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Articles 1 - 9 of 9

Full-Text Articles in Physical Sciences and Mathematics

Increased Yields And Simplified Purification With A Second-Generation Cobalt Catalyst For The Oxidative Formation Of Trans-Thf Rings., Cory Palmer, Nicholas A Morra, Andrew C Stevens, Barbora Bajtos, Ben P Machin, Brian L Pagenkopf Nov 2009

Increased Yields And Simplified Purification With A Second-Generation Cobalt Catalyst For The Oxidative Formation Of Trans-Thf Rings., Cory Palmer, Nicholas A Morra, Andrew C Stevens, Barbora Bajtos, Ben P Machin, Brian L Pagenkopf

Chemistry Publications

The synthesis of a second-generation cobalt catalyst for the formation of trans-THF products via the Mukaiyama aerobic oxidative cyclization is reported. Two procedures have been developed with the new water-soluble catalyst that give superior yields and greatly simplify purification compared to the previous catalysts.


Electrochemical And Photovoltaic Properties Of Electropolymerized Poly(Thienyl-Silole)S, Joshua C. Byers, Paul M. Dicarmine, Mahmoud M. A. R. Moustafa, Xin Wang, Brian Pagenkopf, Oleg A. Semenikhin Nov 2009

Electrochemical And Photovoltaic Properties Of Electropolymerized Poly(Thienyl-Silole)S, Joshua C. Byers, Paul M. Dicarmine, Mahmoud M. A. R. Moustafa, Xin Wang, Brian Pagenkopf, Oleg A. Semenikhin

Chemistry Publications

Electrochemical and photoelectrochemical properties were studied of a series of donor−acceptor materials based on polythiophene modified with silole moieties. The materials were prepared by electrochemical anodic polymerization of 2,5-bis([2,2′-bithiophen]-5-yl)-1,1-dimethyl-3,4-diphenylsilole and 2,5-bis([2,2′-terthiophen]-5-yl)-1,1-dimethyl-3,4-diphenylsilole, as well as copolymerization of these monomers with 2,2′-bithiophene. Photocurrent measurements showed that introduction of silole resulted in a considerable enhancement of the photovoltaic properties of silole-containing materials and especially the fill factor. However, as demonstrated by Mott−Schottky measurements, electropolymerized silole-containing materials showed a substantial degree of disorder and high density of states in the midgap, which negatively affected their photovoltaic properties. Atomic force microscopy (AFM) and phase imaging …


A General Asymmetric Aldol Reaction Of Silyl Ketene Acetals Derived From Simple Esters To Aryl Alpha-Ketoesters, Brian Pagenkopf, Julie Le Engers Oct 2009

A General Asymmetric Aldol Reaction Of Silyl Ketene Acetals Derived From Simple Esters To Aryl Alpha-Ketoesters, Brian Pagenkopf, Julie Le Engers

Chemistry Publications

No abstract provided.


Synthesis Of Tetrahydroisoquinocarbazoles Via C-2 Alkylation Of Indoles With 2-Alkoxycyclopropanoate Esters., Barbora Bajtos, Brian L Pagenkopf Jun 2009

Synthesis Of Tetrahydroisoquinocarbazoles Via C-2 Alkylation Of Indoles With 2-Alkoxycyclopropanoate Esters., Barbora Bajtos, Brian L Pagenkopf

Chemistry Publications

A concise method for the synthesis of several tetrahydroisoquinocarbazole derivatives is reported, where the core is prepared in six steps from tryptophol in 51% overall yield. The pentacyclic analogs are constructed via a dipolar C-2 alkylation of a 3-substituted indole with a 2-alkoxycyclopropanoate ester and a SmBr(2)-HMPA mediated ketyl-alkene ring closure.


Pictorial Quantum Chemistry, Theory And Application Of Valency Interaction Formulas, Vif, Joseph D. Alia Apr 2009

Pictorial Quantum Chemistry, Theory And Application Of Valency Interaction Formulas, Vif, Joseph D. Alia

Chemistry Publications

No abstract provided.


