Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- 1 (98)
- 2 (82)
- Synthesis (60)
- Adsorption (52)
- Antimicrobial activity (47)
-
- 3 (44)
- Phthalocyanine (34)
- Antibacterial activity (29)
- Cytotoxicity (27)
- Molecular docking (26)
- Preconcentration (26)
- Palladium (25)
- Voltammetry (25)
- Cyclic voltammetry (24)
- Copper (23)
- Fluorescence (23)
- Schiff base (23)
- Lamiaceae (22)
- Spectrophotometry (22)
- Antioxidant activity (19)
- DFT (19)
- Kinetics (19)
- Chitosan (18)
- Nanoparticles (18)
- Cadmium (17)
- Antioxidant (16)
- Electrospinning (16)
- Photocatalysis (16)
- 4-triazole (15)
- Antimicrobial (15)
- Publication Year
Articles 2251 - 2280 of 2628
Full-Text Articles in Physical Sciences and Mathematics
Determination Of Calcium, Magnesium And Aluminium In Magmatic Rocks After Ultrasonic Leaching By Flame Aas, M. Hi̇kmet Özkan, Mehmet Akçay
Determination Of Calcium, Magnesium And Aluminium In Magmatic Rocks After Ultrasonic Leaching By Flame Aas, M. Hi̇kmet Özkan, Mehmet Akçay
Turkish Journal of Chemistry
A method of ultrasonic leaching has been developed for the destructive analysis of magmatic rock samples^1. This method was applied to determine three new elements, Ca, Mg and Al, in magmatic rock samples. The accuracy of the ultrasonic leaching method (C_{ULM}) was tested using standard reference materials (SRMs) and the recovery ratio as K_1 = C_{ULM}/C_{SRM} was defined. Another recovery ratio, K_2, was also defined from the results of the conventional dissolution method (CDM), that is K_2 = C_{ULM}/C_{CDM}. The accuracy and precision of the method are comparable with those of conventional methods. The following recovery ratios were obtained for …
Electrodeposition Of Zinc From Chloride Solution, Yanjerappa Arthoba Naik, Thimmappa V. Venkatesha, Perdur Vasudeva Nayak
Electrodeposition Of Zinc From Chloride Solution, Yanjerappa Arthoba Naik, Thimmappa V. Venkatesha, Perdur Vasudeva Nayak
Turkish Journal of Chemistry
The electroplating of zinc is carried out in the presence of 3,4,5-Trimethoxy benzaldehyde from a chloride bath. The bath constituents are optimized through Hull cell experiments. Operating parameters such as pH, temperature, and current density are also optimized. The current efficiency and throwing power are measured at different current densities. Polarization study is carried out under galvanostatic conditions. Corrosion resistance test indicated good protection of steel by the coating. The consumption of brightener is determined in the laboratory scale. SEM photomicrographs revealed fine-grained structure of the deposit from the optimum bath. IR spectrum of the scratched deposit showed inclusion of …
Non-Covalent Immobilization Of Quince (Cydonia Oblonga) Polyphenol Oxidase, Hülya Yağar, Ayten Sağiroğlu
Non-Covalent Immobilization Of Quince (Cydonia Oblonga) Polyphenol Oxidase, Hülya Yağar, Ayten Sağiroğlu
Turkish Journal of Chemistry
A partially purified polyphenol oxidase from quince (Cydonia oblonga) was immobilized on bentonite by simple adsorption at pH 6.8. The properties of the immobilized enzyme were compared to those of the free enzyme. Optimum pH and temperature were determined to be 9.0 and 45°C, respectively, showing the alteration of pH and temperature profiles by immobilization. No drastic change was observed in the K_m value after immobilization. Catechol, L-DOPA, p-cresole and pyrogallol were tested as substrates. Thermal and storage stability and reusability experiments were carried out. It was observed that the immobilized enzyme had storage stability for a period of one …
