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Articles 1771 - 1800 of 2720
Full-Text Articles in Chemistry
Pregnane Steroids From The Heartwood Of Azadirachta Indica, Bina Shaheen Siddiqui, Syed Kashif Ali, Syed Tariq Ali, Fayyaz Ahmed
Pregnane Steroids From The Heartwood Of Azadirachta Indica, Bina Shaheen Siddiqui, Syed Kashif Ali, Syed Tariq Ali, Fayyaz Ahmed
Turkish Journal of Chemistry
The heartwood of Azadirachta indica (Meliaceae) yielded a new steroid (2\alpha, 3\beta, 4\beta-trihydroxypregnan-16-one) and 2 known steroids (2\beta, 3\beta, 4\beta-trihydroxypregnan-16-one and 2\alpha, 3\alpha, 4\beta-trihydroxypregnan-16-one). Their structures were elucidated through spectral studies including 2D NMR (COSY, NOESY, J-resolved, HMQC, HMBC) experiments.
Chemical Constituents And Mushroom Tyrosinase Inhibition Activity Of Chloroxylon Swietenia Leaves, G. Venkatateswara Rao, K. Sambasiva Rao, Tiruganasambandham Annamalai, Narayanasamy Radhakrishnan, Triptikumar Mukhopadhyay
Chemical Constituents And Mushroom Tyrosinase Inhibition Activity Of Chloroxylon Swietenia Leaves, G. Venkatateswara Rao, K. Sambasiva Rao, Tiruganasambandham Annamalai, Narayanasamy Radhakrishnan, Triptikumar Mukhopadhyay
Turkish Journal of Chemistry
From the leaves of Chloroxylon swietenia DC., 5 known secondary metabolites, namely 6, 8-diprenylumbelliferone (1), bergaptan (2), isopimpinellin (3), tritriacontanol (4), and isoquercetrin (5), were isolated from a folklore medicinal plant. Three compounds were isolated for the first time from this genus. The structures of these compounds were elucidated by UV, IR, 1D and 2D NMR techniques. Different fractions from the leaves of C. swietenia were investigated for their tyrosinase inhibition activity.
2,2'-Binaphthylene Phosphorochloridite (Binol-Pcl) As A Bulky And Efficient Reagent For The Conversion Of Primary And Secondary Alcohols Into Iodides, And Tertiary Alcohols Stereo- And/Or Regioselectively Into Olefin(S), Nader Noroozi-Pesyan, Jabbar Kalaphy, Hossein Khani-Meinagh
2,2'-Binaphthylene Phosphorochloridite (Binol-Pcl) As A Bulky And Efficient Reagent For The Conversion Of Primary And Secondary Alcohols Into Iodides, And Tertiary Alcohols Stereo- And/Or Regioselectively Into Olefin(S), Nader Noroozi-Pesyan, Jabbar Kalaphy, Hossein Khani-Meinagh
Turkish Journal of Chemistry
Primary and secondary alcohols were transformed in high yield to corresponding iodides by 4-chloro-3,5-dioxaphosphacyclohepta [2,1-\alpha; 3,4-\alpha'] dinaphthalene (BINOL-PCl) at room temperature. The tertiary alcohols formed corresponding alkenes by stereo- and/or regioselective elimination reactions. (E)-1,2-Diphenyl-1-propene and 2,3-diphenyl-1-propene were stereoselectively obtained from 1,2-diphenyl-2-propanol, as representative. No (Z)-1,2-diphenyl-1-propene was observed. 2-Methyl-1-phenylcyclopentene and 3-methyl-2-phenylcyclopentene were regioselectively obtained from 2-methyl-1-phenylcyclopentanol. ^{13}C chemical shifts for the \alpha-methylene carbon of some alkyl iodides empirically calculated through a very simple additive relationship lead to similar or even better values than the reported values. All primary alkyl iodides showed the iodine heavy atom effect on the \alpha-methylene carbon chemical …
Zeolite Catalyzed Efficient Synthesis Of Perimidines At Room Temperature, Akbar Mobinikhaledi, Naser Forughifar, Nemat Bassaki
Zeolite Catalyzed Efficient Synthesis Of Perimidines At Room Temperature, Akbar Mobinikhaledi, Naser Forughifar, Nemat Bassaki
Turkish Journal of Chemistry
Arylperimidines, 3(a-l), were synthesized in good yields by cyclocondensation reaction of 1,8-diaminonaphthalene and aromatic aldehydes in the presence of NaY zeolite as a catalyst. The simple environmentally benign nature, reusability of the catalyst, and the easy work-up reaction are some of the advantages of this protocol.
