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Your search keyword '"Hogen-Esch, Thieo E."' showing total 251 results
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251 results on '"Hogen-Esch, Thieo E."'

19. DFT based Monte Carlo simulations of poly(9,9-dialkylfluorene-2,7-diyl) polymers in solution

Author

Jun Ling, Fomina, Nadezda, Rasul, Golam, and Hogen-Esch, Thieo E.

Subjects
Monte Carlo method -- Analysis, Density functionals -- Usage, Chemicals, plastics and rubber industries
Abstract

A study was conducted to explore the dilute solution properties of poly(9,9-dihexylfluorene-2,7-diyl) (PDHF). The results offer insight into the torsion angle selectivity of the 'selective random walk' (SRW) and 'selective self-avoiding random walk' (SSAW) simulations which predict long chain sections punctuated by sudden sharp loops.

Published
2008

23. Lewis base activation of Lewis acids. Vinylogous aldol reactions

Author

Denmark, Scot E., Beutner, Gregory L., Hogen-Esch, Thieo E., and Thompson, Mark E.

Subjects
Chemical reactions -- Research, Chemistry, Physical and theoretical -- Research, Aldehydes -- Chemical properties, Chemistry
Abstract

A highly regioselective, chiral-Lewis-base-catalyzed, vinylogous aldol reaction is developed that provides gamma-hydroxy enones in high enantio- and disastereoselectives for a number of aldehyde and dienol ether structures. Low catalyst loadings (1 mol %) can be used without compromising yields or selectivities.

Published
2003

24. Sensitive quantitative nucleic acid detection using oligonucleotide microarrays

Author

Vainrub, Arnold, Pettitt, B. Montgomery, Hogen-Esch, Thieo E., and Thompson, Mark E.

Subjects
DNA microarrays -- Analysis, Nucleic acids -- Research, Chemistry
Abstract

A simple new criteria to optimize detection is presented. Theoretical analysis of on-array hybridization reveals the importance of the interface electrostatic interactions appearing due to the high negative charge of nucleic acid oligomers.

Published
2003

25. Phosphoroscene quenching by conjugated polymers

Author

Sudhakar, Mahusoodhan, Djurovich, Peter I., Hogen-Esch, Thieo E., Thompson, Mark E., and Reif, Bernd

Subjects
Dielectric films -- Research, Dielectric films -- Optical properties, Dielectric films -- Atomic properties, Thin films -- Research, Thin films -- Optical properties, Thin films -- Atomic properties, Light-emitting diodes -- Research, Light-emitting diodes -- Optical properties, Light-emitting diodes -- Atomic properties, Exciton theory, Chemistry
Abstract

Organic light-emitting diodes (OLEDs) are fabricated with low-molecular weight materials. Hole-electron recombination in these OLEDs leads to the formation of both singlet and triplet excited states (excitons) within the molecular thin film.

Published
2003

26. Synthesis and characterization of macrocyclic vinyl-aromatic polymers. Molecular weight-dependent glass transition temperatures and emission of macrocyclic polystyrene

Author

Alberty, Kurt A., Hogen-Esch, Thieo E., Carlotti, Stéphane, Loker Hydrocarbon Res Inst & Dept Chem, University of Southern California (USC), Laboratoire de Chimie des polymères organiques (LCPO), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure de Chimie et de Physique de Bordeaux (ENSCPB)-Université Sciences et Technologies - Bordeaux 1-Institut de Chimie du CNRS (INC), Team 1 LCPO : Polymerization Catalyses & Engineering, Laboratoire de Chimie des Polymères Organiques (LCPO), and Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)

Subjects
[CHIM.POLY]Chemical Sciences/Polymers, cycles, glass transition temperature, polystyrene (PS), anionic polymerization
Abstract

International audience; Matching macrocyclic and linear polystyrenes (PS) were synthesized by the initiation of styrene with 2,7dimethyl-3,6-diphenyloctane dianion lithium salt followed by high dilution coupling with 1,4-bis(bromomethyl)benzene or protonation. Liquid chromatography at the critical condition shows the presence of less than 4% of linear PS impurities in the fractionated cycles. SEC studies confirm that the ratios of apparent MWs of cyclic and linear PS increase from about 0.7 to more than 0.9 as MWs decrease. Fluorescence studies show that the monomer emissions at 285 nm strongly increase with decreasing MW whereas those of the linear polymers are not significantly affected. This may be due in part to the increased rigidity of the smaller cycles that decreases the rate of radiation-less deactivation.

Published
2005
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28. Enhanced fluorescence of macrocyclic polystyrene

Author

Yaodong Gan, Dahai Dong, Carlotti, Stephane, and Hogen-Esch, Thieo E.

Subjects
Polymerization -- Research, Polymers -- Research, Polystyrene -- Research, Ultraviolet radiation -- Research, Chemistry
Abstract

Research is presented demonstrating the significant increase, in macrocyclic polystyrenes having narrow molecular weight distribution (MWD), of excimer emission intensity when compared with identical MWD and tacticity linear polymers as the degree of polymerization increases.

Published
2000

36. Synthesis of New Vinyl Monomers for Chemical Agent Sensing Applications

Author

UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES LOKER HYDROCARBON RESEARCH INST, Hogen-Esch, Thieo E., UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES LOKER HYDROCARBON RESEARCH INST, and Hogen-Esch, Thieo E.

Abstract

The synthesis of styrene momomer p-vinylbenzoylacetophenone (monomer i) has been carried by the acetylation of 2- chloroethylbenzene and base elimination of the resulting 4-acetyl-2-chloroethylbenzene to give 4-acetylstyrene. This monomer was benzoylated by a sodium hydride mediated Claisen reaction with excess ethylbenzoate to give the monomer 1. This monomer that is of interest in ARO in sensing applications was characterized by proton NMR and by mass spectrometry. Each of the three steps was optimized to give an overall yield of about 35 percent from the starting products. A large amount (50 grams of this monomer) was synthesized and shipped to Dr. Amanda Jenkins.

Published
2001

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