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Calcined Eggshell for the Removal of Victoria Blue R Dye from Wastewater Medium by Adsorption
(2021) Tosun Satır, İlknur; Erol, Kadir
In this study, the use of calcined eggshell (CE) as an adsorbent in removing Victoria Blue R (VBR) dyestuff from the solution medium was investigated. For this purpose, pH, interaction time, adsorbate concentration, amount of adsorbent, and salt effect parameters were studied to determine the appropriate adsorption conditions. The highest adsorption yield was obtained at pH 2, 2.0 g/L adsorbent, and a stirring time of 5 minutes. 97% of the dye was removed under optimum adsorption conditions. The results obtained from the experimental studies showed that the adsorption mechanism is compatible with the pseudo-second-order kinetic model and the Langmuir isotherm model. SEM and IR analysis were performed for the characterization of CE.
Manganese Oxoborate-Based Nanostructures as Novel Oxygen Evolution Catalysts in Neutral Media
(Wiley-V C H Verlag Gmbh, 2021) Elmacı, Gökhan; İçten, Okan; Özer, Demet; Özgenç, Gökhan; Ertekin, Zeliha; Köse, Dursun Ali; Zümreoğlu Karan, Birgül
The development of electrocatalysts for the OER (oxygen evolution reaction) process is an ongoing challenge in producing sustainable energy systems. Herein, we report QS (quasi-spherical), IR (irregular), and NR (nanorod) Mn2OBO3 (manganese oxoborate), modified with a carbon support, as candidate electrocatalysts for OER in a neutral medium. QS-, IR- and NR-Mn2OBO3 catalysts displayed low onset potentials of 201 mV, 205 mV, and 208 mV and Tafel slope results of 94 mV dec(-1), 97 mV dec(-1), and 106 mV dec(-1), respectively. As a result of the long-term stability tests, it was determined that the NR-Mn2OBO3 sample was extremely stable compared to the QS- and IR-catalysts. This work introduces a new Mn2OBO3/C composite catalyst that displays efficient OER performance at a neutral medium and provides a different perspective for catalyst development strategies.
Mn(II) and Co(II) mixed-ligand coordination compounds with acesulfame and 3-aminopyridine: synthesis and structural properties
(Taylor & Francis Ltd, 2021) Yurdakul, Ömer; Köse, Dursun Ali; Şahin, Onur; Özer, Demet
Two mixed ligand complexes containing acesulfame (acs) and 3-aminopyridine (3-ap) ligands of Mn(II) and Co(II) were synthesized. The obtained compounds were characterized by various analysis methods. The geometries of complexes, C18H28MnN6O12S2 (1) and C18H32CoN6O14S2 (2), are distorted octahedra. Coordination of metal cations is provided by two molecules of 3-ap and four water ligands. In both structures, the 2+ charge of the metal required two monoanionic acs molecules located outside the coordination sphere. Complex 1 contains no hydrate water, while 2 contains two molecules of hydrate water. The crystal system of 1 is monoclinic and space group P2(1)/c, while the crystal system of 2 is triclinic and space group P-1. Data on the removal of hydrate and crystalline waters in structures from thermal analysis curves support the described molecular structures. The bending vibrations of the bonds obtained from the FT-IR spectra match the crystal structure described. As a result of thermal analysis of both complexes, it was determined that the relevant metal cations remained in the reaction vessel as oxide (MnO and CoO) residues.