Corrosion Of Reinforcing Steel In Concrete Immersed In Chloride Solution And The Effects Of Detergent Additions On Diffusion And Concrete Porosity, Hülya Kahyaoğlu, Mehmet Erbi̇l, Bi̇rgül Yazici, Ayşe Bahar Yilmaz
Corrosion Of Reinforcing Steel In Concrete Immersed In Chloride Solution And The Effects Of Detergent Additions On Diffusion And Concrete Porosity, Hülya Kahyaoğlu, Mehmet Erbi̇l, Bi̇rgül Yazici, Ayşe Bahar Yilmaz
Turkish Journal of Chemistry
In order to investigate the corrosion of reinforcing steel in concrete and the effects of chloride ions, oxygen diffusion and detergent additives of linear alkylbenzene (LAB) and linear alkylbenzene sulfonate (LAS), potentiokinetic experiments were carried out. Thus, by embedding steel electrodes into concrete specimens with a water/cement (W/C) ratio of 0.45, current-potential curves were obtained and the compressive strength of the specimens was measured. The electrochemical approach can be used to identify the effect of chloride on steel corrosion in concrete. It was found that the diffusion of chloride and oxygen through concrete and the reduction of oxygen on the …
Radio Frequency-Induced Plasma Polymerization Of Allyl Alcohol And 1-Propanol, Şennur Candan
Radio Frequency-Induced Plasma Polymerization Of Allyl Alcohol And 1-Propanol, Şennur Candan
Turkish Journal of Chemistry
The effect of the composite parameters' plasma power (P)-to-monomer flow rate (\phi) ratio (P/\phi) in the plasma polymerization of allyl alcohol and 1-propanol was studied. The radio-frequency plasmas of deposits operated at low power (1-15 W) were investigated using deposition rate measurements. Detailed chemical information on the plasma polymers was obtained by X-ray photoelectron spectroscopy (XPS). The study of the surface chemistry of films created from allyl alcohol and 1-propanol demonstrates the importance of the double bond for good \underline{C}-O group retention. The deposition rates of both plasma polymers were found to increase with increasing P. The comparison of the …
Bifunctional Allyl-Sulphonium Salt As A Novel Addition--Fragmentation Agent For Photoinitiated Cationic Polymerization, Utku Küçüktömbeki̇ci̇, Mustafa Deği̇rmenci̇, Yusuf Yağci
Bifunctional Allyl-Sulphonium Salt As A Novel Addition--Fragmentation Agent For Photoinitiated Cationic Polymerization, Utku Küçüktömbeki̇ci̇, Mustafa Deği̇rmenci̇, Yusuf Yağci
Turkish Journal of Chemistry
Bifunctional allyl tetrahydrothiophenium hexafluoroantimonate was synthesized via a one-pot reaction of 3-chloro-2-chloromethylpropene with thiophene in the presence of sodium hexafluoroantimonate. The initiation capability of this salt, in conjunction with a photochemical free radical source such as 2,2-dimethoxy-2-phenyl acetophenone and benzophenone, via an addition-fragmentation mechanism in the cationic polymerization of cyclohexene oxide and butyl vinyl ether is investigated.
Synthesis And Characterization Of Some 3-Alkyl-4-Amino-5-Cyanomethyl-4h-1,2,4-Triazoles, Nesli̇han Demi̇rbaş, Ahmet Demi̇rbaş, Kemal Sancak
Synthesis And Characterization Of Some 3-Alkyl-4-Amino-5-Cyanomethyl-4h-1,2,4-Triazoles, Nesli̇han Demi̇rbaş, Ahmet Demi̇rbaş, Kemal Sancak
Turkish Journal of Chemistry
The preparation and characterization of some 3-alkyl-4-amino-5-cyanomethyl-4H-1,2,4-triazoles with active methylene groups are described and their structural properties using NMR and IR spectra and elemental analyses are given.
