Chemistry Commons^™

A Case Study Of Antiaromaticity: Carbomethoxy Cyclopropenyl Anion, Zi̇kri̇ Altun, Erdi̇ Ata Bleda, Carl Trindle

Turkish Journal of Chemistry

The simplest ideas of antiaromaticity refer to regular monocyclic systems and the eigenfunctions of the H\"{u}ckel Hamiltonian for 4n $\pi $ electrons in such systems. The antiaromaticity is expressed in the energy penalty for such idealized systems relative to the H\"{u}ckel energy for 2n noninteracting $\pi $ pairs. Observed systems seldom achieve the regular planar geometry assumed in this picture, owing to their ability to ease the antiaromaticity penalty by departures from the regular geometry and also by export of the 4n $\pi $ electrons' charge to substituents. In this report we estimate numerical values for the stabilization derived from …

An Exploration Of New Avenues Regarding Deep Tissue Penetration And Higher Singlet Oxygen Efficiencies: Novel Near-Ir Photosensitizers For Photodynamic Therapy, Ni̇sa Yeşi̇lgül, Bi̇lal Kiliç

Turkish Journal of Chemistry

A series of novel BODIPY-bearing electron-withdrawing groups at the meso position are reported here. According to the optical measurements, it may be clearly seen that the introduction of electron-donating groups into 3,5-positions and the presence of electron-withdrawing groups at the meso position of the BODIPY core resulted in spectacular bathochromic shifts (up to ∼ 304 nm), and the projected photosensitizers had absorption bands in the therapeutic window of the electromagnetic spectrum (600-900 nm). The absorption maxima of compounds 4,5,6, and 7 were at 886 nm, 890 nm, 760 nm, and 761 nm, respectively. The singlet oxygen generation experiments revealed that …

Modification Of Biomass-Derived Activated Carbon With Magnetic $\Alpha $-Fe$_{2}$O$_{3}$ Nanoparticles For Co$_{2}$ And Ch$_{4}$ Adsorption, Çi̇sem Kirbiyik

Turkish Journal of Chemistry

Magnetic and nonmagnetic activated carbons (ACs) were successfully prepared by using AC obtained from spent coffee grounds (SCGs) for use in CO$_{2}$ and CH$_{4}$ capture. SCGs were activated by chemical activation to produce ACs and a magnetic $\alpha $-Fe$_{2}$O$_{3}$/AC composite was prepared by coprecipitation method from the ACs produced. Magnetic and nonmagnetic samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDX) techniques. The textural properties of samples were determined by nitrogen adsorption-desorption using the Brunauer--Emmett--Teller (BET) and Barrett--Joyner--Halenda (BJH) methods. The results showed that the porosity of …

Protonation Behavior Of Dextran Amino Acid Esters, Konrad Hotzel, Lidjia Fras Zemljic, Matej Bracic, Thomas Heinze

Turkish Journal of Chemistry

Dextran esters of different amino acids (glycine, $\beta $-alanine, L-ornithine, L-lysine) are investigated regarding their pK$_{a}$ values by potentiometric titration. The pK$_{a}$ values of the dextran derivatives are generally dependent on the position of the amino group in relation to the ester group, i.e. the nearer they are located in the molecule, the lower the resulting pK$_{a}$ values are, L-ornithine ester being the exception. An influence of the polymer backbone is ruled out. Stability against hydrolysis at different pH values and over longer periods at constant pH value is measured by potentiometric and polyelectrolyte titration. The $\beta $-alanine ester shows …

On The Azo Dyes Derived From Benzoic And Cinnamic Acids Used As Photosensitizers In Dye-Sensitized Solar Cells, Luka Matovic, Nikola Tasic, Nemanja Trisovic, Jelena Ladarevic, Vesna Vitnik, Zeljko Vitnik, Branimir Grgur, Dusan Mijin

Turkish Journal of Chemistry

In order to get a better insight into the relationship between molecular structure and photovoltaic performance, six monoazo dye molecules containing benzoic and cinnamic acid moieties were synthesized and their photovoltaic properties were studied. Three of them have not been previously used in solar cells. Spectroscopic measurements of the investigated compounds coupled with theoretical calculations were performed. Short-circuit current density, open-circuit voltage, and fill-factor were determined. It was found that a larger amount of short-circuit current density will be generated if the HOMO--LUMO energy gap is lower, determined by the stability of the molecule and the electronic effect of the …

Extraction Of High-Purity Silica From Rice Husk Via Hydrochloric Acid Leaching Treatment, Seitkhan Azat, Zhanar Sartova, Kalampyr Bekseitova, Kydyr Askaruly