Synthetic routes to manganese oxoborate and correlations between experimental parameters and properties
(Elsevier Sci Ltd, 2021) İçten, Orkun; Özgenç, Gökhan; Özer, Demet; Köse, Dursun Ali; Elmacı, Gökhan; Ertekin, Zeliha; Zümreoğlu Karan, Birgül
This study examines manganese oxoborate synthesis in three different routes and the role of process parameters on structure and morphology of the products. Borax or boric acid and simple manganese salts were used as raw materials. In this regard, the samples prepared by hydrothermal, solid-state, and solution combustion methods were characterized by powder X-ray diffraction (XRD), vibrational spectroscopy (FT-IR and Raman), thermal analysis (DSC and TGA), scanning and transmission electron microscopy (SEM and TEM), chemical analysis and BET surface area measurements. It was found that all three strategies yielded warwickite-type Mn2OBO3 nanoparticles, but with significant changes in morphology, size, and surface characteristics. The hydrothermal approach has proven to be a general approach for synthesizing manganese oxoborate nanorods at pH 7.5. Solution combustion technique appeared the most practical and promising not only as a time-saving route but also in the production of ca. 100 nm, quasi-spherical, mesoporous manganese oxoborate nanoparticles.
Therapeutic Effects of Newly Synthesized Boron Compounds (BGM and BGD) on Hepatocellular Carcinoma
(Humana Press Inc, 2021) Koldemir Gündüz, Meliha; Bülter Bolat, Melda; Kaymak, Güllü; Berikten, Derya; Köse, Dursun Ali
Boron has an important potential for facilitating biological activity and for use in pharmaceutical drug design. Boron glycine monoester (BGM) and boron glycine diester (BGD) compounds containing boron atoms were synthesized and investigated their cytotoxic, oxidative stress, and antimicrobial activities on the HepG2 cancer cell line. The cytotoxic activity of newly synthesized boron compounds on hepatocellular carcinoma was determined by the MTT method for 48 h. Antioxidant (CAT, GSH), lipid peroxidation (MDA), and enzyme activity (ACP, ALP) analyses were determined by spectrophotometric methods in HepG2 cells. Antimicrobial activity was determined by the disk diffusion method. After 48 h of BGM and BGD application to HepG2 cells, we found the IC50 values as 9.9 mM and 24 mM, respectively. While CAT and ACP enzyme activities decreased in all groups compared to the control, ALP enzyme activity did not change in the BGM group but increased in the BGD group. It was determined that the GSH level did not change in all groups, while the MDA level increased. It has been stated that these IC50 doses of BGM and BGD have antibacterial effects on Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922. Newly synthesized boron compounds, particularly BGM, with their cytotoxic, oxidative stress, and antimicrobial effects, could provide a new therapeutic approach for the treatment of hepatocellular carcinoma.
Water-soluble polymeric particle embedded cryogels: Synthesis, characterisation and adsorption of haemoglobin
(Walter De Gruyter Gmbh, 2021) Erol, Kadir; Bolat Bülter, Melda; Köse, Dursun Ali; Kaplan Can, Hatice
Making cryogels, which are among today's accepted adsorbents, more functional with different methods, has been one of the subjects spent overtime. In this study, water-soluble poly(maleic anhydride-alt-acrylic acid) polymer embedded in poly(2-hydroxyethyl methacrylate) cryogels. Copper ionswere then immobilised to this structure, and this polymer was used for adsorption of haemoglobin from aqueous systems. Adsorption interaction was carried out on an electrostatic basis, and approximately 448.62 mg haemoglobin/g polymer adsorption capacity value was obtained. Itwas found that the same material hasmanaged to maintain its adsorption ability by 90.3% even after the use of it five times in the adsorption/desorption cycle. The adsorption interaction was determined to be appropriate for the Langmuir model by isotherm studies. The change in Gibbs free energy value was calculated as -2.168 kJ/mol.
