Browsing by Author "Gulcan, M."

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Biocatalysis: Fundamentals and Solvent Parameters
(Elsevier, 2020) Acidereli, H.; Sogut, E.G.; Mustafov, S.D.; Gulcan, M.; Sen, F.
Biocatalysis involves the use of one or more enzymes to catalyze chemical reactions. Compared to conventional methods, biocatalysis has advantages such as high stereo-, regio-, and chemoselectivity, efficient catalysis, both complex and straightforward transformations, low rate of by-product formation, inexpensive refining and purification (uncomplicated), mild reaction conditions, and reduced impact on the environment by reducing waste production. To have these advantages, the solvent character of the enzyme should be optimally determined. Thus, all the advantages of biocatalysis are utilized. In this review, it has been tried to present the parameters that will provide optimum conditions for biocatalysis. Biocatalysis, which facilitates many disciplines, is the most popular subject in the catalysis field due to its unique facilities and still undiscovered features. © 2021 Elsevier Inc. All rights reserved.
Characterization and Antioxidant-Antimicrobial Activity of Silver Nanoparticles Synthesized Using Punica Granatum Extract
(Springer, 2022) Aygun, A.; Ozdemir, S.; Gulcan, M.; Yalcin, M. S.; Ucar, M.; Sen, F.
In this study, low-cost, simple, and eco-friendly green synthesis of silver nanoparticles was performed using pomegranate extract (Ag NPs/PG). Punica granatum extract acts as a reducing agent and capping agent in the synthesis of Ag NPs. The presence of Ag NPs/PG was analyzed using characterization methods such as UV-Vis absorption spectroscopy (UV-Vis), Fourier transform infrared spectrophotometer (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). XRD, TEM, and XPS analysis showed the presence elements, surface morphology, various shapes, and the presence of Ag NPs in the sample. The Ag NPs/PG particle sizes were found to be 5-45 nm in TEM analysis. By using the XRD technique, Ag NPs were determined to be a cubic crystal structure with face-centered. Furthermore, the antioxidant and antibacterial properties of Ag NPs/PG were also investigated. The enhanced biological activity of Punica granatum-mediated green synthesized Ag NPs was investigated based on antioxidant, antimicrobial, and DNA cleavage studies. The Ag NPs showed 91.6% DPPH (2,2-diphenyl-1-picrylhydrazyl) radical inhibition rate activity at the highest concentration (500 mg mL(-1)). It exhibited significant chemical nuclease activity. Ag NPs/PG had significant antibacterial activity against gram-positive and gram-negative bacteria, but gram-negative bacteria more susceptible than gram-positive. Biogenic synthesis of Ag NPs with the help of Punica granatum extract is a useful and environmentally safe synthesis technique. It is thought that Ag NPs obtained using Punica granatum may have potential use in the fields of nanomedicine, nanobiosensor, and nanobiotechnology in the near future.
Electrical Characteristics of Organic/Inorganic Pt(Ii) Complex/P-si Semiconductor Contacts
(Elsevier Sci Ltd, 2014) Imer, A. Gencer; Temirci, C.; Gulcan, M.; Sonmez, M.
We produced Pt(II)) complexes using the bidentate ligand N-aminopyrimidine-2-thione (APTH). The optical transmission of thin Pt-APTH films was measured. The optical bandgap of the material was 2.58 eV. With the expectation that it might have semiconductor properties and that the Pt-APTH complex might exhibit rectifier behavior when brought into appropriate contact with a semiconductor, we fabricated Pt-APTH/p-Si contacts by direct addition of a solution of Pt-APTH to the front side of p-Si wafers. Forward bias current-voltage measurements revealed satisfactory rectifying behavior for the Pt-APTH/p-Si contacts, with a mean rectification ratio of 4.40 x 10(2) and a mean barrier height of 0.765 eV. Cheung and Norde functions were used to obtain and verify some electrical characteristics of the contacts. The results obtained from both methods are compared and discussed. (C) 2014 Elsevier Ltd. All rights reserved.
Hydrogen Generation by Hydrolysis of Nabh4 Using Nanocomposites
(Elsevier, 2020) Kızıltas, N.; Karatas, Y.; Gulcan, M.; Mustafov, S.D.; Sen, F.
Alternative energy sources are needed while maintaining sustainable atmospheric greenhouse gas levels to meet global energy demands. Our current use of hydrogen for a sustainable energy system has been promising due to its sustainability, environmental emissions, and energy security. In addition to being used as fuel, great efforts are being made to safely produce, store, and transport hydrogen. The hydrogen storage model is developed to meet the need for sustainable energy, the hydrogen produced by the electrolysis of water using photovoltaic panels, that is, by using electrical energy with generators, stored using the hydrolysis of sodium borohydride. Significant progress has been made with this model, which seeks to meet optimum conditions in terms of high density, high stability, and safety. The studies suggest that the reaction of sodium borohydride is an essential chemical in the introduction of hydrogen into portable fuel cells due to its ease of control and nontoxicity. In this chapter, NaBH4 properties are examined as an energy source, and environment-based hydrogen/energy carriers are summarized. Moreover, its use as a reducing agent and hydrogen carrier, and hydrogen production by hydrolysis and thus developed catalytic systems are discussed in terms of environmental and economic concerns. © 2021 Elsevier Inc. All rights reserved.
A Novel Highly Active and Reusable Carbon Based Platinum-Ruthenium Nanocatalyst for Dimethylamine-Borane Dehydrogenation in Water at Room Conditions
(Nature Research, 2020) Karatas, Y.; Acidereli, H.; Gulcan, M.; Sen, F.