Oxorhenium(V)-Mediated Syntheses And Structures Of Oxypyridinium-Ammonium Zwitterions, Abubak'r Abrahams, Thomas Gerber, Eric Hosten, Peter Mayer
Oxorhenium(V)-Mediated Syntheses And Structures Of Oxypyridinium-Ammonium Zwitterions, Abubak'r Abrahams, Thomas Gerber, Eric Hosten, Peter Mayer
Turkish Journal of Chemistry
Treatment of N,N-bis(2-hydroxybenzyl)-2-(2-aminoethyl) dimethylamine (H_2had) with trans-[ReO_2(py)_4]I in acetone affords the iodide salts of the oxypyridinium-ammonium zwitterions N^1-(2-hydroxybenzyl)-N^2,N^2-dimethyl-N^1-((2-oxypyridinium)-1- methyl)ethane-1,2-diamine [Hhpd]^+ and N^2,N^2-dimethyl-N^1- bis((2-oxypyridinium)-1- methyl)ethane-1,2-diamine [dod]^+. The products were characterized by X-ray structure analysis, and NMR and IR spectroscopy.
Hydrogen Storage Via Physisorption: The Combined Role Of Adsorption Enthalpy And Entropy, Carlos Otero Arean, Barbara Bonelli, Montserrat Rodriguez Delgado, Edoardo Garrone
Hydrogen Storage Via Physisorption: The Combined Role Of Adsorption Enthalpy And Entropy, Carlos Otero Arean, Barbara Bonelli, Montserrat Rodriguez Delgado, Edoardo Garrone
Turkish Journal of Chemistry
Materials capable of cost-effective on-board hydrogen storage and delivery are currently being sought worldwide as a means to facilitate a hydrogen-based energy transition in the transportation sector. Among the solutions proposed, hydrogen storage by physisorption on porous solids constitutes a main avenue of research, and for intelligent design of such materials a detailed knowledge of gas adsorption thermodynamics is of the utmost importance. Analysis of the available data for hydrogen adsorption on alkali and alkaline-earth cation exchanged zeolites clearly shows that standard adsorption enthalpy (\Delta H^0) and entropy (\Delta S^0) are correlated, in the sense that larger \Delta S^0 values …
Dynamic ^1h-Nmr Demonstration Of Anomeric Effect And Structure: Conformational And Configurational Analysis Of N-2-(1,4-Dioxane)-N'-(P-Methylbenzenesulfonyl)- O-(P-Methylphenoxy) İsourea, Ali Reza Modarresi-Alam, Hossein A. Dabbagh
Dynamic ^1h-Nmr Demonstration Of Anomeric Effect And Structure: Conformational And Configurational Analysis Of N-2-(1,4-Dioxane)-N'-(P-Methylbenzenesulfonyl)- O-(P-Methylphenoxy) İsourea, Ali Reza Modarresi-Alam, Hossein A. Dabbagh
Turkish Journal of Chemistry
The conformational and configurational behavior and the structure of N-2-(1,4-dioxane)-N'-(p-methylbenzenesulfonyl)-O- (p-methylphenoxy) isourea (1) were studied using dynamic NMR. The endo-anomeric effect, hydrogen bonding, temperature, and polarity of solvent control the population of dioxane ring conformers or anomers but not the configuration interconversion of the imine of the imidoyl moiety. Dynamic ^1H-NMR, \Delta H°, \Delta S°, \Delta G°, and \Delta G^{\ddag} analysis of 1 demonstrates that the dioxane ring adopts the chair conformation, that the imidoyl amino group prefers axial conformation, and that the tosyl and tolyl groups about the C=N bond retain the E configuration.
Synthesis Of Methyl (E)-2',4''-Thiazachalcones And Their N-Alkyl Derivatives, Photochemistry With Theoretical Calculations And Antimicrobial Activities, Asu Usta, Ahmet Yaşar, Nuran Yayli, Şengül Alpay Karaoğlu, Nuretti̇n Yayli
Synthesis Of Methyl (E)-2',4''-Thiazachalcones And Their N-Alkyl Derivatives, Photochemistry With Theoretical Calculations And Antimicrobial Activities, Asu Usta, Ahmet Yaşar, Nuran Yayli, Şengül Alpay Karaoğlu, Nuretti̇n Yayli
Turkish Journal of Chemistry
A series of 9 new (E)-thiazachalcones (1-3), and their N-alkyl substituted derivatives (4-6), and stereoselective dimerization products (7-9) were synthesized, then tested for antimicrobial activity against all test microorganisms except Pseudomonas aeruginosa. The new compounds (1-6) without dimerization products (7-9) showed good antimicrobial property against Staphylococcus aureus, Listeria monocitogenes, and Enterococcus faecalis. The possible dimerization products of compounds (1-3) were calculated theoretically. Experimental and theoretical calculation showed that \delta-truxinic type dimer is the most stable isomer.
Secondary Metabolites From Nepeta Heliotropifolia, Zühal Güvenalp, Hi̇lal Özbek, Ayşe Kuruüzüm-Uz, Cavi̇t Kazaz, L. Ömür Demi̇rezer
Secondary Metabolites From Nepeta Heliotropifolia, Zühal Güvenalp, Hi̇lal Özbek, Ayşe Kuruüzüm-Uz, Cavi̇t Kazaz, L. Ömür Demi̇rezer
Turkish Journal of Chemistry
Two iridoid glycosides, ixoroside (1) and nepetanudoside B (2); 1 phenylpropanoid glycoside, coniferine (3); 2 flavone glycosides, apigenin 7-O-glucuronide (4) and apigenin 7-O-glucopyranoside (5); 2 triterpenes, oleanolic acid (6) and ursolic acid (7); and 1 sterol, \beta-sitosterol (8), were isolated from the aerial parts of Nepeta heliotropifolia Lam. (Lamiaceae). Their structures were identified by means of spectroscopic methods (1D- and 2D-NMR, UV, and EIMS).
A Systematic Study On The Absorption And Fluorescence Properties Of 2,4,6-Triaryl And Tripyridylpyridines, Esra Findik, Mustafa Arik, Mustafa Ceylan
A Systematic Study On The Absorption And Fluorescence Properties Of 2,4,6-Triaryl And Tripyridylpyridines, Esra Findik, Mustafa Arik, Mustafa Ceylan
Turkish Journal of Chemistry
Eight different 2,4,6-triaryl, and tripyridylpridines compounds were synthesized and their fluorescent properties were studied by using steady-state and time-resolved fluorescence and UV-Vis absorption spectroscopy techniques in 6 different solvents. Especially, 2,4,6-triarylpyridines showed strong fluorescence properties with high fluorescence quantum yields but small Stokes shifts.
Antioxidant Galloylated Flavonoids From Geranium Tuberosum L. Subsp. Tuberosum, Di̇dem Şöhretoğlu, Mahmut Koray Sakar, Suna Atasayar Sabuncuoğlu, Hi̇lal Özgüneş, Olov Sterner
Antioxidant Galloylated Flavonoids From Geranium Tuberosum L. Subsp. Tuberosum, Di̇dem Şöhretoğlu, Mahmut Koray Sakar, Suna Atasayar Sabuncuoğlu, Hi̇lal Özgüneş, Olov Sterner
Turkish Journal of Chemistry
Phytochemical investigations on the most active EtOAc extract led to the isolation of 9 flavonoids [quercetin (1), quercetin 3-O-\beta-glucopyranoside (2), quercetin 3-O-\beta-galactopyranoside (3), quercetin 3-O-(2''-O-galloyl)-\beta-glucopyranoside (4), quercetin 3-O-(2''-O-galloyl)-\beta-galactopyranoside (5), quercetin 3-O-(6''-O-galloyl)-\beta-glucopyranoside (6), quercetin 3-O-(6''-O-galloyl)-\beta-galactopyranoside (7), quercetin-3-O-\alpha -arabinofuranoside (8), and quercetin-3-O-\alpha-rhamnopyranosyl-(1\to 6)-\beta-glucopyranoside (9)] and a simple phenolic compound (methyl gallate) (10). The structures of the compounds were elucidated by 1- and 2-dimensional NMR techniques (^1H, ^{13}C, COSY, HMBC, and HMQC) and ESI-TOF-MS spectrometry. H_2O_2-induced lipid peroxidation inhibitor effects in human red blood cells of different extracts of G. tuberosum L. subsp. tuberosum aerial parts were also investigated. All the compounds tested …
Reactions Of The Solvent-Stabilized Compound [Moocl_2(Thf)_2] With Aromatic Nitrogen Donor Ligands: Spectroscopic Characterization And Semiempirical Am1* Calculations, Gülşah Kiliçkaya, Başak Doğan, Nursel Acar, Işil Topaloğlu Sözüer
