Chemistry Commons^™

Simulation Of Electronic And Geometric Degrees Of Freedom Using A Kink-Based Path Integral Formulation: Application To Molecular Systems, Randall W. Hall

Collected Faculty Scholarship

A kink-based path integral method, previously applied to atomic systems, is modified and used to study molecular systems. The method allows the simultaneous evolution of atomic and electronic degrees of freedom. Results for CH₄, NH₃, and H₂O demonstrate this method to be accurate for both geometries and energies. Comparison with DFT and MP2 level calculations show the path integral approach to produce energies in close agreement with MP2 energies and geometries in close agreement with both DFT and MP2 results.

Solvent Extraction Separation And Determination Of Yttrium With Cyanex272, Manjusha Karve, Bhagyashree P. Vaidya

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

A simple and selective method for the liquid - liquid extraction of yttrium with Cyanex272 is presented. The influence of the pH of aqueous phase, concentration of extractant, nature of diluent, extraction time, type of stripping agent and stripping time were evaluated to optimize the conditions for quantitative extraction of yttrium. The effect of certain foreign ions on the extraction of yttrium was studied. Yttrium was quantitatively extracted at pH = 7.0 with 5 x 10-4 M Cyanex272 in xylene. It was stripped from the organic phase with 4M nitric acid and determined spectrophotometrically with Arsenazo (Ill) at 650nm.

Regional Scale Evidence For Improvements In Surface Water Chemistry 1990-2001, B. L. Skjelkvåle, J. L. Stoddard, D. S. Jeffries, K. Tørseth, T. Høgåsen, J. Bowman, J. Mannio, D. T. Monteith, R. Mosello, M. Rogora, D. Rzychon, J. Vesely, J. Wieting, A. Wilander, A. Worsztynowicz

United States Environmental Protection Agency: Publications

The main aim of the international UNECE monitoring program ICP Waters under the Convention of Long-range Transboundary Air Pollution (CLRTAP) is to assess, on a regional basis, the degree and geographical extent of the impact of atmospheric pollution, in particular acidification, on surface waters. Regional trends are calculated for 12 geographical regions in Europe and North America, comprising 189 surface waters sites. From 1990-2001 sulphate concentrations decreased in all but one of the investigated regions. Nitrate increased in only one region, and decreased in three North American regions. Improvements in alkalinity and pH are widely observed. Results from the ICP …

The Composition Of Coexisting Jarosite-Group Minerals And Water From The Richmond Mine, Iron Mountain, California, Heather E. Jamieson, Clare Robinson, Charles N. Alpers, D. Kirk Nordstrom, Alexei Poustovetov, Heather A. Lowers

United States Geological Survey: Staff Publications

Jarosite-group minerals accumulate in the form of stalactites and fine-grained mud on massive pyrite in the D drift of the Richmond mine, Iron Mountain, California. Water samples were collected by placing beakers under the dripping stalactites and by extracting pore water from the mud using a centrifuge. The water is rich in Fe³⁺ and SO₄^2–, with a pH of approximately 2.1, which is significantly higher than the extremely acidic waters found elsewhere in the mine. Electron-microprobe analysis and X-ray mapping indicate that the small crystals (<10 > μm in diameter) are compositionally zoned with respect to Na …

Recurrent Structural Rna Motifs, Isostericity Matrices And Sequence Alignments, Neocles B. Leontis, Aurélie Lescoute, Christian Massire, Eric Westhof

Chemistry Faculty Publications

The occurrences of two recurrent motifs in ribosomal RNA sequences, the Kink-turn and the C-loop, are examined in crystal structures and systematically compared with sequence alignments of rRNAs from the three kingdoms of life in order to identify the range of the structural and sequence variations. Isostericity Matrices are used to analyze structurally the sequence variations of the characteristic non-Watson-Crick base pairs for each motif. We show that Isostericity Matrices for non-Watson-Crick base pairs provide important tools for deriving the sequence signatures of recurrent motifs, for scoring and refining sequence alignments, and for determining whether motifs are conserved throughout evolution. …

Stability Of Single Particle Tracers For Differentiating Between Heavy- And Light-Duty Vehicle Emissions, Deborah S. Gross, Alexander R. Barron, Ellen M. Sukovich, Benjamin S. Warren, Julia C. Jarvis, David T. Suess, Kimberly A. Prather