Acesulfame complex compounds of some lanthanide group metal cations. Synthesis and characterization
(Elsevier, 2021) Zeybel, Leriman; Köse, Dursun Ali
Some rare earth metal cations (Eu3+, Tb3+, HO3+ , Er3+ and Yb3+) of the acesulfame ligand and complex compounds were synthesized by hydrothermal method. Elemental analysis, infrared spectroscopy, mass analysis and solid-state UV-vis spectroscopy methods were used for the structural characterization of these compounds. In addition, TGA curves were recorded to determine the thermal degradation steps and possible degradation products of complex structures. As a result of the analysis of the structures, it was determined that the load equivalence of the metal cations having +3 oxidation steps provided with three monoanionic acesulfame ligands included in the structure. Rare earth elements, which have high coordination due to their large radii, are thought to exhibit hexadecimal coordination in synthesized molecules. The coordination sphere is complemented by two acesulfame and 2 aqua ligands showing acidic -N and carbonyl oxygen binding to the bidentate. One acesulfame ligand is thought to be located outside the coordination sphere as a counter ion. According to the recorded TGA curves, all molecules were found to contain one hydrate water. It was determined by FT-IR analysis that all complex structures formed the metal oxides in the reaction vessels as thermal decomposition products. (C) 2020 Elsevier B.V. All rights reserved.
Novel mixed ligand coordination compounds of some rare earth metal cations containing acesulfamato/N,N-diethylnicotinamide
(Scientific Technical Research Council Turkey-Tubitak, 2021) Zeybel, Leriman; Köse, Dursun Ali
The mixed ligand coordination compounds containing acesulfamato and N,N-diethylnicotinamide biomolecules of some rare earth metal cations (Eu3+, Tb3+, Ho3+, Er3+ and Yb3+) were synthesized, and their structural properties were investigated. Possible structural formulas have been proposed by determining the chemical composition of molecules (elemental analysis), binding properties (infrared spectroscopy, mass analysis, solid-state UV-vis spectroscopy), thermal degradation properties (TGA / DTA curves). Based on the data collected, it is suggested that rare earth metal cations with a 3+ oxidation state have sextet coordination. The geometries of the structures were thought to be distorted octahedral. The charge balance of the coordination sphere is balanced by a monoanionic acesulfamato located outside the coordination sphere. When the thermal behaviours of the complexes were examined, it was determined that the compounds with Eu3+, Tb3+, and Yb3+ metal cations contained one hydrate water outside the coordination sphere. Hydrate waters do not exist in the Ho3+ and Er3+ metal cation-centred complexes. At the end of the thermal decomposition analysis of all complex structures, it was determined that they leave the relevant metal oxides in the reaction vessels as final decomposition products.
Reducing lactose content of milk from livestock and humans via lactose imprinted poly(2-hydroxyethyl methacrylate-N-methacryloyl-L-aspartic acid) cryogels
(Walter De Gruyter Gmbh, 2021) Erol, Kadir; Arslan Akveran, Gönül; Köse, Kazım; Köse, Dursun Ali
Lactase, which can cause lactose intolerance in its deficiency, is a vital enzyme concerning digestion. To overcome lactose intolerance for patients with digestion problem depending of this kind of issue, lactose in food should be removed. In this study, lactose imprinted poly(2-hydroxyethyl methacrylate-N-methacryloyl-L-aspartic acid), poly(HEMA-MAsp), cryogels were synthesized to reduce the amount of lactose content of milk samples. Occurrence of desired bounds, structural integrity, and surface characteristics were analyzed via Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), scanning electron microscope (SEM), micro computed tomography (CT), and confocal microscope methods. Water retention characteristic were tested in solution with different electrolytic nature. Adsorption parameters were optimized in an aqueous medium. The adsorption performance of imprinted cryogels was studied in milk samples obtained from cow, sheep, goat, buffalo, and from human volunteers at different intervals after birth. Amount of lactose adsorbed in aqueous media and milk sample from humans were 322 (56.7%) and 179.5 (5.94%) mg lactose/g polymer, respectively. Selectivity studies revealed an approximately 8-fold increase in adsorption rate of molecularly imprinted cryogels as compared to that of nonimprinted cryogels. In addition, competitive adsorption was conducted using lactose-imprinted cryogels in aqueous media containing lactose, glucose, and galactose molecules resulting in adsorption rates of 220.56, 57.87, and 61.65 mg biomolecule/g polymer, respectively.