Reactions Of The Solvent-Stabilized Compound [Moocl_2(Thf)_2] With Aromatic Nitrogen Donor Ligands: Spectroscopic Characterization And Semiempirical Am1* Calculations, Gülşah Kiliçkaya, Başak Doğan, Nursel Acar, Işil Topaloğlu Sözüer
Turkish Journal of Chemistry
Reaction of the solvent-stabilized dioxo-molybdenum(VI) compound [MoO_2Cl_2(THF)_2] with PPh_3 yielded the oxomolybdenum(IV) species [MoOCl_2(THF)_2] (1) by the removal of one oxygen atom as PPh_3O. The complexes [MoOCl_2(=NC_6H_4CN)] 2, [MoOCl_2(CNC_6H_4OH)] 3, [MoOCl_2(=NC_6H_4NH_2)] 4, and [MoOCl_2(=NC_6H_4OCH_3)] 5, were synthesized by the reactions of [MoOCl_2(THF)_2] with XC_6H_4Y (X = NH_2, Y = CN; X= CN, Y = OH; X = Y = NH_2; X = NH_2, Y = OCH_3). All the new compounds were characterized by elemental analyses, and FTIR, UV-Vis, and ^1H- and ^{13}C-NMR spectra. Geometrical parameters and molecular orbital calculations showed that compounds 2-5 are stabilized by a charge transfer between …
A Highly Soluble Asymmetric Perylene-Bis (Dicarboximide)-Acceptor System Incorporating A Methylene Bridged Methoxybenzene-Donor: Solvent Dependence Of Charge Transfer Interactions, Rene M. Williams
Turkish Journal of Chemistry
The synthesis and photophysical properties of an asymmetrically substituted perylene-bis(dicarboximide), (PDI), system (1) containing a methylene bridged 4-methoxy-benzene donor and a solubilizing branched C_{13} alkyl chain are described. As compared to most PDIs, the fluorescence of 1 is strongly quenched in polar (but not in non-polar) solvents due to a photo-induced electron transfer process. Transient absorption spectroscopy and time resolved emission in e.g. acetonitrile indicates that upon excitation the radical anion of the PDI is formed with a rate of ca. 3.5 \times 10^9s^{-1}, and the charge transfer state has a lifetime of ca. 3 ns. A Frontier Molecular Orbital …
A Study Of Growth And Breakdown Of Passive Film On Copper Surface By Electrochemical Impedance Spectroscopy, Amtul Naseer, Athar Yaseen Khan
A Study Of Growth And Breakdown Of Passive Film On Copper Surface By Electrochemical Impedance Spectroscopy, Amtul Naseer, Athar Yaseen Khan
Turkish Journal of Chemistry
Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry were used to investigate the oxide layer formed on a copper disc electrode and the changes that took place when treated potentiostatically in the range of -0.3 V to 0.9 V in aqueous buffer solution of pH 9.2. Equivalent circuits were used to model the response of the electrode, initially at equilibrium to an applied potential. These circuits were proposed for different potential ranges in order to illustrate the Cu/oxide/electrolyte system and its properties in terms of 2 interfaces. A criterion for the applicability of equivalent circuit models was discussed. Changes in the …
Synthesis, Characterization, And Antibacterial Activity Of Some Transition Metals With The Schiff Base N-(2-Furanylmethylene)-3-Aminodibenzofuran, Aurora Reiss, Stelian Florea, Theodor Caproiu, Nicolae Stanica
Synthesis, Characterization, And Antibacterial Activity Of Some Transition Metals With The Schiff Base N-(2-Furanylmethylene)-3-Aminodibenzofuran, Aurora Reiss, Stelian Florea, Theodor Caproiu, Nicolae Stanica
Turkish Journal of Chemistry
This paper presents the structure and antibacterial properties of some complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) with a new Schiff base N-(2-furanylmethylene)-3- aminodibenzofuran. The structure of each complex was characterized by spectroscopic methods (IR, UV-Vis, ^1H-NMR, and ESR), conductometric and magnetic data, and thermogravimetric and elementary analysis. According to these data, we propose an octahedral geometry for Co(II), Ni(II), and Cu(II) complexes, and a tetrahedral geometry for Zn(II), Cd(II), and Hg(II) complexes. Antibacterial activity of the ligand and its complexes was tested against selected bacteria. The ligand and all the complexes possess antimicrobial activity, and antimicrobial activity …
4h-Pyran-4-One Derivatives:; Leading Molecule For Preparation Of Compounds With Antimycobacterial Potential, Demet Us, Ece Gürdal, Barkin Berk, Si̇nem Öktem, Tanil Kocagöz, Berrak Çağlayan, Işil Aksan Kurnaz, Di̇lek Demi̇r Erol
