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Kyung Soo Yoo

Publications and source records attributed to Kyung Soo Yoo.

6 recordsLinked to original sources
PubMed2006

Oxidative palladium(II) catalysis: A highly efficient and chemoselective cross-coupling method for carbon-carbon bond formation under base-free and nitrogenous-ligand conditions.

We report herein the development of a general and mild protocol of oxygen-promoted Pd(II) catalysis resulting in the selective cross-couplings of alkenyl- and arylboron compounds with various olefins. Unlike most cross-coupling reactions, this new methodology works well even in the absence of bases, consequently averting undesired homo-couplings. Nitrogen-based ligands including dimethyl-phenanathroline enhance reactivities and offer a highly efficient and stereoselective methodology to overcome challenging substrate limitations. For instance, oxidative palladium(II) catalysis is effective with highly substituted alkenes and cyclic alkenes, which are known to be incompatible with other known catalytic conditions. Most examined reactions progressed smoothly to completion at low temperatures and in short times. These interesting results provide mechanistic insights and utilities for a new paradigm of palladium catalytic cycles without bases.

Alkenes↗
PubMed2004

Capillary microextraction on sol-gel dendrimer coatings.

Sol-gel capillary microextraction (CME) is a new direction in the solventless sample preparation for the preconcentration of trace analytes, and presents significant interest in environmental, pharmaceutical, petrochemical, biomedical, agricultural, food, flavor, and a host of other important areas. It utilizes advanced material properties of organic-inorganic hybrid sol-gel polymers to perform efficient extraction and preconcentration of target compounds from a wide variety of matrices. In the present work, a novel benzyl-terminated dendron-based sol-gel coating was developed for CME. A detailed investigation was conducted to evaluate the performance of the newly developed sol-gel dendrimer coatings to perform solventless extraction of a wide range of polar and nonpolar analytes. The characteristic branched architecture of dendrons makes them structurally superior extraction media compared with their traditional linear polymeric counterparts. Sol-gel chemistry was used to chemically immobilize dendritic macromolecules on fused silica capillary inner surface. Due to the strong chemical bonding with the capillary inner walls, sol-gel dendron coatings showed excellent thermal and solvent stability in capillary microextraction in hyphenation with chromatographic analysis. Efficient extraction of a wide range of analytes from their aqueous solutions was accomplished using sol-gel dendron coated fused silica capillaries. Low parts per trillion level detection limits were achieved in CME-GC for both polar and nonpolar analytes including polyaromatic hydrocarbons (PAHs), aldehydes, ketones, phenols, and alcohols.

Chromatography, Gel↗
PubMed2003

Routes to metallodendrimers: synthesis of isomeric neutral metallomacromolecules based on bis(2,2':6',2"-terpyridine)ruthenium(II) connectivity.

Routes for the syntheses of isomeric, zwitterionic, bisterpyridine-Ru(II)-based macromolecules are described. Access to these novel architectures is facilitated by the construction of terpyridine-modified, 1-->3 C-branched, ester-terminated building blocks. Constitutional isomers result from the interchangable placement of methyl and tert-butyl ester groups on both the branched framework near the Ru(II) centers and the termini of the branched construct. Water solubility is imparted to each isomer through selective transformation of the tert-butyl esters to their corresponding carboxylates. Along with the standard characterization techniques, electrochemical and spectroscopic data also support the structural formation.

Journal Article↗
PubMed2003

Polymeric enzyme mimics: catalytic activity of ribose-containing polymers for a phosphate substrate.

The polymers containing ribose rings: poly(5'-acrylamido-5'-deoxy-1',2'-O-isopropylidene-alpha-D-ribose) (11), poly(5'-acrylamido-5'-deoxy-alpha-D-ribose) (12) and poly(5'-acrylamido-5'-deoxy-1'-O-methyl-D-ribose) (13) were prepared as enzyme mimics. Polymers 12 and 13 with free vic-cis-diol groups catalyzed the hydrolysis of phosphodiester (ethyl p-nitrophenyl phosphate and N-methylpyridinium 4-tert-butylcatechol cyclic phosphate) and phosphomonoester substrates with a rate acceleration of 10 approximately equal to 10(3) compared with the uncatalyzed reaction. They also catalyzed the reverse reactions, i.e., the esterification of phosphomonoester to phosphodiester and the phosphorylation of alcohols with phosphate ions. The catalytic activity was attributable to the vic-cis-diols of riboses on polymer chains, which formed hydrogen bonds with two phosphoryl oxygen atoms of phosphates so as to activate the phosphorus atoms to be attacked by nucleophiles. The catalytic activity was negligible for polymer 11 where vic-cis-diol groups were blocked with isopropylidene groups. The catalytic activity was attributable to the vic-cis-diols of riboses on polymer chains, which formed hydrogen bonds with two phosphoryl oxygen atoms of phosphates so as to activate the phosphorus atoms to be attacked by nucleophiles.

Catalysis↗