Sun Kyung Choi

Bio: Sun Kyung Choi is an academic researcher from Ewha Womans University. The author has contributed to research in topics: Medicine & Chemistry. The author has an hindex of 5, co-authored 6 publications receiving 712 citations.

A highly active zinc catalyst for the controlled polymerization of lactide.

Abstract: We report the preparation, structural characterization, and detailed lactide polymerization behavior of a new Zn(II) alkoxide complex, (L1ZnOEt)2 (L1 = 2,4-di-tert-butyl-6-{[(2‘-dimethylaminoethyl)methylamino]methyl}phenolate). While an X-ray crystal structure revealed the complex to be dimeric in the solid state, nuclear magnetic resonance and mass spectrometric analyses showed that the monomeric form L1ZnOEt predominates in solution. The polymerization of lactide using this complex proceeded with good molecular weight control and gave relatively narrow molecular weight distribution polylactide, even at catalyst loadings of <0.1% that yielded Mn as high as 130 kg mol-1. The effect of impurities on the molecular weight of the product polymers was accounted for using a simple model. Detailed kinetic studies of the polymerization reaction enabled integral and nonintegral orders in L1ZnOEt to be distinguished and the empirical rate law to be elucidated, −d[LA]/dt = kp[L1ZnOEt][LA]. These studies also showed ...

Mechanistic Insights into the Reversible Formation of Iodosylarene–Iron Porphyrin Complexes in the Reactions of Oxoiron(IV) Porphyrin π‐Cation Radicals and Iodoarenes: Equilibrium, Epoxidizing Intermediate, and Oxygen Exchange

Abstract: We have shown previously that iodosylbenzene-iron(iii) porphyrin intermediates (2) are generated in the reactions of oxoiron(iv) porphyrin p- cation radicals (1) and iodobenzene (PhI), that 1 and 2 are at equilibrium in the presence of PhI, and that the ep- oxidation of olefins by 2 affords high yields of epoxide products.In the pres- ent work, we report detailed mechanis- tic studies on the nature of the equilib- rium between 1 and 2 in the presence of iodoarenes (ArI), the determination of reactive species responsible for olefin epoxidation when two intermedi- ates (i.e., 1 and 2) are present in a re- action solution, and the fast oxygen ex- change between 1 and H2 18 O in the presence of ArI.In the first part, we have provided strong evidence that 1 and 2 are indeed at equilibrium and that the equilibrium is controlled by factors such as the electronic nature of iron porphyrins, the electron richness of ArI, and the concentration of ArI. Secondly, we have demonstrated that 1 is the sole active oxidant in olefin ep- oxidation when 1 and 2 are present concurrently in a reaction solution.Fi- nally, we have shown that the presence of ArI in a reaction solution containing 1 and H2 18 O facilitates the oxygen ex- change between the oxo group of 1 and H2 18 O and that the oxygen exchange is markedly influenced by factors such as ArI incubation time, the amounts of ArI and H2 18 O used, and the electronic nature of ArI.The latter results are ra- tionalized by the formation of an unde- tectable amount of 2 from the reaction of 1 and ArI through equilibrium that leads to a fast oxygen exchange be- tween 2 and H2 18 O.

Big data and artificial intelligence (AI) methodologies for computer-aided drug design (CADD)

Abstract: There have been numerous advances in the development of computational and statistical methods and applications of big data and artificial intelligence (AI) techniques for computer-aided drug design (CADD). Drug design is a costly and laborious process considering the biological complexity of diseases. To effectively and efficiently design and develop a new drug, CADD can be used to apply cutting-edge techniques to various limitations in the drug design field. Data pre-processing approaches, which clean the raw data for consistent and reproducible applications of big data and AI methods are introduced. We include the current status of the applicability of big data and AI methods to drug design areas such as the identification of binding sites in target proteins, structure-based virtual screening (SBVS), and absorption, distribution, metabolism, excretion and toxicity (ADMET) property prediction. Data pre-processing and applications of big data and AI methods enable the accurate and comprehensive analysis of massive biomedical data and the development of predictive models in the field of drug design. Understanding and analyzing biological, chemical, or pharmaceutical architectures of biomedical entities related to drug design will provide beneficial information in the biomedical big data era.

Chemical Routes for the Transformation of Biomass into Chemicals

Abstract: 3.2.3. Hydroformylation 2467 3.2.4. Dimerization 2468 3.2.5. Oxidative Cleavage and Ozonolysis 2469 3.2.6. Metathesis 2470 4. Terpenes 2472 4.1. Pinene 2472 4.1.1. Isomerization: R-Pinene 2472 4.1.2. Epoxidation of R-Pinene 2475 4.1.3. Isomerization of R-Pinene Oxide 2477 4.1.4. Hydration of R-Pinene: R-Terpineol 2478 4.1.5. Dehydroisomerization 2479 4.2. Limonene 2480 4.2.1. Isomerization 2480 4.2.2. Epoxidation: Limonene Oxide 2480 4.2.3. Isomerization of Limonene Oxide 2481 4.2.4. Dehydroisomerization of Limonene and Terpenes To Produce Cymene 2481

Controlled ring-opening polymerization of lactide and glycolide.

Abstract: 23 Stereocontrol of Lactide ROP 6164 231 Isotactic Polylactides 6164 232 Syndiotactic Polylactides 6166 233 Heterotactic Polylactides 6166 3 Anionic Polymerization 6166 4 Nucleophilic Polymerization 6168 41 Mechanistic Considerations 6168 42 Catalysts 6169 421 Enzymes 6169 422 Organocatalysts 6169 43 Stereocontrol of Lactide ROP 6170 44 Depolymerization 6170 5 Cationic Polymerization 6170 6 Conclusion and Perspectives 6171 7 Acknowledgments 6173 8 References and Notes 6173

Organocatalytic ring-opening polymerization.

Abstract: Modern synthetic methods have revolutionized polymer chemistry through the development of new and powerful strategies for the controlled synthesis of complex polymer architectures. 1-5 Many of these developments were spawned by new classes of transition metal catalysts for the synthesis of new polyolefin microstructures, 5 the design of highly efficient families of “living” polymerization strategies for the synthesis of block, graft, and star polymers, 6-12 controlled methods for the synthesis of dendritic macromolecules, 3,13,14

Polymers from Renewable Resources: A Perspective for a Special Issue of Polymer Reviews

Abstract: The field of polymers derived from non‐petrochemical feedstocks is gaining a great deal of momentum from both a commercial and academic sense Using annually renewable feedstocks, such as biomass, for the production of new plastics can have both economic and environmental benefits Fundamental research in the production, modification, property enhancement, and new applications of these materials is an important undertaking The new materials, concepts, and utilizations that result from these efforts will shape the future of polymers from renewable resources This issue of Polymer Reviews focuses on the production and properties of renewable resource polymers and highlights current trends and research directions