Chemistry Faculty Work

To determine the size and chemical composition of particles derived from on-road vehicle emissions, individual particles were sampledcontinuously with an aerosol time-of-flight mass spectrometer (ATOFMS) at the Caldecott Tunnel in Northern California. In this tunnel, traffic is segregated, such that in theory only light duty vehicle emissions or a mix of heavy- (HDV) and light-duty vehicle (LDV) emissions can be sampled separately. Two studies were carried out, one in November 1997 anda secondin July 2000, time periods with average ambient temperatures of 10–15 and 26–32 1C, respectively, with the instrument operating at ambient outdoor temperatures. Analysis of the chemical composition …

The Edam Project: Mining Atmospheric Aerosol Datasets, Raghu Ramakrishnan, James J. Schauer, Lei Chen, Zheng Huang, Martin M. Shafer, Deborah S. Gross, David R. Musicant

Chemistry Faculty Work

Data mining has been a very active area of research in the database, machine learning, and mathematical programming communities in recent years. EDAM (Exploratory Data Analysis and Management) is a joint project between researchers in Atmospheric Chemistry and Computer Science at Carleton College and the University of Wisconsin-Madison that aims to develop data mining techniques for advancing the state of the art in analyzing atmospheric aerosol datasets. There is a great need to better understand the sources, dynamics, and compositions of atmospheric aerosols. The traditional approach for particle measurement, which is the collection of bulk samples of particulates on filters, …

Fluorescence Prediction Through Computational Chemistry, Daniel Craig Lathey

Theses, Dissertations and Capstones

With the growing demand for diverse fluorescent dyes, it is imperative to find a more efficient methodology by which to synthesize dyes. Our research group has found a computational method that can efficiently predict the optical properties of a molecule before it is synthesized. By evaluating different semi-empirical methods, we have found a way to predict the fluorescence maxima. With the new ability of Hyperchem 7.5 to geometrically optimize a molecule in an excited state, we can predict not only the absorption maxima, but we can also predict the fluorescence maxima within 25 nm of the actual fluorescence.

With this …

Electrochemical Detection Of Nanoscale Phase Separation In Binary Self-Assembled Monolayers, R. Carlisle Chambers, Christina E. Inman, James E. Hutchison

Faculty Publications - Department of Biological & Molecular Science

Developing methods to probe the nature and structure of nanoscale environments continues to be a challenge in nanoscience. We report a cyclic voltammetry investigation of internal, hydrogen-bond driven phase separation of amide-containing thiols and alkane thiols. Amide-containing thiols with a terminal ferrocene carboxylate functional group were investigated in two binary monolayers, one homogeneously mixed and the other phase separated. The electrochemical response of the ferrocene probe was used to monitor adsorbate coverage, environment and phase separation within each of these monolayers. The results demonstrate that the behavior of ferrocene containing monolayers can be used to probe nanoscale organization.

Preservation Of Eumelanin Hair Pigmentation In Proopiomelanocortin-Deficient Mice On A Nonagouti (A/A) Genetic Background, Andrzej Slominski, Przemyslaw M. Plonka, Alexander Pisarchik, James L. Smart, Virgine Tolle, Jacobo Wortsman, Malcolm J. Low

Faculty Publications - Department of Biological & Molecular Science

No abstract provided.

Crystal Structure Of The Cis-Bis[4-Chloro-N-(Pyrrolidine-1-Carbothioyl)-Benzamido] Copper(Ii) Complex, Nevzat Külcü, Ulrich Flörke, Hakan Arslan

Turkish Journal of Chemistry

The crystal and molecular structure of the cis-bis[4-chloro-N-(pyrrolidine-1-carbothioyl)-benzamido] copper(II) complex was determined by single-crystal X-ray diffraction. The title compound, C_{24}H_{24}N_4O_2 S_2Cl_2Cu, crystalizes in the triclinic space group P-1, with Z = 4 and unit cell parameters a = 8.3877(5) Å, b = 12.7904(8) Å, c = 24.160(2) Å, \alpha = 95.923(1) °, \beta = 96.001(1) °, and \gamma = 95.048(1) °. The copper atom is 4-fold coordinated by 2 S and 2 O atoms and shows a slightly distorted planar quadratic ligand arrangement.

