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10 results on '"Xiu R Bu"'

1. The readily available tert-pentyl group as a most effective simple directing group for asymmetric synthesis: a case study on Salen–Mn(III)-catalyzed epoxidation

Author

Xiu R. Bu, Sidney Liang, Anne Gaquere, and Fu-Lian Hsu

Subjects
Inorganic Chemistry, Chemistry, Stereochemistry, Group (periodic table), Organic Chemistry, Enantioselective synthesis, General Medicine, Physical and Theoretical Chemistry, Medicinal chemistry, Catalysis
Abstract

The tert -pentyl group has been found to produce a pronounced stereodirecting effect, which is manifested in a study on Salen–Mn(III) complexes bearing such groups.

Published
2002

2. Combined phase transfer catalysis and ultrasound to enhance tandem alkylation of azo dyes

Author

Jie Wang, Joycelyn S. Harrison, Xiu R. Bu, Richard Mason, and Xiang Li

Subjects
endocrine system diseases, Tandem, Organic Chemistry, Chromophore, Alkylation, Photochemistry, Biochemistry, Catalysis, chemistry.chemical_compound, chemistry, Phase (matter), Drug Discovery, Molecule, Bifunctional, Derivative (chemistry)
Abstract

Ultrasound has been found to enhance N-substitution against elimination in the reaction of carbazole-containing bromides 3 with a Disperse Orange 3 derivative 2 under PTC condition. Upon using combined PTC and ultrasound conditions, a series of bifunctional molecules 1 have been prepared to possess charge-transporting agents and nonlinear optical chromophores in 2:1 ratio.

Published
2002

3. Low temperature fabricationphotocatalytical activity of carbon fiber-supported TiO2 with different phase compositions

Author

Zhifeng Wang, Kohji Yoshinaga, Ming Zhang, and Xiu R. Bu

Subjects
Anatase, Environmental Engineering, Materials science, Photochemistry, Health, Toxicology and Mutagenesis, Inorganic chemistry, Nanoparticle, Metal Nanoparticles, Catalysis, chemistry.chemical_compound, X-Ray Diffraction, Phase (matter), Methyl orange, Environmental Chemistry, High-resolution transmission electron microscopy, Waste Management and Disposal, Titanium, Hydrogen-Ion Concentration, Pollution, Cold Temperature, Chemical engineering, chemistry, Rutile, Titanium dioxide, Photocatalysis, Microscopy, Electron, Scanning, Spectrophotometry, Ultraviolet, Azo Compounds
Abstract

Crystalline TiO2 nanoparticles with different phase compositions were fabricated on carbon fibers. The fabrication is achieved at low temperature. The process includes the treatment of Ti(OH)4 with hydrogen peroxide in the presence of carbon fibers. Neither additional acids nor bases, or additives are used during the process. Carbon fibers prior to and after TiO2 loading are characterized by FE-SEM, XRD, and UV-vis absorption spectroscopy. The photocatalytic activity was assessed via photocatalytic degradation of methyl orange solution, and found to be phase composition-dependent & pH dependent. Carbon fibers loaded with mixed-phase TiO2 led to the best photocatalytic performance. HRTEM reveals the anatase/rutile heterojunction which helps explain the high efficiency of photocatalysis. They have been demonstrated to be re-usable in the continuous photocatalytic degradation process.

Published
2014

4. Phase Transfer Catalysis for Tandem Alkylation of Azo Dyes for the Synthesis of Novel Multifunctional Molecules

Author

Xiang Li, Eric A. Mintz, Oliver Zehnder, Peter Günter, Xiu R. Bu, and Christian Bosshard

Subjects
chemistry.chemical_classification, Carbazole, Organic Chemistry, Halide, Chromophore, Alkylation, Photochemistry, Biochemistry, Catalysis, chemistry.chemical_compound, chemistry, Phase (matter), Drug Discovery, Molecule, Alkyl
Abstract

Potentially photorefractive molecules, which possess both a charge transfer component and a nonlinear optical chromophore, were prepared by the direct N -monoalkylation of Disperse Orange 3 ( 1 ) with a carbazole alkyl bromide ( 2 ) utilizing phase transfer catalysis. Further N -alkylation of the remaining active N–H with alkyl halides with various chain lengths allowed the thermal properties of the Disperse Orange 3 derivatives to be fine-tuned.

