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Hoan Kiem District, Vietnam

Anh D.T.P.,Hanoi University of Science and Technology | Duong T.B.,Institute of Industrial Chemistry | Hoang V.D.,Hanoi University of Science and Technology
Natural Product Research | Year: 2014

A new chromone, 5,7-dihydroxy-6,8-dimethoxy-2-methyl-4H-chromen-4-one (1), together with seven known compounds, 5,7-dihydroxy-6-methoxy-2-methyl-4H-chromen-4-one (pisonin B) (2), 5,7-dihydroxy-2-methyl-4H-chromen-4-one (noreugenin) (3), 5-hydroxy-7-methoxy-2-methyl-4H-chromen-4-one (eugenin) (4), (2S)-7,4′-dihydroxyflavan (5), 3′,7-dihydroxy-4′-methoxy-8-methylflavan (6), 3′,7-dihydroxy-4′-methoxyflavan (7) and 6,8-dimethyl-5,7,4′-trihydroxyflavanone (-)-farrerol) (8), were isolated from Hymenocallis littoralis Salisb. (Amaryllidaceae) growing in Vietnam. Their structures were determined based on spectroscopic and physicochemical analyses. © 2014 © 2014 Taylor & Francis. Source


Yen N.T.H.,University of Greifswald | Yen N.T.H.,Institute of Industrial Chemistry | Bogdanovic X.,University of Greifswald | Palm G.J.,University of Greifswald | And 2 more authors.
Journal of Biological Inorganic Chemistry | Year: 2010

Crystal structures of polypeptide deformylase (PDF) of Escherichia coli with nickel(II) replacing the native iron(II) have been solved with chloride and formate as metal ligands. The chloro complex is a model for the correct protonation state of the hydrolytic hydroxo ligand and the protonated status of the Glu133 side chain as part of the hydrolytic mechanism. The ambiguity that recently some PDFs have been identified with Zn2+ ion as the active-site centre whereas others are only active with Fe2+ (or Co2+, Ni2+) is discussed with respect to Lewis acid criteria of the metal ion and substrate activation by the CD loop. © 2009 SBIC. Source


Hao Q.,Key Laboratory of Soft Chemistry and Functional Materials | Xie X.,Institute of Industrial Chemistry | Lei W.,Institute of Industrial Chemistry | Xia M.,Institute of Industrial Chemistry | And 2 more authors.
Journal of Physical Chemistry C | Year: 2010

Semiconducting polytriphenylene (PTP), a bright blue-green-light emitter, with good electrochemical behavior, excellent thermal stability, and the electrical conductivity of 10-3 S cm-1 was synthesized successfully by direct anodic oxidation of triphenylene (TP) in different media. The oxidation potential onset of TP in boron trifluoride diethyl etherate containing 3% concentrated sulfuric acid (SA) was reduced to 0.94 V, compared with other electrolyte media. The possible structure of the obtained PTP was investigated by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and 1D and 2D NMR techniques, respectively. The results showed that the PTP was grown via the coupling of the monomer mainly at the meta position of the benzene ring in TP. Fluorescence spectra indicated that the electrochemically polymerized PTP was an excellent blue-green-light-emitting material with fluorescence quantum yield as high as 0.43. In addition, the morphology and thermal stability of the polymers were also explored by means of scanning electron microscopy and thermal analyzer. The average molecular weight (19 980 g mol-1) and its polydispersity of dedoped PTP were determined by gel permeation chromatography. © 2010 American Chemical Society. Source

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