Physical Sciences and Mathematics Commons^™

Extraction-Spectrophotometric Determination Of Trace Amounts Of Barium And Strontium By 18-Crown-6 And Rose Bengal Using Partial Least Squares, Jahan B. Ghasemi, Alireza Nikrahi, Ali Niazi

Turkish Journal of Chemistry

Partial least squares modeling is a powerful multivariate statistical tool applied to extraction-spectrophotometric simultaneous determination of mixtures of barium and strontium. The method is based on the formation of the ternary complexes with 18C6 and rose bengal with barium and strontium. The 18C6-Ba-RB and 18C6-Sr-RB ternary complexes are quantitatively extracted into dichloromethane and the resolution of the mixtures is accomplished by partial least squares (PLS). In this study, the calibration model is based on absorption spectra in the 500-600 nm range for 25 different mixtures of barium and strontium. Calibration matrice's ranges were 0.05-5.50 and 0.03-4.50 \mu g mL^{-1} and …

Reactions Of Alkenes With Sodium Perborate And Sodium Chloride, Erdal Şenocak, Yavuz Taşkesengi̇l, Ferhan Tümer, Cavi̇t Kazaz

Turkish Journal of Chemistry

Sodium perborate oxidatively chlorinates a variety of alkenes with sodium chloride to form the corresponding chloro derivatives under mild conditions.

Synthesis Of 2-[2-(3,4,5-Trimethoxybenzoyloxy)Ethyl]Pyrrolidine Hydrochloride Controlled By Gc-Ms, ^1h And ^{13}C Nmr Analyses, Alicja Wodnicka, Malgorzata Dzieciol

Turkish Journal of Chemistry

The synthesis of 2-[2-(3,4,5-trimethoxybenzoyloxy)ethyl]pyrrolidine hydrochloride was performed using 2-(2-hydroxyethyl)pyrrolidine as a starting material. Before the O-acylation reaction with 3,4,5-trimethoxybenzoyl chloride, the amino group was protected using benzyl chlorocarbonate. The removal of the blocking group was carried out in modified conditions, avoiding the alcoholysis of the ester bond. The final product was separated from its structural isomer by precipitation as its hydrochloride salt. Some steps of the synthesis were controlled by GC-MS. The identification of the respective compounds was performed by mass spectra analyses and confirmed by ^1H NMR, ^{13}C NMR, IR and elemental analyses.

Characterization Of Tio_2 Synthesized In Alcohol By A Sol-Gel Process: The Effects Of Annealing Temperature And Acid Catalyst, Funda Sayilkan, Meltem Asi̇ltürk, Hi̇kmet Sayilkan, Yunus Önal, Murat Akarsu, Ertuğrul Arpaç

Turkish Journal of Chemistry

The effects of annealing temperature and hydrolysis catalyst on the crystalline form and crystallite size of TiO_2 prepared by a sol-gel process were investigated. Three types of TiO_2 were synthesized by hydrolysis of titanium(IV)-iso-propoxide with water in n-propanol without catalyst (Type-A) and with HCl as catalyst, where the H^+ /Ti^{4+} mol ratio was 0.54 for Type-B and 0.2 for Type-C. Hydrolysis products were thermally treated at 100, 200, 300, 400 and 500 °C for 1 h after drying at room temperature. Characterization of the particles was carried out using XRD, BET, TG/DTA and SEM analysis. The pore size distributions were …

Methyl Methacrylate Oligomerically-Modified Clay And Its Poly (Methyl Methacrylate) Nanocomposites, Xiaoxia Zheng, David D. Jiang, Charles A. Wilkie

Chemistry Faculty Research and Publications

A methyl methacrylate oligomerically-modified clay was used to prepare poly(methyl methacrylate) clay nanocomposites by melt blending and the effect of the clay loading level on the modified clay and corresponding nanocomposite was studied. These nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and cone calorimetry. The results show a mixed intercalated/delaminated morphology with good nanodispersion. The compatibility between the methylacrylate-subsituted clay and poly(methyl methacrylate) (PMMA) are greatly improved compared to other oligomerically-modified clays.

Comparative Study Of Structural Properties Of Yba2cu3o7 Thin Films On Srtio3 Single Crystal And Bicrystal Substrates By X- Ray Diffraction, M. Navacerrada, A. Mehta, H. Sahibudeen, Juana Acrivos

Faculty Publications, Chemistry

We present a comparative study in terms of structural properties deduced from X - ray diffraction diagrams between YBa2Cu3O7 (YBCO) thin films fabricated on SrTiO3 (STO) single crystal substrates and bicrystallines substrates with a symmetrical tilt angle of 24 degrees. Periodic Lattice Distortions (PLD) have been observed around different Bragg peaks in YBCO thin films deposited on STO bicrystals while only diffraction peaks have been measured in the diagrams corresponding to the YBCO thin films deposited on STO single crystal substrates. Only in regions situated a 3.5 mm at both sides of the grain boundary the PDL have been investigated. …

Yba2cu3o7 Electro-Magneto-Optic Effects In Ba L2,3 X-Ray Absorption Near Tc, Juana Vivó Acrivos

