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Articles 61 - 73 of 73

Full-Text Articles in Materials Chemistry

Etching Of Silicon In Fluoride Solutions, Kurt W. Kolasinski Jan 2009

Etching Of Silicon In Fluoride Solutions, Kurt W. Kolasinski

Chemistry Faculty Publications

No abstract provided.


Preparation And Characterization Of Some Substituted Benzyl N-Nitrosocarbamates Containing An N-2-(Methylthio)Ethyl Or A Bis(2-Aminoethyl)Sulfide Functionality, Satya Venkata, Eric Shamo, Vladimir Benin Jan 2009

Preparation And Characterization Of Some Substituted Benzyl N-Nitrosocarbamates Containing An N-2-(Methylthio)Ethyl Or A Bis(2-Aminoethyl)Sulfide Functionality, Satya Venkata, Eric Shamo, Vladimir Benin

Chemistry Faculty Publications

The synthesis and characterization of some substituted benzyl N-nitrosocarbamates with an N-2-(methylthio)ethyl or a bis(2-aminoethyl)sulfide functionality is reported, as a part of a long-term goal to design and prepare novel photolabile structures that could be used as substances for controlled release of alkylating and/or crosslinking agents. The synthesis was accomplished by reaction of benzyl chloroformates with the corresponding amines, resulting in the preparation of carbamates. The latter were subsequently nitrosated, utilizing two different N-nitrosation methods, to yield the target structures.


Preparation Of Halogenated Derivatives Of Thiazolo[5,4-D]Thiazole Via Direct Electrophilic Aromatic Substitution, Vladimir Benin, Alan T. Yeates, Douglas Dudis May 2008

Preparation Of Halogenated Derivatives Of Thiazolo[5,4-D]Thiazole Via Direct Electrophilic Aromatic Substitution, Vladimir Benin, Alan T. Yeates, Douglas Dudis

Chemistry Faculty Publications

Chlorination and bromination reactions of thiazolo[5,4-d]thiazole led to the generation of its mono- and dihalogenated derivatives. These are the first instances of successful direct electrophilic aromatic substitution in the thiazolo[5,4-d]thiazole ring system. X-ray analysis demonstrates that both 2-bromothiazolo[5,4-d]-thiazole and 2,5-dibromothiazolo[5,4-d]thiazole are planar structures, with strongly manifested π-stacking in the solid state. Theoretical analysis of the pyridine-catalyzed halogenation (MP2/6-31+G(d) and B3LYP/6-31+G(d)calculations) reveals that introduction of one halogen actually leads to a slightly enhanced reactivity towards further halogenation. Several halogenation mechanisms have been investigated: 1) The direct C-halogenation with N-halopyridine as electrophile; …


Dirubidium Digallium Oxide Bis(Orthoborate), Robert W. Smith, Chunhua Hu, Christopher D. Despain Feb 2008

Dirubidium Digallium Oxide Bis(Orthoborate), Robert W. Smith, Chunhua Hu, Christopher D. Despain

Chemistry Faculty Publications

The title compound, Rb2Ga2O(BO3)2, is part of the homologous series A2Ga2O(BO3)2 (A = Na, K, Rb and Cs). The structure contains pairs of gallium-centered tetrahedra connected through a shared oxygen vertex. Orthoborate triangles connect the basal vertices of the tetrahedra, forming a three-dimensional network with voids occupied by rubidium ions.