Diels-Alder Reactions Of New Methoxysubstituted-6-Arylfulvenes, Nüket Öcal, Emi̇ne Bağdatli, Mesut Arslan

Turkish Journal of Chemistry

Fulvenes 1, 2 and 3 were prepared and their Diels-Alder cycloaddition reactions with maleic anhydride, N-phenylmaleimide and dimethyl acetylenedicarboxylate (DMAD) as dienophiles leading to endo- and exo- [4+2] adducts shown.

Determination Of Trace Copper By Faas After Solid Phase Extraction And Preconcentration Onto Amberlite Xad-2 Loaded With Nitroso-R Salt, Mohammad Ali Taher, Sayed Ziae Mohammadi Mobarakeh, Ali Reza Mohadesi

Turkish Journal of Chemistry

A procedure for the separation and preconcentration of trace amounts of copper is proposed. It is based on the adsorption of copper(II) ions solution onto a column of Amberlite XAD-2 resin loaded with disodium 1-nitroso-2-naphthol-3, 6-disulfonate (nitroso-R salt). Copper is quantitatively retained on the column in the pH range 5.5-7.8 at a flow rate of 2 mL min^{-1}. The copper complex eluted with 5 mL of dimethylformamide (DMF) and copper was measured by flame atomic absorption spectrometry (FAAS) at 324.8 nm. In this case, 0.10 \mu g of copper can be concentrated in the column from 800 mL of aqueous …

Development And Characterization Of A Cationic Emulsion Formulation As A Potential Pdna Carrier System, Kudret Di̇lşat Barut, Fatma Fi̇li̇z Coşkun Ari, Fi̇li̇z Öner

Turkish Journal of Chemistry

The development of efficient and stable carriers for the delivery of DNA to the body is becoming an increasingly important issue in the fields of gene therapy and vaccination. The present study was designed to prepare an emulsion-based gene delivery system. Oil-in-water emulsions containing cetyltrimethylammonium bromide (CTAB) as a cationic surfactant and Pluronic F-68 as a nonionic co-surfactant were formulated and their physical characteristics were investigated. The cationic emulsion, referred to as B13d, containing a liquid crystal phase, was found to be stable and suitable for parenteral application. Complex formation between pGL3 plasmid DNA and B13d emulsion achieved at the …

Potentiometric Studies On The Protonation Constants And Solvation Of Some \Alpha-Amino Acid Benzyl- And T-Butyl- Esters In Ethanol-Water Mixtures, Alev Doğan, Esma Kiliç

Turkish Journal of Chemistry

To gain more information about the effect of solvent on \alpha -amino acid benzyl- and t-butyl- esters, the stoichiometric protonation constants of 10 esters (glycine benzyl ester, L-alanine benzyl ester, L-valine benzyl ester, L-serine benzyl ester, glycine t-butyl ester, L-alanine t-butyl ester, L-valine t-butyl ester, L-leucine t-butyl ester, L-phenylalanine t-butyl ester and L-isoleucine t-butyl ester) in 20%-80% (v/v) ethanol-water mixtures were determined at an ionic strength of 0.10 M NaCl and at 25.0 \pm 0.1 °C under nitrogen atmosphere. A potentiometric method was used and the calculation of constants was carried out using the PKAS computer program. The logarithm of …

Synthesis And Characterization Of Novel Hyperbranched Polyimides Based On Silsesquioxane Nanocomposite Networks, Turgay Seçki̇n, Ahmet Gültek, Süleyman Köytepe

Turkish Journal of Chemistry

A series of nanosized polyimides was successfully prepared by condensation polymerization of an octaamino-functionalized silsesquioxane and a series of commercially available dianhyride monomers. The polymerization of the octaamino silsesquioxane was carried out in 1-methyl-2-pyrrolidone (NMP) at room temperature, giving poly(amic acid) as precursor polymers that were readily converted to the corresponding polyimides by thermal treatment in the subsequent step, which is similar to the conventional 2-stage method. The appropriate molar ratio of the silsesquioxane monomer to a dianhyride was 1:1. These polyimides are readily soluble in polar aprotic solvents such as 1-methyl-2-pyrrolidone, and N,N-dimethylacetamide at room temperature, and show high …