Juana Vivó Acrivos

The onset of electro magneto-optic effects, observed at the Ba L2,3 edges synchrotron X-ray absorption by a YBa2Cu3O7 single crystal, 10 K above the transition temperature to superconductivity, Tc ~ 92 K is used to identify the role played by the Ba donor layer in the transition to superconductivity in the CuO2 layers. Negative permeability leads to Faraday rotation of the transmitted beam below T = 112 to 56 K for the 22 μm thick single crystal (c-axis orientation of 8π/18 relative to εX-rays) and sharp changes in the density of empty final states lead to zero transmitted radiation in …

Characterization Of The Electronic Excited-State Energetics And Solution Structure Of Lanthanide(Iii) Complexes With The Polypyridine Ligand 6,6'-Bis[Bis(2-Pyridylmethyl)Aminomethyl]-2,2'-Bipyridine, Gilles Muller, P. Gawryszewska, J. Sokolnicki, A. Dossing, J. P. Riehl, J. Legendziewicz

Gilles Muller

Absorption, emission, and excitation spectra for solid-state and solution of Tb(III), Dy(III), and Gd(III) complexes with the polypyridine ligand 6,6‘-bis[bis(2-pyridylmethyl)-aminomethyl]-2,2‘-bipyridine (C36H34N8) are presented. Measurements of excited-state lifetimes and quantum yields in various solvents at room temperature and 77 K are also reported and used to characterize the excited-state energetics of this system. Special attention is given to the characterization of metal-to-ligand energy transfer efficiency and mechanisms. The measurement of circularly polarized luminescence (CPL) from the solution of the Dy(III) complex following circularly polarized excitation confirms the chiral structure of the complexes under study. No CPL is present in the luminescence …

Reduced Macrophage Apoptosis Is Associated With Accelerated Atherosclerosis In Low-Denstiy Lipoprotein Receptor-Null Mice, Michael Sinensky, J. Liu, D. P. Thweke, Y. R. Su, M. F. Linton, S. Fazio

Michael Sinensky

Objective— The majority of apoptotic cells in atherosclerotic lesions are macrophages. However, the pathogenic role of macrophage apoptosis in the development of atherosclerosis remains unclear. Elevated expression of Bax, one of the pivotal proapoptotic proteins of the Bcl-2 family, has been found in human atherosclerotic plaques. Activation of Bax also occurs in free cholesterol-loaded and oxysterol-treated mouse macrophages. In this study, we examined the effect of Bax deficiency in bone marrow-derived leukocytes on the development of atherosclerosis in low-density lipoprotein receptor-null (LDLR−/−) mice. Methods and Results— Fourteen 8-week-old male LDLR−/− mice were lethally irradiated and reconstituted with either wild-type (WT) …

Stereochemical Promiscuity In Artificial Transcriptional Activators, Brian Brennan, Sara Buhrlage, Aaron Minter, Anna Mapp

Brian B. Brennan

Small molecule replacements of transcriptional activation domains are highly desirable targets due to their utility as mechanistic tools and their long-term therapeutic potential for a variety of human diseases. Here, we examine the ability of amphipathic isoxazolidines differing only in the placement of constituent side chains to function as transcriptional activation domains. The results reveal that precise positioning of functional groups within a conformationally constrained small molecule scaffold is not required for transcription function; rather, the balance of polarity and hydrophobicity within the scaffold is the more important determinant of transcription function. This suggests that a number of different organic …

A Solvent-Free Baeyer–Villiger Lactonization For The Undergraduate Organic Laboratory: Synthesis Of Γ-T-Butyl-Ε-Caprolactone, John Esteb, James Hohman, Diana Schlamadinger, Anne Wilson

John Esteb

We present an experiment involving the Baeyer–Villiger oxidation reactionfor a first-year organic chemistry class. The Baeyer–Villiger reactionprovides an efficient method to convert ketones to esters or lactones. Most organictextbooks cover the Baeyer–Villiger reaction but owing to a lack of suitableexperiments, students seldom get to explore the reaction in the undergraduateteaching laboratory. In this experiment, m-chloroperoxybenzoic acid(m-CPBA) and4-tert-butylcyclohexanone are mixed together for 30 minutes under solvent-freeconditions to produce γ-t-butyl-ε-caprolactone in 95%yield. The solvent-free nature of this procedure greatly limits the quantityof waste generated by students and keeps costs low by removing the need for solvent.

Note:Link is to the article …

Environment Friendly Organic Synthesis Using Bismuth Compounds. An Efficient Method For Carbonyl-Ene Reactions Catalyzed By Bismuth Triflate, Ram S. Mohan, Erin D. Anderson, Justin J. Ernat, Mai P. Nguyen, Ann C. Palma

Ram S. Mohan

A Study Of Epoxyolefin Cyclizations Catalyzed By Bismuth Trifluoromethanesulfonate And Other Metal Triflates, Ram S. Mohan, Joshua R. Lacey, Peter W. Anzalone, Christopher M. Duncan, Matthew J. Hackert

Ram S. Mohan

The Discovery-Oriented Approach To Organic Chemistry. 6. Selective Reduction In Organic Chemistry: Reduction Of Aldehydes In The Presence Of Esters Using Sodium Borohydride, Ram S. Mohan, Ashvin R. Baru

Ram S. Mohan

Interactions Between Xenon And Phospholipid Bicelles Studied By 2h/129xe/131xe Nmr And Optical Pumping Of Nuclear Spins, Xiaoxia Li, Caitlin Newberry, Indrajit Saha, Panayiotis Nikolaou, Nicholas Whiting, Boyd M. Goodson

Nicholas Whiting