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    Novel coordination networks of phthalate/nicotinamide mixed-ligand metal-organic architectures of transition metals - a comparative IR-TGA study and crystal structure of the Zn(II) complex
    (Elsevier B.V., 2026) Telli, Merve; Bolat, Melda; Köse, Dursun Ali; Sari, Esma; Sibel Şahin, Zarife
    AbstractIn this research, mixed-ligand Co(II), Ni(II), Cu(II), and Zn(II) complexes containing phthalic acid (phthalate, O-donor) and nicotinamide (N-donor) were synthesized and characterized in detail by FT-IR, TGA/DTA, and for the Zn(II) complex single-crystal X-ray diffraction (XRD). It was observed that the Δν values obtained from the asymmetric and symmetric vibration bands of carboxylate groups in FT-IR spectra changed depending on the metal center, generally indicating a binding regime between monodentate and bridging. The largely preserved position of the Amide I band of nicotinamide indicates that the amide carbonyl oxygen does not participate in coordination, while the ν(M–N) signals in the low-frequency region support N-donor bonding through the pyridine nitrogen. The appearance of distinct and sharp bands in the high-frequency region (N–H and O–H) in the Zn(II) complex indicated the presence of multiple/non-equivalent hydrogen bonding environments in the crystal; this finding was consistent with the dense H–bonding network observed in the X-ray structure. Single-crystal XRD revealed that phthalate acts as a μ₂-η¹:η¹ bridge for Zn(II), with each Zn center forming a four-coordinate, significantly distorted tetrahedral environment with a pyridine–N and three phthalate–O. TGA/DTA data were found to be consistent with multi-step decomposition profiles across all complexes (water loss at low temperatures, organic component decomposition at intermediate temperatures, and metal oxide formation at high temperatures); the resulting residues were confirmed to be the corresponding metal oxides. When all the data were evaluated together, it was concluded that thermally stable coordination architectures were obtained, guided by the bridging tendency of phthalate and the N–donor binding of nicotinamide, and that the IR-XRD-TGA results were consistent with each other. © 2026 Published by Elsevier B.V.
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    Öğe
    Synthesis and characterization of transition metal complex cationed heptaborate structures
    (Turkish Energy Nuclear and Mining Research Institute, 2023) Genç, Ahmet; Köse, Dursun Ali; Şahin, Onur
    In recent years, interest in the study of cyclic borate structures (hexaborate, heptaborate, etc.), which draws attention due to their piezoelectric properties, has increased. In the scope of our study, heptaborate rings using the transition metal cation coordination compound as cation were synthesized and tried to be structurally characterized by elemental analysis, melting point determination, FT-IR, TGA/DTA analysis, UV analysis, powder x-ray diffraction (P-XRD) analysis methods. The presence of the cationic coordination sphere in the structures was determined by the stretching vibrations of (-M-N)phen and (-M-N)pyrd observed in the infrared spectra.-OH peaks of characteristic B-OH bonds of heptaborate rings and sharp asymmetric and symmetric stretching vibrations were detected confirming the presence of trigonal borate molecule in the rings. Due to the similar thermal decomposition properties of the molecules, it was determined that the hydrated waters that precipitated out of the coordination sphere in all structures moved away from the structures in a single step. As the second degradation step of heptaborate salt structures, the presence of water in amounts attributable to the removal of-OH groups in borate rings as water vapor in all structures was calculated. It has been observed that this degradation step occurs in a single step in all structures and the relevant experimental theoretical mass losses are compatible with each other. Combustion degradation of organic ligands was observed as the final degradation step of the heptaborate salt structures with metal cation complexes. While peaks belonging to heptaborate rings were observed from the recorded powder x-ray diffraction patterns, electronic transition data also supported that the metal cation complex was in octahedral geometry. © 2023, Turkish Energy Nuclear and Mining Research Institute. All rights reserved.
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    Öğe
    The Structural and Thermal Characterization of New Cu-Arginate Complex; Experimental and Simulated Hydrogen Adsorbstion Properties
    (2016) Şahin, Zarife Sibel; Öztürk, Zeynel; Yurdakul, Ömer; Köse, Dursun Ali
    The copper-arginate complex was synthesized and characterized by using FTIR, TG/DTA-DrTG, UV-Vis spectroscopy and elemental analysis methods. In addition, experimental and theoretical hydrogen storage capabilities were investigated. The unit cell of complex structure included that one mole CuII as centered cation and one mole of free NaI cation and one mole of NaSO4- as coordinated to arginine ligand and two moles of arginate ligands and one mole of aqua ligand as coordinated to NaSO4-. The CuII cation had square-pyramidal coordination sphere and the Na1 metal cation had trigonal coordination scheme. The other sodium metal cation (Na2) was implemented in the released position as counter ion of NaSO4-. It was found that the arginine complex, synthesized in this work have 0.533 m2/g BET surface area and 6.92E-3 wt. % hydrogen storage capacity at 77 K and 1 bar while simulated value was 3.27E-3 wt. % for the same conditions.