Synthesis Of 1,4-Diazepine Nucleosides, M. Zia-Ul-Haq, Shahid Hameed, Helmut Duddeck, Roshan Ahmed
Synthesis Of 1,4-Diazepine Nucleosides, M. Zia-Ul-Haq, Shahid Hameed, Helmut Duddeck, Roshan Ahmed
Turkish Journal of Chemistry
The phenolic \beta-diketones I prepared by modified Baker-Venkataraman rearrangement were converted to the flavones II in acidic medium which on treatment with aqueous ethylenediamine/propylenediamine gave diazepine derivatives III. After coupling with acetobromo sugars in the presence of mercuric cyanide and nitromethane, deacetylation in methanolic ammonia yielded nucleosides V. The structures of all the intermediates and final products were confirmed with the help of modern spectroscopic techniques.
Trace Element Accumulation In Selected Bioindicators Exposed To Emissions Along The Industrial Facilities Of Danube Lowland, Heide Spiegel
Trace Element Accumulation In Selected Bioindicators Exposed To Emissions Along The Industrial Facilities Of Danube Lowland, Heide Spiegel
Turkish Journal of Chemistry
The scope of this study was to investigate the effects of the atmospheric emissions of two significant industrial centres of the Danube Lowland: the Schwechat and Slovnaft refineries. In this connection the environmental pollution of emission zones by heavy metals on the base of selected bioindicators (soil, lucerne, wheat, earthworms) should be evaluated. The phenomenon of the atmospheric impact of heavy metal aerosols on the food chain and substance transfer for the model studied (soil - plants - terrestrial invertebrates) was quantified by transfer (bioaccumulation) factors. Due to the orographic depression between the Eastern Alps and Western Carpathian Mountains and …
Conformational Analysis Of Pol-Rfamide Ii (Glu}^{1}-Trp^{2}-Leu^{3}-Lys^{4}-Gly^{5}-Arg^{6}-Phe^{7}-Nh_{2}) Heptapeptide, Lütfü Demi̇r, Niftali Mihrali Godjaev
Conformational Analysis Of Pol-Rfamide Ii (Glu}^{1}-Trp^{2}-Leu^{3}-Lys^{4}-Gly^{5}-Arg^{6}-Phe^{7}-Nh_{2}) Heptapeptide, Lütfü Demi̇r, Niftali Mihrali Godjaev
Turkish Journal of Chemistry
The geometrical structure of the sea anemone and sea pansies neuropeptide Pol-RFamide II Glu^{1}-Trp^{2}-Leu^{3}-Lys^{4}-Gly^{5}-Arg^{6}-Phe^{7}-NH_{2} was carried out by molecular mechanics (MM). The linkage bonds are characterised by the torsional angles \phi, \psi and \omega and the side groups characterised by the torsional angles \chi_{1}, \chi_{2}, \chi_{3},... subsequently. The energy-map for each monopeptide of the Pol-RFamide II was drawn in the range of -180° to 180° with increments of 20°. Conformation facilities for monopeptides were decided from these maps. These results were used in the analysis of the dipeptide Glu^{1}-Trp^{2}. Then, the Glu^{1}-Trp^{2}-Leu^{3} tripeptide was examined by using the calculated results …
Acid-Base Equilibria Of Some N-Substituted Thiophene-2-Carboxamidoximes In Non-Aqueous Media, Nedi̇me Dürüst, Yaşar Dürüst, İlknur Meri̇ç
Acid-Base Equilibria Of Some N-Substituted Thiophene-2-Carboxamidoximes In Non-Aqueous Media, Nedi̇me Dürüst, Yaşar Dürüst, İlknur Meri̇ç
Turkish Journal of Chemistry
The protonation constants of the amino nitrogens of some N-substituted thiophene-2-carboxamidoximes have been determined in acetic acid by means of potentiometric titration with perchloric acid. pK_{a} values of the title compounds were interpreted on the basis of structural effects due to the substituents and the main skeleton.