Kaurane Diterpenoids From Three Sideritis Species, Maurizio Bruno, Franco Piozzi, Nelly Apostolides Arnold, K. Hüsnü Can Başer, Nurhayat Tabanca, Neşe Kirimer

Turkish Journal of Chemistry

Some kaurane diterpenoids were isolated from 3 species of the genus Sideritis (Lamiaceae) growing in the Eastern Mediterranean region. Sideritis libanotica subsp. libanotica contained siderol 2 and sideridiol 3. Sideritis erythrantha var. erythrantha yielded sideridiol 3. Sideritis perfoliata gave siderol 2, sideridiol 3 and sideritriol 4. The products are known as they occur in another species of Sideritis growing in Italy and in other species growing also in Turkey. The products are isolated for the first time from these 3 species. The taxonomic significance of these results is discussed.

Flavonoids From The Leaves Of Impatiens Bicolor, Aurangzeb Hasan, Muhammad Nawaz Tahir

Turkish Journal of Chemistry

Three new flavanone glycosides, naringenin 4'-O-\beta-D-glucuronopyranoside, naringenin 4'-O-\alpha-L rham\-nopyranoside and naringenin 4'-O-\beta-D-xylopyranoside, were characterized from the leaves of Impatiens bicolor, together with 6 known glycosides: naringenin 4'-O-\beta-D-glucopyranoside, kaempferol 7-O-\beta-D-glucuronopyranoside, quercetin 3-O-\beta-D-glucopyranoside, kaempferol 5-O-\beta-D-xylopyranoside, kaempferol 3-O-\beta-D-galactopyranoside and kaempferol 7-O-\beta-D-xylopyranoside. The structures were determined by means of co-chromatography, UV, HPLC, EI-MS, FAB-MS and ^1H NMR.

Secondary Metabolites Of Phlomis Viscosa And Their Biological Activities, İhsan Çaliş, Hasan Kirmizibekmez, John A. Beutler, Ali̇ Arslan Dönmez, Funda Nuray Yalçin, Ekrem Kiliç, Meral Özalp, Peter Rüedi, Deni̇z Taşdemi̇r

Turkish Journal of Chemistry

Further phytochemical studies on the aerial parts of Phlomis viscosa (Lamiaceae) led to the isolation of 24 compounds: 3 iridoid glycosides, 10 phenylethanoid glycosides, a megastigmane glycoside and a hydroquinone glycoside, as well as 2 lignan glucosides and 7 neolignan glucosides, 1 of which is new (17b). Compound 17b was obtained as a minor component of an inseparable mixture (2:1) of 2 neolignan glucosides (17a/b), and characterized as 3',4-O-dimethylcedrusin 9-O-\beta -glucopyranoside. Full NMR data of the known 8-O-4' neolignan glucoside, erythro-1-(4-O-\beta-glucopyranosyl-3-methoxyphenyl)- 2-{2-methoxyl-4-[1-(E)-propene-3-ol]-phenoxyl}-propane-1,3-diol (18) are also reported. All isolated compounds were screened for cell growth inhibition versus 3 tumor cell lines …

The Synthesis And Applications Of Cr-Doped Glymo And Glymo/Damo Surface Coating Systems For Absorbing Uv-Light By Sol-Gel Process, Meltem Asi̇ltürk, Funda Sayilkan, Gali̇p İçduygu, Hi̇kmet Sayilkan

Turkish Journal of Chemistry

A new glass coating system, containing \gamma- glycidoxypropyltrimethoxysilane/Cr^{3+} (system I:GLYMO/ Cr^{3+}) and \gamma-glycidoxypropyltrimethoxysilane/N-aminoethyl-3- aminopropyltrimethoxysilane/Cr^{3+} (system II:GLYMO/DAMO/Cr^{3+}), was synthesized by the sol-gel technique for UV light absorption applications. UV-visible spectroscopy (UV-VIS) was utilized to investigate the optical properties of coating materials. Especially system II showed very low transmission in the UV wavelength regions (300--400 nm) after thermal treatment of the coated surface. The UV transmission property of surfaces did not change at 80, 100, 450 or 500 °C, but a T value as low as 0.07% was obtained between 150 and 450 °C.