C–N Bond Rotation And E–Z Isomerism In Some N-Benzyl-N-Methylcarbamoyl Chlorides: A Dft Study, Michael Horwath, Vladimir Benin Feb 2008

C–N Bond Rotation And E–Z Isomerism In Some N-Benzyl-N-Methylcarbamoyl Chlorides: A Dft Study, Michael Horwath, Vladimir Benin

Chemistry Faculty Publications

The current report presents the first theoretical study of the restricted CN bond rotation in carbamoyl chlorides. Several N-benzyl-N-methylcarbamoyl chlorides were investigated, with varying pattern of substitution in the aromatic ring. Optimizations and frequency calculations were conducted employing DFT at the B3LYP/6-31+G(d) level of theory. Each of the studied structures exhibits a pair of rotamers (s-Z and s-E), generated upon rotation around the C(O)N bond. The s-E isomer is the global minimum in every case, but the preference for it is usually less than 1 kcal/mol. Two possible transition state structures were identified …


Synthesis Of The Giant Dielectric Constant Material Cacu3ti4o12 By Wet-Chemistry Methods, Jianjun Liu, Robert W. Smith, Wai-Ning Mei Jan 2007

Synthesis Of The Giant Dielectric Constant Material Cacu3ti4o12 By Wet-Chemistry Methods, Jianjun Liu, Robert W. Smith, Wai-Ning Mei

Chemistry Faculty Publications

CaCu3Ti4O12 (CCTO) has a giant dielectric constant of up to 105 at room temperature and great potential for technological application. In this work, we report two wet-chemistry methods to synthesize CCTO at relatively low temperatures and short reaction times. The pure-phase sample was obtained at 800 °C for 0.5 h, and the grain size of a pellet sample sintered at 1030 °C has a homogeneous distribution in the range of 0.4–1.5 μm.


Secondary N-Nitrosocarbamate Anions: Structure And Alkylation Reactions. A Dft Study, Vladimir Benin May 2006

Secondary N-Nitrosocarbamate Anions: Structure And Alkylation Reactions. A Dft Study, Vladimir Benin

Chemistry Faculty Publications

The current article reports theoretical studies (DFT: B3LYP/6-31+G(d)) on the structure and alkylation reactions of the anions of some secondary N-nitrosocarbamates, a class of ambident nucleophiles whose chemistry has been little explored. Several anions (1–4), with an increasing size of the carbamate alkyl (aryl) group were investigated, in an attempt to establish the influence of the size of that group on the thermal stability and regioselectivity of alkylation of the title anions. The conclusion is that thermal stability and the mode of reaction are affected significantly only in the presence of very large and branched carbamate groups. The thermal …


Orientational Disorder In Sodium Cadmium Trifluoride Trihydrate, Nacdf3·3h2o, Robert W. Smith, Arthur Mar, Jianjun Liu, Stan Schnell, John R. Hardy Mar 2006

Orientational Disorder In Sodium Cadmium Trifluoride Trihydrate, Nacdf3·3h2o, Robert W. Smith, Arthur Mar, Jianjun Liu, Stan Schnell, John R. Hardy

Chemistry Faculty Publications

Attempts to synthesize the hypothetical anhydrous fluoroperovskite NaCdF3, which has been predicted to be stable, resulted instead in a hydrated fluoride of nominal composition NaCdF3·3H2O. It decomposes to sodium fluoride, cadmium fluoride, and water at 60 °C. Its structure has been determined by single-crystal X-ray diffraction. Na0.92(2)Cd1.08F3.08·2.92H2O crystallizes in the cubic space group with a = 8.2369(4) Å and Z = 4. The structure is based on the NaSbF6-type (an ordered variant of the ReO3-type) and features tilted sodium- and cadmium-centred octahedra …


Preparation Of Some Substituted Terephthalic Acids, Susanna Branion, Vladimir Benin Jan 2006

Preparation Of Some Substituted Terephthalic Acids, Susanna Branion, Vladimir Benin

Chemistry Faculty Publications

We report in detail the preparation of two substituted terephthalic acids: 2‐sulfomethylterephthalic acid (1) and 2‐phosphonoterephthalic acid (2). Efficient, short syntheses have been developed for both compounds. They are potentially useful monomers for construction of acid‐pendant polymer chains.


