Oriented Thin Films of the Low-Band-Gap Polymer PTB7 by Friction Transfer Method

Low-band-gap polymers are promising materials for organic photovoltaic application. We prepared an oriented thin film of a low-band-gap polymer, PTB7, by friction transfer method. The oriented film showed a strong dichroic absorption in the whole visible range. The orientation of molecular chain was characterized by two-dimensional grazing incident X-ray diffraction (2D-GIXD) with synchrotron radiation. 2D-GIXD results showed PTB7 molecular plane parallel to the substrate plane, i.e., “face on orientation.”     

Asymmetric Synthesis of Agrochemically Attractive Trifluoromethylated Dihydroazoles and Related Compounds under Organocatalysis

The unique, partially saturated, fluorinated five‐membered heterocyclic compounds, trifluoromethylated dihydroazoles, and their derivatives, have emerged as a new class of heterocycles with remarkable biological activities in the 21st century. Despite their small molecular structures, a single sterically demanding tetrasubstituted trifluoromethylated stereogenic carbon center has prevented chemists from achieving the asymmetric synthesis of these compounds. In this account, we describe our recent progress in the catalytic asymmetric synthesis of a series of trifluoromethylated heterocycles, such as isoxazolines and pyrrolines having a stereogenic carbon center, based on organocatalysis. Our protocols have advantages in terms of employing inexpensive reagents and organocatalysts and they would be useful for industrial production.     

Through‐Space Conjugated Molecular Wire Comprising Three π‐Electron Systems

A [2.2]paracyclophane‐based through‐space conjugated oligomer comprising three π‐electron systems was designed and synthesized. The arrangement of three π‐conjugated systems in an appropriate order according to the energy band gap resulted in efficient unidirectional photoexcited energy transfer by the Förster mechanism. The energy transfer efficiency and rate constants were estimated to be >0.999 and >10¹² s^?1, respectively. The key point for the efficient energy transfer is the orientation of the transition dipole moments. The time‐dependent density functional theory (TD‐DFT) studies revealed the transition dipole moments of each stacked π‐electron system; each dipole moment was located on the long axis of each stacked π‐electron system. This alignment of the dipole moments is favorable for fluorescence resonance energy transfer (FRET).     

Diastereoselective Additive Trifluoromethylation/Halogenation of Isoxazole Triflones: Synthesis of All-Carbon-Functionalized Trifluoromethyl Isoxazoline Triflones

Highly functionalized 5-trifluoromethyl-2-isoxazoline derivatives featuring a triflyl (SO₂CF₃) group at the 4-position were successfully synthesized via diastereoselective trifluoromethylation and halogenation of isoxazole triflones using the Ruppert– Prakash reagent. The trifluoromethylation is quite general in terms of the substrates including 3,5-diaryl isoxazole triflones and 3-aryl-5-styrylisoxazole triflones to provide products in high yields with excellent diastereoselectivities. The highly functionalized 5-trifluoromethyl-2-isoxazoline derivatives are expected to be a new class of antiparasiticides. Thus the triflyl group both activates isoxazoles and the 4-postion of CF₃ adducts, and has a potential biological function.     

Rapid automatic identification and quantification of compounds in complex matrices using comprehensive two-dimensional gas chromatography coupled to high resolution time-of-flight mass spectrometry with a peak sentinel tool

Comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC × GC–MS) is a powerful tool for comprehensive analysis of organic pollutants. In this study, we developed a powerful analytical method using GC × GC for rapid and accurate identification and quantification of compounds in environmental samples with complex matrices. Specifically, we have developed an automatic peak sentinel tool, T-SEN, with free programming software, R. The tool, which consists of a simple algorithm for on peak finding and peak shape identification, allows rapid screening of target compounds, even for large data sets from GC × GC coupled to high resolution time of flight mass spectrometry (HRTOFMS). The software tool automatically assigns and quantifies compounds that are listed in user databases. T-SEN works on a typical 64 bit workstation, and the reference calculation speed is 10–20 min for approximately 170 compounds for peak finding (five ion count setting) and integration from 1–2 GB of sample data acquired by GC × GC–HRTOFMS. We analyzed and quantified 17 PCDD/F congeners and 24 PCB congeners in a crude lake sediment extract by both GC × GC coupled to quadrupole mass spectrometry (qMS) and GC × GC–HRTOFMS with T-SEN. While GC × GC–qMS with T-SEN resulted in false identification and inaccurate quantification, GC × GC–HRTOFMS with T-SEN provided correct identification and accurate quantification of compounds without sample pre-treatment. The differences between the values measured by GC × GC–HRTOFMS with T-SEN and the certified values for the certified reference material ranged from 7.3 to 36.9% for compounds with concentrations above the limit of quantification. False positives/negatives were not observed, except for when co-elution occurred. The technique of GC × GC–HRTOFMS in combination with T-SEN provides rapid and accurate screening and represents a powerful new approach for comprehensive analysis.     

Nickel Acetylacetonate-Induced 1,4-Additions of 1-Alkenyl(Disiamyl)Boranes to α,β-Unsaturated Ketones,Esters and Nitriles

The conjugate addition of 1-alkenyl(disiamyl)boranes to α,β-unsaturated ketones, esters, or nitriles was carried out in the presence of Ni(acac)₂ and triethylamine in DMF. The reactions provided γ,δ-unsaturated ketones, esters, and nitriles in high yields while retaining the original configuration of the 1-alkenylboranes. A similar addition reaction of 1-alkenyl(disiamyl)boranes to 1-acetyl-2-vinylcyclopropane produced the terminal and internal coupling products, 5,8-alkadien-2-on and 5-ethenyl-6-alken-2-on, in high yields in some cases with high regioselectivity favoring the terminal addition products.     

Synthesis of Arsenical Adduct: Synthesis and Transformation of Dimercapto Compound to Arsenical Adduct

Reaction of isothiocyanates with thioamide in presence of pyridine afforded 1,3-dimercapto substrates in good yield. Adipoin reacts with phenylarsine oxide and triphenylarsine to give the bicyclic 1,3,2-dioxarsole derivatives. A variety of 1,3,2-arsadithiolane derivatives were obtained by reaction of 1,3-dimercapto substrate with arsenic trioxide, phenylarsine oxide, triphenylarsine triphenylarsine oxide in ethanol or better in chloroform.     

Extended Hypervalent 5c–6e Interactions: Linear Alignment of Five C─Z- - -O- - -Z─C (Z = S,Se) Atoms in Anthraquinone and Anthracene Systems

Abstract

Structures of 1,8-(ArZ)₂C₁₄H₆O₂ and 9-(MeO)-1,8-(ArZ)₂C₁₄H₇ (Z = S, Se) are determined by X-ray crystallographic analysis. Five C─Z- - -O- - -Z─C atoms of the compounds align linearly, which are analyzed by the extended hypervalent 5c–6e model, based on QC calculations. CT of the 5c–6e occurs as the σ^*(C─Z) ← n _p (O)→ σ*(Z─C) direction.