Novel monoanionic diphenate-nicotinamide/N,N-diethylnicotinamide complexes of Ni-II, Zn-II. Synthesis, structural investigations and hydrogen adsorption study
(Elsevier, 2020) Yurdakul, Ömer; Şahin, Zarife Sibel; Köse, Dursun Ali; Şahin, Onur; Akkurt, Fatih
The coordination compounds and polymers in which the transition metals are taken centrally are of interest due to their very different properties. The studies on the synthesis and structural properties of these compounds due to their potential applications for nanotechnology, sensor applications, magnets, optoelectronics, energy conversation and storage, gas storage, separation, catalysis and similar industrial applications are of great interest
Synthesis, characterization and antibacterial application of silver nanoparticle embedded composite cryogels
(Elsevier, 2020) Erol, Kadir; Bolat Bülter, Melda; Tatar, Demet; Nigiz, Cengiz; Köse, Dursun Ali
Water treatment applications; they consist of processes that desalination, softening, removals of dissolved organic matter, color, particle and microorganism. In traditional treatment processes, microorganisms cause thick film layer on the membrane to be used and not enough treatment. Silver nanoparticles (AgNPs), known to stop bacterial growth due to their superior antibacterial properties even at low concentrations due to their contact with microorganisms, are used for water disinfection. Membrane production with a combination of AgNPs and polymers has started to attract attention in recent years due to advanced optics, conductivity and antibacterial properties. The ability of AgNP to exhibit its antibacterial effect depends on the property of this material to be homogeneously dispersed in the polymer. In this study, Poly(2-hydroxyethyl methacrylate-glycidyl methacrylate), Poly(HEMA-GMA), cryogels were synthesized as solid support. In order to gain antibacterial properties to synthesized cryogels, AgNPs of different sizes were embedded in cryogels. These structures have been used as a kind of antibacterial filter in the purification of water obtained from natural sources used as drinking and using water in the local region. Particle Size analysis was used to determine the size of synthesized AgNPs. Swelling test, Scanning Electron Microscopy (SEM), Elemental Analysis, Fourier Transform Infrared Spectroscopy (FT-IR), and surface area (BET) analysis were performed for characterization of cryogels. (C) 2019 Elsevier B.V. All rights reserved.
Electrochemical Glucose Detection Using PdAg Nanoparticles Anchored on rGO/MWCNT Nanohybrids
(Springer/Plenum Publishers, 2020) Uzunoğlu, Aytekin; Köse, Dursun Ali; Gökmeşe, Ebru; Gökmeşe, Faruk
The combination of multi-walled carbon nanotube (MWCNT) and graphene (Gr) to extend their unique physicochemical properties to 3-dimensions (3D) is known to be an effective way to achieve high catalytic properties in electrochemistry. In this context, PdAg metal nanoparticles (MNPs) were anchored on 3-D MWCNT-rGO nanohybrids to construct high-performance enzyme-free electrochemical glucose sensors. The PdAg/MWCNT-rGO nanohybrids were prepared via a one-pot synthesis route and characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) methods. The XRD and TEM results confirmed the successful immobilization of PdAg nanoparticles on the support surface and the EDS results revealed a homogeneous MNP distribution. The PdAg content anchored on the hybrids was found to be 39 wt% by TGA analysis, which is compatible with the starting stoichiometric ratio. The constructed sensors showed the sensitivities of 13.16 +/- 0.4 and 5.22 +/- 0.07 mu A mM(-1) cm(-2) in the concentration windows of 0.05 to 4 and 4 to 42 mM, respectively. A wide linear range of 0.05 to 42 mM with a low limit of detection (51 mu M) was obtained from the sensors.
