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Öğe A new zinc(II) complex with N2O2-tetradentate schiff-base derived from pyridoxal-S-methylthiosemicarbazone: Synthesis, characterization, crystal structure, DFT, molecular docking and antioxidant activity studies(Pergamon-Elsevier Science Ltd, 2021) Poladian, Qumars; Sahin, Onur; Karakurt, Tuncay; Ilhan-Ceylan, Berat; Kurt, YaseminA new unsymmetrical N2O2-tetradentate Schiff-base complex of zinc(II) was synthesized by the template reaction of pyridoxal-S-methylthiosemicarbazone and 2-hydroxy-4-methoxy-benzaldehyde as starting compounds. S-methylthiosemicarbazone (1) and zinc(II) complex [Zn(L)CH3OH] ( 2) were characterized by elemental analysis, FT-IR, UV-visible, H-1, and C-13 NMR spectra. The molecular structure of the complex (2) was determined by single crystal X-ray diffraction technique. The structure consists of a distorted square-pyramidal geometry around the central metal, Zn(II). Quantum chemical calculations were carried out using density functional theory DFT/B3LYP, 6-31G (d), and LanL2DZ basis sets for theoretical characterization of the compounds. The experimental and theoretical data were compared comprehensively. The potential energy distribution (PED) analysis was performed for the assignment of vibration frequencies. In order to support in vitro studies, molecular docking studies have been carried out so that the title compound can be an inhibitor of Epidermal Growth Factor Receptor (1 m17), and the relationship between calculated HOMO energies and docking studies has been examined. In addition, the total antioxidant capacity (as TEAC value) and free radical scavenging activity of the compounds were determined by Cupric Reducing Antioxidant Capacity (CUPRAC) and 1,1-diphenyl-2-picryl hydrazyl (DPPH) methods, respectively. (C) 2021 Elsevier Ltd. All rights reserved.Öğe Cobalt(II)/(III) complexes bearing a tetradentate thiosemicarbazone: Synthesis, experimental and theoretical characterization, and electrochemical and antioxidant properties(Wiley, 2020) Kaya, Busra; Akyuz, Duygu; Karakurt, Tuncay; Sahin, Onur; Koca, Atif; Ulkuseven, BahriNew cobalt complexes,Co1andCo2, were synthesized starting from acetylacetone-S-methylthiosemicarbazone. The square planar cobalt(II) and octahedral cobalt(III) complexes were characterized by FT-IR, UV-visible,H-1 NMR, and X-ray diffraction spectroscopies and mass spectrometry. Frontier orbitals of the complexes were theoretically obtained to better understand the complex structures and intermolecular interactions. The electrochemical behaviors ofCo1andCo2were investigated and the results were evaluated by comparing with each other and with similar published compounds to determine their possible usage in various electrochemical technologies, such as energy storage devices, electrocatalysts, and electrosensors. Metal-based oxidation at around 0 V and metal-based reduction at around -1.0 V indicated that these complexes are valuable for the proposed applications. By determining the trolox equivalent antioxidant capacity and the radical scavenging activity of the cobalt complexes, the compatibility between the antioxidant qualification, redox, and theoretical calculation results was discussed.Öğe Computational and biological evaluation of palladium(II) complexes as VEGFR-2 inhibitors: a molecular docking, dynamics, and cytotoxicity study(Elsevier, 2026) Karakurt, Tuncay; Kaya, Busra; Sahin, Onur; Altiparmak, Elif Avcu; Bal-Demirci, Tulay; Ulkuseven, BahriIn this study, three novel palladium(II) complexes based on S-methylthiosemicarbazone ligands derived from 1,3-butanedione and 2,4-pentanedione-functionalized with methyl (CH3), trifluoromethyl (CF3), and thiophene groups-were synthesized and structurally characterized by spectroscopic methods and single-crystal X-ray diffraction. To evaluate their potential as VEGFR-2 inhibitors, a comprehensive computational investigation was performed. Molecular docking and molecular dynamics (MD) simulations were employed to assess the binding affinities and dynamic stability of the co-ligand (colig) and three complexes (comp1, comp2, and comp3) with the VEGFR-2 receptor (PDB ID: 3CJG). Binding analyses consistently identified colig as the most potent binder, exhibiting the most favorable binding free energy (triangle G(bind) of -106.282 kJ/mol). MD simulations revealed two distinct stability profiles: colig and comp1 formed highly stable and rigid complexes, confirmed by low RMSD and RMSF values. In contrast, comp2 and comp3 were found to be significantly more flexible. Per-residue energy decomposition revealed that this stability is achieved through two different mechanisms: superior van der Waals interactions for colig, and a powerful electrostatic anchor with ASP1044 for comp1. Additionally, MTT assays on HUVEC cells revealed low cytotoxicity (IC50 > 50 mu M) for all synthesized complexes. Considering its high dynamic stability, unique electrostatic binding mechanism, and favorable safety profile, comp1 emerges as the most promising synthesized candidate for further development. These combined findings provide valuable insights for designing next-generation palladium(II)-based VEGFR-2 inhibitors.