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Öğe Silica gel-immobilized 5-aminoisophthalohydrazide: A novel sorbent for solid phase extraction of Cu, Zn and Pb from natural water samples(Wiley Online Library, 2020-03-11) Aydın, Funda; Çakmak, Reşit; Levent, Abdulkadir; Soylak, MustafaA novel silica sorbent, silica gel‐immobilized 5‐aminoisophthalohydrazide (SiO2‐APH), was prepared by the condensation of 3‐chloropropyl‐functionalized silica gel with 5‐aminoisophthalohydrazide (APH) derived from dimethyl 5‐aminoisophthalate as a starting material and used for separation and preconcentration of Cu, Zn, and Pb metals in water samples using Flame Atomic Absorption Spectrometry (FAAS). The characterization of the new sorbent was carried out by Elemental Analysis, Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Important analytical parameters including as pH, amount of sorbent, type and amount of eluting solvent, sample volume, vortex and ultrasonic bath time, matrix ions that effect the developed SiO2‐APH‐solid phase extraction (SPE) method were investigated and optimum parameters were detected. Recoveries of examined metals were obtained as 98% for Cu and Pb and 101% for Zn. The relative standard deviation (RSD, n = 8) of Cu, Zn and Pb metals were 3.2, 2.8 and 1.6%, respectively. Limit of detections (LODs) (n = 10) were found as 2.7 μg L−1 for Cu, 7.4 μg L−1 for Zn and 3.5 μg L−1 for Pb μg L−1. The accuracy of the new method was assessed by analyzing of TMDA‐51.4 and TMDA‐70.2 certified reference materials. The results obtained for metals were in a good agreement with certified values. Addition/recovery test was applied to the real well, river, dam and stream water samples to check the accuracy of the method. The results showed that the developed SiO2‐APH‐SPE method can be effectively used as an alternative method for determination of Cu, Zn, and Pb metals in water samples.Öğe Asymmetric organocatalytic efficiency of synthesized chiral β-amino alcohols in ring-opening of glycidol with phenols(Springer Nature, 2012-04-11) Aral, Tarık; Karakaplan, Mehmet; Hoşgören, HalilA series of novel chiral β-amino alcohols 3-5 and 7-10 were synthesized by regioselective ring opening of epoxides and chiral amines with a straightforward method in high yields (up to 99 %). Kinetic resolution of racemic glycidol with phenols was achieved by using chiral amino alcohols as organocatalysts. Amino alcohols 5, 8 and 10 exhibited the highest enantioselectivities with p-cresol, phenol, and p-methoxyphenol by 63, 65, 58 % ee, respectively. The moderate enantioselectivities were observed with catalyst 9b towards all the nucleophiles (34-48 % ee). The ee values of the desired 3-aryloxy-1, 2-diols were determined by HPLC. This study presents an attractive tool for the synthesis of β-blockers and structurally complex molecules.Öğe Voltammetric behavior of testosterone on bismuth film electrode: Highly sensitive determination in pharmaceuticals and human urine by square‐wave adsorptive stripping voltammetry(Wiley Online Library, 2015-03-20) Levent, Abdulkadir; Altun, Ahmet; Taş, Süleyman; Yardım, Yavuz; Şentürk, ZühreIn this paper, an electrochemical application of bismuth‐film electrode (BiFE) fabricated via ex‐situ electrodeposition onto a glassy carbon electrode for testosterone determination was investigated in aqueous and aqueous/surfactant solutions. In cyclic voltammetry, the compound showed one irreversible and adsorption‐controlled reduction peak. The BiFE revealed good linear response in the examined concentration range of 1 to 45 nmol L−1 testosterone in BrittonRobinson buffer, pH 5.0 containing 3 mmol L−1 cetyltrimethylammonium bromide. The limit of detection was 0.3 nmol L−1 (0.09 ng mL−1). Finally, the BiFE was satisfactorily applied for quantitation of testosterone in both pharmaceutical (oil‐based ampoule) and biological (human urine) samples.Öğe Synthesis and anticorrosion studies of 4-[(2-nitroacetophenonylidene)-amino]-antipyrine on SAE 1012 carbon steel in 15 wt.% HCl solution(Taylor & Francis, 2020-11-16) Gerengi, Hüsnü; Çakmak, Reşit; Dağ, Beşir; Solomon, M. M; Tüysüz Akbal, Hatice Aslıhan; Kaya, ErtuğrulA novel corrosion inhibitor, ((E)-1,5-dimethyl-4-((1-(3-nitrophenyl)ethylidene)amino)-2-phenyl-1,2-dihydro-3H-pyrazol-3-one) (DNPP) was synthesized in high yield by the condensation reaction of 4-aminoantipyrine with 2-nitroacetphenone derived from acetophenone as a starting material and characterized by FT-IR, 1H, and 13C NMR techniques. DNPP was tested against the corrosion of SAE 1012 carbon steel in 15 wt.