Computational design of organometallic oligomers featuring 1,3-metal-carbon bonding and planar tetracoordinate carbon atoms.

Density functional theory computations (B3LYP) have been used to explore the chemistry of titanium-aromatic carbon "edge complexes" with 1,3-metal-carbon (1,3-MC) bonding between Ti and planar tetracoordinate Cß . The titanium-coordinated, end-capping chlorides are replaced with OH or SH groups to afford two series of difunctional monomers that can undergo condensation to form oxide- and sulfide-bridged oligomers. The sulfide-linked oligomers have less molecular strain and are more exergonic than the corresponding oxide-linked oligomers. The HOMO-LUMO gap of the oligomers varies with their composition and decreases with growing oligomer chain. This theoretical study is intended to enrich 1,3-MC bonding and planar tetracoordinate carbon chemistry and provide interesting ideas to experimentalists. Organometallic complexes with the TiE2 (E = OH and SH) decoration on the edge of aromatic hydrocarbons have been computationally designed, which feature 1,3-metal-carbon (1,3-MC) bonding between titanium and planar tetracoordinate ß-carbon. Condensation of these difunctional monomers by eliminating small molecules (H2O and H2S) produce chain-like oligomers. The HOMO-LUMO gaps of the oligomers decreases with growing oligomer chain, a trend that suggests possible semiconductor properties for oligomers with longer chains.

Linear, planar, and tubular molecular structures constructed by double planar tetracoordinate carbon D2hC2(BeH)4 species via hydrogen-bridged -BeH2Be- bonds.

This computational study identifies the rhombic D2hC2 (BeH)4 (2a) to be a species featuring double planar tetracoordinate carbons (ptCs). Aromaticity and the peripheral BeBeBeBe bonding around CC core contribute to the stabilization of the ptC structure. Although the ptC structure is not a global minimum, its high kinetic stability and its distinct feature of having a bonded C2 core from having two separated carbon atoms in the global minimum and other low-lying minima could make the ptC structure to be preferred if the carbon source is dominated by C2 species. The electron deficiency of the BeH group allows the ptC species to serve as building blocks to construct large/nanostructures, such as linear chains, planar sheets, and tubes, via intermolecular hydrogen-bridged bonds (HBBs). Formation of one HBB bond releases more than 30.0 kcal/mol of energy, implying the highly exothermic formation processes and the possibility to synthesize these nano-size structures.

2-[(E)-(4-Bromo-phenyl)imino-methyl]-4-chloro-phenol.

In the title compound, C13H9BrClNO, the dihedral angle between the substituted benzene rings is 44.25 (11)°. There are strong intra-molecular O-H⋯N hydrogen bonds, which generate S(6) rings, and also inter-molecular Cl⋯Cl [3.431 (3) Å] and Br⋯ Br [3.846 (1) Å] contacts. The crystal packing a C-H⋯O and C-H⋯π inter-actions.

4-[(5-Chloro-2-hy-droxy-benzyl-idene)amino]-3-ethyl-1H-1,2,4-triazole-5(4H)-thione.

The title compound, C11H11ClN4OS, crystallizes with two mol-ecules, A and B, in the asymmetric unit in which the dihedral angles between the triazole and benzene rings are 54.6 (3) and 56.0 (3)°. Both mol-ecules feature an intra-molecular O-H⋯N hydrogen bond, which generates an S(6) ring. In the crystal, A-B dimers are linked by pairs of weak C-H⋯S hydrogen bonds along with π-π stacking inter-actions between the triazole rings [centroid-centroid separations = 3.631 (3) and 3.981 (4)Å]. N-H⋯S hydrogen bonds link the dimers into [100] chains, which feature R 2 (2)(8) loops.

4-[(5-Bromo-2-hy-droxy-benzyl-idene)amino]-3-ethyl-1H-1,2,4-triazole-5(4H)-thione.