Zwitterionic amino acids as precursors for nonmetal cation pentaborate salts
(Wiley-V C H Verlag Gmbh, 2020) Sızır, Umit; Yurdakul, Ömer; Köse, Dursun Ali; İçten, Okan
Nonmetal cation (NMC) pentaborate structures were synthesized using the amino acid molecules as cations precursors. Chemical composition analysis, infrared spectroscopy, mass analysis, boron nuclear magnetic resonance, and thermal gravimetric analysis (TGA/DTA) methods were used for structural characterization. The hydrogen storage efficiency of molecules was also determined experimentally. The recorded infrared spectra support the structural similarities of the molecules. Stretchings of pentaborate rings and characteristic peaks of amino acids were detected in infrared spectra. When the thermal analysis curves were recorded, it was found that the structures showed similar decomposition steps. Due to the result of thermal decay, glassy boron oxide (B2O3) formation was observed as the final decomposition products of all molecules. Peaks associated with boric acid, triborate, and pentaborate were observed in the B-11 spectra of these salts. Powder X-ray diffraction spectroscopy supports the presence of BO3 and BO4- groups regarding the presence of pentaborate rings. It also indicates the high crystallinity of the structures. The molecular cavities detected by brunauer-emmett-teller analysis were found to be 3.586, 1.922, 1.673, and 1.923 g/cm(3). Low-molecular cavities can be attributed to the high hydrogen-bonding capacity of the structures. The hydrogen capture efficiency of the pentaborate salts was found to be in the range of 0.039-0.
Development of novel copper modified cryogels for biochemical isolation
(Springer, 2020) Köse, Kazım; Erol, Kadir; Köse, Dursun Ali
Cu(II) anchored polymeric cryogels are synthesized for the isolation of B12. The poly(2-hydroxyethyl methacrylate) [poly(HEMA)] is used as solid support and N-methacryloyl-l-aspartic acid, is used as a ligand. Synthesis success is proved by the Fourier transform infrared spectroscopy, H-1 and C-13 nuclear magnetic resonance, scanning electron microscope, N-2 adsorption method (Brunauer, Emmet ve Teller), elemental analysis, induction coupled plasma optical emission spectroscopy. In the first part of the work, the polymeric material is synthesized and characterized, and in the second part, adsorptive treatment was carried out to determine the optimum B12 adsorption conditions with this synthesized material in varying conditions. The B12 isolation from cheese is carried out to determine the performance of the polymeric material in the real environment. The antioxidant capacity of the obtained B12 is an indication that the isolation process is successfully carried out.
Novel Non-Metal Cation (NMC) Pentaborate Salts of Some Amino Acids
(Mdpi, 2019) Sızır, Ümit; Yurdakul, Ömer; Köse, Dursun Ali; Akkurt, Fatih
Non-metal cation (NMC) pentaborate structures, in which some amino acids (valine, leucine, isoleucine, and threonine) were used as cations, were synthesized. The structural characterization of molecules was carried out by elemental analysis, FT-IR, mass, B-11-NMR, and thermal analysis (TGA/DTA) methods. The hydrogen storage capacity of molecules was also calculated by taking experimental results into consideration. The FT-IR spectra support the similarity of structures. The characteristic peaks attributable to pentaborate rings and amino acids were observed. When thermal analysis data were examined, it was observed that pentaborate salts gave similar degradation steps and degradation products. As a final degradation product of all thermal analysis experiments, a glassy form of B2O3 was observed. The valine pentaborate is the most thermally stable. Also, the amounts of hydrate water outside the coordination sphere of the compounds were determined by thermal analysis curves. The peaks of boric acid, triborate, and pentaborate structures were obtained in ppm with the B-11-NMR results of synthesized pentaborate compounds. With powder X-ray spectroscopy, all structures were found to be crystalline but not suitable for single-crystal X-ray analysis. The molecular cavities of the compounds detected by BET were found to be 3.286, 1.873, 2.309, and 1.860 g/cm(3), respectively. A low number of molecular cavities can be interpreted in several existing hydrogen bonds in structures. The hydrogen storage capacities of the molecules were found to be in the range of 0.04 to 0.07% by mass.
Synthesis of CeO2-based core/shell nanoparticles with high oxygen storage capacity
(Springer International Publishing Ag, 2017) Uzunoğlu, Aytekin; Köse, Dursun Ali; Stanciu, Lia A.
