Application of standard DFT theory for nonbonded interactions in soft matter: prototype study of poly-para-phenylene

We present a detailed analysis of the application of density functional theory (DFT) methods to the study of structural properties of molecular and supramolecular systems, using as a paradigmatic example three para-phenylene-based systems: isolated biphenyl, single chain poly-para-phenylene, and crystalline biphenyl. We use different functionals for the exchange correlation potential, the local density (LDA), and generalized gradient approximations (GGA), and also different basis sets expansions, localized, plane waves (PW), and mixed (localized plus PW), within the reciprocal space formulation for the hamiltonian. We find that regardless of the choice of basis functions, the GGA calculations yield larger interring distances and torsion angles than LDA. For the same XC approximation, the agreement between calculations with different basis functions lies within 1% (LDA) or 0.5% (GGA) for distances, and while PW and mixed basis calculations agree within 1 degrees for torsion angles, the localized basis results show larger angles by approximately 8 degrees and a nonmonotonic dependence on basis size, with differences within 6 degrees. The most prominent features, namely the torsion between rings for isolated molecule and infinite chain, and planarity for the molecule in crystalline environment, are well reproduced by all DFT calculations.     

密度泛函活性理论中的信息论方法

密度泛函活性理论(DFRT)运用简单的密度泛函探讨和定量化分子的反应活性,是近来发展起来的一个关于分子活性理论的新方法。在新近的文献中,这样的简单密度泛函的例子包括香农熵,费舍尔信息以及其它来自信息论中的密度泛函。本文综述了DFRT信息论方法的原理,包括物理信息极小原理、最小信息增益原理和信息守恒原理。总结了DFRT信息论方法在电子密度、形态密度和分子中的原子三种表述下的理论框架。此外,还介绍了运用信息论方法在定量描述空间位阻效应、亲电性、亲核性和区域选择性中的突出应用,以及对亲电芳香取代反应的邻对间位取代效应的起源和本质提供的一个全新诠释。最后简要地展望了该领域的几个可能的未来发展方向。     

Improved Thin‐Film Transistor Performance Through a Melt of Poly(para‐phenyleneethynylene)

The performance of polymer field‐effect transistors (PFETs) based on short rigid rod semiconducting poly(2,5‐didodecyloxy‐p‐phenyleneethynylene) (D‐OPPE) is highlighted. The controlled heating and cooling of thin films of D‐OPPE allows for a recrystallization from the melt, boosting the performance of D‐OPPE‐based transistors. The improved film properties induced by controlled annealing lead to a hole field‐effect mobility around 0.014 cm² V⁻¹ s⁻¹, an on/off ratio of 10⁶, a sub‐threshold swing of 3 V dec⁻¹ and a threshold voltage of −35 V, employing a poly(methyl methacrylate) (PMMA) gate dielectric. Thus, PFETs out of D‐OPPE compete now with spin‐coated, polycrystalline poly(3‐hexylthiophene)‐based PFETs.

     

Preparation,characterization and application of a new 25,27‐bis‐[2‐(5‐methylthiadiazole)thioethoxyl]‐26,28‐dihydroxy‐para‐tert‐butyl calix[4]arene stationary phase for HPLC

A new para‐tert‐butylcalix[4]arene column containing thiadiazole functional groups was prepared and used for the separation of polycyclic aromatic hydrocarbons, phenolic compounds, aromatic amines, benzoic acid and its derivatives by high‐performance liquid chromatography (HPLC). The effect of organic modifier content in the mobile phase on retention and selectivity of these compounds were investigated. The results indicate that the stationary phase behaves like reversed‐phase packing. However, hydrogen bonding, π–π and inclusion interactions seem to be involved in the separation process. The column has been successfully employed for the analysis of clenbuterol in pork and pig casing; the limit of detection and the limit of quantitation for this method by HPLC‐UV detection was 0.03 and 0.097 μg/mL, respectively; the method is demonstrated to be suitable and a competitive alternative analytical method for the determination of clenbuterol.     

三角柱直眼掏槽爆破参数研究

通过对三角柱直眼掏槽爆破进行试验研究 ,认为爆破槽腔的形成过程可分成两个阶段 ,即岩石破坏阶段和破碎岩石抛出阶段 ;进而 ,依照岩石压缩破坏与剪切破坏的力学准则 ,导出三角柱直眼掏槽炮眼间距与装药系数的计算式 ;根据计算结果 ,在井下巷道工程实际应用中进行对比 ,证实了它的可靠性。     

四(对-辛酰氧基)苯基卟啉配合物的红外光声光谱

测试并研究了四(对-辛酰氧基)苯基卟啉及其Mn(Ⅲ)、Fe(Ⅲ)、co(Ⅱ)、Ni(Ⅱ)、Cu(Ⅱ)、Zn(Ⅱ)配合物在3600～190cm^-1范围内的傅立叶变换红外光声光谱,对主要谱带进行了经验归属.结果表明:3318.0和968.0cm^-1处的吸收谱带分别是四(对-辛酰氧基)苯基卟啉N-H键的伸缩振动和面内弯曲振动,生成配合物后这些谱带消失.～243cm^-1处的吸收谱带是M-N键伸缩振动和卟啉环变形振动的复合振动,～320cm^-1处的吸收谱带是M-Cl键的伸缩振动,金属敏感带出现在1504,1350,1022,995,796和235cm^-1处.     

