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    Öğe
    Ni(II), Zn(II), and Fe(III) complexes derived from novel unsymmetrical salen-type ligands: preparation, characterization and some properties
    (Taylor & Francis Ltd, 2022) Dilmen Portakal, Eylem; Kaya, Yeliz; Demirayak, Emire; Karacan Yeldir, Elif; Ercag, Ayse; Kaya, İsmet
    By using a half-salen ligand (HL) and substituted salicylaldehydes, new unsymmetrical salen-type ligands (H2L1, H2L2, and H2L3) and their Ni(II), Zn(II) and Fe(III) complexes were synthesized. The compounds were characterized based on elemental analysis, IR, H-1 NMR, X-ray diffraction (for HL), spectroscopy, mass spectrometry, magnetic moment, molar conductance measurements, and thermal analysis (TGA). The unsymmetrical salen ligands, during complexation, are attached to the metal by two imine nitrogen atoms and two phenolic oxygen atoms in all complexes; in the Fe(III) complexes, the fifth coordination is completed by chloride. Square planar geometry or distorted square planar geometry for [NiL1-3], [ZnL1-3], and square pyramidal geometry for [FeL1-3Cl] are proposed. Conductance measurements suggest non-electrolytic nature of the metal complexes. Thermogravimetric analysis showed that the complexes exhibit higher stability than the ligands. The electrochemical properties of the compounds were studied by cyclic voltammetry. HOMO-LUMO energy levels and electrochemical band gaps (E '(g)) were calculated. The solid state electrical conductivity of the iodine-doped compounds was measured and their semiconductor properties were determined. In addition, fluorescence properties of ligands and Zn(II) complexes were investigated.
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    Öğe
    Synthesis and characterization of oligo-2-[(2-hydroxymethylphenylimino) methyl] phenol and oligo-2-[(2-hydroxymethylphenylimino) methyl]-5-bromo-phenol
    (Tubitak Scientific & Technological Research Council Turkey, 2007) Kaya, İsmet; Ercag, Ayse; Culhaoglu, