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Öğe Catalytic and biological activities of homoleptic palladium(II) complexes bearing the 2-aminobenzothiazole moiety(Elsevier, 2021) Dayan, Serkan; Tercan, Melek; Özdemir, Fethi Ahmet; Aykutoğlu, Gürkan; Özdemir, Namık; Şerbetçi, Zafer; Dinçer, Muharrem; Dayan, OsmanThe palladium(II) complexes PdL1-3, bearing bi-dentated Schiff base ligands (L1-3) were synthesized and characterized by FT-IR, NMR and single crystal-XRD techniques, and the structural, spectroscopic and electronic properties were obtained using the B3LYP density functional method (DFT). The fabricated complexes were used as catalysts in the reduction of some organic pollutants (4-nitrophenol (4-NP), Rhodamine B (Rh B) and methylene blue (MB)) in water at an ambient temperature. The PdL3 complex was recorded as the best catalyst compared to the other complexes and the highest conversion rates were in the order of MB > RhB > 4-NP. Also, the antimicrobial and antifungal activities of all the compounds (ligands and complexes) and the cytotoxic effects on DU-145 and SH-SY5Y cells were investigated. The PdL1-3 complexes show cytotoxic effects, especially against the SH-SY5Y cells. All the synthesized com- pounds showed moderate antimicrobial and antifungal properties.Öğe Dye sensitized solar cell-based optoelectronic device using novel [Ru(L1)(L2)(NCS)2] complex(Elsevier B.V., 2021) Dayan, Osman; Gençer İmer, Arife; Tercan, Melek; Dere, Ayşegül; Al-Sehemi, Abdullah G.; Al-Ghamdi, Ahmed A.; Yakuphanoğlu, FahrettinA dye sensitized solar cell-based photodiode was prepared using novel [Ru(L1)(L2)(NCS)2] complex for solar energy and optoelectronic applications. The new heteroleptic ruthenium(II) complex [Ru(L1)(L2)(NCS)2], was synthesized from the reaction of (pyridyl)benzimidazole ligands. The possible usage of [Ru(L1)(L2)(NCS)2] complex in dye synthesized solar cell-based photodiode was investigated using electrical and capacitance characteristics. The device was irradiated under various solar light intensities. The change in photocurrent of the device confirms the photoconducting behavior of prepared device. The device exhibited both the photocapacitance and photoresponse behavior with solar illumination. The obtained optoelectrical results suggest that the studied photodiode with [Ru(L1)(L2)(NCS)2] complex could be used in optoelectronic device for optical switching and controlling applications.Öğe Highly effective palladium nanocatalyst supported in polymeric networks for the catalytic hydrogen generation from borane-morpholine complex(Wiley-V C H Verlag Gmbh, 2022) Ozay, Hava; Tercan, Melek; Özay, Özgür; Ilgin, PinarThis study describes the synthesis of Pd-0 nanoparticles supported in hydrogel networks (SPVI@Pd) and their catalytic activity for the borane-morpholine complex (MB) hydrolysis reaction. In this respect, while our study is one of the limited number of studies reported for the catalytic hydrolysis of MB, it is the first study in which Pd-0 nanoparticles supported in hydrogel networks were used in the catalytic hydrolysis of MB. The synthesized Pd-0 nanoparticles were characterized using structural and morphological characterization techniques and as a result of these analyses, the sizes of Pd-0 nanoparticles were determined average as 7.01 +/- 1.90 nm. The E-a value and the turnover frequency (TOF) value at 303 K for the SPVI@Pd-3.0 catalyzed MB hydrolysis reaction were determined as 49.46 kJ/mol and 187.74 mol(H2)center dot mol(pd)(-1).h(-1). It was also observed that the SPVI@Pd-3.0 catalyst had good catalytic activity even after eight cycles.