Ceria plays a key role in various applications including sensing and catalysis owing to its high oxygen storage capacity (OSC). The aim of this work is to prepare novel MO (x) /CeO2 (M: Zr, Ti, Cu) metal oxide systems with core/shell structures using a facile two-step chemical precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and N-2 adsorption methods. The OSC property of the samples was evaluated using TGA analysis conducted at 600 A degrees C under reductive (5% H-2/Ar) and oxidative (synthetic air) environments. The OSCs of the samples were found to be 130, 253, and 2098 A mu mol-O-2/g for ZrO2/CeO2, TiO2/CeO2, and CuO/CeO2, respectively. Effects of heat treatment on the physical and redox properties of the samples were also evaluated. In this regard, the samples were exposed to 500 A degrees C for 5 h under ambient environment. It was observed that the heat treatment induced the formation of mixed metal oxide alloys and the BET surface area of the samples diminished significantly. The OSC of the samples, however, did not experience any significant chance, which was attributed to the compensation of the loss in the surface area by the alloy formation after the heat treatment.
Effect of immobilization on the activity of catalase carried by poly(HEMA-GMA) cryogels
(Elsevier B.V., 2019) Erol, Kadir; Koncuk Cebeci, Büşra; Köse, Kazım; Köse, Dursun Ali
Hydrogen peroxide is converted by catalase to molecular oxygen and water to remove oxidative stress. In this study, catalase immobilization was performed using poly(2-hydroxyethyl methacrylate-glycidyl methacrylate) (poly(HEMA-GMA)) cryogels with different amounts of GMA. Catalase adsorption capacity of 298.7 ± 9.9 mg/g was achieved at the end of 9 h using the poly(HEMA-GMA)-250 cryogel. Kinetic parameters and the inhibitory effects of pesticides such as 4,4?-DDE and 4,4?-DDT on the activity of free and immobilized catalase enzyme were investigated. While the V max value of the immobilized enzyme was reduced 4-fold compared to the free enzyme, in the case of the comparison of the K M values, the affinity of the immobilized enzyme was increased by 1.94 times against the substrate. The inhibitory effect of 4,4?-DDT pesticide was found to be higher for the immobilized and free enzyme. NaCl (1 M, pH: 7.0) solution was used for desorption of the adsorbed catalase enzyme. A desorption ratio of 96.45% was achieved. The technique used in this study is promising regarding for the immobilization of catalase enzyme to increase the operational activity. Therefore, poly(HEMA-GMA) cryogels have the potential to be used for immobilization of catalase enzyme in the fields of biology and biochemistry. © 2018 Elsevier B.V.
Novel mixed ligand complexes of alkaline earth metals with coumarilic acid and nicotinamide
(Turkish Chemical Society, 2021) Karaer, Emrah; Köse, Dursun Ali
Coordination compounds with mixed ligands were synthesized with 2A group (Mg2+, Ca2+, Ba2+, Sr2+) alkaline earth metal cations of coumarilic acid and nicotinamide ligands. Afterward, the structural properties of these new molecules were investigated by melting point, elemental analysis, infrared spectroscopy, thermal analysis (TGA / DTA) curves, powder X-ray diffraction (P-XRD) spectroscopy. It has been suggested that the complex structure with the Mg2+ metal center is different from the other three structures. In this structure, it was determined that four aqua and two nicotinamide ligands were located in the coordination sphere, and the coordination number was six, as expected. With two monoanionic coumarilic acids located outside the coordination sphere, complex charge equivalence was achieved. The other three molecules, Sr2+ and Ba2+, have iso-structural properties, and it is suggested that both structures contain a dinuclear metal center, and two aqua ligands are located in the bridging position between metal centers. Besides, the two coumarilate ligands involved in coordination are thought to coordinate with the primary metal cation through carbonyl and acidic oxygens while coordinating with the secondary metal cation through furan oxygen, providing the third bridge connection between metal centers. Metal cations with nine coordination numbers complete the coordination sphere with two terminal aqua and one nicotinamide ligands, each included in the structure. In the molecule with Ca2+ cation, which differs little from these metal cation structures, the difference according to these structures can be interpreted as the coordination of furan oxygen with the secondary metal center due to the octet coordination of the Ca2+ cation. From the thermal analysis curves, it was determined that only the Mg2+ cation complex contained hydrate. As a result of thermal decomposition, it was determined that relevant metal oxide residues remained in all structures, and this situation was defined by powder XRD. © 2021, Turkish Chemical Society. All rights reserved.