Turkish Journal of Chemistry

The present paper aimed at the investigation of the effect of preliminary acid treatment on the structure and purity of extracted silica. In this study, the acid leaching of rice husk (RH) in 2 M hydrochloric acid solution before the calcination process at 600 $^{\circ}$C was proposed to achieve completely white silica with high specific surface area and low content of impurities. RH, selected from the Almaty Region, Kyzylorda Region, and Turkestan Region was used as the main silica source. The results confirmed that the highest purity (98.2%-99.7%) amorphous silica with a specific surface area between 120 and 980 m$^{2}$ …

Anticancer And Antiangiogenesis Activities Of Novel Synthesized 2-Substituted Benzimidazoles Molecules, Adem Güner, Eli̇fsu Polatli, Tamer Akkan, Hakan Bektaş, Canan Albay

Turkish Journal of Chemistry

In this study, novel 2-substituted benzimidazoles molecules having triazole, thiadiazole, and oxadiazole rings were synthesized and were evaluated by anticancer, antioxidant/oxidant status, genotoxicity, and antiangiogenesis assays. Anticancer activity of the compounds was determined by MTT (0.5, 5, and 50 $\mu $g/mL) and lactate dehydrogenase (LDH) release assays against human prostate and breast cancer cells. Oxidative status of cells was elicited by total oxidative stress and total antioxidant capacity methods. Chick chorioallantoic membrane assay was used to evaluate the antiangiogenic activity. Genotoxicity was evaluated by the sister chromatid exchange (SCE) and micronucleus (MN) tests in lymphocyte cultured human blood. Our results …

Electrochemical Responses Of Flexible Graphite In H$_2$So$_4$, Mehmet Suha Yazici

Turkish Journal of Chemistry

Asymmetric capacitors are gaining attention due to their hybrid nature with higher power and energy density compared to individual batteries or capacitors. Electrochemical and structural characteristics of flexible graphite in 40% H$_{2}$SO$_{4\, }$electrolyte are investigated using electrochemical and microscopy techniques. There is a correlation between intercalation of electrolyte and the enlargement of interlayer spacing and electrochemical response. Conditions favoring planar orientation are electrochemically less active and more stable in such corrosive electrolytes. There are response variations between plain and resin-impregnated flexible graphite samples. The reaction peak seems to be reversible for resin impregnated samples while plain samples show continuous intercalation. …

Synthesis And Characterization Of Novel Indanone-Based Spiro-Dihydrobenzofuran Derivatives, Meli̇ha Burcu Gürdere, Neşe Dürü, Yakup Budak, Mustafa Ceylan

Turkish Journal of Chemistry

In this study, the synthesis and characterization of novel indanone-based spiro-dihydrobenzofuran derivatives were examined. Firstly, chalcone-like compounds 4a-k, ($E)$-2-benzylidene-2,3-dihydro-1$H$-inden-1-one derivatives, were synthesized by the base-catalyzed addition of benzaldehyde derivatives to 2,3-dihydro-1$H$-inden-1-one. Then Mn(OAc)$_{3}$-mediated addition of dimedone (2) to the chalcone-like compounds gave two novel spiro-dihydrobenzofuran isomers: (3$S)$-6,6-dimethyl-3-aryl-6,7-dihydro-3$H$-spiro [benzofuran-2,2'-indene]-1',4(3'$H$,5$H)$-dione (5a-k) and (2'$S)$-6,6-dimethyl-2-aryl-6,7-dihydro-2$H$-spiro[benzofuran-3,2'-indene]-1',4(3'$H$,5$H)$-dione (6a-k) in good yields. The isomers were separated by column chromatography and their structures were elucidated on the basis of spectral data (NMR, IR) and elemental analysis.

Synthesis Of Hofmann-Type Zn(H$_2$O)$_2$Ni(Cn)$_4$.Ng (G = Water And 1,4-Dioxane) Clathrates And The Determination Of Their Structural Properties By Various Spectroscopic Methods, Zeki̇ Kartal, Onur Şahi̇n, Abdülkeri̇m Yavuz

