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    Highly Promising Antitumor Agent of a Novel Platinum(II) Complex Bearing a Tetradentate Chelating Ligand
    (Amer Chemical Soc, 2020) Yilmaz, Ismail; Akar, Okan Remzi; Erkisa, Merve; Selvi, Selin; Sengul, Abdurrahman; Ulukaya, Engin
    A new mononuclear cationic platinum(II) coordination compound with 6,6'-bis(NH-benzimidazol-2-yl)-2,2'-bipyridine (L) ligand having N-4-tetradentate binding pocket [Pt(L)]-Cl-2.2H(2)O (Complex 1) was synthesized and characterized by FTIR(ATR), UV-vis, H-1 NMR, APCI and MALDI MS, and CHN analysis. The antigrowth effect of Complex 1 was tested in breast cancer (MDA-MB-231), lung cancer (A549), colorectal cancer (HCT-116), prostate cancer (PC-3) cell lines, and bronchial epithelial cell line (BEAS-2B) by the SRB and ATP cell viability assays. Apoptosis was detected with Annexin V, mitopotential, BCL-2 inactivation, and gamma H2AX assays by flow cytometry. Complex 1 was found to have cytotoxic activity of MDA-MB-231, A549, HCT-116, and PC-3 cancer cell lines in a dose-dependent manner for 48 h. Complex 1 has been found to cause cell death through different mechanisms depending on the type of cancer. The findings indicated that complex induced intrinsic apoptosis with the increased mitochondrial membrane depolarization level, Bcl-2 inactivation, and DNA damage in PC-3 and A549 cell lines.
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    Spectroscopic, EPR, X-ray structural, and DFT studies of the complex compound of N4-donor ligand with copper(II)
    (Elsevier, 2020) Yilmaz, Ismail; Acar, Nursel S.; Coles, Simon J.; Sengul, Abdurrahman
    A new mononuclear neutral five-coordinate copper(II) coordination compound [Cu(L)(H2O)] (1) (L = 6,6'-bis(NH-benzimidazol-2-yl)-2,2'-bipyridine) was synthesized and characterized by IR, UV-Vis, EPR and LC-MS (APCI) analysis. The crystal structure was also determined by X-ray crystallography. In 1, the copper(II) center adopts a five-coordinate distorted square-pyramidal (SP) geometry in which the basal plane formed by four of the nitrogen atoms of the ligand while the apical position is occupied by the oxygen atom of the water molecule. The four Cu-N bond lengths are 1.987(4), 1.992(4), 2.020(5) and 2.027(4) angstrom, and the longest bond of the apical Cu-O-w is 2.234(4) angstrom. The ligand undergoes deprotonation upon coordination to the metal center and acts as a dianionic tetradentate chelate to form a neutral complex [CuN4O]. The X-band EPR data of 1 are in agreement with the crystallographic data indicating a typical five-coordinate SP geometry. This geometry is also obtained by Density Functional Theory calculations. Time-dependent (TD) DFT calculations were used to shed light on the assignment and the nature of the electronic transitions observed in the UV-Vis spectrum. The calculated results are found to be consistent with the experimental data. Non-linear optical properties were also calculated by DFT calculations. (C) 2020 Elsevier B.V. All rights reserved.
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    Spectroscopic, structural and DFT studies of luminescent Pt(II) and Ag(I) complexes with an asymmetric 2,2?-bipyridine chelating ligand
    (Elsevier, 2021) Yilmaz, Ismail; Acar-Selcuki, Nursel; Coles, Simon J.; Pekdemir, Fatih; Sengul, Abdurrahman
    A new unsymmetrically substituted 2,2'-bipyridine ligand, 5-methyl-5'-carbomethoxy-2,2'-bipyridine (L) was isolated from the dry distillation of the copper(II) complex, mono-aqua-bis(trans-5-methyl-pyridine2-carboxylato- N,O)copper(II). The ligand was fully characterized. The spectroscopic and single-crystal Xray diffraction (SCXRD) studies of the coordination compounds of the ligand with platinum(II) and silver(I); cis-Pt(L)Cl-2 (1) and [Ag(L)(2)]PF6 (2), respectively are reported. In 1, the Pt centre coordinates to tertiary N atoms of the ligand and two chloride ions to form a neutral square-planar coordination sphere, while in 2, the Ag(I) centre is coordinated by two ligands through N atoms to generate a cationic flattened tetrahedron geometry in which two mean planes intersect each other at 50.93 degrees. The pyridine rings are nearly coplanar as revealed by the torsion angle of N2-C7-C6-N1 1.32(5)degrees. In both complexes, L acts as a chelating ligand through pyridyl N atoms. In 1, the molecular units are stacked in a head-to-tail fashion with a Pt center dot center dot center dot Pt separation of 3.5 degrees A. Supramolecular self-assembly of the molecular units by extensive intermolecular contacts through C-H center dot center dot center dot Cl and C-H center dot center dot center dot O between the adjacent units results in an infinite two-dimensional flattened-out herringbone structure in the crystalline state. In 2, the molecular units are interconnected with each other by C-H center dot center dot center dot O contacts between the adjacent units running parallel to each other. Both complexes are fluorescent in solution and have emission maxima in the UV-Vis regions, which is a very important property for optoelectronic applications. DFT (density functional theory) and TD-DFT (time-dependent-DFT) calculations were performed at B3LYP/6-311+G(d,p)/LANL2DZ level to explore structural, electronic, and spectroscopic properties to compare with the experimental results. The molecular orbitals (MOs) were carried out with DFT at the same level. (C) 2020 Elsevier B.V. All rights reserved.