Spectrophotometric Determination Of Mexiletine Hydrochloride In Capsules Using Bromothymol Blue, Zeynep Aydoğmuş, S. Müge Çeti̇n, Sedat Tosunoğlu
Spectrophotometric Determination Of Mexiletine Hydrochloride In Capsules Using Bromothymol Blue, Zeynep Aydoğmuş, S. Müge Çeti̇n, Sedat Tosunoğlu
Turkish Journal of Chemistry
A new spectrophotometric method based on the formation of an ion-pair using bromothymol blue as ion-pair complexing reagent was developed for the determination of mexiletine hydrochloride in capsules. The ion-pair formed was highly coloured and easily extracted with dichloromethane. The calibration curve was linear over the concentration range 1.08--10.8 \mu g.ml^{-1} at \lambda_{max} = 408 nm (r = 0.9999). The results obtained from the developed method were compared statistically with those obtained by the British Pharmacopeia method.
The Protonation Constants Of Some Aliphatic Alkylamines In Ethanol-Water Mixtures, Esma Kiliç, Gülteki̇n Gökçe, Esi̇n Canel
The Protonation Constants Of Some Aliphatic Alkylamines In Ethanol-Water Mixtures, Esma Kiliç, Gülteki̇n Gökçe, Esi̇n Canel
Turkish Journal of Chemistry
Protonation constants of methyl-, ethyl-, propyl- and butylamines Were determined potentiometrically using an electrode system calibrated in concentration units of hydrogen ion in ethanol-water mixtures (10\% -80\% ethanol, v/v) at an ionic strength of 0.1 and at 25°C. The trend in the values of protonation constants of these aliphatic amines was explained in terms of the number of alkyl groups and solvent composition. The basicity orders were found to be NH_{3} < R_{3}N < RNH_{2} < R_{2}NH (R:-CH_{3}, -C_{2}H_{5}, -n-C_{3}H_{7} and --n-C_{4}H_{9}) in all the solvent mixtures studied.
Swelling Of Superabsorbent Acrylamide/Sodium Acrylate Hydrogels Prepared Using Multifunctional Crosslinkers, Erdener Karadağ, Dursun Saraydin
Swelling Of Superabsorbent Acrylamide/Sodium Acrylate Hydrogels Prepared Using Multifunctional Crosslinkers, Erdener Karadağ, Dursun Saraydin
Turkish Journal of Chemistry
Superwaterabsorbent acrylamide-sodium acrylate hydrogels were Prepared by free radical polymerization in aqueous solutions of acrylamide and of acrylamide with sodium acrylate as comonomer. For each copolymerization, nine different compositions were used and in all systems a concentration of a multifunctional crosslinker such as trimethylolpropane triacrylate, ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate and N,N'-methylenebisacrylamide was employed. As a result of dynamic swelling tests, the influence of crosslinkers and the relative content of sodium acrylate on the swelling properties, the initial swelling rate and the swelling rate constant, swelling exponent, swelling coefficients and diffusional behaviour of water in the hydrogel systems were examined. …
Modeling Of Taqi Endonuclease Purification By Hplc, Mehmet Düzenli̇, Kutlu Ö. Ülgen
Modeling Of Taqi Endonuclease Purification By Hplc, Mehmet Düzenli̇, Kutlu Ö. Ülgen
Turkish Journal of Chemistry
The present work is based on the previously reported purification study of TaqI endonuclease^{5} and aimed to simulate the experimentally obtained chromatograms in order to reduce the time and cost in the design, optimization and scaling up of purification processes. Three different models depending on equilibrium, rate and plate theories are used in the mathematical description of experimental elution profiles and the solutions of the model equations are compared. The equilibrium-dispersive theory provides excellent results in predicting the experimental chromatograms. It is thus recognized that band dispersion takes place in the column through axial dispersion and nonequilibrium effects. The user-friendly …
The Selective Protection And Deprotection Of Ambident Nucleophiles With Parent And Substituted Triarylmethyls, İbrahi̇m Demi̇rtaş, Bülent Büyükkidan, Mahfuz Elmastaş
The Selective Protection And Deprotection Of Ambident Nucleophiles With Parent And Substituted Triarylmethyls, İbrahi̇m Demi̇rtaş, Bülent Büyükkidan, Mahfuz Elmastaş
Turkish Journal of Chemistry
N-triphenylmethyl and N-4,4'-dimethoxytriphenylmethyl of o-aminophenol, m-aminophenol, and p-aminophenol compounds were easily prepared from triphenylmethyl chloride and 4,4'-dimethoxytriphenyl- methyl chloride. S-triphenylmethyl-2-mercapto ethanol was also selectively synthesized using the triphenylmethyl chloride and 2-mercapto ethanol. The reactivity of nitrogen and sulfur versus oxygen in the protection reactions was compared. In principle, the protection of aminophenols and 2-mercapto ethanol with triarylmethyls (trityls) may take place on the oxygen. However, in this framework, we discuss the different reactivities of oxygen, nitrogen and sulfur towards triphenylmethyl chloride (TrCl) and 4,4'-dimethoxytriphenylmethyl chloride (DMTrCl) and find that nitrogen and sulfur are more reactive than oxygen.
Synthesis Of Novel Acidic Mono Azo Dyes And An Investigation Of Their Use In The Textile Industry, Emel Yildiz, Hami̇t Boztepe
Synthesis Of Novel Acidic Mono Azo Dyes And An Investigation Of Their Use In The Textile Industry, Emel Yildiz, Hami̇t Boztepe
Turkish Journal of Chemistry
1,2-hydroxo phenyl azo,8-amino naphthalene, 3,6-disulfonic acid Mono sodium salt (HFANS) and its metal complex with chromium (III) salt (ligand metal ratio 1:1) were synthesized as H-acid derivatives. Having an acidic character these dyes are used for dyeing polyamide and protein fibers. Their properties such as dyeing, wash fastness and color classification were investigated according to international standard methods.
Anodic Behavior Of Tungsten In H_{3}Po_{4}-K_{2}So_{4}-H_{2}So_{4}/Koh Solutions, Mustafa Anik
Anodic Behavior Of Tungsten In H_{3}Po_{4}-K_{2}So_{4}-H_{2}So_{4}/Koh Solutions, Mustafa Anik
Turkish Journal of Chemistry
Potentiodynamic and potentiostatic polarizations were used to study the effect of pH on the anodic reaction characteristics of tungsten (W) in a very broad pH range (0.4-13). The open circuit potential was observed to decrease with a constant slope of 58 mV/pH, as pH increased. The oxide phase of W showed typical amphoteric surface behavior in the acidic regime. The oxide dissolution went through a minimum at pH 2.5, which was identified as the point of zero charge (pzc) of W--oxide. The oxide dissolution below the pzc was H^{+} -assisted and above the pzc was OH^{-}-assisted. At around the pzc …
Bromination Of Benzonorbornadiene Using A Mixture Of Sodium Bromide And Sodium Perborate At High Temperatures, Erdal Şenocak, Yavuz Taşkesenli̇gi̇l, Ferhan Tümer
Bromination Of Benzonorbornadiene Using A Mixture Of Sodium Bromide And Sodium Perborate At High Temperatures, Erdal Şenocak, Yavuz Taşkesenli̇gi̇l, Ferhan Tümer
Turkish Journal of Chemistry
Bromination of benzonorbornadiene (1) with sodium bromide in the presence of sodium perborate at room temperature gave only one product, the dibromide 2 produced via Wagner-Meerwein rearrangement. However, at high temperatures, bromination resulted predominantly in the formation of rearranged solvolytic products whose formation mechanisms are discussed.