Direct assignment of positional isomers by mass spectrometry: ortho,meta and para acyl and amidyl anilines and phenols and derivatives

A direct MS/MS method for the ortho, meta or para configuration assignment of any single molecule that forms reference ions upon ionization and dissociation is demonstrated. Gas-phase structure diagnostic ion–molecule reactions with acetonitrile are shown to distinguish the isomeric 2-, 3- and 4-hydroxybenzoyl cations and the 2- from the 3- and 4-aminobenzoyl cations. These reference ions, which display indistinguishable 15 eV collision-induced dissociation product ion mass spectra, react with acetonitrile to yield characteristic ratios of product ions, most particularly for the 2-isomers. The reactivity of the 2-benzoyl cations is the most characteristic since the ortho configuration allows for [4⁺ + 2] polar cycloaddition that yields relatively stable heterocycles in N-protonated forms. Distinction of the reference isomeric 2-, 3- and 4-hydroxy- and aminobenzoyl cations permits, therefore, partially or completely, direct ‘MS-only’ positional assignment of either ortho, meta or para configuration for any single molecule that forms such reference ions upon ionization and dissociation. This “class-universal” method for direct MS assignment of a single positional isomer should therefore be applicable to many members of the homologous series of isomeric ortho, meta and para acyl and amidyl anilines and phenols and derivatives. Such molecules dissociate, or are likely to dissociate, after or during ionization processes to form the reference and structurally diagnostic ortho, meta or para hydroxy- or aminobenzoyl cations. Copyright © 2004 John Wiley & Sons, Ltd.     

Fabrication of ultra‐small ruthenium nanoparticles on porous modified reduced graphene oxide and its application in solvent‐free oxidation of cyclohexene with molecular oxygen

In the present work, ruthenium nanoparticles were synthesized on functionalized reduced graphene oxide (rGO). First, the surface of rGO was modified with two para‐arsanilic acid and dithiooxamide promoters to create the rGO with scattered hydrophilic positions. The ruthenium nanoparticles were synthesized and immobilized simultaneously in small hydrophilic micro‐reactors under mild conditions. Characterization of the synthesized nanocatalyst was confirmed with different techniques, such as transmission electron microscopy (TEM), X‐ray diffraction, Fourier transform‐infrared and scanning electron microscopy. TEM images of the synthesized catalyst show the Ru nanoparticles have diameters less than 6 nm. The designed nanocatalyst was investigated for the selective liquid phase oxidation of cyclohexene with molecular oxygen in an autoclave under solvent‐free conditions, which obtained a maximum of 91% conversion and 90% selectivity under optimized conditions. The catalytic activity over rGO‐AO‐TO/Ru recycled catalyst remained at a satisfactory state after at least five runs.     

An emerging post‐polymerization modification technique: The promise of thiol‐para‐fluoro click reaction

Post‐polymerization modification (PPM) of polymers is extremely beneficial in terms of designing brand new synthetic pathways toward functional complex polymers. Fortunately, the new developments in the field of organic chemistry along with controlled/living radical polymerization (CLRP) techniques have enabled scientists to readily design and synthesize the functionalized‐polymers for wide range of applications via the PPM. In this regard, the reactivity of para‐fluorine atom in the fluorinated aromatic structures toward the nucleophilic substitution reactions has made the polymers possessing this group to become a very strong candidate that can undergo efficient PPM. Besides, it has been proven that the thiol‐functionalized compounds react with the para‐fluorine atom of the pentafluorophenyl group more rapidly and efficiently than the amine‐ and the hydroxyl‐functionalized compounds. Furthermore, the milder experimental conditions to achieve quantitative conversions have led to the reaction between the thiol and the structures possessing pentafluorophenyl groups to be referred to as a click‐type reaction. Given this information, this review article aims to present the scientific developments regarding the thiol‐para‐fluoro “click” (TPF‐click) chemistry, and its impact on PPM to construct novel polymeric structures. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1181–1198     

Decoration Strategy in Para Boron Position: An Effective Way to Achieve Ideal Multi-Resonance Emitters

Narrowband, full-color, and quenching-resistant emitters are urgently needed for the next generation high-resolution displays. Though the flourishment of narrowband multiple resonance (MR) emitters in blue region, these materials still face thorny challenges such as effective light-color regulation strategies and concentration-induced spectral broadening/emission quenching. Herein, the research status of an effective “decoration strategy for para B position” is highlighted. On one hand, the introduction of an electron donor or acceptor could induce a hypsochromic- or bathochromic-shift emission, respectively, without undesirable FWHM broadening. On the other hand, a more advanced molecular motif is further proposed through adopting a peripheral benzene ring on the para position of the B-substituted phenyl in MR core to construct the high-purity, high-efficiency, quenching-resistant and stable MR emitters. Such concept is expected to provide a possible way for the modification, optimization and expansion of MR emitters to meet more possible applications.