Turkish Journal of Chemistry

Two new 2-dimensional cyanide-bridged coordination polymers [Zn(H$_{2}$O)$_{2}$Ni(CN)$_{4}$ 6(H$_{2}$O) and Zn(H$_{2}$O)$_{2}$ Ni(CN)$_{4}$ 3(C$_{4}$H$_{8}$O$_{2})$], which were similar to Hofmann-type clathrates, were synthesized based on [Ni(CN)$_{4}$]$^{2-}$ and Zn$^{2+}$ as building blocks. These substances were synthesized as compounds in crystalline form. Thes tructures of the crystalline compounds were characterized via their spectral analyses. General information about the structures of the newly obtained Hofmann-type clathrates was obtained from their vibration spectra by considering significant changes in the vibration peaks of the cyanide group, water ligand molecule, and guest molecules (water and 1,4-dioxane). The thermal behavior of the Hofmann-type clathrates was investigated in the range of …

Dispersive Liquid-Liquid Microextraction Of Parabens From Pharmaceuticals And Personal Care Products Prior To Their Determination Using Hplc-Dad, Malek Hassan, Usama Alshana, Nusret Ertaş

Turkish Journal of Chemistry

Dispersive liquid--liquid microextraction followed by a back-extraction step was combined with HPLC-DAD for the determination of four parabens (i.e. methyl-, ethyl-, propyl-, and butylparaben). Optimum extraction conditions were found as follows: 225 $\mu $L of chloroform, 0.75 mL of ethanol, 7.5 mL of aqueous solution and within an extraction time of 15 s. Back-extraction into 100 $\mu $L of 50 mM sodium hydroxide solution within 20 s resulted in a reversed-phase HPLC-compatible extract. The analytes were separated at 20 $^{\circ}$C using methanol (A) and water (B), 40:60 (A:B, v/v) as the mobile phase, a flow rate of 1.0 mL min$^{-1}$ …

Aqueous Two-Phase Extraction Technique Based On Magnetic Ionic Liquid-Nonionic Surfactant For Phenolic Acids In Grape, Apple, Pear, And Banana, Taşkin Mumcu, Serap Seyhan Bozkurt

Turkish Journal of Chemistry

An aqueous two-phase extraction system was constituted using magnetic ionic liquid-nonionic surfactant for phenolic acids and the developed method was applied to apple, grape, pear, and banana samples. Ionic liquids based on imidazolium containing butyl, allyl, and benzyl groups were used for extraction. The parameters influencing the extraction efficiency such as volume of ionic liquids, type and amount of surfactant and salt, ultrasound extraction time, temperature, and sample pH were optimized. The extraction efficiencies of ionic liquids were compared for phenolic acids under optimized conditions. Limits of detection and limits of quantification were in the range of 1.34-1.56 μg L$^{-1\, …

Nanomaterials Of Iron Oxide, Boron, And Boron Nitride: On The Path To Magnetic Guided Bioconjugates For Medical Applications, John Ryan Wozny

Graduate Research Theses & Dissertations

The functionalization of boron-based bioconjugates has long been studied for their potential use as a drug candidate for boron neutron capture therapy (BNCT). Also, magnetic nanoparticles have received greater attention due to their interesting magnetic properties and behaviors for selectively guiding them with an external magnetic field through the blood. A combination of the two ideas gives the framework for nanotechnology that has the potential to revolutionize drug delivery systems. This thesis will focus systematically on individual elements required for the many moving pieces required for magnetic drug targeting.

The research discussed in this thesis is divided into three parts. …

Development Of Synthetic Methodologies Of Nucleophile-Electrophile Chemistry, Michael R. Stentzel

Graduate Research Theses & Dissertations

The work outlined in this dissertation describes the development of synthetic methodologies utilizing a wide electrophilicity range of substrates towards the synthesis of new compounds. Substitution, addition, and superelectrophilic chemistry are powerful tools to afford potentially important compounds. These concepts are summarized in chapter 1.

Chapter 2 describes the capture of superacid catalyzed fluorenyl cations with nitriles (Ritter reaction) and alcohols. Optimization of reaction conditions and extensive scope studies were performed.

In chapter 3, the Michael addition of organometallic reagents with N-heterocyclic substituted olefins is explored. The nucleophilic carbanion intermediate species is shown to have reactivity towards strong electrophiles. With …

The Design, Synthesis, And Evaluation Of Inhibitors Of The Ispf Enzyme In The Mep Pathway, Christopher G. Stewart

Graduate Research Theses & Dissertations

Isoprenoids are a class of over 50,000 compounds that serve as key precursors for many compounds in plants and animals. These compounds play critical roles in many biological functions such as cellular growth, respiration, and go on to form critical compounds such as steroids and vitamins. Despite their overall necessity to life their biosynthesis only follows two synthetic pathways. These pathways are the Mevalonic Acid (MVA) Pathway and the 2-C-Methyl-D-Erythritol-4-Phosphate (MEP) Pathway also known as the non-mevalonate pathway. The MVA pathway is found primarily in humans and some higher plants while the MEP pathway is found in bacteria and some …

