Taming Charge Transport in Semiconducting Polymers with Branched Alkyl Side Chains

The solid‐state packing and polymer orientation relative to the substrate are key properties to control in order to achieve high charge carrier mobilities in organic field effect transistors (OFET). Intuitively, shorter side chains are expected to yield higher charge carrier mobilities because of a denser solid state packing motif and a higher ratio of charge transport moieties. However our findings suggest that the polymer chain orientation plays a crucial role in high‐performing diketopyrrolopyrrole‐based polymers. By synthesizing a series of DPP‐based polymers with different branched alkyl side chain lengths, it is shown that the polymer orientation depends on the branched alkyl chain lengths and that the highest carrier mobilities are obtained only if the polymer adopts a mixed face‐on/edge‐on orientation, which allows the formation of 3D carrier channels in an otherwise edge‐on‐oriented polymer chain network. Time‐of‐flight measurements performed on the various polymer films support this hypothesis by showing higher out‐of‐plane carrier mobilities for the partially face‐on‐oriented polymers. Additionally, a favorable morphology is mimicked by blending a face‐on polymer into an exclusively edge‐on oriented polymer, resulting in higher charge carrier mobilities and opening up a new avenue for the fabrication of high performing OFET devices.     

Field‐Induced n‐Doping of Black Phosphorus for CMOS Compatible 2D Logic Electronics with High Electron Mobility

Black phosphorus (BP) has been considered as a promising two‐dimensional (2D) semiconductor beyond graphene owning to its tunable direct bandgap and high carrier mobility. However, the hole‐transport‐dominated characteristic limits the application of BP in versatile electronics. Here, we report a stable and complementary metal oxide semiconductor (COMS) compatible electron doping method for BP, which is realized with the strong field‐induced effect from the K⁺ center of the silicon nitride (Si_xN_y). An obvious change from pristine p‐type BP to n type is observed after the deposit of the Si_xN_y on the BP surface. This electron doping can be kept stable for over 1 month and capable of improving the electron mobility of BP towards as high as ~176 cm² V^–1 s^–1. Moreover, high‐performance in‐plane BP p‐n diode and further logic inverter were realized by utilizing the n‐doping approach. The BP p‐n diode exhibits a high rectifying ratio of ~10⁴. And, a successful transfer of the output voltage from “High” to “Low” with very few voltage loss at various working frequencies were also demonstrated with the constructed BP inverter. Our findings paves the way for the success of COMS compatible technique for BP‐based nanoelectronics.     

Assembly of isoquinolines via CuI-catalyzed coupling of beta-keto esters and 2-halobenzylamines

CuI-catalyzed coupling of 2-halobenzylamines with beta-keto esters or 1,3-diketones in i-PrOH under the action of K(2)CO(3) produced 1,2-dihydroisoquinolines as the coupling/condensative cyclization products, which underwent smooth dehydrogenation under air atmosphere to afford substituted isoquinolines.     

Hypothesis of active components in volatile oil from a Chinese herb formulation, 'Shao-Fu-Zhu-Yu decoction', using GC-MS and chemometrics

Traditional Chinese medicine (TCM) with few or no side effects has increasingly attracted attention all over the world. However, the bioactive components and the therapeutic mechanisms are usually not understood because of the complex chemical compositions of these medicines. In this paper, GC-MS coupled with a chemometric method was developed for analysis of active components in volatile oil from a Chinese herb formulation, "Shao-Fu-Zhu-Yu Decoction". The volatile oils, obtained by hydrodistillation from "Shao-Fu-Zhu-Yu Decoction" (SFZYD) and its constituent herbs with abundant volatile oil (Angelica sinensis, Ligusticum chuanxiong, Cinnamomum cassia, Foeniculum vulgare, Zingiber officinale), were chemically analyzed using GC-MS and bioassayed using oxytocin-induced uterine contraction assay in vitro. Then, a mathematic model relating the chemical compositions and their activities in inhibiting mice uterine contraction was established for hypothesis of the bioactive compounds based on chemometrics. As a result, nine compounds which might contribute to the inhibition of oxytocin-induced uterine contraction were selected, and the activities of some of them were further confirmed by our experiments and/or the literature. The data suggest that the developed method is helpful for screening bioactive components from complex mixtures, such as the extracts of TCM.     