Öğe Investigation of the catalytic activity of Ag(0) nanoparticles supported into anionic hydrogel networks for hydrogen production process(Taylor & Francis Inc, 2024) Tercan, Melek; Ozay, Hava; Özay, ÖzgürIn the presented study, the hydrogen production from the hydrolysis of the morpholine-borane (MB) with hydrogel supported Ag(0) nanoparticle catalyst system was reported. For this purpose, nanosized p(sulfopropyl acrylate potassium salt-co-itaconic acid)@Ag composite material, (p-SIH@Ag), was prepared and used as catalyst. In this study, the effects of base, catalyst amount, MB substrate concentration and temperature were investigated for the MB hydrolysis reaction. p-SIH@Ag catalyzed MB hydrolysis reaction at 30 degrees C, the activation energy (Ea) was determined as 24.3 kjmol(-1) and the turn over frequency (TOF) as 37.52 mol H-2(mol Ag(0).h)(-1). In reusability studies, the catalyst preserved 72% of its activity even after the 5(th) catalytic cycle despite the sensitivity of Ag metal to oxidation. Our study is the first in the literature to use hydrogel supported Ag metal catalyst system in hydrogen production via MB hydrolysis.Öğe Investigation of the effect of alkyl substitution on DSSC efficiency of Ru(II) complexes bearing tridentate benzimidazole ligands(Taylor & Francis Inc, 2020) Tercan, Melek; Dayan, OsmanIn this study, tridentate 2,6-bis(5,6-dimethyl-1H-benzimidazol-2-yl)pyridine ligand (L1) and eight derivatives (L2-9) were prepared by substitution with alkyl chains and Ru(II) complexes of these ligands (C1-9) were synthesized. The synthesized ligands and their Ru(II) complexes were characterized by FTIR, UV-vis, H-1-NMR, and ESI/MS spectroscopic methods. The absorption and the emission spectra of the complexes were examined, HOMO-LUMO energy levels of the complexes were determined by cyclic voltammetry and their use as photosensitizer in dye-sensitized solar cells (DSSCs) was investigated. The effects of alkyl chain substitution on absorption in the visible region and on the current-potential characteristics of the complexes are discussed. The effects of this modification on the important parameters for DSSCs such as absorption, current density were examined and power conversion efficiency values of the Ru(II) complexes are reported.Öğe Magnetically isolable Pd(0) nanoparticles supported on surface functionalized Fe3O4 for hydrogen generation via ammonia borane hydrolysis(John Wiley and Sons Inc, 2023) Tercan, MelekPd(0) nanoparticles supported on surface functionalized magnetite (Fe3O4/SiO2-NH2/HB@Pd) were prepared as catalyst for hydrolysis of ammonia borane (AB). The obtained magnetic nanocomposite material was seperated from the reaction media through a permanent magnet and characterized by FT-IR, XRD, SEM-EDX, TEM, ICP-OES and XPS techniques. 100 mg Fe3O4/SiO2−NH2/HB@Pd nanocomposite with Pd metal content of 6.00±0.14 catalyzed the hydrolysis of 10 mM AB at 25 °C with 100 % yield. The presented work includes the effect of catalyst amount and temperature on the rate of the hydrolysis reaction of AB. As a result of the kinetic studies, the activation energy (Ea) for the Fe3O4/SiO2−NH2/HB@Pd catalyzed AB hydrolysis reaction was calculated as 34±1 kJ.mol−1, and the TOF value was calculated as 133 mol H2.(mol Pd(0).h)−1. The designed heterogenous magnetic nanocomposite catalyst demonstrated significant catalytic activity for AB hydrolysis reaction at 25 °C.Öğe P(2-VP) supported Ru(II) material as catalyst for H2 production from the methanolysis of NaBH4(Taylor & Francis Inc, 2020) Tercan, Melek; Karacan Yeldir, Elif; Dayan, Osman; Oral, AyhanExisting energy resources are not sufficient to meet the energy needs of the increasing world population so the need for clean and renewable energy systems is increasing day after day. Hydrogen is a good alternative energy source because of its clean by-products and high energy capacity. Studies on hydrogen storage systems that provide instant hydrogen production in the literature are of great interest. In this study, poly-2-vinylpyridine (p(2-VP)) polymer was prepared by photopolymerization method and reacted with 2,6-bis(2-benzimidazolyl)pyridine ligand containing Ru(II) complex to give p(2-VP) supported Ru(II) material. The synthesized Ru(II) complex was characterized by FT-IR, UV-Vis and H-1-NMR spectroscopic techniques. Also the p(2-VP) polymer was characterized by FT-IR spectroscopy. The obtained p(2-VP) supported Ru(II) material was used as catalyst in hydrogen generation from NaBH4 metanolysis reaction and the reaction kinetic was investigated.