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101.
102.
Wu Du Quang Truong Hongbo Qi Yan Guo Harry R. Chobanian William K. Hagmann Jeffrey J. Hale 《Tetrahedron letters》2007,48(13):2231-2235
Herein we report a high yielding one-pot ‘green’ synthesis of 3-substituted-5-carbonylmethyl-1,2,4-oxadiazoles from readily available β-keto esters and amidoximes under simple and convenient solvent-free conditions. No additional base is needed. The reaction likely goes through an acyl ketene intermediate. 相似文献
103.
104.
Numerical Algorithms - In this paper, in order to solve the split common null point problem, we investigate a new explicit iteration method, base on the shrinking projection method and... 相似文献
105.
Dr. Dianna Truong Dr. Nelson Y. S. Lam Dr. Meder Kamalov Mie Riisom Dr. Stephen M. F. Jamieson Prof. Paul W. R. Harris Prof. Margaret A. Brimble Prof. Nils Metzler-Nolte Prof. Christian G. Hartinger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(12):e202104049
The number of donor atoms available on peptides that can competitively coordinate to metal centers renders the site-selective generation of advanced metal-peptide conjugates in high purity a challenging venture. Herein, we present a transmetalation-based synthetic approach on solid support in which an imidazolium pro-ligand can be used to selectively anchor a range of transition metal half-sandwich complexes onto peptides in the presence of multiple coordinative motifs. Amenable to solid support, a range of N-terminus and/or lysine conjugated metal-peptide conjugates were obtained in high purity after cleavage from the resin. The metalated peptides were evaluated for their anticancer properties against human cancer cell lines. While no cytotoxic activity was observed, this platform has the potential to i) provide a pathway to site-selective peptide labelling, ii) be explored as a biorthogonal handle and/or iii) generate a new strategy for ligand design in transition metal catalysts. 相似文献
106.
Xudong Hou Giang Truong Nguyen Tingting Xu Dr. Haipeng Wei Dr. Tun Seng Herng Dr. Guifei Huo Dr. Dingguan Wang Prof. Jun Ding Dr. Shaofei Wu Prof. Liviu Ungur Prof. Jishan Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(31):e202200687
The incorporation of organic radicals into coordination polymers was considered as a promising strategy to promote metal-ligand exchange interactions, but there are only a very limited number of stable organic radical-based ligands that can serve well such a purpose. Herein, we report two new tris(2,4,6-trichlorophenyl)methyl (TTM) radical-based ligands L1 and L2 with two and three imidazole substituents, respectively. The imidazole unit serves as a coordination site and it can also stabilize the TTM radical by intramolecular donor–acceptor interaction. Coordination of L1 and L2 with cobalt(II) ions gave the corresponding one- ( CoCP - 1 ) and two-dimensional ( CoCP - 2 ) coordination polymers, the structures of which were confirmed by X-ray crystallographic analysis. Magnetic measurements and theoretical calculations suggest antiferromagnetic coupling between the paramagnetic cobalt(II) ions and the radical ligands. Our study provides a rational design for stable organic radical-based ligands and further demonstrated the feasibility of a metal–radical approach toward magnetic materials. 相似文献
107.
Truong Son Pham László Balázs Imre Petneházy Zsuzsa Jászay 《Tetrahedron: Asymmetry》2010,21(3):346-351
An enantioselective Michael addition of diethyl cyanomethyl phosphonate to chalcones catalysed by bifunctional catalysts based on cinchona alkaloids has been developed, producing enantiomerically enriched cyanophosphonate precursors of α-substituted β-aminophosphonates. 相似文献
108.
109.
Improvements of reliability for methylmercury determination in environmental samples 总被引:1,自引:0,他引:1
Dan-Yi Yang Hoang-Yen Thi Truong Yu-Wei Chen Nelson Belzile 《Analytica chimica acta》2009,633(2):157-164
The determination of methylmercury (MeHg) in environmental samples by ethylation derivation-gas chromatography-atomic fluorescence spectrometry (ED-GC-AFS) is associated with an intimate problem of water moisture accumulation introduced in the ethylation step, which enters the detection system and cause a spectroscopic interference. With a simple modification on the GC-AFS system, this problem was eliminated and the analytical quality of the measurements was significantly improved. The presence of dissolved sulfide in samples can also cause serious chemical interference in the ethylation step resulting in lower or total loss of the MeHg signal. It was found that a masking system of CuSO4-Na2C2O4 was able to eliminate this interference. With this system, the accurate determination of trace amount of MeHg in high dissolved sulfide containing samples was achieved. Satisfactory analytical results were obtained with the certified reference sediment IAEA405, sulfate reducing bacteria culture and sulfide containing water samples. The limit of detection and quantitation of this masking system is 0.01 and 0.04 ng L−1 respectively. Other factors affecting ethylation are also discussed. 相似文献
110.
The dissociation mechanism of a water molecule at an oxygen vacancy on the MgO(100) surface was studied by using the embedded cluster method at the DFT/B3 LYP level, while the energetic information was refined by using the IMOMO method at the CCSD level. We found that a water molecule initially adsorbs on one of the magnesium ions surrounding the vacancy site with a binding energy of 15.98 kcal mol(-1). It then can dissociate on the MgO(100) surface along two possible dissociation pathways. One pathway produces a hydroxyl group bonded to the original magnesium with a proton filling the vacancy via a transition state with a barrier of 4.67 kcal mol(-1) relative to the adsorbed water configuration. The other pathway yields two hydroxy groups; the hydroxy group originally belonging to the water molecule fills the vacancy, while the hydrogen atom binds with the surface oxygen to form the other hydroxy group. Hydrogen atoms of these hydroxy groups can recombine to form a hydrogen molecule and the surface is healed. Although the barrier (14.09 kcal mol(-1)) of the rate-controlling step of the latter pathway is higher than that of the former one, the energies of all of its stationary points are lower than that of the separated reactants (H(2)O+cluster). The effects of water coadsorption are modeled by placing an additional water molecule near the active center, which suggests that the more coadsorbed water molecules further stabilize the hydroxy species and prevent the hydrogen molecule formation through the latter pathway. The results support the photoemission spectral evidence of water dissociation on the defective MgO(100) surface at low water coverage. 相似文献