Kinetics Study Of Lead Ion Adsorption On Active Carbon, Riaz Qadeer, Sohail Akhtar

Turkish Journal of Chemistry

The kinetics of the adsorption of lead ions on active carbon from aqueous solutions was studied at room temperature at different lead ion concentrations (i.e. 0.1-0.5 g/L). The kinetics of the lead ion adsorption on active carbon is explained through mass transfer adsorption phenomena and the rate determining step was found to be film diffusion

Cobalt Impregnated Alumina: Nitrogen Adsorption Study At 77 K, Riaz Qadeer, Sumeera Ikram

Turkish Journal of Chemistry

Alumina powder is impregnated with cobalt in the concentration range 5% to 20% (w/v) and is characterized by nitrogen adsorption at 77 K by continuous flow method using the Quantasorb sorption system. It was observed that cobalt metal on impregnation does not contribute any extra surface to alumina. Values of BET surface area determined from nitrogen adsorption data follow the sequence Co (20% w/v) - Al_2O_3 < Co (10% w/v) - Al_2O_3 < Co (5% w/v) - Al_2O_3 < Pure Al_2O_3. Pore size distribution curves demonstrate the mesoporous nature of cobalt impregnated alumina.

Synthesis And Complex Formation Of Some Novel Vic-Dioxime Derivatives Of Hydrazones, Nursabah Sarikavakli, Gazi̇ İrez

Turkish Journal of Chemistry

Three novel vic-dioxime compounds and their transition metal complexes were synthesized for the first time. These ligands are anti-glyoximehydrazine (GH_2), anti-2-pyridinealdehydeglyoxime hydrazone (PyGH_2) and anti-2-furancarboxaldehydeglyoxime hydrazone (FGH_2). The synthesized anti-glyoximehydrazine was reacted with 2-pyridinealdehyde or 2-furancarboxaldehyde to obtain the PyGH_2 and FGH_2 ligands. Mononuclear complexes of these ligands with a metal-ligand ratio of 1:2 were prepared with Ni(II), Co(II) and Cu(II) ions. The structures of the ligands and complexes were determined by ^1H n.m.r, i.r spectroscopy and elemental analytical techniques.

Anhydrous Proton Conductive Polystyrene Sulfonic Acid Membranes, Ayhan Bozkurt

Turkish Journal of Chemistry

A novel anhydrous proton conducting polymer electrolyte based on polystyrene sulfonic acid, PSSA and benzimidazole (BnIm) was synthesized. The PSSA-BnIm interactions were studied by FT-IR. The thermal properties of the blends were investigated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The proton conductivities of these materials were measured by AC impedance technique. The conductivities of these materials increase with increasing BnIm content and temperature and maximum conductivity was found to be approximately 5 \times 10^{-4} S/cm at 150 °C.

Synthesis And Characterization Of New Triheterocyclic Compounds Consisting Of 1,2,4-Triazol-3-One, 1,3,4-Thiadiazole And 1,3,4-Oxadiazole Rings, Nesli̇han Demi̇rbaş

Turkish Journal of Chemistry

A series of acetic acid derivatives (2a-c) was synthesized by the condensation of compounds 1a-c with chloroacetic acid. The treatment of carboxylic acid derivatives with thiosemicarbazide in phosphorus oxychloride and subsequent diazotation of the products (3a-c) afforded 5-alkyl-2-[(5-chloro-1,3,4-thiadiazol-2-yl)methyl]- 2,4-dihydro-3H-1,2,4-triazol-3-one derivatives (4a-c). The treatment of compounds 4a-c with thiourea produced 5-alkyl-2-[(5-mercapto-1,3,4- thiadiazol-2-yl)methyl]-2,4-dihydro-3H-1,2,4-triazol-3-one derivatives (5a-c). Subsequently, compounds 5a-c were converted to acid hydrazides by treatment with hydrazine hydrate after esterification (7a-e). Moreover, the reaction of compounds 7a-c with carbon disulfite in the presence of KOH afforded 5-alkyl-2-[(5-\{[(5- mercapto-1,3,4-oxadiazol-2-yl)methyl]thio\}-1,3,4-thiadiazol-2-yl)methyl]- 2,4-dihydro-3H-1,2,4-triazol-3-ones (8a-c).