Öğe Rapid preparation of Ru(0) nanoparticles stabilized with water-soluble biopolymer for hydrogen production from ammonia borane: Development of battery-like hydrolysis media(Pergamon-Elsevier Science Ltd, 2023) Seref, Elif; Tercan, Melek; Ozay, Hava; Ilgin, Pinar; Özay, ÖzgürThe biohybrid Na-Alg@Ru catalyst was prepared as a result of stabilizing Ru(0) nano particles with biopolymer chains of sodium alginate. The in-situ prepared Ru(0) nano particles had an average particle size of 1.023 & PLUSMN; 0.097 nm. The monodisperse Ru(0) nanoparticles prepared with a very practical, inexpensive and rapid method were used as a catalyst in hydrogen production by the hydrolysis reaction of ammonia borane (AB). The Na-Alg@Ru catalyst containing 3 mg Ru(0) metal catalyzed the hydrolysis of 50 mM AB with 100% yield, and the activation energy (Ea) of the reaction was estimated as 61.05 kJ mol-1. In addition, the Na-Alg@Ru nanoparticles were prepared with acrylamide as p(AAm)/NaAlg@Ru hydrogel films suitable for use in hydrogen production in fuel cells, which represents a battery-like environment, and used for hydrogen production from AB. Thus, it was shown that the catalysts prepared in a few nm size could easily be used in battery-like environments.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Simultaneous degradation and reduction of multiple organic compounds by poly(vinyl imidazole) cryogel-templated Co, Ni, and Cu metal nanoparticles(Royal Soc Chemistry, 2020) Tercan, Melek; Demirci, Şahin; Dayan, Osman; Şahiner, NurettinSuperporous poly(vinyl imidazole) (p(VI)) cryogel was employed to prepare Co, Ni and Cu metal nanoparticles in situ. The catalytic performance of p(VI)-M cryogel composites in the degradation of methylene blue (MB) and eosin yellow (EY) and in 4-nitrophenol (4-NP) reduction in the presence of NaBH4 in aqueous media was determined as Co > Cu > Ni for MB, Co > Ni > Cu for EY and Ni approximate to Co > Cu for 4-NP. Binary and tertiary mixtures of these substrates (dyes and 4-NP) were also used to assess the best catalytic performance among the p(VI)-M composites, showing that p(VI)-Co was the best catalyst with over 95% conversion in 5 min regardless of single, binary or tertiary substrate mixtures. It was further shown that over 99% conversion for each substrate in the MB + EY + 4-NP triple mixture can be readily attained within similar to 30 min of reaction time. P(VI)-Co composite catalysts are capable of simultaneous elimination of multiple toxic organic compounds from aqueous environments, providing great opportunities in real applications.Öğe Simultaneous reduction of 4-nitrophenol, 4-nitroaniline and methylene blue organic pollutants via TiO2 supported Pd(II) complex catalyst bearing 2-(6-methylpyridin-2-yl)-1H-benzimidazole type ligand(Elsevier Ltd, 2023) Tercan, Melek; Dayan, Osman; Özdemir, NamıkIn this study, 2-(6-methylpyridin-2-yl)-1H-benzimidazole derivative ligand (L) and its Pd(II) complex (Pd(L)Cl2) were synthesized and characterized by spectroscopic techniques. The crystal structure of L was characterized by X-ray diffraction method, and the structural, spectroscopic and electronic properties were obtained using density functional method (DFT). The catalyst material of the Pd(II) complex was prepared by attaching the complex to the titanium dioxide (TiO2) inorganic support material at a ratio 15 % (15 % Pd(L)Cl2-TiO2). 15 % Pd(L)Cl2-TiO2 catalyst material was characterized by FT-IR, TG, SEM-EDX and XRD analysis methods and used as catalyst in the catalytic reduction of 4-nitrophenol (4-NP), 4-nitroaniline (4-NA) and methylene blue (MB) organic pollutants. High conversion values were obtained for the reduction of 4-NP, 4-NA and MB substrates by 15 % Pd(L)Cl2-TiO2 catalyst material as a synergistic result of the unique catalytic properties of the Pd metal and the photocatalyst property of the TiO2 semiconductor that used as the inorganic support material.