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    Synthesis of a new ?-chlorido-bridged tetra-nuclear copper(II) complex containing 2,3,5,6-tetra(2-pyridyl)pyrazine (tppz), chlorido and perchlorato ligands: non-planar central pyrazine rings
    (Taylor & Francis Ltd, 2023) Yilmaz, Ismail
    A & mu;-chlorido-bridged tetra-nuclear copper(II) complex containing 2,3,5,6-tetra(2-pyridyl)pyrazine (tppz), chlorido, and perchlorato ligands, starting from 2-aminomethyl pyridine (AMP) and Cu(OAc)(2)& BULL;H2O, was synthesized. The structure of the complex was determined by single-crystal X-ray diffraction (SCXRD), Fourier transform infrared spectroscopy (FT-IR), and electronic absorption spectroscopy (UV-Vis). The redox behavior of the complex was explored by cyclic voltammetry. The tetra-nuclear structure is formed by combining the di-nuclear copper complex of the two tppz ligands with a chloride bridge. The Cu(1) center adopts a distorted octahedral geometry, whereas the other three Cu centers adopt square pyramid geometries. Crystal data of the complex are monoclinic, P2(1)/c, a = 13.602(4) & ANGS;, b = 13.438(4) & ANGS;, c = 29.412(8) & ANGS;, & alpha; = 90 & DEG;, & beta; = 95.258(8)& DEG;, & gamma; = 90 & DEG;, V = 5353(3) & ANGS;(3), Z = 4. When the SCXRD structure was examined, it was determined that the two central pyrazine rings deviated from planarity, which is one of the four criteria for aromaticity. The aromaticity of the central pyrazine rings, whose planarity is disturbed, is decreased. Based on these bond lengths, the harmonic oscillator aromaticity model (HOMA) values of the non-planar central pyrazine rings were calculated as 0.964926 and 0.942886, respectively.
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    Synthesis of catena-Poly[[di-aqua(2,2?-bipyridine)copper (II)]-?2-sulfato-?2O:O'] 1D coordination polymer and [di-chloro (2,2?-bipyridine)copper(II)] complex, redetermination of their crystal structures
    (Pergamon-Elsevier Science Ltd, 2024) Yilmaz, Ismail
    The title compounds [Cu(bpy)(H2O)(2)(SO4)](n )(1) and [Cu(bpy)Cl2] (2) were successfully synthesized, and their crystal structures were redetermined as some corrections were needed. The Cu(II) centers in 1 are coordinated in elongated octahedral geometry by the two nitrogen atoms of a bpy ligand and four oxygen atoms belonging to aqua molecules and sulfato ligands, forming a polymeric chain by bridging the sulfato ligands. The Cu(II) center in 2 is coordinated by the two chloride ions and the two nitrogen atoms of the bipyridine ligand, forming a distorted square planar geometry. The [Cu(bpy)(H2O)(2)(SO4)](n )complex crystallizes in the monoclinic crystal system with space group C2/c. The unit cell parameters were determined to be a =15.154(3) angstrom, b =12.477(3) angstrom, c = 7.0158(14) angstrom, alpha = 90 degrees, beta = 105.873(12)degrees, gamma = 90 degrees, V = 1276.0(5) angstrom(3), Z = 4. The Cu-N, Cu-O(aqua) and Cu-O (sulfate) bond lengths are 2.000(3) angstrom, 1.978(2) angstrom and 2.464(2) angstrom, respectively. The [Cu(bpy)Cl-2] complex crystallizes in the monoclinic crystal system with space group I2/a. The unit cell parameters were determined to be a = 7.306(2) angstrom, b = 9.016(2) angstrom, c = 15.879(6) angstrom, alpha = 90, fi = 92.141(15), gamma = 90 degrees, V =1045.2(5) angstrom(3), Z = 4. The Cu-N and Cu-Cl bond lengths are 2.031(5) angstrom and 2.2662(17) angstrom, respectively.
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    Synthesis, structural characterization, and thermal properties of octahedral diperchlorato complexes of copper(II) with the chelating 2-aminomethylpiperidine and 2-aminomethylpyridine ligands
    (Taylor & Francis Inc, 2023) Yilmaz, Ismail
    Two distorted octahedral copper(II) coordination compounds; [Cu(AMPp)(2)(OClO3)(2)] (1) and [Cu(AMP)(2)(OClO3)(2)] (2) (2-aminomethylpiperidine and 2-aminomethylpyridine) have been synthesized on a SP Sephadex C-25 cation exchanger resin for high purity. Their structures have been determined by single-crystal X-ray diffraction, fourier transform infrared spectroscopy, and also thermal analysis. In both structures, the metal center adopts an elongated octahedral geometry in which two chelating amine ligands occupy the square plane in a trans-position, and two perchlorate ligands occupy the axial sites. The thermal stability of both complexes is relatively high. However, the thermal stability of 2 with the aromatic ring was 12 degrees C higher, due to intermolecular hydrogen bonds, pi MIDLINE HORIZONTAL ELLIPSIS pi, and pi MIDLINE HORIZONTAL ELLIPSISO interactions.