The title compound, C11H11BrN4OS, crystallized as a racemic twin with two symmetry-independent mol-ecules in the asymmetric unit. The dihedral angles between the benzene and triazole rings of the two independent mol-ecules are 56.41 (18) and 54.48 (18)°. An intra-molecular O-H⋯N hydrogen bond occurs in each mol-ecule. In the crystal, pairs of symmetry-independent mol-ecules are linked by pairs of almost linear N-H⋯S hydrogen bonds, forming cyclic dimers characterized by an R 2 (2)(8) motif. There are weak π-π inter-actions between the benzene rings of symmetry-independent mol-ecules, with a centroid-centroid distance of 3.874 (3) Å.

The ATP-binding cassette transporter subfamily G member 4 mediates cuticular hydrocarbon transport to regulate drought tolerance in Acyrthosiphon pisum.

ABC transporters are a highly conserved membrane protein class that promote the transport of substances across membranes. Under drought conditions, insects primarily regulate the content of cuticular hydrocarbon (CHC) to retain water and prevent evaporative loss. Involvement of ABC transporter protein G (ABCG) subfamily genes in insect CHC transport has been relatively understudied. In this study, we demonstrated that ABCG4 gene in Acyrthosiphon pisum (ApABCG4) is involved in CHC transport and affects drought tolerance by regulating CHC accumulation. ApABCG4 is strongly expressed in the abdominal cuticle and embryonic stages of A. pisum. Effective silencing of ApABCG4 was achieved using RNAi, and the silencing duration was analyzed. ApABCG4 silencing resulted in a significant decrease in the total and component contents of the CHC and cuticular waxy coatings of A. pisum. Nevertheless, the internal hydrocarbon content remained unchanged. The lack of cuticular hydrocarbons significantly reduced the drought tolerance of A. pisum, shortening its survival time under drought stress. Drought stress caused significant upregulation of ApABCG4. Molecular docking showed that ApABCG4 has a high binding affinity for nine n-alkanes of CHC through electrostatic interactions. These results indicate that ApABCG4 is a novel RNAi target with key applications in aphid biological control.

4-[(5-Bromo-2-hy-droxy-benzyl-idene)amino]-3-propyl-1H-1,2,4-triazole-5(4H)-thione.

The asymmetric unit of the title compound, C(12)H(13)BrN(4)OS, contains two independent mol-ecules in which the dihedral angles between the triazole and benzene rings are 2.9 (3) and 7.5 (3)°. The thione group is of the form R(2)C=S. An intra-molecular O-H⋯N hydrogen bond occurs in each mol-ecule. The crystal structure features weak N-H⋯S inter-actions and π-π stacking of the benzene rings [centroid-centroid distance = 3.667 (3) Å].

Nine new species of Cnodalonini (Coleoptera: Tenebrionidae) from Hainan Island, with additional records of other Tenebrionidae.

Seven known species of Tenebrionidae are recorded from Hainan Island, of which six species are recorded from this island for the first time. Also nine new species of Cnodalonini are described from Hainan Is. under the names of Androsus pullus sp. n., Euhemicera hirtipes sp. n., Gnesis amabilis sp. n., Hemicera (Hemicera) viridula sp. n., Plamius laoshei sp. n., Pseudonautes fulgidicollis sp. n., Taichius caeruleopunctatus sp. n., Tetragonomenes sylvestris sp. n. and Tetraphyllus hlaicolus sp. n.

[Hypoxia increases the expression of heparitinase and the invasiveness through the hypoxia inducible factor-1alpha dependent pathway in human ovarian cancer cell line SKOV3].

OBJECTIVE: To investigate the heparitinase (HPA) expression and cell invasiveness in human ovarian cancer cell line SKOV3 during hypoxia, and explore their relationship with hypoxia inducible factor-1alpha (HIF-1alpha). METHODS: SKOV3 cells were incubated with normoxia, hypoxia, and hypoxia plus rapamycin, respectively. SKOV3 cells of hypoxia group were incubated in 5% CO2 + 1% O2. Cells in hypoxia plus rapamycin group were incubated with 10 ng/ml of rapamycin before cultured under hypoxic condition. Cells in each group were collected for analysis after incubated with hypoxia for 12, 24, and 36 hours, respectively. Western blotting and RT-PCR were performed to detect the expressions of HIF-1alpha and HPA. Cell invasiveness was measured by matrigel invasion assay. RESULTS: Western blotting showed that the expression of HIF-1alpha significantly increased compared with normoxic group (P < 0.05). However, hypoxia had no obvious impact on HIF-1alpha mRNA expression. The expressions of HPA protein and mRNA of SKOV3 cells of hypoxia group were significantly higher than normoxic group (P < 0.05). The up-regulation of HPA expression in hypoxic group decreased after the utilization of rapamycin. The cell invasion of hypoxic group was significantly higher than that of normoxic group (P < 0.05); meanwhile, the expression of HPA was positively correlated with the invasiveness of SKOV3 cells (r = 0.9863, P < 0.05). CONCLUSION: Hypoxia may promote the expression of HPA and the invasiveness of SKOV3 cells through the HIF-1alpha pathway, which plays an important role in the pathogenesis of ovarian cancer.