The electrochemical performance of manganese oxoborate cathodes for lithium-ion batteries: Effect of synthesis method
(Elsevier Ltd, 2021) Ertekin, Zeynep; Özgenç, Gökhan; Özer, D.; İçten, Orkun; Elmacı, Gökhan; Köse, Dursun Ali; Zümreoğlu Karan, Bilge
Cathodes for lithium-ion batteries (LIBs) present stability and performance issues; therefore, searching for alternative novel electrode materials or modifications of known ones is one of the main issues. Warwickite-type Mn2OBO3 samples synthesized by hydrothermal (HT), solid-state (SS), and solution combustion (SC) methods were investigated for the first time as cathode materials for LIBs. The prepared Mn2OBO3 electrodes were analyzed using scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques in order to correlate the surface properties and electrochemical behaviour. X-ray photoelectron spectroscopy (XPS) revealed the existence of +2 and + 3 oxidation states of Mn in the electrodes. The band gaps (Eg) for all electrodes were calculated between 1.75 and 2.04 eV. The electrochemical performance of the Mn2OBO3 electrodes (E) prepared with the SC method was significantly improved. The E-SC electrode showed the highest initial discharge capacity of about 155 mAhg-1 and found to be more stable at a current density of 30 mAg-1. The results presented here provide a new approach to the utilization of manganese oxoborate compounds as promising cathode materials for high-performance energy storage systems and emphasize that homogeneously structured cathode electrodes with a high surface area are desirable for LIBs. © 2021 Elsevier Ltd and Techna Group S.r.l.
Novel coordination compounds of alkaline earth metals with coumarilic acid. Synthesis and characterization
(Elsevier B.V., 2021) Karaer, Emrah; Köse, Dursun Ali; Şahin, Zarife Sibel; Şahin, Onur
In this study, novel coordination compounds of coumarilic acid with 2A group alkaline earth metal cations [Mg2+ (1), Ca2+ (2), Sr2+ (3) and Ba2+(4)] were synthesized and structural characterized. The structural properties of the new molecules obtained were studied by melting point, elemental analysis, infrared spectroscopy, single crystal x-ray diffraction (SC-XRD), powder x-ray diffraction (P-XRD) spectroscopy. In addition, the thermal stability of the compounds were examined by thermal analysis (TGA/DTA) curves in an inert nitrogen atmosphere. When the structural properties of the molecules were examined, it was seen that the structure numbered 1 {[Mg(H2O)6].2(C9H5O3)} differed from the others and it was a kind of aqua complex. The coumarilate anions anionically located outside the coordination sphere serve as the counter-ion of the molecule. It has been determined that the other structures 2 {?-(H2O)2[Ca(C9H5O3)(H2O)3]2.2(C9H5O3)}, 3 {?-(H2O)3[Sr(C9H5O3)(H2O)2]2.2(C9H5O3)} and 4 {?-(H2O)3[Ba(C9H5O3)(H2O)2]2.2(C9H5O3)} are in polymeric form and the coordination number of metals are eight. According to the spectroscopic analysis, these three structures are thought to be in isostructure form. It has been determined that in the unit cell in the structure 3 whose single crystal structure has been resolved, aqua and coumarilate ligands of two metal cations are connected to each other in the bridge position and coordination is ensured with aqua and bidentate anionic coumarilate ligands located in the terminal position. At the end of thermal decomposition, it was determined that relevant metal oxide residues remained in all structures and this situation was defined by powder XRD. © 2021

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