New Triterpenic Saponins From Cephalaria Transsylvanica, Süheyla Kirmizigül, Hüseyi̇n Anil
New Triterpenic Saponins From Cephalaria Transsylvanica, Süheyla Kirmizigül, Hüseyi̇n Anil
Turkish Journal of Chemistry
Three new triterpenic saponins, 3-O-[\beta-D-xylopyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin 28-O-[\beta-D-glucopy\-ranosyl (1 \to 4)-\beta-D-glucopyranosyl] ester (1), 3-O-[\beta-D-glucopyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin 28-O-[\beta -D-glucopyranosyl] ester (2) and 3-O-[\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin(3) were isolated from Cephalaria transsylvanica. After cleavage of the ester-glycosidic linkage of the bisdesmosidic compounds, two new prosapogenins, 3-O-[\beta-D-xylopyranosyl (1 \to 4)-\beta-D-glucpyranosyl (1 \to 4)-\beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin (4) and 3-O-[\beta-D-glucopyranosyl (1 \to 4)- \beta-D-glucopyranosyl (1 \to 3)-\alpha-L-rhamnopyranosyl (1 \to 4)-\beta-D-xylopyranosyl] hederagenin (5) were also isolated. The structures …
Pyridine And Benzene Templated Potential Peptidomimetics, Kadi̇r Dabak
Pyridine And Benzene Templated Potential Peptidomimetics, Kadi̇r Dabak
Turkish Journal of Chemistry
This study provides a new approach for the synthesis of pyridine and benzene templated potential peptidomimetics. By the attachment of various amino acid side chains in different combinations on the pyridine template at the 2- and 3- positions and on the benzene core at 1,2,4 positions, different peptidomimetics may be obtained. Arg-10, Leu-11 and Tyr-13 amino acid side chain mimics and their precursors were attached to the pyridine and benzene core with a special arrangement to produce potential peptidomimetics of omega-conotoxin MVIIA.
Metallation Of Mesitylene By Organolithium Compounds In The Presence Of Lithium Polyether Alkoxides, Tuba Kayhan, Ni̇han Nugay, Turgut Nugay
Metallation Of Mesitylene By Organolithium Compounds In The Presence Of Lithium Polyether Alkoxides, Tuba Kayhan, Ni̇han Nugay, Turgut Nugay
Turkish Journal of Chemistry
The catalytic effect of polyether alkoxides (PEAs) on the activity Of organolithium compounds as a metallating agent studied. The sites of metallation as mono, di, tri, and gem metallation at three different benzylic positions were investigated in terms of relative yield by using gas chromatography-mass spectroscopy (GC-MS couple) techniques. The yield of the trimetallated (1,3,5-metallated) mesitylene was optimized by improving the metallation conditions. Special attention was paid to the effect of metal type, alkoxide structure, solvent polarity, temperature and also relative mole ratios of was reactants such as alkoxide to mesitylene and n-butyllithium to mesitylene on metallation reactions. It was …
Determination Of Cadmium By Faas After Solid-Phase Extraction Of Its 1-Benzylpiperazinedithiocarbamate Complex On Microcrystalline Naphthalene, Hasan Cesur, Beki̇r Bati
Determination Of Cadmium By Faas After Solid-Phase Extraction Of Its 1-Benzylpiperazinedithiocarbamate Complex On Microcrystalline Naphthalene, Hasan Cesur, Beki̇r Bati
Turkish Journal of Chemistry
By using 1-benzylpiperazinedithiocarbamate (1-BPzDC) as a new reagent, a method of solid-phase extraction is described for the pre-concentration of cadmium in water samples prior to its determination by flame atomic absorption spectrometry (FAAS). This method is based on the fact that cadmium forming in aqueous phase cadmium 1-benzylpiperazinedithiocarbamate complex (Cd(1-BPzDC)_{2}) can be extracted with microcrystalline naphthalene on solid phase, then back-extracted with potassium cyanide solution into aqueous phase and measured by FAAS. The optimum experimental parameters for the extraction and back-extraction of cadmium were investigated. The obtained recovery was nearly 97% when the enrichment factor was 500 for spiked cadmium …
Determination Of The Protonation Constants Of Some Substituted Salicylideneanilines By The Spectrophotometric Method In Ethanol-Water Mixtures, M. Abdülkadi̇r Akay, Esi̇n Canel, Esma Kiliç, Fi̇tnat Köseoğlu
