Sample records for benzopyrroles

  1. Computational Design of a Family of Light-Driven Rotary Molecular Motors with Improved Quantum Efficiency. (United States)

    Nikiforov, Alexander; Gamez, Jose A; Thiel, Walter; Filatov, Michael


    Two new light-driven molecular rotary motors based on the N-alkylated indanylidene benzopyrrole frameworks are proposed and studied using quantum chemical calculations and nonadiabatic molecular dynamics simulations. These new motors perform pure axial rotation, and the photochemical steps of the rotary cycle are dominated by the fast bond-length-alternation motion that enables ultrafast access to the S1/S0 intersection. The new motors are predicted to display a quantum efficiency higher than that of the currently available synthetic all-hydrocarbon motors. Remarkably, the quantum efficiency is not governed by the topography (peaked versus sloped) of the minimum-energy conical intersection, whereas the S1 decay time depends on the topography as well as on the energy of the intersection relative to the S1 minimum. It is the axial chirality (helicity), rather than the point chirality, that controls the sense of rotation of the motor.

  2. Dynamics of copper-phthalocyanine molecules on Au/Ge(001)

    Energy Technology Data Exchange (ETDEWEB)

    Sotthewes, K.; Heimbuch, R.; Zandvliet, H. J. W. [Physics of Interfaces and Nanomaterials, MESA" + Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands)


    Spatially resolved current-time scanning tunneling spectroscopy combined with current-distance spectroscopy has been used to characterize the dynamic behavior of copper-phthalocyanine (CuPc) molecules adsorbed on a Au-modified Ge(001) surface. The analyzed CuPc molecules are adsorbed in a “molecular bridge” configuration, where two benzopyrrole groups (lobes) are connected to a Au-induced nanowire, whereas the other two lobes are connected to the adjacent nanowire. Three types of lobe configurations are found: a bright lobe, a dim lobe, and a fuzzy lobe. The dim and fuzzy lobes exhibit a well-defined switching behavior between two discrete levels, while the bright lobe shows a broad oscillation band. The observed dynamic behavior is induced by electrons that are injected into the LUMO+1 orbital of the CuPc molecule. By precisely adjusting the tip-molecule distance, the switching frequency of the lobes can be tuned accurately.

  3. NMR screening of new carbocyanine dyes as ligands for affinity chromatography. (United States)

    Cruz, Carla; Boto, Renato E F; Drzazga, Anna K; Almeida, Paulo; Queiroz, João A


    Four new carbocyanines containing symmetric and asymmetric heterocyclic moieties and N-carboxyalkyl groups have been synthesized and characterized. The binding mechanism established between these cyanines and several proteins was evaluated using saturation transfer difference (STD) NMR. The results obtained for the different dyes revealed a specific interaction to the standard proteins lysozyme, α-chymotrypsin, ribonuclease (RNase), bovine serum albumin (BSA), and gamma globulin. For instance, the two un-substituted symmetrical dyes (cyanines 1 and 3) interacted preferentially through its benzopyrrole and dibenzopyrrole units with lysozyme, α-chymotrypsin, and RNase, whereas the symmetric disulfocyanine dye (cyanine 2) bound BSA and gamma globulin through its carboxyalkyl chains. On the other hand, the asymmetric dye (cyanine 4) interacts with lysozyme and α-chymotrypsin through benzothiazole moiety and with RNase through dibenzopyrrole unit. Thus, STD-NMR technique was successfully used to screen cyanine-protein interactions and determine potential binding sites of the cyanines for posterior use as ligands in affinity chromatography.

  4. [Coupling of gas chromatography with single photon ionization time-of-flight mass spectrometry and its application to characterization of compounds in diesel]. (United States)

    Xie, Yuanyuan; Hua, Lei; Chen, Ping; Hou, Keyong; Jiang, Jichun; Wang, Yan; Li, Haiyang