Öğe Cytotoxic and oxidative stress-related effects of N2O2-type Ni(II)-thiosemicarbazone complexes: Experimental and computational studies(Elsevier Ireland Ltd, 2026) Guner, Adem; Poladian, Qumars; Karakurt, Tuncay; Ilhan-Ceylan, Berat; Sahin, Onur; Kurt, YaseminNew thiosemicarbazone-based Ni(II) complexes, [Ni(L1-3)] (1-3), were synthesized, structurally characterized, and evaluated for their cytotoxic potential in a panel of human cervical (HeLa), lung (A549), breast (MDA-MB231), and pancreatic (PANC-1) cancer cells, along with a non-cancerous human embryonic kidney (HEK-293) cell line. The complexes exhibited selective cytotoxic effects, with HeLa cells showing the highest sensitivity. Among them, complex 2 demonstrated the most pronounced antiproliferative activity and selectivity compared to complexes 1 and 3. Cellular studies in HeLa cells revealed increased oxidative stress markers, mitochondrial dysfunction, and apoptosis-related alterations accompanying the observed cytotoxicity. Chemical antioxidant assays indicated higher radical-scavenging activity for the free ligand, whereas complex 2 displayed the highest TEAC value among the metal complexes. To support the experimental findings, computational studies including quantum chemical calculations, molecular docking, molecular dynamics simulations, and MM/GBSA analyses were performed, revealing favourable electronic properties and stable interactions of the complexes with the PI3K alpha/mTOR kinase. Overall, the combined experimental and computational results highlight complex 2 as a promising Ni(II)-thiosemicarbazone scaffold with selective cytotoxic activity associated with altered oxidative stress parameters.Öğe Four and six-coordinated cobalt complexes based on thiosemicarbazone. Formation, experimental and theoretical characterization(Elsevier, 2022) Kaya, Busra; Karakurt, Tuncay; Sahin, Onur; Ulkuseven, BahriThe template reaction was performed between benzoylacetone-S-propylthiosemicarbazone and salicylaldehyde in the presence of Co(ClO4)(2) and a square planar cobalt(II) complex, [Co(L)] (Co1) where L is a dibasic thiosemicarbazidato ligand was isolated. It was aimed to synthesize the octahedral cobalt complexes by using the co-ligands, pyridine and 2-amino pyridine. An octahedral cobalt(III) complex, [Co(L)(py)(2)]ClO4 (Co2), with two axial-pyridine ligands was obtained. Reaction with 2-amino pyridine gave an unexpected cobalt(III) centered structure, [Co(L-1)]center dot H2O (Co3), where L-1 is a new sixdentate (N4O2) ligand that yielded by the addition of the amino group of pyridine to the L ligand. L-1 has tribasic thiosemicarbazidato structure that altered by the participation of an oxygen atom in addition to the amines. Experimental characterizations of three complexes have been completed using IR, NMR, UV-Vis, ESI-MS techniques and X-ray data. In order to better understand the intermolecular interactions of the structures, the Nonlinear Optical (NLO) properties and frontier orbitals (FMO) of the complexes were obtained using the Gaussian 09 program, DFT/B3LYP with 6-31 G (d, p) bas set for the C, N, O, H atoms and with LanL2DZ basic set for Co metal atom. (C) 2021 Elsevier B.V. All rights reserved.Öğe Manganese(III) complexes with a tetradentate thiosemicarbazone. Structural characterization, electrochemistry, antioxidant capability, molecular docking and dynamics simulation on the potential inhibitory activity of cyclin-dependent kinase 2(Pergamon-Elsevier Science Ltd, 2024) Ortaboy, Sinem; Karakurt, Tuncay; Kaya, Busra; Sahin, Onur; Ulkuseven, BahriTwo manganese(III) complexes with the general formula [Mn III (L)X] (where L is a tetradentate thiosemicarbazone; X = Cl (Mn1) or N 3 (Mn2 is new) were synthesized and verified the expected structures by experimental and theoretical methods. Electrochemical behavior of the manganese complexes were studied using cyclic voltammetry (CV) and square wave voltammetry (SWV). TEAC and DPPH values were determined and compared with