Öğe Syntheses and molecular structures of novel Ru(II) complexes with bidentate benzimidazole based ligands and their catalytic efficiency for oxidation of benzyl alcohol(Elsevier Science Bv, 2016) Dayan, Osman; Tercan, Melek; Ozdemir, NamikFive bidentate ligands derived from quinoline-2-carboxylic acid, i.e. 2-(1H-benzimidazol-2-yl)quinoline (L1), 2-(1-benzyl-1H-benzimidazol-2-yl)quinoline (L2), 2-[1-(2,3,5,6-tetramethylbenzyl)-1H-benzimidazol-2-yliquinoline (L3), 2-[1-(4-chlorobenzyl)-1H-benzimidazol-2-yl]quinoline (L4), and 2-[1-(4-methylbenzyl)-1H-benzimidazol-2-yl]quinoline (L5) were synthesized. Treatment of L1-5 with [RuCl2(p-cymene)](2) and KPF6 afforded six-coordinate piano-stool Ru(II) complexes, namely, [RuCI(L1)(p-cymene)]PF6 (C1), [RuCI(L2)(p-cymene)]PF6 (C2), [RuCI(L3)(p-cymene)]PF6 (C3), [RuCI(L4)(p-cymene)] PF6 (C4), and [RuCI(L5)(p-cymene)]PF6 (C5). Synthesized compounds were characterized with different techniques such as H-1 and C-13 NMR, FT-IR, and UV-vis spectroscopy. The solid state structure of L1 and C3 was confirmed by single-crystal X-ray diffraction analysis. The single crystal structure of C3 verified coordination of L3 to the Ru(II) center. The Ru(II) center has a pseudo-octahedral three legged piano stool geometry. The complexes C1-5 were tested as catalysts for the catalytic oxidation of benzyl alcohol to benzaldehyde in the presence of periodic acid (H5IO6) (Substrate/Catalyst/Oxidant = 1/0.01/0.5). The best result was obtained with C2 (3 h -> 90%). (C) 2016 Elsevier B.V. All rights reserved.Öğe Synthesis and DSSC Applications of Ru(II) Complexes Bearing Benzimidazole Type Ligands(Springer, 2019) Tercan, Melek; Dayan, OsmanIn this study, the synthesis of 7 Ru(II) polypyridine complexes (C1-7) and their characterization by FT-IR, UV-Vis, H-1-NMR and ESI-MS spectroscopic methods have been reported. The use of the complexes as photosensitizers in dye-sensitized solar cells (DSSCs) has been investigated. The photovoltaic characteristics of the fabricated DSSC devices were examined under 1.5 G solar simulation and TiO2 was used as a semiconductor. Absorption and emission spectra of the complexes were examined, cyclic voltammograms of the Ru complexes were performed and HOMO-LUMO energy levels were calculated. Thus, electrochemical properties of the complexes and the energy diagrams, which shows the charge transfer characteristics of the complexes were studied. The alterations in the current-potential characteristics of the Ru sensitizers by modifications in ligands have been investigated. The effects of the substitutions on ligands are evaluated and power conversion efficiency value up to half of the reference sensitizer was obtained by C6 complex.Öğe Synthesis and photovoltaic properties of new Ru(II) complexes for dye-sensitized solar cells(Springer, 2018) Dayan, Osman; Ozdemir, Namik; Yakuphanoglu, Fahrettin; Serbetci, Zafer; Bilici, Ali; Cetinkaya, Bekir; Tercan, MelekTwo groups Ru(II) complexes, (1A-C and 2A) (A-C = 2,6-bis(2-benzimidazolyl)pyridines, bbpy, with various substituents at 2-, 5-, and 6-positions) have been prepared and applied for dye-sensitized solar cells (DSSC). The compounds were characterized by various techniques. The optical and electrical properties of sensitizers were investigated with UV-Vis absorption spectroscopy and cyclic voltammetry. High power conversion efficiencies up to 5.16%, have been achieved with 2Ae. Current-voltage characteristics of DSSCs clearly affected by the changing of the ligands at sensitizers. Additionally, computational studies show that locations of frontier molecular orbitals are significantly important for power-conversion efficiencies in DSSCs.Öğe Synthesis, DFT computations and antimicrobial activity of a Schiff base derived from 2-hydroxynaphthaldehyde: Remarkable solvent effect(Elsevier, 2020) Tercan, Melek; Ozdemir, Namik; Ozdemir, Fethi Ahmet; Serbetci, Zafer; Erdener, Digdem; Cetinkaya, Bekir; Dayan, OsmanA new Schiff base bearing sulfonamide group was synthesized and characterized by spectroscopic techniques. Its spectroscopic properties were investigated through density functional theory (DFT/B3LYP) method with the 6-311++G(d,p) basis set theoretically and the zwitterion reversible arrow enol tautomerization was studied using IEF-PCM approximation. The thermodynamic (entropy, enthalpy and Gibbs free energy changes) and energetic quantities of the zwitterion reversible arrow enol tautomerization indicate that the migration of single proton between zwitterion reversible