Determination Of The Protonation Constants Of Some Substituted Salicylideneanilines By The Spectrophotometric Method In Ethanol-Water Mixtures, M. Abdülkadi̇r Akay, Esi̇n Canel, Esma Kiliç, Fi̇tnat Köseoğlu
Turkish Journal of Chemistry
Protonation constants of salicylideneaniline and methyl-, ethyl-, methoxy- fluoro-, chloro-, bromo- and iodo- substituted salicylideneanilines were determined by spectrophotomeric titrimetry in 10, 30, 50 and 70% ethanol-water mixtures at constant ionic strength and at 25^{o}C. The results obtained from this work were compared with those obtained using the potentimetric method. The difference between the results found with these two methods was approximately \pm $ 0.20 logK units. The spectrophotometric method was judged to be more suitable than the potentiometric method for halogen substituted salicylideneanilines with the low logK values and in the solvent mixture containing 10% ethanol, due to the …
Synthesis, Characterization And Biological Activity Of Triorganotin Carboxylates Containing Germanium, Muhammad Aziz Choudhary, Muhammad Mazhar, Saqib Ali, Umm-E Salma, Saima Ashraf, Abdul Malik
Synthesis, Characterization And Biological Activity Of Triorganotin Carboxylates Containing Germanium, Muhammad Aziz Choudhary, Muhammad Mazhar, Saqib Ali, Umm-E Salma, Saima Ashraf, Abdul Malik
Turkish Journal of Chemistry
Some new triorganotin carboxylates containing germanium with general formulae (R^{1}GeCHR^{2}CH_{2}COO) Sn(CH_{2}C(CH_{3})_{3})_{3} where R^{1} = N(CH_{2}CH_{2}O)_{3} and C_{6}H_{5}, R^{2} = C_{6}H_{5}, p-C_{6}H_{4}OCH_{3} and o-/p-C_{6}H_{4}F were synthesized and characterized by elemental analysis, infrared, multinuclear (^{1}H, ^{13}C, ^{119}Sn) NMR and mass spectrometry. Antibacterial activity of these compounds was evaluated against the standard drugs ampicilline and amoxicilline, and found to be more active in some cases than the standard drugs.
An Investigation Of The Interaction Of 4-Membered Rings With Adjacent Carbanion Centers, Özden Özel Güven, N. Beki̇r Peyni̇rci̇oğlu
An Investigation Of The Interaction Of 4-Membered Rings With Adjacent Carbanion Centers, Özden Özel Güven, N. Beki̇r Peyni̇rci̇oğlu
Turkish Journal of Chemistry
A series of cyclobutylcarbinyl phenyl ketones was prepared and the rates of base catalyzed hydrogen-deuterium exchange of \alpha -hydrogen atoms were compared with those of appropriate model compounds, to test the validity of an earlier finding, which suggested that a four-membered ring, like the three-membered ring, has the ability to stabilize an adjacent carbanion center. In this study, unlike the cyclopropyl group, no clearly defined stabilization of the adjacent carbanion center was detected by the 1-phenyl- and 1-p-nitrophenyl- substituted cyclobutyl groups and only a very slight rate enhancement by the 3-phenylcyclobutyl group was detected. Attempts to detect a stabilization of …
Iridoid And Phenylethanoid Glycosides From Euphrasia Pectinata, Tayfun Ersöz, M. Zi̇ver Berkman, Deni̇z Taşdemi̇r, İhsan Çaliş, Chris M. Ireland
Iridoid And Phenylethanoid Glycosides From Euphrasia Pectinata, Tayfun Ersöz, M. Zi̇ver Berkman, Deni̇z Taşdemi̇r, İhsan Çaliş, Chris M. Ireland
Turkish Journal of Chemistry
Two specimens of Euphrasia pectinata collected from different regions of northern Anatolia were studied to determine their iridoid and phenylethanoid glycosides. Four iridoid glucosides, aucubin (1), euphroside (2), ixorodoside (3), and boschnaloside (4), and two phenylethanoid glycosides, acteoside (5) and leucosceptoside A (6), were isolated, and characterized from the aerial parts of E. pectinata} collected from Zigana pass (Trabzon). From the aerial parts of E. pectinata} collected from Kartalkaya (Bolu), a phenethyl alcohol glycoside, decaffeoylacteoside (7), was isolated in addition to previously isolated compounds. The structures of the isolated compounds were established by spectroscopic evidence.