those of ascorbic acid (AA). Further, the correlation between the antioxidant data and redox potentials was discussed. Molecular dynamics (MD) simulations were performed after calculating the binding affinities to cyclin-dependent kinase 2 for Mn1, Mn2, and AA to clarify some information about their thermodynamic and dynamic properties and to validate the molecular docking results. The calculations gave the binding affinities that are -6.0, -8.6 and -9.4 kcal/mol for AA, Mn1 and Mn2, respectively. The experimental and theoretical results revealed that complex Mn2 having azide ion has a better antioxidant performance and also the highest docking score with the protein. The study demonstrated that such manganese complexes are suitable candidates to drug development against diseases caused by oxidative stress.Öğe Sentezlenen Yeni Ni (II) Komplekslerinin Spektroskopik ve antifungal özelliklerinin İncelenmesi(2020) Karakurt, Tuncay; Meral, Seher; Ağar, Ayşen Alaman; Onaran, AbdurrahmanBu çalışmada, 6,6'-((1E,1'E)-(propan-1,3 diilbis(azanildien))bis(fenillmetanildien))bis(3-(oktiloks)fenol) (HL1)ve 6,6’-((1E,1’E)-(etan-1,2-diilbis(azanildien))bis(fenillmetanildien))bis(3-(oktiloks)fenol) (HL2) ligandları ile Ni metal atomunun iki farklı kompleksi (HL1Ni ve HL2Ni ) sentezlendi ve NMR, FT–IR ve UV–Vis spektroskopik yöntemleri ile karakterize edildi. İki kompleks yapının in vitro koşullar altında Rhizoctonia solanive Fusarim oxysporum f.sp radicis–lycopersici (FORL) bitki patojenlerine karşı antifungal aktivite çalışmaları yapıldı. Etkinliği belirlenen bileşiklerin doz miktarına göre test edilen patojenlere karşı orta ve yüksek düzeyde aktivite sergilediği belirlendi. Ayrıca Kompleks yapıların moleküller arası etkileşimlerin daha iyi anlaşılabilmesi amacıyla da bileşiklerin HOMO–LUMO orbitalleri teoriksel olarak elde edildi. Son olarak da moleküler doking çalışması ile reseptör–kompleks etkileşimleri simüle edildi. Bu hesaplama sonucunda komplekslere ait afinitedeğerleri (Doking skoru) sırasıyla -6.9 ve -6.4 kcal/mol olarak hesaplandı. Kompleks yapıların doking skorları ile HOMO orbital enerjilerinin birbirleriyle ilişki olduğu gözlendiÖğe Synthesis of the nickel(II) complexes bearing tetradentate thiosemicarbazone through Michael addition of n-alcohols. Experimental, theoretical characterization and antioxidant properties(Springer/Plenum Publishers, 2022) Karakurt, Tuncay; Kaya, Busra; Sahin, Onur; Ulkuseven, BahriNew thiosemicarbazone derivative, 3-benzylidene-2,4-pentanedione-S-methyl-thiosemicarbazone hydrogen iodide (TSC), was synthesized and characterized by elemental analysis, IR, H-1 NMR and single crystal X-ray diffraction. The novel nickel(II) complexes, Ni1-4, were synthesized from the TSC and salicylaldehyde by template effect of nickel(II) ion. The reactions were accomplished by a proton provided from the addition of alcohols which are methyl, ethyl, propyl and allyl for complexes Ni1, 2, 3 and 4, respectively. Spectroscopic data indicated that the formation of the complexes occurred through Michael addition of the alcohols to the 2,4-pentanedione moiety of the TSC. Distorted square planar structures of complexes Ni1 and Ni2 were confirmed by single crystal X-ray diffraction. In addition, the detailed computations were performed by using the theory DFT for experimentally obtained structures of the TSC, Ni1 and Ni2. The antioxidant property of the TSC and nickel(II) complexes along with the standard ascorbic acid was studied by using DPPH radical scavenging and Cupric Reducing Antioxidant Capacity (CUPRAC) assays.Öğe Synthesis, Spectroscopic Characterization, Crystal Structure and Theoretical Studies on New Organic Single Crystal of 1-(3,5-Difluorophenyl)-3-(2-Nitrophenyl)Urea(2021) Güngör, Tuğba; Karakurt, Tuncay; Sahın, Zarıfe SıbelA new organic compound, 1-(3,5-difluorophenyl)-3-(2-nitrophenyl)urea was synthesized from 2-nitroaniline, 3,5-difluoroaniline and triphosgene in sequential two steps with 92% yield. The product was crystallized by the slow evaporation using THF and ethyl acetate solvent system to obtain its single crystal. The pure crystals were characterized with melting point, FT-IR, 1H NMR, 13C NMR and MS. The structure of the compound was brought to light by X-ray single-crystal structure determination. Density functional theory calculations were applied by using (DFT/B3LYP) method with the 6-311G(d,p) basis set level. The potential energy surface (PES) scanning was performed to determine the stability of the molecule. Frontier molecular orbitals of the compound were calculated. AIM charge and MEP analyzes were performed.