% HCl solution using electrochemical and surface characterization techniques. Results obtained show that DNPP is effective in retarding the corrosion of SAE 1012 carbon steel. With 4 mM of DNPP, the charge transfer resistance of SAE 1012 in 15 wt.% HCl solution is raised from 17.42 to 140.50 Ω cm2 and the substrate surface is protected by 87%. The inhibition is through adsorption mechanism (mixed-adsorption type) and has been confirmed by SEM and EDAX results. Potentiodynamic polarization results reveal that DNPP acted as a mixed-type corrosion inhibitor. DNPP is a promising candidate for the formulation of an inhibitor cocktail for the strong acid environment.Öğe Organogels as novel carriers for dermal and topical drug delivery vehicles(Kimyagerler Derneği, 2017) Barış Cebe, Deniz; Çolak, Mehmet; Hoşgören, HalilÖğe Mesogenic properties of PAA/6BA binary liquid crystal complexes(Elsevier, 2018-09-19) Okumuş, Mustafa; Eskalen, Hasan; Sünkür, Murat; Özgan , ŞükrüA novel supramolecular liquid crystal complex has been designed and formed from pure liquid crystalspara-azoxyanisole (PAA) and 4-hexylbenzoic acid (6BA). Thermal and microstructural properties offormed PAA/6BA binary liquid crystal complex system are investigated by differential scanning calo-rimeter (DSC), polarized optical microscopy (POM) and X-ray diffractometer (XRD). Fourier transformedinfrared spectroscopy (FTIR) is used to confirm the formation of hydrogen bond between the PAA and6BA molecules. The XRD results show that the molecular ordering of the hydrogen bonded PAA/6BAcomplex is arranged in the orthorhombic structure. The DSC and POM results clearly indicate that thePAA/6BA binary complex exhibits liquid crystalline properties due to the hydrogen bonds formed be-tween the PAA and 6BA molecules. The PAA/6BA complex shows the phase transition peaks indicatingCr/N/I and I/N/SmA/Cr phase sequence during continuous heating and cooling, respectively, byDSC. These phase sequences have also been confirmed by POM observations. Furthermore, the effect ofthe heating rate on the phase transition temperature values is investigated. As the heating rate increases,the phase transition temperature values increase as well. Moreover, the activation energies for the phasetransitions of the PAA/6BA liquid crystal complex are calculated by using Kissinger, Ozawa and Takhormethods. The calculated results clearly show that the phase transitions are regular.Öğe Organogels as novel carriers for dermal and topical drug delivery vehicles(Elsevier, 2016-11-24) Uzan, Serhat; Barış Cebe, Deniz; Çolak, Mehmet; Aydın, Haluk; Hoşgören, HalilAminoalcohol based bis-(aminoalcohol)oxalamides (BAOAs) (1,6-amino alcohol=leucinol, isoleucinol, valinol, phenylglycinol, phenylalaninol and 2-amino-1-butanol) have been explored to develop drug depot systems and illustrated as a novel dermal and topical drug delivery vehicle for non-steroidal anti-inflammatory drug molecules. FAE's (Fatty acid ethyl and isopropyl esters) with different chain lengths, ethyl laurate, ethyl myristate, ethyl palmitate, isopropyl laurate, isopropyl myristate, isopropyl palmitate, have been chosen as they are biocompatible organic fluids used typically in cosmetic industry. Ibuprofen (Ib), acting as a model drug, was entrapped in the supramolecular organogels. The release behavior of Ib molecules in the supramolecular organogels was investigated by using UV–vis spectroscopy. The influence of the organogelator and drug concentration, pH values of the accepting media, and nature of solvent (different FAE's) on the release behavior of Ib was investigated under static conditions. The results indicated that the release rate of Ib from the supramolecular organogels was effectively retarded with an increase of the organogelator concentration. Also, the release rates of Ib increased on increasing the Ib content. Furthermore, the release behavior of Ib was found to be different at various pH values in buffers as accepting media. The study of the release kinetics indicated that the release behavior of Ib was in accord with the Higuchi equation and the diffusion-controlled mechanism involved in the Fickian model. These observations indicate that bis-(aminoalcohol)oxalamides gels may act as delivery vehicles for non-steroidal anti-inflammatory drug molecules and also show that the release profiles for such systems can be fine-tuned by the correct choice of gelator-FAE combination.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.
