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51.
Thanh Nga Pham Huu Dien Pham Dinh Kim Dang Thi Thuy Duong Thi Phuong Quynh Le Quang Duong Nguyen 《Natural product research》2019,33(9):1345-1348
Four thymol derivatives and two phenolic compounds were isolated from the aerial parts of Eupatorium fortunei. The new structures were elucidated to be 7,8,9-trihydroxythymol (1), and 8,10-didehydro-7,9-dihydroxythymol (2) by means of MS and NMR analysis. The known compounds were identified as 8,9,10-trihydroxythymol (3), 10-acetoxy-8,9-dihydroxythymol (4), o-coumaric acid (5) and 4-(2-hydroxyethyl)benzaldehyde (6). Compound 3 showed strongest inhibitory effect on the growth of Microcystis aeruginosa in comparison with CuSO4. 相似文献
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The bilayer lipid membrane (BLM) system containing metallo-porphyrins (M-TPP) and dyes as photosensitizers and electron mediators was studied. Cyclic voltammetry was used to determine photoconductivity and photo-emf of the system. The largest photoconductivity was observed for the Mg-TPP containing BLM with methyl viologen (MV2+ ) and iodine (I2 ) present in the aqueous solution. Photoactive dyes, due to their redox ability caused photovoltage up to 30 mV to develop, but no conductance change was observed under illumination in absence of Mg-TPP. The relevance of cyclic voltammetry to the photoconductance and the photo-emf observed in the BLM is discussed. 相似文献
55.
Dynamically obtained current/voltage curves of bilayer lipid membranes partitioning a solution of lipophilic ions are compared with the results of the type expected in a voltammetry experiment involving ionic transport across a liquid/liquid interface. Lipophilic ions yielding “voltammograms” analogous to reversible and irreversible voltammograms (in conventional electrochemical systems) are reported. Also reported are examples of ions which yield what may be analogous to a masked response, a phenomenon known in the literature of liquid/liquid interfaces. Although the behavior of the two systems is similar, there exist differences in the interpretation of the voltammograms and suggestions are offered for an energetic and mechanistic interpretation of the membrane voltammogram. 相似文献
56.
Gas-phase derivatization of [C3H5]+ ions using tandem mass spectrometry methods A13C labelling study
Nguyen Kieu My Marita Schilling Helmut Schwarz 《Journal of mass spectrometry : JMS》1987,22(5):254-258
The study of specifically 13C-labelled precursors sheds further light on the gas-phase chemistry of allyl and 2-propenyl cations. It is demonstrated that both species are formed from allyl and 2-propenyl bromide upon 70 eV electron impact ionization without skeletal reorganization. Gas-phase derivatization of the [C3 H5]+ ions with benzene facilitates, as suggested and observed earlier, the distinction of the two isomers using collision-induced dissociation of the Wheland complexes (or isomers thereof). The 13C labelling data clearly demonstrate that 64% of allyl cations survive the derivatization while 36% isomerize to 2-phenylpropyl cations; the latter are also formed via the reaction of 2-propenyl cation with benzene, protonation of α-methylstyrene and water loss from protonated 2-phenyl-2-propanol, respectively. Unimolecular loss of C2H4 from protonated allylbenzene proceeds via two competing reaction channels: one involves heterolysis of 1-phenylpropyl cations (~30%); the major pathway (~70%), however, involves decomposition via propylene benzenium ions. 相似文献
57.
The crystal and molecular structures of three sydnone derivatives are reported. The compound 3-cyclohexylsydnone crystallizes in space group C2/c of the monoclinic system with sixteen molecules in a cell of dimensions a = 19.326 (3), b = 9.471 (2), c = 20.005 (4)Å, β = 106.85(1)°. The structure has been refined to a final value of 0.0581 for the conventional R-factor based on 2222 independent observed intensities. Form I of 3-(3-pyridyl)sydnone crystallizes in space group P2/n of the monoclinic system with eight molecules in a cell of dimensions a = 7.317(2), b = 9.283 (2), c = 20.891 (6) Å, β = 99.61(2)°. The structure has been refined to a final value of 0.0514 for the conventional R-factor based on 1208 independent observed intensities. Form II of 3-(3-pyridyl)sydnone crystallizes in space group P21/c of the monoclinic system with eight molecules in a cell of dimensions a=9.073 (2), b = 22.267 (5). c = 7.494(2)Å, β = 112.15 (2)°. The structure has been refined to a final value of 0.0462 for the conventional R-factor based on 1330 independent observed intensities. Each of the three structures contains two crystallographically independent molecules in the cell. In the case of 3-cyclohexylsydnone, one of the independent molecules exhibits disorder around the exocyclic bond at N(3). A comparison of bond lengths indicates that the (electron donating) cyclohexyl group brings about enhanced electron density in the N(3)-C(4) bond, and possibly in the N(3)-N(2) bond. All three structures studied here exhibit intermolecular hydrogen bonding involving C(4)-H(4)…O(6) interactions. Although there are no stacking interactions in the cyclohexyl derivative, there is evidence for such interactions in the 3-pyridyl derivatives. 相似文献
58.