Published
2000

5. Y-shaped two-photon absorbing molecules with an imidazole–thiazole core

Author

Cleber Renato Mendonça, Xiu R. Bu, Lino Misoguti, Ke Feng, Fu-Lian Hsu, Leonardo De Boni, and Michael A. Meador

Subjects
Sulfonyl, chemistry.chemical_classification, Stereochemistry, Imidazoles, Metals and Alloys, General Medicine, General Chemistry, Catalysis, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Core (optical fiber), Thiazoles, chemistry.chemical_compound, Crystallography, Absorptiometry, Photon, Two-photon excitation microscopy, chemistry, Group (periodic table), Materials Chemistry, Ceramics and Composites, Nitro, Imidazole, Photon absorptiometry, Molecule, Thiazole
Abstract

Two new classes of two-photon absorbing Y-shaped molecules have been developed to possess an imidazole-thiazole core and a stilbene-type conjugation pathway with either nitro or sulfonyl as terminal electron-accepting group.

Published
2004

6. Tertiary Pentyl Groups Enhance Salen Titanium Catalyst for Highly Enantioselective Trimethylsilylcyanation of Aldehydes

Author

Sidney Liang and Xiu R. Bu

Subjects
Titanium, chemistry.chemical_classification, Steric effects, Aldehydes, Acetonitriles, Magnetic Resonance Spectroscopy, Schiff base, Molecular Structure, Nitrile, Silicon Compounds, Organic Chemistry, Enantioselective synthesis, Stereoisomerism, Cyanation, Ethylenediamines, Aldehyde, Catalysis, Benzaldehyde, Structure-Activity Relationship, chemistry.chemical_compound, chemistry, Pentanes, Organic chemistry
Abstract

tert-Pentyl groups are recognized to be highly effective steric groups that can enhance enantioselectivity of salen titanium complexes when they are used in asymmetrical cyanation of aromatic aldehydes. High ee (92-97%) has been obtained with several aldehyde substrates. Compared to its tert-butyl analogue, the tert-pentyl group has been found to improve enantioselectivity and in some cases quite dramatically.

Published
2002

7. ChemInform Abstract: Phase Transfer Catalysis and Ultrasound in Tandem Alkylation of Azo Dyes for Bifunctional Molecules

Author

Javier Santos, Xiang Li, and Xiu R. Bu

Subjects
chemistry.chemical_compound, endocrine system diseases, Tandem, Chemistry, Bromide, Phase (matter), Molecule, General Medicine, Alkylation, Photochemistry, Bifunctional, Derivative (chemistry), Catalysis
Abstract

Ultrasound has been found to enhance N -substitution against elimination in the reaction of carbazole-containing bromide with disperse orange 3 derivative under PTC conditions.

Published
2010

8. ChemInform Abstract: Tertiary Pentyl Groups Enhance Salen Titanium Catalyst for Highly Enantioselective Trimethylsilylcyanation of Aldehydes

Author

Sidney Liang and Xiu R. Bu

Subjects
chemistry.chemical_classification, Steric effects, chemistry, Enantioselective synthesis, chemistry.chemical_element, General Medicine, Cyanation, Aldehyde, Medicinal chemistry, Catalysis, Titanium
Abstract

tert-Pentyl groups are recognized to be highly effective steric groups that can enhance enantioselectivity of salen titanium complexes when they are used in asymmetrical cyanation of aromatic aldehydes. High ee (92-97%) has been obtained with several aldehyde substrates. Compared to its tert-butyl analogue, the tert-pentyl group has been found to improve enantioselectivity and in some cases quite dramatically.

Published
2010

9. Phase transfer catalysis and ultrasound in tandem alkylation of azo dyes for bifunctional molecules

Author

Xiu R. Bu, Xiang Li, and Javier Santos

Subjects
endocrine system diseases, Tandem, Organic Chemistry, Alkylation, Biochemistry, Combinatorial chemistry, Catalysis, chemistry.chemical_compound, chemistry, Bromide, Phase (matter), Drug Discovery, Molecule, Bifunctional, Derivative (chemistry)
Abstract

Ultrasound has been found to enhance N -substitution against elimination in the reaction of carbazole-containing bromide with disperse orange 3 derivative under PTC conditions.

Published
2000

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