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Öğe Synthesis, characterization and experimental, theoretical, electrochemical, antioxidant and antibacterial study of a new Schiff base and its complexes(Elsevier, 2014-09-15) Baykara, Hacı; İlhan, Salih; Levent, Abdulkadir; Seyitoğlu, Mehmet Salih; Özdemir, Sadin; Okumuş, Veysi; Öztomsuk, Abdussamet; Cornejo, MauricioA new Schiff base ligand was synthesized by reaction of salicylaldehyde with 1,6-bis(4-chloro-2-aminophenoxy)hexane. Then the Schiff base complexes were synthesized by metal salts and the Schiff base. The metal to ligand ratio of metal complexes was found to be 1:1. The Cu(II) complex is proposed to be square planar and the Co(II), Ni(II), Mn(II) and Zn(II) complexes are proposed to be tetrahedral geometry. The Ti(III) and V(III) complexes are proposed to be a capped octahedron in which a seventh ligand has been added to triangular face. The complexes are non-electrolytes as shown by their molar conductivities (ΛM). The structure of metal complexes is proposed from elemental analysis, FT-IR, UV–vis, magnetic susceptibility measurements, molar conductivity measurements, Mass Spectra and thermal gravimetric analysis. In addition antimicrobial and antioxidant studies, cyclic voltammetry of the complexes, theoretical 1H NMR and HOMO–LUMO energy calculations of the new di-functional ligand were done.Öğe Imine containing C2-Symmetric chiral half sandwich h6-p-cymene-Ru(II)- phosphinite complexes: Investigation of their catalytic activityin the asymmetric transfer hydrogenation of ketones(Journal of Molecular Structure, 2020-01-15) Aral, Tarık; Paşa, Salih; Kayan, Cezmi; Meriç, Nermin; Sünkür, Murat; Aydemir, Murat; Baysal, Akın; Durap, Feyyaz; Saleh, Najmuldain AbdullahNew chiral C2-symmetric bis(phosphinite) ligands containing imine group were synthesized from 1-({[(1R,2R)-2-{[(2-hydroxynaphthalen-1-yl)methylidene] amino}cyclohexyl]- imino}methyl)- naphthalen-2-ol and two equivalents of Ph2PCl, (i-Pr)2PCl or (Cy)2PCl, in high yields. Binuclear C2-symmetric half sandwich η6-p-cymene-Ru(II) complexes of the chiral phosphinite ligands were synthesized by treating of [Ru(η6-p-cymene)(μ-Cl)Cl]2 with the phosphinites in 1:1 M ratio in CH2Cl2. Their catalytic activities in asymmetric transfer hydrogenation (ATH) were investigated for the reaction of acetophenone derivatives with isopropyl alcohol. The corresponding optically active secondary alcohols were obtained in excellent levels of conversion (96–99%) and moderate enantioselectivity (up to 60% ee). Among three complexes investigated, complex 4 was the most efficient one.Öğe Electrochemical determination of melatonin hormone using a boron-doped diamond electrode(Elsevier, 2012-01) Levent, AbdulkadirIn this study, a boron-doped diamond electrode was used for the electroanalytical determination of melatonin in the pharmaceutical tablet and urine samples by square-wave voltammetry. Melatonin yielded a well-defined voltammetric response in Britton-Robinson buffer, pH 3.0 at + 0.88 V (vs. Ag/AgCl). Using the optimal square-wave voltammetry conditions, the oxidation peak was used to determine melatonin in the concentration range of 5.0 × 107 M to 4.0 × 106 M (r = 0.998, n = 8), a detection limit of 1.1 × 107 M (0.025 μg/mL) and relative standard deviation was 2.06% at the 2.0 × 106 M level (n = 10). Recoveries of melatonin were in the range of 97.67–105%, for both tablet and spiked human urine samples.Öğe In vitro antimicrobial and antioxidant activity of ethanol extract of three hypericum and three achillea species from Turkey(Taylor & Francis, 2011-02-25) Barış Cebe, Deniz; Kızıl, Murat; Aytekin, Mehmet Çetin; Kızıl, Göksel; Yavuz, Murat; Çeken Toptancı, Bircan; Ertekin, Alaattin SelçukThe present study was conducted to determine the antimicrobial, antifungal and antioxidant activity of the ethanol extract of Hypericum scabrum L (HSm), Hypericum lysimachioides var. lysimachioides (HL), and Hypericum retusum Aucher (HR) and ethanol extracts of Achillea aleppica D.C. subsp. aleppica (AA), Achillea aleppica D.C. subsp. zederbaueri (Hayek) Hub.-Mor (AZ), and Achillea biebersteinii Afan. (AB). The antioxidant properties of extracts were evaluated using different antioxidants tests, including reducing power, free radical scavenging, deoxyribose assay, metal chelating activities and determination of total phenolic compounds. The extracts obtained from Hypericum and Achillea species showed high antioxidant properties. The protective effects of plant extracts were compared with a well known antioxidant, Butilated Hydroxytoluen (BHT) and α-tocopherol. Total antioxidant activity of ethanol extracts of plants were also tested by using ferric thiocyanate (FTC) and thiobarbituric acid (TBA) methods. Antioxidative activities of plant extracts were found to be comparable with Vitamin E. The results showed that the ethanol extracts of all tested plant exhibited different activity against tested microorganisms. Since most of the studied extracts have good antimicrobial and antioxidant activity, it might be possible to use them as natural food additives that act both as antioxidants and as spices.