Targeting Mitochondria In Cancer Therapy Could Provide A Basis For The Selective Anticancer Activity, Dmitri Rozanov, Anton Cheltsov, Aaron Nilsen, Christopher Boniface, Isaac Forquer, James Korkola, Joe Gray, Multiple Additional Authors

Chemistry Faculty Publications and Presentations

To determine the target of the recently identified lead compound NSC130362 that is responsible for its selective anti-cancer efficacy and safety in normal cells, structure-activity relationship (SAR) studies were conducted. First, NSC13062 was validated as a starting compound for the described SAR studies in a variety of cell-based viability assays. Then, a small library of 1,4-naphthoquinines (1,4-NQs) and quinoline-5,8-diones was tested in cell viability assays using pancreatic cancer MIA PaCa-2 cells and normal human hepatocytes. The obtained data allowed us to select a set of both non-toxic compounds that preferentially induced apoptosis in cancer cells and toxic compounds that induced …

Aerosol Gas-Phase Components From Cannabis E‑Cigarettes And Dabbing: Mechanistic Insight And Quantitative Risk Analysis, Jiries Meehan-Atrash, Wentai Luo, Kevin J. Mcwhirter, Robert M. Strongin

Chemistry Faculty Publications and Presentations

Consumption of cannabis by nontraditional methods has surged since the advent of legalization in North America and worldwide. Inhaling cannabis extracts using vaporizers and via dabbing has risen in popularity, while concerns over product safety have not hindered their proliferation. The work herein is the first step toward assessing the safety of vaporizing and dabbing concentrated cannabis extracts as a function of gas-phase reaction products. The gas-phase thermal degradants of Δ9- tetrahydrocannabinol (THC) have not been previously investigated. It was found that users may be exposed to concerning degradants such as methacrolein, benzene, and methyl vinyl ketone when using cartridge …

Spatial Fingerprinting Of Biogenic And Anthropogenic Volatile Organic Compounds In An Arid Unsaturated Zone, Christopher T. Green, Wentai Luo, Christopher H. Conaway, Karl B. Haase, Ronald J. Baker

Chemistry Faculty Publications and Presentations

Subsurface volatile organic compounds (VOCs) can pose risks to human and environmental health and mediate biological processes. Volatile organic compounds have both anthropogenic and biogenic origins, but the relative importance of these sources has not been explored in subsurface environments. This study synthesized 17 yr of VOC data from the Amargosa Desert Research Site in Nevada with the goal of improving understanding of spatial and temporal variations that distinguish sources of VOCs from a landfill and from ambient sources including biogenic VOCs (bVOCs). Gas samples were collected from 1999 to 2016 from an array of shallow sample points (0.5- and …

Energy Transfer Between Eu2+ And Mn2+ For Na(Sr,Ba)Po4 And Ba2mg(Bo3)2, Kevin Bertschinger

Dissertations, Master's Theses and Master's Reports

There is no debate of the affect that solid-state lighting has had on the world we live in. Throughout the centuries, lighting has continued to improve from kerosene lanterns to white light emitting diodes. Even though lighting today is sufficient there is still much room to improve color rendering index and efficiency. An active area of research to improve today's lighting technology is by doping inorganic phosphors with luminescent ion centers. There have been numerous reports of inorganic phosphors showing a variety of emission color and luminescence. In this thesis we discuss two new inorganic phosphors codoped with Eu^{2+ …}

Rapid Analysis Of Magnesium In Infant Formula Powder Using Laser-Induced Breakdown Spectroscopy, Maria Markiewicz-Keszycka, Ming Zhao, Xavier Cama-Moncunill, Toufic El Arnaout, Dana Becker, Colm O'Donnell, P. J. Cullen, Carl Sullivan, Maria Piedad Casado-Gavalda

Articles

Laser-induced breakdown spectroscopy (LIBS) was investigated to determine magnesium (Mg) content in infant formula powder. To predict Mg content in the range established by the Codex Alimentarius, a partial least squares regression (PLSR) model was developed using a calibration data set (n = 30) based on full cross-validation and validated using an independent validation data set (n = 21). The prediction model performance was evaluated using the regression coefficients of determination (Rcv2 = 0.94 and Rp2 = 0.85) with the root mean square errors on cross-validation and prediction (RMSECV = 60 mg kg−1 and RMSEP = 80 mg kg−1). The …