4h-Pyran-4-One Derivatives:; Leading Molecule For Preparation Of Compounds With Antimycobacterial Potential, Demet Us, Ece Gürdal, Barkin Berk, Si̇nem Öktem, Tanil Kocagöz, Berrak Çağlayan, Işil Aksan Kurnaz, Di̇lek Demi̇r Erol
Turkish Journal of Chemistry
A series of 3-hydroxy-6-methyl-2-((4-substitutedpiperazin-1- yl)methyl)-4H-pyran-4-one structured compounds were synthesized by reacting 5-hydroxy-2-methyl-4H-pyran-4-one with suitable piperazine derivatives using Mannich reaction conditions. Antibacterial activities of the compounds for E. coli, S. paratyphi, S. flexneri, E. gergoviae, and M. smegmatis were assessed in vitro by using broth dilution for determination of the minimum inhibitory concentration (MIC). In addition, their inhibitory effects over DNA gyrase enzyme were evaluated using a DNA gyrase supercoiling assay. Among the synthesized compounds; compound 7 showed a 4 \mu g/mL MIC value for M. smegmatis, whereas the other compounds demonstrated moderate to high activity. Those tested in the supercoiling …
Antioxidant And Anticholinesterase Constituents Of Salvia Poculata, Ufuk Kolak, Işil Hacibeki̇roğlu, Mehmet Öztürk, Fevzi̇ Özgökçe, Gülaçti Topçu, Ayhan Ulubelen
Antioxidant And Anticholinesterase Constituents Of Salvia Poculata, Ufuk Kolak, Işil Hacibeki̇roğlu, Mehmet Öztürk, Fevzi̇ Özgökçe, Gülaçti Topçu, Ayhan Ulubelen
Turkish Journal of Chemistry
Two triterpenoids, namely 2\alpha,3\alpha-dihydroxy-24-nor- 4(23),12-oleanadien-28-oic acid (1) and ursolic acid (2); 4 flavonoids, namely 5-hydroxy-7,4'-dimethoxyflavone (3), cirsimaritin (4), eupatilin (5), and salvigenin (6); a diterpenoid, namely sclareol (7); and a steroid, namely \beta-sitosterol (8), were isolated from the aerial parts of Salvia poculata Nab., a Turkish endemic Salvia species. Total phenolic and flavonoid contents of the crude extract were determined as pyrocatechol and quercetin equivalents, respectively. The antioxidant activity of the crude extract and the isolated compounds (2-8) was established using \beta-carotene bleaching, superoxide anion radical, and ABTS cation radical scavenging activity. In addition, the anticholinesterase activity of the crude …
Pore Structure And Surface Acidity Evaluation Of Fe-Pilcs, Suna Balci, Eli̇f Gökçay
Pore Structure And Surface Acidity Evaluation Of Fe-Pilcs, Suna Balci, Eli̇f Gökçay
Turkish Journal of Chemistry
Fe-PILCs via different conditions using smectites from Hancili (Turkey) and Wyoming (USA) were synthesised. Presaturation had little effects on the basal spacing values while it had important effects on thermal stabilities of the products. Products having basal spacing (d_{001}) around 1.30 nm and surface area up to 160 m^2 g^{-1} were obtained. The thermal behaviour, X-ray diffraction (XRD) patterns, and nitrogen adsorption/desorption experiments confirmed that thermally stable and micro-mesoporous products were obtained although at elevated calcination temperature. Delaminated sample with basal spacing value of 2.79 nm was obtained. Surface acidity of clay was enhanced by pillaring. Chemically sorbed pyridine Fourier …
Synthesis, X-Ray Structure, And Bioassay Of Newly Synthesized Trimethyltin(Iv) 2,3-Methylenedioxy Benzoate, Mukhtiar Hussain, Muhammad Hanif, Saqib Ali, Saira Shahzadi, Helen S. Evans
Synthesis, X-Ray Structure, And Bioassay Of Newly Synthesized Trimethyltin(Iv) 2,3-Methylenedioxy Benzoate, Mukhtiar Hussain, Muhammad Hanif, Saqib Ali, Saira Shahzadi, Helen S. Evans
Turkish Journal of Chemistry
Trimethyltin(IV) complex containing the carboxylate ligand 2,3-methylenedioxybenzoic acid (HL) have been synthesized and characterized in solution state by multinuclear NMR (^1H, ^{13}C and ^{119}Sn) using the noncoordinating solvent and also in solid sate by FTIR, mass spectrometry, and X-ray crystallography. Spectroscopic data have shown that methylenedioxy moiety has not coordinated with tin atom; instead, the coordination site is a -COO group, which is proved by spectral and XRD data. The solid state structure shows the trigonal bipyramidal geometry with a space group P2_1/c. This compound was tested for its in vitro antitumor activity.