Total Synthesis Of (±)-Quebrachamine Via [3+2] Cycloaddition And Efficient Chloroacetamide Photocyclization, Brian Pagenkopf, Barbora Bajtos Jan 2009

Total Synthesis Of (±)-Quebrachamine Via [3+2] Cycloaddition And Efficient Chloroacetamide Photocyclization, Brian Pagenkopf, Barbora Bajtos

Chemistry Publications

The total synthesis of (±)-quebrachamine has been completed in 13 linear steps and 17.8 % overall yield. The indole core was constructed via a formal [3+2] dipolar cycloaddition between a functionalized nitrile and donor-acceptor cyclopropane, and the synthetically challenging nine-membered ring was secured by an efficient chloroacetamide photocyclization.


Poly(Styrene-Co-Vinylbenzylchloride-Co-Divinylbenzene) Coated Iron Oxide: Synthesis And Effects On Size And Morphology, M. D. Shultz, J. R. Marin, S. H. Naik, J. Wilkins, J. M. Laza, J. L. Vilas, M. Rodriguez, N. Perez, E. E. Carpenter Jan 2009

Poly(Styrene-Co-Vinylbenzylchloride-Co-Divinylbenzene) Coated Iron Oxide: Synthesis And Effects On Size And Morphology, M. D. Shultz, J. R. Marin, S. H. Naik, J. Wilkins, J. M. Laza, J. L. Vilas, M. Rodriguez, N. Perez, E. E. Carpenter

Chemistry Publications

Iron oxide nanoparticles were coated with a polymer synthesized from the monomers of styrene, divinylbenzene, and vinylbenzylchloride. The resultant polymer microspheres from synthesis without nanoparticle loading are primarily monodispersed with a diameter of 3.45 μm as measured by scanning electron microscopy. The addition of 1% nanoparticles by mass appears to decrease the size of the microspheres down to 2.04 μm as well as increase the polydispersity. This trend is also seen to continue as you add more nanoparticles to the system going from 3.45 μm with 0% nanoparticles down to below 1 μm for 5% nanoparticles. This indicates that the …


Microscopic Dynamics Of The Orientation Of A Hydrated Nanoparticle In An Electric Field, C. D. Daub, D. Bratko, A. Towshif, A. Luzar Jan 2009

Microscopic Dynamics Of The Orientation Of A Hydrated Nanoparticle In An Electric Field, C. D. Daub, D. Bratko, A. Towshif, A. Luzar

Chemistry Publications

We use atomistic simulations to study the orientational dynamics of a nonpolar nanoparticle suspended in water and subject to an electric field. Due to molecular-level effects we describe, the torque exerted on the nanoparticle exceeds continuum-electrostatics based estimates by about a factor of two. The reorientation time of a 16.2×16.2×3.35 ̊A3 nanoparticle in a field E > 0.015V/ ̊A is an order of magnitude less than the field-free orientational time (∼ 1 ns). Surprisingly, the alignment speed is nearly independent of the nanoparticle size in this regime. These findings are relevant for design of novel nanostructures and sensors and development of …


One Parameter Control Of The Size Of Iron Oxide Nanoparticles Synthesized In Reverse Micelles, M. D. Shultz, W. Braxton, C. Taylor, E. E. Carpenter Jan 2009

One Parameter Control Of The Size Of Iron Oxide Nanoparticles Synthesized In Reverse Micelles, M. D. Shultz, W. Braxton, C. Taylor, E. E. Carpenter

Chemistry Publications

Iron oxide nanoparticles were synthesized via reverse micelle methods. The initial iron concentration was varied, while maintaining all other parameters constant, in order to investigate the effect of the iron concentration on the resultant iron oxide nanoparticle size. Increasing the iron concentration from 0.125M to 0.5M yielded an increase in average nanoparticle diameter from 4.71 to 7.95 nm, as measured by transmission electron microscopy. Three other concentrations between 0.125M and 0.5M showed corresponding size variations, all with statistical significance. Magnetic characterization by vibrating sample magnetometry and powder x-ray diffraction was performed to verify proper phase and material. Further insight into …