The production of hydrocarbons from photoautotrophic growth ofDunaliella salina 1650

Microalga,Dunaliella salina 1650 was selected to produce hydrocarbons that may possibly substitute for fossil fuels in the near future. It can produce 0.22 (mg/L) of hydrocarbons over 20 d batch cultivation, maintaining 1.32 (g-dry wt./L) of cell density. Its productivity was similar to that fromBotryococcus braunii, which was known to economically produce liquid fuels. Optimal growth conditions for the alga were also determined as pH 7.2, 28°C, and 0.00034 (Kcal/cm²/h) of light intensity. It was shown that the hydrocarbon production from the alga was closely related to cell growth, except for the later periods of batch cultivation. Better hydrocarbon production was observed during light periods in light/dark cycle cultivation. Under chemostat conditions, maximum steady cell concentration was maintained as 1.1 (g-dry wt./L) at 0.12 (1/d) of dilution rate. The system reached to the steady state after 30 d of the cultivation. The maximum specific hydrocarbon production rate, 0.024 (mg/cell/d) was also obtained under this condition. It proves that the hydrocarbon production fromD. salina 1650 can compete with that fromB. braunii. Index Entries: Algal hydrocarbon production; photoautotrophic growth;Dunaliella salina     

Synthesis and characterization of mononuclear copper(II) and cadmium(II) complexes with di-(2-picolyl)sulfur

The reaction of Cu(ClO₄)₂·6H₂O and Cd(ClO₄)₂ with di-(2-picolyl)sulfur (dps) leads to the formation of mononuclear complexes [Cu(dps)(H₂O)(ClO₄)](ClO₄) (1) and [Cd(dps)₂](ClO₄)₂ (2). The crystal structure of 1 exhibits a distorted square pyramidal geometry, coordinated by one sulfur and two nitrogen atoms from the dps ligand, one water molecule and one perchlorate oxygen atom. For 2, the environment around cadmium atom is in a distorted octahedron with four nitrogen and two sulfur atoms from the dps ligand. Cyclic voltammetric data show that complexes undergo two waves of a one-electron transfer corresponding to M(II)/M(III) and M(II)/M(I) processes. Spectral and electrochemical behaviors of the complexes are also discussed.     

Synthesis and characterization of copper(II) hexaazamacrotetracyclic complexes containing organic ligands

Two mononuclear copper(II) complexes [Cu(L)(NO₂)](ClO₄) (1) and [Cu(L)(MO₄)]₂· 5H₂O (2) (L = 1,3,10, 12,16,19-hexaazatetracyclo[17,3,1,1^12.16,0^4.9]tetracosane) have been synthesized and their structures determined. Both compounds show a distorted square-pyramidal geometry with the two secondary and two tertiary amines of the macrocycle and one ligand coordinated at the axial position. Cyclic voltammetry of the complexes gives two one-electron waves corresponding to Cu^II/Cu^III and Cu^II/Cu^I processes. The electronic spectra and electrochemical behavior of the complexes are significantly affected by the nature of the organic ligands.     

Bis[3,6-bis(6-methyl-2-pyridyl)pyridazine-κ2N2,N3]chlorocopper(II) perchlorate

The title compound, [CuCl(C₁₆H₁₄N₄)₂]ClO₄, consists of a mononuclear complex cation and a perchlorate anion. The coordination of the copper(II) ion exhibits a trigonal bipyramidal geometry, where the equatorial plane is composed of the Cl atom and two N atoms of the two pyridazine rings, and the axial positions are occupied by the N atoms of two methyl­pyridine rings.     

Unidirectional adsorbate motion on a high-symmetry surface: "walking" molecules can stay the course

Step edges and low-symmetry faces of metal crystals can restrict the diffusive motion of adsorbates, yet they offer little flexibility with regards to the location and/or direction of the guided motion. We show inherently unidirectional motion of an organic molecule on a high-symmetry thermodynamic-equilibrium metal surface [Cu(111)]. Sequential placement of the substrate linkers of 9,10-dithioanthracene prevents it from rotating or veering off course. A combination of low temperature scanning tunneling microscopy and density functional theory simulations provide atomistic insight.     

Self-assembly of copper(II) tetraaza macrocyclic complex with cyclohexane-1,3-dicarboxylic acid-5-monocarboxylate linked by hydrogen bond

A novel complex with the composition {[Cu(L)](Cl)(H,H-cdc)(H₂O)} _n (1) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane; H,H-cdc = cyclohexane-1,3-dicarboxylic acid-5-monocarboxylate) has been synthesized and structurally characterized by X-ray diffraction method. It crystallizes in the monoclinic system P2₁/n with a = 9.507(9), b = 12.624(3), c = 26.922(4) Å, = 96.79(1)°, V = 3208(3) ų, Z = 4. The complex contains a 1D hydrogen-bonded polymeric chain with copper(II) macrocycle and bridging H,H-cdc ligand. The copper(II) coordination geometry is best described as a square-plane with four Cu–N bonds. The weak interaction between copper(II) ion and the chloride ion is also found.     