Huu-Hung Nguyen Thi-Phuong Nguyen Nguyen Tien Trung Cam-Tu D. Phan Thi-Bich-Ngoc Dao Dinh-Tri Mai Jirapast Sichaem Ngoc-Hong Nguyen Cong-Luan Tran Thuc-Huy Duong 《Arabian Journal of Chemistry》2021,14(7):103189
Two new cycloartanes, combretanones G and H (1 and 2), were isolated from the leaves of Combretum quadrangulare. Their structures were elucidated by applying a set of spectroscopic methods, while their relative configurations were determined using DFT-NMR chemical shift calculations and subsequent assignment of DP4 probabilities. Compounds 1 and 2 are C-23/C-24 stereoisomers of the previously-reported euphonerin E. Both exhibited moderate cytotoxicity against three human cancer cell lines. Compound 2 was shown to be a potent antiparasitic. Our results confirm the traditional medicinal uses of Combretum quadrangulare in Vietnam. 相似文献
59.
Nazish Parveen Mohammad Omaish Ansari Thi Hiep Han Moo Hwan Cho 《Journal of Solid State Electrochemistry》2017,21(1):57-68
This paper reports a simple methodology for the synthesis of a polyaniline/titanium oxide/graphene hybrid (Pani/TiO2/GN) using a simple methodology, and their application as a supercapacitor electrode material for energy storage. The Pani/TiO2/GN hybrid was prepared by a simple approach by simultaneous generation of Pani and TiO2 in situ from aniline and titanium iso-propoxide, respectively, in the presence of GN under ice bath conditions. The incorporation of GN improved the electrical conductivity of Pani and helped to decrease the charge transfer resistance, whereas TiO2 generation by an in situ method increased the surface area considerably and enhanced the capacitance of the Pani/TiO2/GN hybrid. TEM showed that Pani and TiO2 were well incorporated and coated on the GN successfully. The shift of the peaks in the FTIR spectrum and XRD pattern of the Pani/TiO2/GN hybrid compared to their pure counterparts suggested that TiO2 and Pani had been perfectly coated on the GN, and there was a strong interaction among Pani, GN, and TiO2 particles. The electrochemical performance of the as-prepared Pani/TiO2/GN hybrid electrode showed a high specific capacitance of 403.2 F g?1 at a current density of 2 A g?1 and excellent cycling stability for up to 1000 cycles. This suggested that the effective incorporation of GN and TiO2 into Pani and the high surface area could simultaneously increase the electrochemical capacitance and cyclic stability of the Pani/TiO2/GN hybrid, leading to superior electrochemical performance. 相似文献
60.
Ngoc Binh Vo Le Anh Nguyen Tung Lam Pham Duy Tien Doan Thanh Binh Nguyen Quoc Anh Ngo 《Tetrahedron letters》2017,58(25):2503-2506
A procedure to exclusively obtain 3′S-cyanoanhydrovinblastine 12 from two naturally occurring vinca-alkaloids (catharanthine and vindoline) in one step with good yield is described. Stereoselective reductions of 12, providing straightforward access to three new vinca-alkaloids, including two diastereomers 3′S-cyano-(4′R,5′-dihydro)-anhydrovinblastine and 3′S-cyano-(4′S,5′-dihydro)-anhydrovinblastine as well as (3′S-aminomethyl)-(4′S,5′-dihydro)-anhydrovinblastine in good yields is also reported. 相似文献