نتایج جستجو برای: optically active

تعداد نتایج: 453664  

Journal: :Journal of the American Chemical Society 2006
Na Ji Kai Zhang Haw Yang Yuen-Ron Shen

A sum-frequency generation (SFG) microscope that is sensitive toward molecular chirality was demonstrated for the first time. Optically active images of chiral 1,1'-bi-2-naphthol solutions were obtained with submicron spatial resolution. Three-dimensional sectioning capability of our microscope was also demonstrated. This optically active SFG microscopy can potentially become a powerful imaging...

2003
Y. Gu Igor L. Kuskovsky J. Fung R. Robinson I. P. Herman G. F. Neumark X. Zhou S. P. Guo M. C. Tamargo

The size and chemical composition of optically active CdZnSe/ZnSe and CdZnSe/Zn0.97Be0.03Se quantum dots (QDs) are determined using photoluminescence, photoluminescence excitation and polarized Raman scattering spectroscopies. We show that the addition of Be into the barrier enhances the Cd composition and the quantum size effect of optically active QDs. Additionally, surface phonons from QDs a...

Journal: :Chemical communications 2013
Shoko Hachiya Yoshio Kasashima Fumitoshi Yagishita Takashi Mino Hyuma Masu Masami Sakamoto

Optically active materials could be generated by simple solidification of achiral materials without an external chiral source. When achiral cis-3,4-diphenylsuccinimides were solidified in the presence of a catalytic amount of DBU by evaporating the solvent with stirring, optically active trans-3,4-diphenylsuccinimides were obtained quantitatively with high enantiomeric excesses.

Journal: :Chemical communications 2015
Chandra M R Volla Eleonora Fava Iuliana Atodiresei Magnus Rueping

A dual catalytic system consisting of indium triflate and a chiral imidazolidinone catalyzes the asymmetric addition of aldehydes to N-acyl quinoliniums furnishing optically active dihydroquinolines in good yields and excellent selectivities. The products were further functionalized into optically active tetrahydroquinolines, quinolines and 6-oxa-2-aza-bicyclo[3.3.1]nonanes.

Journal: :Chemical communications 2014
Binjie Guo Chunling Fu Shengming Ma

A method using quinidine and optically active binol-derived phosphoric acid as a cocatalyst to catalyze the asymmetric semipinacol rearrangement of 2,3-allenols forming optically active 3-bromo-3-enals that contain an all-carbon quaternary stereocenter has been developed. After some further treatments, the products with practical enantiomeric purity could be prepared.

Journal: :Chemical communications 2007
Shinzo Kobayashi Kazuhide Morino Eiji Yashima

An optically active helical poly(phenylacetylene) was synthesized by the copolymerization of phenylacetylenes bearing optically active hydroxy or ester groups obtained by the kinetic resolution of a racemic phenylacetylene with lipase; the helix-sense was inverted from one helix to another by the further chemical modification of the hydroxy groups with achiral bulky isocyanates or an acid chlor...

Journal: :Bioscience, biotechnology, and biochemistry 2011
Yuta Murai Yasuyuki Hashidoko Makoto Hashimoto

We report here a novel synthesis of optically active bishomotyrosine. The bishomotyrosine skeleton was constructed by using a Friedel-Crafts reaction between phenol and optically active N-Tfa-Glu(Cl)-OMe in triflic acid under the mild condition. Reduction and subsequent deprotection then afforded bishomotyrosine derivatives without any loss of optical purity.

Journal: :Chemosensors 2022

Natural diamonds with a rich variety of optically blind and active nitrogen impurity centers were explored at nano/microscale on the surface in bulk by number advanced chemical structural analytical tools order to achieve comprehensive characterization establishing enlightening links between their analysis results. First, novel compositional relationships established high-energy X-ray photoelec...

Journal: :Bulletin of the Chemical Society of Japan 1980

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