arrow enol tautomer's is unfavored for both directions in all phases. During the change from the water phase to the gas phase, the tautomeric energy barrier increases for the proton transfer reaction from the zwitterion form to the enol form, while the barrier decreases from the enol form to the zwitterion form. On the other hand, experimental studies (UV-vis. and NMR spectroscopies) release that there are two tautomeric species which are the zwitterion form in polar and the enol form in apolar solvents for the soluted compound. Furthermore, the antibacterial effect of the compound was investigated in two different solvents (DMSO and THF) to demonstrate the effect of dominant tautomeric species. The results indicate that the solution in which the enol form is dominant than the zwitterionic form has more antimicrobial efficiency for all bacterial species. (C) 2020 Elsevier B.V. All rights reserved.Öğe The preparation of new palladium (II) complexes with Schiff base type ligands and its impregnated Al2O3materials: As the catalysts for degradation/reduction of organic dyes(Wiley, 2020) Selvi, Gizem; Tercan, Melek; Ozdemir, Namik; Dayan, OsmanThe removal of organic dyes used in many sectors such as textile, paper, leather, and packaging from water sources is very important in terms of preventing the spread of industrial pollutants to the environment. Transition metal complexes supported to an inorganic solid material are frequently used for the degradation/reduction of organic dyes causing this pollution. In this study, new Pd (II) complexes with Schiff base ligands were synthesized and structurally characterized by nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR), mass spectrometry (MS), and single-crystal X-ray diffraction (sc-XRD) spectroscopic methods. Then, the Al2O3-impregnated materials of these Pd (II) complexes were prepared and characterized by scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), FT-IR, and thermogravimetry (TG) techniques. The catalytic activities of the synthesized Pd (II) complexes and their Al2O3-impregnated materials were comparatively analyzed to investigate the degradation/reduction of organic dyes (2-nitroaniline, 4-nitroaniline, 4-nitrophenol, eosin yellow, and methylene blue). The catalytic results indicate that Al2O3-impregnated materials are very active catalysts for the degradation/reduction of organic dyes under those circumstances. Conversions of up to 98% for all substrates were obtained after 5 min at ambient temperature.Öğe Utilization of superabsorbent xanthan films cross-linked with Ru0 nanoparticles for hydrogen generation from ammonia borane(Pergamon-Elsevier Science Ltd, 2024) Ozay, Hava; Tercan, Melek; Özay, ÖzgürXanthan is a biopolymer that can easily gelified even at low concentrations owing to its great number of hydroxyl groups it carries. Preparation of ruthenium nanoparticles (Ru NPs) stabilized in xanthan biopolymer chains was performed as a result of the interaction of xanthan functional groups and the Ru3+ ions that act as a cross linking agent. The prepared Xthn@Ru-0 biocomposite film was used as catalyst in hydrogen generation via ammonia borane (NH3BH3) hydrolysis. Xthn@Ru-0 biocomposite film catalyst with Ru-0 metal composition of 2 mg carried out the hydrolysis of NH3BH3 (50 mM) with 100% efficiency. The activation energy (E-a) of the Xthn@Ru-0 biocomposite film catalyzed NH3BH3 hydrolysis reaction was determined to be 38.8 kJ mol(-1) and the TOF value to be 29.14 mol H-2(mol Ru-0min)(-1) at 30 degrees C. The Ru-0 metal content, morphology, elemental distribution, crystal properties and the oxidation state of the surface elements of Xthn@Ru-0 biocomposite catalyst were investigated by various techniques. In addition to examining the NH3BH3 amount, catalyst amount and temperature effect for the Xthn@Ru-0 biocomposite film catalyzed NH3BH3 hydrolysis reaction, reusability and storing studies were carried out. The prepared Xthn@Ru-0 film catalyst with a biodegradable polymer and low Ru-0 metal composition, catalyzed NH3BH3 hydrolysis reaction without a significant decrease in its beginning activity even after long storage periods.