    A novel analytical method coupling gas chromatography (GC) with single photon ionization time-of-flight mass spectrometry (SPI-TOF MS) has been developed. First of all, a double-wall-tube transfer line was built to combine GC with SPI-TOF MS, which realized seamless connection between GC and SPI ion source. Based on this, standard n-pentadecane and benzene/toluene/xylene standard gas mixtures were used to study important voltage parameters of the ion source. After the optimization of the ion source voltages, pure molecular ion peaks of the analytes were obtained in the mass spectra and qualitative analysis of different kinds of organic compounds were eventually realized rapidly and accurately. At last, GC/SPI-TOF MS was applied to the characterization of volatile and semvolatile organic compounds in diesel and two-dimensional spectra of GC×SPI-TOF MS were obtained. Without complicated spectra interpretation and data processing, volatile and semi-volatile organic compounds in diesel have been classified qualitatively by ion mass-to-charge ratio (m/z) in SPI mass spectra, including aliphatic compounds, aromatic compounds and nitrogen-containing compounds with low concentration such as benzopyrroles. Isomeric compounds in diesel were separated and identified by retention times of chromatographic peaks. The results indicate that the proposed analytical method of GC/SPI-TOF MS is suitable for the characterization of complicated samples such as diesel and environmental pollutants with easy operation and high efficiency.

  5. Methyl Anthranilate as a Repellent for Western Corn Rootworm Larvae (Coleoptera: Chrysomelidae). (United States)

    Bernklau, E J; Hibbard, B E; Norton, A P; Bjostad, L B


    Methyl anthranilate was identified as the active compound in extracts of maize (Zea mays L.) roots that were shown to be repellent to neonate western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae. A bioassay-driven approach was used to isolate the active material from diethyl ether extracts of roots from germinating maize seeds. Separation of the extract on a Florisil column yielded an active fraction of 90:10 hexane:diethyl ether. Analysis with gas chromatography-mass spectrometry identified two compounds in the active fraction: indole (2,3-benzopyrrole) and methyl anthranilate (methyl 2-aminobenzoate). When tested in behavioral bioassays, methyl anthranilate elicited a significant (P repellent response at doses of 1, 10, and 100 µg. In subsequent single-choice bioassays, 1, 10, and 100 µg of methyl anthranilate prevented larvae from approaching 10 mmol/mol concentrations of carbon dioxide, which is normally highly attractive to the larvae. Indole, the other compound identified from the active fraction, did not elicit a behavioral response by the larvae. Methyl anthranilate has potential for development as a management tool for western corn rootworm larvae and may be best suited for use in a push-pull control strategy.

  6. 畜禽粪便中抗生素抗性基因(ARGs)污染问题及环境调控%Pollution and Environmental Regulation of Antibiotic Resistance Genes(ARGs)in Livestock Manure

    Institute of Scientific and Technical Information of China (English)

    邹威; 罗义; 周启星


    There are increasing concerns about contamination of antibiotic resistance genes(ARGs)due to extensive uses of antibiotics in livestock and poultry breeding industries. After having induced in animal guts, antibiotic resistance bacteria are excreted via feces and then enter into soil environment through horizontal gene transfers, thus increasing the risk of ARGs propagation in soil and groundwater. It is un-known whether composting, a traditional method for utilization of animal wastes, could eliminate ARGs. This article summarized the current pollution situation of ARGs in livestock manure, and reviewed the changes of microbial community structure and their influencing factors and the dynamics of ARGs during composting. It is recommended that composting could be used as an effective way to reduce ARGs. During composting, high temperature could effectively kill antibiotic resistance bacteria and plasmids. Also chemical inhibitors such as lime nitro-gen, amine and benzopyrrole could directly diminish enteric microorganisms, thus decreasing the abundance of ARGs. It is necessary to car-ry out a comprehensive research on ARGs removal through composting to mitigate the propagation of ARGs in the environment.%抗生素在畜禽养殖业的大量使用造成抗生素抗性基因(ARGs)污染日益严重。动物体内诱导出的抗性菌株随粪便排出后,通过基因水平转移进入土壤进而污染土壤和地下水环境。堆肥作为一种将粪便资源化的优良传统方法,能否有效去除畜禽粪便中的ARGs而防止环境污染值得探讨。通过总结畜禽粪便ARGs污染现状,粪便堆肥过程中微生物群落结构变化与影响微生物变化的因素以及堆肥可能对粪便中ARGs造成的影响,提出将堆肥作为去除畜禽粪便中ARGs的一种有效手段,利用堆肥产生的高温去除抗性菌株和抗性质粒等,并且考虑加入能直接灭杀肠道微生物的化学抑制剂(如石灰氮、胺类、