New Polyamides Based On Bis(P-Amidobenzoic Acid)-P-Phenylene Diacrylic Acid And Hydantoin Derivatives: Synthesis And Characterization, Khalil Faghihi
New Polyamides Based On Bis(P-Amidobenzoic Acid)-P-Phenylene Diacrylic Acid And Hydantoin Derivatives: Synthesis And Characterization, Khalil Faghihi
Turkish Journal of Chemistry
Bis(p-amidobenzoic acid)-p-phenylene diacrylic acid (6) as a new monomer containing p-phenylenediacryloyl moiety was synthesized by using a 3-step reaction. At first p-phenylenediacrylic acid (3) was prepared by reaction of terephthal aldehyde (1) with malonic acid (2) in the presence of pyridine, and then diacid 3 was converted to p-phenylenediacryloyl chloride (4) by reaction with thionyl chloride. Finally bis(p-amidobenzoic acid)-p-phenylene diacrylic acid (6) was prepared by the condensation reaction of phenylenediacryloyl chloride (4) with p-aminobenzoic acid (5). Then 6 new polyamides (8a-f) containing p-phenylenediacryloyl and hydantoin moiety in the main chain were prepared by the direct polycondensation reaction of bis(p-amidobenzoic acid)-p-phenylene …
Cyanoacetamide Derivatives As Synthons In Heterocyclic Synthesis, Ahmed Ali Fadda, Samir Bondock, Ramy Rabie, Hassan Ali Etman
Cyanoacetamide Derivatives As Synthons In Heterocyclic Synthesis, Ahmed Ali Fadda, Samir Bondock, Ramy Rabie, Hassan Ali Etman
Turkish Journal of Chemistry
This review presents a systematic and comprehensive survey of the methods of preparation and the chemical reactivity of cyanoacetamide derivatives. These compounds are important intermediates for the synthesis of a variety of otherwise difficult to obtain synthetically useful and novel heterocyclic systems.
New Flame-Retardant Poly(Ester-Imide)S Containing Phosphine Oxide Moieties In The Main Chain: Synthesis And Properties, Khalil Faghihi
New Flame-Retardant Poly(Ester-Imide)S Containing Phosphine Oxide Moieties In The Main Chain: Synthesis And Properties, Khalil Faghihi
Turkish Journal of Chemistry
Six new flame-retardant poly(ester-imide)s (9a-f) with high inherent viscosity and containing phosphine oxide moieties in the main chain were synthesized from the polycondensation reaction of N,N-(3,3-diphenylphenyl phosphine oxide) bistrimellitimide diacid chloride (7) with 6 aromatic diols (8a-f) by 2 different methods:--solution and microwave-assisted polycondensation. The results showed that compared to solution polycondensation, the microwave-assisted polycondensation reaction using a domestic microwave oven proceeded rapidly and was completed within about 9-12 min. All of the obtained polymers were fully characterized by means of elemental analysis, viscosity measurement, solubility testing, and FT-IR spectroscopy. Thermal properties and flame retardant behavior of the PEIs (9a-f) …
Investigation Of Solid State Synthesis And Characterizations Of Novel Sodium Rare-Earth Oxyphosphates, Semi̇h Seyyi̇doğlu, Maci̇t Özenbaş, Ayşen Yilmaz
Investigation Of Solid State Synthesis And Characterizations Of Novel Sodium Rare-Earth Oxyphosphates, Semi̇h Seyyi̇doğlu, Maci̇t Özenbaş, Ayşen Yilmaz
Turkish Journal of Chemistry
A new orthorhombic phase of Na_2LaOPO_4 (sodium lanthanum oxyphosphate), and novel Na_2NdOPO_4 (sodium neodymium oxyphosphate), Na_2SmOPO_4 (sodium samarium oxyphosphate) were synthesized by solid state reactions of Na_2CO_3, NH_4H_2PO_4, and Ln_2O_3 (Ln = La, Nd, and Sm). The unit cell dimensions were calculated using their X-ray powder diffraction data, which were a = 13.60(1), b = 12.71(1), and c = 6.96(1) Å, a = 13.466(5), b = 12.547(6), and c = 6.932(5) Å, and a = 13.54(1), b = 12.577(8), and c = 7.047(5) Å, respectively, and the probable space group was Pmm2. Using the same procedure orthorhombic Na_2DyOPO_4 (sodium dysprosium …