Diterpenes From Sideritis Sipylea And S. Dichotoma, Gülaçti Topçu, Ahmet C. Gören, Turgut Kiliç, Y. Kemal Yildiz, Gülendam Tümen
Diterpenes From Sideritis Sipylea And S. Dichotoma, Gülaçti Topçu, Ahmet C. Gören, Turgut Kiliç, Y. Kemal Yildiz, Gülendam Tümen
Turkish Journal of Chemistry
Two Sideritis species afforded eleven kaurene and one beyerene diterpenes. Structures of the compounds from Sideritis sipylea} were elucidated as linearol (1), 7-epicandicandiol (2), sideridiol (3), siderol (4), isolinearol (5), isosidol (6) and epoxyisolinearol (7). Linearol was treated with m -chloroperbenzoic to afford its analogues ent-3\beta ,7\alpha ,17-trihydroxy-18-acetoxykaur-15-ene (1a) and ent}-7\alpha ,17,18-trihydroxy-3\beta -acetoxykaur-15-ene (1b) as new compounds. From the second species, Sideritis dichotoma, the kaurenes sideridiol (3) siderol (4), ent-7\alpha ,18-dihydroxy-15\beta ,16\beta -epoxykaurane (8)}, ent}-7\alpha -acetoxy,18-hydroxy-15\beta ,16\beta -epoxykaurane (9), ent-7\alpha -acetoxy-15,18-dihydroxy-kaur-16-ene (10), ent-7\alpha ,15,18-trihydroxykaur-16-ene (11) and the beyerene ent-7\alpha ,18-dihydroxybeyer-15-ene (12) were isolated. Structural elucidation is based on NMR techniques …
Derivative Spectrophotometric Determination Of Caffeine In Some Beverages, Güzi̇n Alpdoğan, Kadi̇r Karabi̇na, Sidika Sungur
Derivative Spectrophotometric Determination Of Caffeine In Some Beverages, Güzi̇n Alpdoğan, Kadi̇r Karabi̇na, Sidika Sungur
Turkish Journal of Chemistry
Caffeine content was determined in cola, coffee and tea by second and third order derivative spectrophotometry without using any separation or background correction technique and reagent. The method is based on the measurement of the distances between two extremum values (peak to peak amplitudes) in the second order (cola) and third order (coffee and tea) derivative spectra of the sample solution. Calibration curves were constructed for the 2.0-10.0 \mu g ml^{-1}concentration range. As a reference method, reversed phase high performance liquid chromatographic procedure was developed. Commercially available beverages were analyzed by the two methods and the results were statistically compared …
Stabilization Of Papain By Modification With Chitosan, Ali̇ Kilinç, Seçi̇l Önal, Azmi̇ Telefoncu
Stabilization Of Papain By Modification With Chitosan, Ali̇ Kilinç, Seçi̇l Önal, Azmi̇ Telefoncu
Turkish Journal of Chemistry
Papain (EC 3.4.22.2) was immobilized on chitosan by adsorption and subsequent cross-linking with glutaraldehyde. The immobilized papain displayed a lower specific activity than did the native enzyme. The thermal stability of the immobilized papain, relative to that of the free enzyme, was markedly increased. The storage stability of the conjugated enzyme was enhanced such that more than 85% of the initial activity remained after a month storage at 45°C. The optimum pH of immobilized papain was shifted to the acidic region and enzyme stability was increased at pH levels below 3.5.