Synthesis and fungicidal activity of novel 3,5-diarylpyrazole derivatives

(E)-3-(2-chlorophenyl)-1-(2,4-dichlorophenyl) prop-2-en-1-one was prepared from 2-chlorobenzaldehyde followed by cyclization with hydrazine monohydrate. Eight new 3-(2,4-Di-chlorophenyl)-5-(2-chlorophenyl)-4,5-dihydro-N-acylpyrazole derivatives were synthesized and characterized by elemental analysis, IR and ¹H NMR spectroscopy. The experimental results show that the inhibition ratio of compounds 3f towards H. Oryzae and P. oryzae at 50 mg·L⁻¹ is 55.2% and 57.1%, respectively. The inhibition ratio of compounds 3g towards H. Oryzae, P. oryza, S. Sclerotiorum at 50 mg·L⁻¹ is 53.3%, 60.0%, 50.4% respectively. __________ Translated from Chinese Journal of Applied Chemistry, 2007, 27(7): 835–837     

On meromorphic solutions of f 3 + g 3 = 1

We show that meromorphic solutions f, g of f ³ + g ³ = 1 in must be constant, if and have the same zeros (counting multiplicities). Received: 12 March 2007     

An organic p-type dopant with high thermal stability for an organic semiconductor

To overcome the thermal instability of a p-doped organic hole transporting layer using the state-of-the-art p-type dopant, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, a potent electron accepter, 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane, has been found to possess superior thermal stability and proved to be an excellent p-type dopant.     

Effect of swift heavy ions in Ni-Al nanocrystalline films studied by X-ray absorption spectroscopy

X-ray absorption spectroscopic measurements have been used to compare the electronic structures of swift heavy ions (100 MeV Si ions) irradiated and pristine Ni-Al nanocrystalline films. Results from X-ray diffraction (XRD), X-ray absorption near-edge structure (XANES) spectra at Al K-, and Ni L(2,3)-edges and extended X-ray absorption fine structure (EXAFS) at Ni K-edges are discussed. The observed XRD peaks indicate the improvement of crystalline nature and Al(111) clustering after the swift heavy ion interactions. While the XANES spectra at Ni L(2,3)-edges show decrease in the intensity of white line strength, the Al K-edge shows increase in intensity after irradiation. Above results imply that swift heavy ions induce low Z (i.e., Al) ion mass transport, changes in Al sp-Ni-d hybridization, and charge transfer. EXAFS results show that crystalline nature is improved after swift heavy irradiation which is consistent with XRD results.     

Separation of aromatic acids by wide-bore electrophoresis with nanoparticles prepared by electrospray as pseudostationary phase

A model mixture of six aromatic acids has been separated using a laboratory-made wide-bore electrophoretic device with aminopropyl-modified nanoparticles used as pseudostationary phase. Optimization of preparation of nanoparticles by an electrospray (ES) method is described. With the optimized electrophoretic method, 30 mmol/L acetate running buffer, pH 4.5, containing 1.0 mg/mL of nanoparticles as an additive was used, and 3.0 kV applied potential, improved resolution was achieved. The average theoretical plate number obtained was above 5.0 x 10(4) theoretical plates per meter with the highest value achieved in certain runs exceeding 1.0 x 10(5) theoretical plates per meter, which was better than previously reported results (approximately 6.7 x 10(4) theoretical plates per meter). Furthermore, repeatabilities of 2, 6.5, and 6% were obtained for the migration time, peak areas, and peak height, respectively. Additionally, sample capacity and sensitivity were improved by hundredfold using the novel wide-bore electrophoresis system compared to traditional CE.