A New Approach To The Calculation Of N-15 Chemical Shifts Of Cyclic Compounds, Emad A. S. Al-Hyali
A New Approach To The Calculation Of N-15 Chemical Shifts Of Cyclic Compounds, Emad A. S. Al-Hyali
Turkish Journal of Chemistry
Two sets of additive parameters used previously for the calculation of C-13 chemical shifts of mono and poly six-membered cycloalkanes were applied for the prediction of N-15 chemical shifts of some methyl piperidine derivatives. These sets are based on 2 principles: the p-character (substituents electronic effect) of the atom under consideration and the steric effect that reflects the spatial arrangement of the molecule. An additional parameter, namely the ring angle of the studied atom, was added to the other parameters to define the structural distortion that is due to large steric interactions. The p-character in set (1) is represented by …
New Polyamides Derived From 2,5-Bis[(4-Carboxyanilino) Carbonyl] Pyridine And Hydantoin Derivatives: Synthesis And Characterization, Khalil Faghihi, Zohreh Mozaffari
New Polyamides Derived From 2,5-Bis[(4-Carboxyanilino) Carbonyl] Pyridine And Hydantoin Derivatives: Synthesis And Characterization, Khalil Faghihi, Zohreh Mozaffari
Turkish Journal of Chemistry
We synthesized 2,5-bis[(4-carboxyanilino) carbonyl] pyridine (4) as a new monomer containing pyridyl moiety by using a 2-step reaction. At first 2,5-pyridine dicarboxylic acid (1) was converted to 2,5-pyridine dicarbonyl dichloride (2). Then, diacid 4 was prepared by a condensation reaction of diacid chloride (2) with p-aminobenzoic acid (3). Then, 6 new polyamides (6a-f) were synthesized through the polycondensation reaction of 2,5-bis[(4-carboxyanilino) carbonyl] pyridine (4) with 6 different derivatives of hydantoins (5a-f) in a medium consisting of N-methyl-2-pyrrolidone, triphenyl phosphite, calcium chloride, and pyridine. The polycondensation reaction produced a series of novel polyamides containing pyridyl moiety in the main chain in …
Partial Regeneration Of Ni-Based Catalysts For Hydrogen Production Via Methane Cracking, Reyyan Koç, Erdoğan Alper, Eric Croiset, Ali Elkamel
Partial Regeneration Of Ni-Based Catalysts For Hydrogen Production Via Methane Cracking, Reyyan Koç, Erdoğan Alper, Eric Croiset, Ali Elkamel
Turkish Journal of Chemistry
Methane cracking has the potential to produce high purity, carbon monoxide-free hydrogen suitable for application in PEM fuel cells. The 2 products of the reaction are molecular hydrogen and solid carbon. The carbon appears in the form of carbon filaments whose growth is hindered by carbon encapsulation leading to total deactivation of the catalyst. Several attempts have been made to regenerate the catalyst, mainly by gasifying the carbon filament in air or steam. Our work on 5-wt% Ni/\gamma-Al_2O_3 indicated that after complete gasification of the carbon the catalyst lost nearly all its activity toward methane cracking. However, if the gasification …
The Synthesis And Anticonvulsant Activity Of 1-Substituted-7-Methoxy-1,2,4-Triazolo [4,~3-A]Quinoline, Li-Ping Guan, Xian-Yu Sun, Guan-Rong Tian, Kyu-Yun Chai, Zhe-Shan Quan
The Synthesis And Anticonvulsant Activity Of 1-Substituted-7-Methoxy-1,2,4-Triazolo [4,~3-A]Quinoline, Li-Ping Guan, Xian-Yu Sun, Guan-Rong Tian, Kyu-Yun Chai, Zhe-Shan Quan
Turkish Journal of Chemistry