[Study on the spectral properties of caffeic acid and its derivatives].

Caffeic acid, chlorogenic acid and forsythiaside are active components of Chinese herbs and have diverse biological activities. As the similar compounds, they all include 3, 4-dihydroxy-phenyl in their structures. In this paper, the fluorescence and UV spectra of the caffeic acid, chlorogenic acid and forsythiaside were studied in different pH. The spectra properties of fluorescence and UV were further discussed in view of the phenol hydroxyl states, free, dissociative and protonated. It is found that the luminescence intensity, the peak shape and peak wavelength change with pH. Experimental results also indicate that caffeic acid, chlorogenic acid and forsythiaside can emit fluorescence in wide range of pH (2-12), and fluorescent intensity is enhanced as the dissociation of 4-phenol hydroxyl. On the other hand, fluorescent intensity may be quenched as the dissociation of 3-phenol hydroxyl. Furthermore, in strong acidic or in strong basic media, the fluorescence is quenched partly, and the shape of UV spectra changed greatly in strong basic media, meaning that their molecular structures are changed considerable.

Two new species of the Stenochinus amplus species-group from China (Coleoptera, Tenebrionidae, Stenochiini).

Two new species of the Stenochinus amplus species-group are described, S. apiciconcavus sp. n. (CHINA: Shaanxi) and S. xinyicus sp. n. (CHINA: Guangdong). Also, some new distribution data are provided for S. cylindricus (Gebien, 1914), and a key to the seven species of the S. amplus species-group from China is given.

Note on brachypterous Stenochiini from China (Coleoptera, Tenebrionidae) with description of a new species.

A checklist of 29 brachypterous species in the tenebrionid tribe Stenochiini is given for China and neighboring countries. A new species is described and illustrated under the name of Strongylium liangi sp. n. (CHINA: Yunnan). Also, some new distribution data is provided for S. claudum (Gebien, 1914), and a distribution map of all Strongylium species in the checklist is presented.

A new electrochemical sensor of nitro aromatic compound based on three-dimensional porous Pt-Pd nanoparticles supported by graphene-multiwalled carbon nanotube composite.

In this study, an electrochemical sensor of nitro aromatic compound based on three-dimensional porous Pt-Pd nanoparticles (Pt-Pd NPs) supported by reduced graphene oxide (rGO) nanosheets-multiwalled carbon nanotube (CNTs) nanocomposite (marked as Pt-Pd NPs/CNTs-rGO) was investigated for the first time. This hybrid nanocomposite has been prepared via a facile and versatile hydrothermal synthetic strategy while its structure and property are evaluated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS). The result shows that 3D porous Pt-Pd NPs/CNTs-rGO nanocomposite has a large specific surface area of 326.6m(2)g(-1) and exhibited ultrahigh rate capability and good cycling properties at high rates. Electrochemical studies have been performed for the nitro aromatic compounds detection by using different pulse voltammetry (DPV) techniques. The proposed nanocomposite exhibited much enhanced elctrocatalytic activity and high sensitivity toward the detection of nitro aromatic compounds which compared with Pt-Pd NPs dispersed on functionalized rGO, Pt-Pd NPs dispersed on functionalized CNTs, rGO-CNTs and bare glass carbon electrode (GCE). On the basis of the above synergetic electrochemical sensing and synthesis procedure, the hybrid material can be recommended as a robust material for sensor-related applications. Moreover, the proposed sensor exhibits high reproducibility, long-time storage stability and satisfactory anti-interference ability.