Öğe Preparation, spectral studies, theoretical, electrochemical and antibacterial investigation of a new Schiff base and its some metal complexes(Elsevier, 2014-10-05) İlhan, Salih; Baykara, Hacı; Seyitoğlu, Mehmet Salih; Levent, Abdulkadir; Özdemir, Sadin; Dündar, Abdurrahman; Öztomsuk, Abdussamet; Cornejo, MauricioA new Schiff base ligand, 1,6-Bis(2-(5-bromo-2-hydroxybenzylideneamino)-4-chlorophenoxy)hexane was synthesized. Some Schiff metal complexes of the new Schiff base were prepared by the reaction of some metal salts and the Schiff base. The complexes are non-electrolytes as shown by their molar conductivities (ΛM). The structures of metal complexes are proposed from elemental analysis, FT-IR, UV–vis, magnetic susceptibility measurements, molar conductivity measurements, mass spectra and thermal gravimetric analysis. In addition theoretical 1H NMR, HOMO–LUMO studies of the ligand; antimicrobial and cyclic voltammetric studies of the compounds were also carried out. In this study antioxidant and antibacterial activities of the compounds were examined via in vitro methods.Öğe The theoretical and experimental study on double-Gaussian distribution in inhomogeneous barrier-height Schottky contacts(Elsevier, 2010-11) Yıldırım, Nezir; Turut, Abdulmecit; Turut, VeyisWe have considered multi-Gaussian distribution of barrier-heights for non-interactive barrier inhomogeneities in the inhomogeneous Schottky diodes, and we have shown the presence of the intersecting behavior in the forward-bias current-voltage (I-V) curves for the double-Gaussian distribution model at low temperatures. We have tried to eliminate this effect by generating I-V curves at lower temperatures with the bias-dependent barrier-height expression which leads to the ideality factors greater than unity. For this calculation, we have obtained the expressions for the barrier-height change and ideality factor, and for bias-dependency of the BH for the multi-Gaussian model by following the literature. We have shown that the experimental forward-bias I-V curves coincide with the theoretical ones using the bias-dependent inhomogeneous BH expression at low and high temperatures in the double-Gaussian distribution of BHs.Öğe Entropy-based multi-item solid transportation problems with uncertain variables(Springer Nature, 2019-07-01) Dalman, Hasan;This paper focuses on modeling and optimization of entropy-based uncertain multi-item solid transportation problems (MISTPs), in which direct costs, supplies, demands, conveyance capacities are uncertain nature. The purpose is to minimize the total uncertain cost via maximum entropy which ensures uniform delivery of products from sources to destinations through conveyances. The expected value programming and expected constrained programming models for optimizing the entropy-based uncertain MISTPs are constructed. These models are based on uncertainty theory. Subsequently, the constructed models are converted into their deterministic equivalences which are solved using two known mathematical programming methods. Finally, a numerical example is given to illustrate the models.Öğe Synthesis and characterization of 1,2-bis(2-(5-bromo-2-hydroxybenzilidenamino)-4-chlorophenoxy)ethane and its metal complexes: An experimental, theoretical, electrochemical, antioxidant and antibacterial study(Elsevier, 2014-01-24) İlhan, Salih; Baykara, Hacı; Öztomsuk, Abdussamet; Levent, Abdulkadir; Seyitoğlu, Mehmet Salih; Özdemir, SadinA new Schiff base ligand was synthesized by reaction of 5-bromosalicylaldehyde with 1,2-bis(4-chloro-2-aminophenoxy)ethane. Then the Schiff base complexes were synthesized by the reaction of metal salts and the novel Schiff base. The molar conductivity properties of the complexes were studied and found out that the complexes are nonelectrolytes. The structures of the ligand and its metal complexes were characterized by elemental analysis, FT-IR, UV–VIS, magnetic susceptibility measurements, molar conductivity measurements, and thermal gravimetric analysis. In addition antioxidant, theoretical NMR studies and cyclic voltammetry of the complexes were done. Two methods namely metal chelating activity and diphenylpicrylhydrazyl (DPPH) radical scavenging method were used to determine the antioxidant activity, and antibacterial properties of the compounds were also studied.Öğe Protective effect of Hypericum perforatum L. on serum and hair trace elements in rats 7,12-dimethylbenz[a]anthracene-induced oxidative stress(Elsevier, 2012-02-08) Ekin, Suat; Yardım, Yavuz; Oto, Gökhan; Levent, Abdulkadir; Özgökçe, Fevzi; Kusman, TubaThe study was designed to assess the effect of Hypericum perforatum L. (H.P) on serum and hair trace elements and mineral levels, oral administration of 7,12-dimethylbenz[a]anthracene (DMBA) induced oxidative stress in Sprague-Dawley female rats. Analysis of the trace element has been carried out using atomic absorption spectrophotometer method at end of 60th day. It has been found out that the DMBA group contained statistically lower Zn and Cr compared to the control group (p < 0.01) and (p < 0.05), Cu, Mg and Na contained higher than control group (p < 0.05), (p < 0.05) and (p < 0.05). In DMBA + H.P group, Zn higher and Na lower than DMBA group (p < 0.05), (p < 0.05), in hair samples Cd, K and Zn contained lower DMBA compared to the control group (p < 0.05), (p < 0.05) and (p < 0.05). In group DMBA + H.P, Cd was higher than DMBA group and Cr lowered accordance with control group (p < 0.05). The present study demonstrated significantly positive and beneficial effect of H.P on the concentration levels of Zn and Na in serum, also on Cd levels in hair between DMBA and DMBA + H.P groups.