In this paper, we present platinum/ruthenium nanoparticles supported on Vulcan carbon (PtRu@VC) as a nanocatalyst for the dehydrogenation of dimethylamine-borane (DMAB) in aqueous solution under mild conditions. PtRu@VC nanocatalyst was fabricated using the alcohol-reduction techniques which is a facile and effective method. The prepared PtRu@VC nanocatalyst exhibited a good stabilization and an effective catalytic activity for hydrogen evolution from the DMAB dehydrogenation in water at room temperature. The composition of PtRu@VC nanocatalyst was investigated using different analytical techniques inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), powder X-ray diffraction (P-XRD) and X-ray photoelectron spectroscopy (XPS). A monodispersedPt/Ru metals distributions on VC (as supporting material) were revealed by TEM and HR-TEM analyses. The mean particle size of PtRu@VC nanocatalyst was found to be 3.15 ± 0.76 nm. XPS analysis for PtRu@VC nanocatalyst showed that almost Pt-Ru metals were found to be the metallic state. Catalytic experimental results showed that PtRu@VC nanocatalyst has a high catalytic activity with an excellent turn-over frequency (TOFinitial) value of 14926.2 h−1 (248.77 min−1) in the dehydrogenation of DMAB in water at room temperature. Additionally, in the paper, we report some different kinetic data obtained from different experimental parameters of temperature, catalyst and substrate concentrations conducted for DMAB dehydrogenation in water catalyzed with PtRu@VC nanocatalyst. © 2020, The Author(s).
Polymer-Based Nanomaterials To Use in Hydrogen Acquisition and Hydrogen Energy Storage
(Elsevier, 2020) Nas, M.S.; Calimli, M.H.; Acidereli, H.; Karatas, Y.; Gulcan, M.; Sen, F.
Energy demand has increased dramatically worldwide due to population growth. This is because almost all activities take place through energy. The majority of the energy used is derived from fossil sources. The use of fossil-based energy causes pollution to the environment and these resources cannot be recycled. Compared to renewable energy sources, fossil-source energy sources are much cheaper but they increase environmental pollution. Among renewable energy sources, hydrogen is seen as a highly effective resource. With the combustion of hydrogen, there are no chemicals that can be harmful to the environment, and its energy capacity is higher than other energy sources. Numerous studies have been carried out as an alternative to conventional storage methods for the safe storage of hydrogen. In this context, many studies have been carried out by scientists to develop new chemical hydrogen storage materials and to prepare and identify new heterogeneous catalyst systems that produce hydrogen from these materials. Hydrogen can be obtained from various materials such as formic acid and amine-borane (ammonia-borane, methylamine-borane, dimethylamine-borane, and hydrazine borane) compounds in liquid and solid form have a very important place. To release hydrogen from these materials, generally, some suitable catalysts are used. Catalysts are prepared using supporting materials like carbon and carbon derivations with different preparation methods to obtain high catalytic activity catalysts. In this chapter, nanomaterials composed of carbon and carbon derivations as catalysts to obtain hydrogen from hydrogen sources are evaluated. © 2021 Elsevier Inc. All rights reserved.
Synthesis of Bis(Thiosemicarbazone) Derivatives: Definition, Crystal Structure, Biological Potential and Computational Analysis
(Taylor & Francis Ltd, 2018) Ates, D.; Gulcan, M.; Gumus, S.; Sekerci, M.; Ozdemir, S.; Sahin, E.; Colak, N.
(2-(2-(2-methoxyphenyl)hydrazono)cyclohexane-1,3-diylidene) bis(hydrazine carbothioamide) (L-1), 4-(2-(-2,-6-bis(2-carbamothioylhydrazono) cyclohexylidene) hydrazinyl)benzoic acid (L-2), and (2-(2-(4-bromophenyl) hydrazono) cyclohexane-1,3-diylidene) bis(hydrazinecarbothioamide) (L-3) bis(thiosemicarbazone) derivative compounds were synthesized by the condensation reaction of thiosemicarbazide and various ketone compounds. The structures of synthesized compounds were characterized by using FT-IR, H-1 and C-13-NMR spectra, elemental analysis and mass spectra. Also, the structure of L-1 has been determined by X-ray crystallographic analysis. Additionally, the antioxidant activities (free radical (DPPH) scavenging, iron chelating and reducing power) of compounds were evaluated. Especially, L-3 displayed good DPPH activity (84.13%) at 100mg/L. Moreover, pBR322 plasmid DNA cleavage activity was examined and all of the compounds were able to cleave the plasmid DNA. Finally, the ground state geometries of the thiosemicarbazone derivatives were optimized using Density Functional Theory applications at B3LYP/6-31G (d,p) level in order to obtain information about the 3D geometries and electronic structure.
Synthesized Polyvidone-Stabilized Rh(0) Nanoparticles Catalyzed the Hydrolytic Dehydrogenation of Methylamine-Borane in Ambient Conditions
(Royal Soc Chemistry, 2017) Gulcan, M.; Karatas, Y.
Polyvidone (PVP40)-stabilized Rh nanoparticles (Rh@PVP40) were synthesized via a classical alcohol reduction technique and were characterized by carrying out TEM, HR-TEM, TEM/EDX, P-XRD analysis, UV/Vis and XPS spectroscopy investigations. Approximately, non-touch each other 100 particles in were counted TEM image in 50 nm scale and the average particle size of Rh@PVP40 nanocatalyst was found to be 3.32 +/- 0.26 nm. The prepared nanoparticles were found to be one of the most efficient catalytic systems in the literature, with a high TOF value (185.91 min(-1)) and low activation energy (43.88 kJ mol(-1)) for the hydrolytic dehydrogenation of a methylamine-borane compound. Analysis of the effects of catalyst and substrate concentrations on the catalytic reaction indicated that the reaction proceeded to the 1.37-order of the catalyst concentration and nearly zero order of the substrate concentration.