Color Reaction Of 2-(2-Quinolylazo)-5-Dimethylaminoaniline With Palladium And Its Application, Yunsen Si, Qiufen Hu, Zhangjie Huang, Guangyu Yang, Jiayuan Yin

Turkish Journal of Chemistry

A new chromogenic reagent, 2-(2-quinolylazo)-5-dimethylaminoaniline (QADMAA) was synthesized. A sensitive, selective and rapid method for the determination of palladium based on the rapid reaction of palladium(II) with QADMAA was developed. In the presence of 0.5-2.5 mol L^{-1} of hydrochloric acid solution and cetyl trimethylammonium bromide medium QADMAA reacts with palladium to form a violet complex with a molar ratio of 1:2 (palladium to QADMAA). The molar absorptivity of the chelate is 1.35x10^5 L mol^{-1} cm^{-1} at 600 nm. Beer's law is obeyed in the range of 0.01 to 0.6 \mu g mL^{-1}. The detection limit is 1.2 \mu g L^{-1}. …

The Atomic Absorption Spectrophotometric Method For Indirect Determination Of Nimodipine In Tablets, Mevlüde Canlica, Sezen İsli̇myeli̇

Turkish Journal of Chemistry

A simple indirect atomic absorption spectrophotometric (AAS) method is described for the analysis of nimodipine in tablet formulations. The method is based on the reduction of the antihypertensive drug substances including an aromatic nitro group by boiling them with cadmium metal in 0.05 N HC??l medium under CO_2 atmosphere for 1 h under reflux. The amounts of the drugs were calculated by determining the atomic absorbances of the released Cd^{+2}. The calibration graphs were plotted between the absorbance Cd^{+2} concentrations in the range of 0.242 to 1.209 \mu g.cm^{-3} for nimodipine. As a reference method, the spectrophotometric procedure was developed. …

Synthesis Of Some New Isoxazolidines By 1,3-Dipolar Cycloaddition Reaction Of Nitrones And Olefins, Akbar Mobinikhaledi, Naser Forughifar, Zahra Kalate

Turkish Journal of Chemistry

A series of new isoxazolidines 5a-j were synthesized by 1,3-dipolar cycloaddition reaction of different nitrones with substituted olefins under reflux condition. The yields of products following recrystallization from absolute ethanol were of the order of 40%-66%. IR, NMR and mass spectroscopies were used for identification of these compounds.

Synthesis And Antimicrobial Evaluation Of Some New 2-(2-(P-Chlorophenyl) Benzimidazol-1-Yl Methyl)-5-Substituted Amino-[1,3,4]-Thiadiazoles, Gülgün Ayhan Kilcigi̇l, Canan Kuş, Nurten Altanlar, Süheyla Özbey

Turkish Journal of Chemistry

Some 2-(2-(p-chlorophenyl)benzimidazol-1-ylmethyl)-5-substituted amino-[1,3,4]-thiadiazoles were synthesized and their in vitro antimicrobial activities were tested against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Candida albicans and Candida krusei. Compounds 1b and 12b which possess remarkable activity against C. albicans and marginal activity against C. krusei were found to be the most active compounds in this series. Single crystal X-ray diffraction analysis was performed for compound 8b.

Flavonol Glycosides From Asperula Arvensis L., Zühal Güvenalp, L. Ömür Demi̇rezer

Turkish Journal of Chemistry

From the aerial parts of Asperula arvensis L. 9 known flavonol glycosides, namely quercetin (1), isoquercitrin [= quercetin 3-O-\beta-glucopyranoside] (2), hyperin [= quercetin 3-O-\beta -galactopyranoside] (3), quercetin 7-O-\beta-galactopyranoside (4), quercetin 4'-O-\beta-galactopyranoside (5), isorhamnetin 3-O-\beta -galactopyranoside (6), isorhamnetin 5-O-\beta-galactopyranoside (7), dihydrokaempferol 7-4'-dimethylether 3-O-\beta -glucopyranoside (8) and isorhamnetin 3-O-\alpha -rhamnopyranosyl (1''' \to 6'')-\beta -glucopyranosid (9), were isolated. The structures of the compounds were elucidated by high field 1D and 2D NMR and ESI-MS spectroscopies.