Preparation, Characterization And Dft Studies Of Some New N-Nitrosocarbamates And N-Nitrosoureas, Ragavan Narayanan, Helene Hedian, Eric Shamo, Vladimir Benin Jan 2006

Preparation, Characterization And Dft Studies Of Some New N-Nitrosocarbamates And N-Nitrosoureas, Ragavan Narayanan, Helene Hedian, Eric Shamo, Vladimir Benin

Chemistry Faculty Publications

We are presenting the preparation, characterization and density functional theory (DFT) studies {B3LYP/6-31+G(d)) of several reiated classes of N-nitrosocarbamates and N-nitrosoureas. The iong-range goal is the design and preparation of compounds, which would undergo photochemical or hydrolytic decomposition, to yield stabilized cyclic cations that can serve as alkylating agents at various nucleophilic centers, including DNA bases.


Synthesis, Structural Studies And Desilylation Reactions Of Some N-2-(Trimethylsilyl)Ethyl-N-Nitrosocarbamates, Arpitha Thakkalapally, Vladimir Benin May 2005

Synthesis, Structural Studies And Desilylation Reactions Of Some N-2-(Trimethylsilyl)Ethyl-N-Nitrosocarbamates, Arpitha Thakkalapally, Vladimir Benin

Chemistry Faculty Publications

The present report describes the preparation and characterization of several N-2-(trimethylsilyl)ethyl-N-nitrosocarbamates, designed as precursors to thermally unstable secondary N-nitrosocarbamate anions via fluoride-assisted cleavage. X-ray structural studies demonstrate that the core N-nitrosocarbamate moiety has a nearly planar geometry, with an s-E orientation at the N–N bond. DFT calculations (B3LYP/6-31+G(d)) reproduce accurately the structural features of the title compounds and detailed conformational analysis at the same level of theory addresses the long-standing issue of preferred geometries for three classes of related structures: N-nitrosocarbamates, N-nitrosoureas and N-nitrosoamides. Desilylation studies demonstrate that both the …


3-Hydroxykynurenine And 3-Hydroxyanthranilic Acid Generate Hydrogen Peroxide And Promote Α-Crystallin Cross Linking By Metal Ion Reduction, Lee E. Goldstein, Michael C. Leopold, Xudong Huang, Craig S. Atwood, Aleister J. Saunders, Mariana Hartshorn, James T. Lim, Et Al. Jan 2000

3-Hydroxykynurenine And 3-Hydroxyanthranilic Acid Generate Hydrogen Peroxide And Promote Α-Crystallin Cross Linking By Metal Ion Reduction, Lee E. Goldstein, Michael C. Leopold, Xudong Huang, Craig S. Atwood, Aleister J. Saunders, Mariana Hartshorn, James T. Lim, Et Al.

Chemistry Faculty Publications

The kynurenine pathway catabolite 3-hydroxykynurenine (3HK) and redox-active metals such as copper and iron are implicated in cataractogenesis. Here we investigate the reaction of kynurenine pathway catabolites with copper and iron, as well as interactions with the major lenticular structural proteins, the R-crystallins. The o-aminophenol kynurenine catabolites 3HK and 3-hydroxyanthranilic acid (3HAA) reduced Cu(II)>Fe(III) to Cu(I) and Fe(II), respectively, whereas quinolinic acid and the nonphenolic kynurenine catabolites kynurenine and anthranilic acid did not reduce either metal. Both 3HK and 3HAA generated superoxide and hydrogen peroxide in a copper-dependent manner. In addition, 3HK and 3HAA fostered copper-dependent R-crystallin cross-linking. 3HK- …


Observation And Application Of Optical Interference And Diffraction Effects In Reflection From Photochemically Fabricated Gaussian Interfaces, Lynne Koker, Kurt W. Kolasinski Jan 1999

Observation And Application Of Optical Interference And Diffraction Effects In Reflection From Photochemically Fabricated Gaussian Interfaces, Lynne Koker, Kurt W. Kolasinski

Chemistry Faculty Publications

No abstract provided.