A new series of 1-substituted-7-methoxy-5-phenyl-1,2,4-triazolo [4,3-a]quinolines were synthesized using ethyl-3-oxo-3-phenylpropanoate and 4-methoxybenzenamine as the starting material. Their anticonvulsant activity was evaluated by the maximal electroshock (MES) test and 7-methoxy-5-phenyl-1,2,4-triazolo[4,3-a]quinoline (4a) was identified as the most potent compound, with an ED_{50} value of 9.2 mg kg^{-1}, which is comparable to the reference drug phenytoin (ED_{50} = 9.9 mg kg^{-1}). To explore the possible mechanism of its anticonvulsant activity, compound 4a was tested with the rotarod neurotoxicity test, pentylenetetrazole (sc-PTZ) test, and isoniazid test. Compound 4a had a higher protective index (PI = TD_{50}/ED_{50}) value (16.6) than phenytoin (PI = 7.0), and …
Orthogonal Signal Correction -- Partial Least Squares Method For Simultaneous Spectrophotometric Determination Of Nickel, Cobalt, And Zinc, Ali Niazi, Amir Azizi
Orthogonal Signal Correction -- Partial Least Squares Method For Simultaneous Spectrophotometric Determination Of Nickel, Cobalt, And Zinc, Ali Niazi, Amir Azizi
Turkish Journal of Chemistry
The simultaneous determination of nickel, cobalt, and zinc mixtures by spectrophotometric method is a difficult problem in analytical chemistry, due to spectral interferences. By multivariate calibration methods, such as partial least squares (PLS) regression, it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration range. Orthogonal signal correction (OSC) is a preprocessing technique used for removing the information unrelated to the target variables based on constrained principal component analysis. OSC is a suitable preprocessing method for partial least squares calibration of mixtures without loss of prediction capacity using spectrophotometric method. In …
Characterization And Antimicrobial Activity Of Organotin(Iv) Complexes Of 2-[(2´,6´-Diethylphenylamido)]Benzoates And 3-[(2´,6´-Diethylphenylamido)]Propanoates, Saira Shahzadi, Khadija Shahid, Saqib Ali, Mohammad Bakhtiar
Characterization And Antimicrobial Activity Of Organotin(Iv) Complexes Of 2-[(2´,6´-Diethylphenylamido)]Benzoates And 3-[(2´,6´-Diethylphenylamido)]Propanoates, Saira Shahzadi, Khadija Shahid, Saqib Ali, Mohammad Bakhtiar
Turkish Journal of Chemistry
New organotin(IV) complexes with 2-[(2',6'-diethylphenylamido)] benzoic acid (HL^1) and 3-[(2',6' -diethylphenylamido)]propanoic acid (HL^2) were synthesized by the reaction of di- and triorganotin salts in the presence of triethylamine as base or dioctyltin oxide using a Dean and Stark trap for the removal of azeotropic water. All complexes were characterized by elemental analysis, IR, NMR, and mass spectral studies, and proof that tin-ligand coordination involves only the carboxylate group and complexes show hexa-coordinated geometry in solid state. Multinuclear NMR data show that triorganotin complexes exhibit 4-coordinated geometry while diorganotin complexes show a coordination number greater than 4, probably 5 or 6 …
Synthesis And Characterization Of Novel Polyamide And Polyhydrazides Based On The 6,6´-Disubstituted-2,2´-Bipyridine, Abdurrahman Şengül, Hülya Arslan
Synthesis And Characterization Of Novel Polyamide And Polyhydrazides Based On The 6,6´-Disubstituted-2,2´-Bipyridine, Abdurrahman Şengül, Hülya Arslan
Turkish Journal of Chemistry
The monomers namely 6,6'-dicarbonylchloride-2,2'-bipyridine (1) and 6,6'-dihydrazine-2,2'-bipyridine (2) were synthesized and characterized thoroughly. The polyhydrazides (PHZ1 and PHZ2) were obtained by direct polycondensation of 2 with terephtaloylchloride (TPCl}), and novel polyamide (PA1) by direct polycondensation of 1 with hexametyhlenediamine (HMDA}). Polymers with low PDIs were generated in all cases (PD \sim 1.02-1.3). The polymers were characterized by ^1H and ^{13}C NMR, FT-IR, and Gel Permission Chromatography (GPC).