T}}$$ of $$\textsf {D} _{\textsf {sg} }(R)$$ and a full subcategory $$\mathcal {X}$$ of $${\mathcal {T}}$$, we calculate the Rouquier dimension of $${\mathcal {T}}$$ with respect to $$\mathcal {X}$$. Furthermore, we prove that the level in $$\textsf {D} _{\textsf {sg} }(R)$$ of the residue field of R with respect to each nonzero object is at most one.     

Development of headspace SPME method for analysis of volatile organic compounds present in human biological specimens

In recent years, interest has increased regarding the identification of volatile organic compounds (VOCs) for metabolic profiling, human scent identification of the living and deceased, and diagnostic potentials for certain diseases that are known for its association with distinct odor. In this study, a method has been developed that is capable of sampling, identifying, and differentiating the VOCs present in various biological specimens of forensic importance (blood, breath, buccal cells, and urine) taken from the same individuals. The developed method requires a pretreatment step to remove targeted VOCs from the sampling apparatus prior to sampling of the individual specimens. The VOCs collected from the biological specimens were characterized by solid-phase microextraction and gas chromatography/mass spectrometry with ratios of the most abundant and frequent VOCs compared using qualitative and semiquantitative methods. Blood, breath, and buccal cells required extraction procedures ranging from 18 to 21 h in order to optimize the limit of detection, which averaged 5–15 ng across these specimens. The optimal method for measuring urine VOCs was complete in less than an hour; however, the limit of detection was higher with a range of 10–40 ng quantifiable. The demonstrated sensitivity and reproducibility of the methods developed allow for population studies of human scent VOCs from various biological specimen collection kits used in the forensic and clinical fields.     

Comprehensive Microstructure and Molar Mass Analysis of Polybutadiene by Multidimensional Liquid Chromatography

For the first time, polybutadiene is separated according to microstructure using solvent gradient interaction chromatography (SGIC). Superior separation of polybutadienes having different microstructures is obtained on a silica‐based reversed stationary phase and a mobile phase of acetone–hexane. This SGIC system enables the baseline separation of 1,2‐polybutadienes and 1,4‐polybutadienes even in cases where the samples have similar molar masses. 2D liquid chromatography is performed with the SGIC method separating according to microstructure in the first dimension coupled to size exclusion chromatography separating according to molar mass in the second dimension, thus providing comprehensive information on both microstructure and molar mass.