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Index Abstracts     

GC/MS combined with chemometrics methods for quality control of Schizonepeta tenuifolia Briq: Determination of essential oils

A simple and rapid gas chromatography/mass spectrometry (GC/MS) analysis method was developed for the determination of essential oils in the crude extract of Schizonepeta tenuifolia Briq (Sch.t.Briq). Five major volatiles (menthone, pulegone, 2-hydroxy-2-isopropenyl-5-methylcylohexanone, cis-pulegone oxide, and schizonal) were extracted and isolated from Sch.t.Briq as marker compounds for use in the quality control of herbal medicines. Various extraction techniques, such as solvent immersion, mechanical shaking, and sonication, were evaluated, and the greatest efficiency was observed with sonication extraction using petroleum ether. The dynamic range of the GC/MS method depended on the specific analyte; acceptable quantification was obtained between 10 and 1000 μg/mL for menthone and pulegone, and between 2.5 and 75.0 μg/mL for 2-hydroxy-2-isopropenyl-5-methylcylohexanone, cis-pulegone oxide, and schizonal. The method was deemed satisfactory by inter- and intra-day validation and exhibited both high accuracy and precision, with a relative standard deviation < 10%. Overall limits of detection were approximately 0.40–0.50 μg/mL, with a standard deviation (σ)-to-calibration slope (s) ratio (σ/s) of 3. The limit of quantitation in our experiments was approximately 2.5 μg/mL at a σ/s of 10. On the basement of method validation, 21 samples of Sch.t.Briq collected from markets in Korea were monitored for the quality control. In addition, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were performed on the analytical data of 21 different Sch.t.Briq samples in order to classify samples that were collected from different regions.     

Surface modification of hydroxyapatite for hydrogen generation

Hydrogen provides a safe and clean alternative to carbon-based fuels. Having the proper catalytic support for production of hydrogen is a valuable technology. We report on the surface modification of hydroxyapatite as a novel catalytic support material for hydrogen generation. Aside from being inexpensive and durable, we reveal that Ru ion exchange on the HAP surface provides a highly active support for sodium borohydride hydrolysis, exemplifying a high total turnover number on the order of 24,000 mol H(2)/mol Ru. Moreover, we observe that the RuHAP support exhibits a long catalytic lifetime of approximately 1month upon repeated exposure to NaBH(4) solutions. We identified the ability of complex surface morphology to enhance hydrolysis by the catalytic transition metal covered surface. Particularly, we found that the complex morphology of polycrystalline RuHAP catalytic supports exhibits shorter induction times for hydrogen generation as well as improved reaction rates as compared with single crystal supports possessing the same Ru content. By decreasing induction time and enhancing catalytic activity, we find it feasible to further explore this catalyst support in the construction of a practical hydrogen generation system.     

Reporting a new class of divanadium(V) compounds connected by an unsupported hydroxo bridge

Dinuclear oxovanadium(V) compounds [LV(V)O(mu-OH)OV (V)L](PF6) [H2L = N,N'-tert-ethylene bis(salicylideneimine) (H 2Salen) and its derivatives] ( 1- 3) have been obtained by aerial oxidation of V (IV)OL precursors in THF in the presence of added NH 4PF 6. The oxidized vanadium(V) probably extracts an OH (-) ligand from the residual moisture in the solvent and is retained as an unsupported hydroxo-bridge between the metal centers of these compounds as confirmed by single-crystal X-ray diffraction analyses. The molecules of 1- 3 have centrosymmetric structures with each vanadium center having a distorted octahedral geometry. The bridging OH (-) group is located trans to the terminal VO t bond. The latter exerts strong trans labilizing influence to set the participating vanadium centers apart by about 4.1 A. These separations are by far the largest (e.g., V...V#, 4.131 A in 1) among all binuclear compounds containing an unsupported hydroxo bridge reported to date. The complexes retain their identity also in solution as established by (1)H NMR spectroscopy. Electrochemically, the behaviors of 1-3 are quite interesting as studied by cyclic voltammetry in acetonitrile, each undergoing three (except 3) nearly reversible metal-based reductions, all in the positive potential range (e.g., at E (1/2) = 0.57, 0.39, and 0.04 V versus Ag/AgCl reference for 1) as indicated by steady state voltammetry. The electrode process at 0.39 V appears to involve a single-step two-electron transfer as revealed from the normal and differential pulse voltammetric data and probably includes a combination of V(V)-V(IV) <--> V(III)-V(IV) mixed oxidation states. Compounds 1-3 thus provide a unique example of divanadium compounds in which the metal centers are linked by an unsupported hydroxo-bridge.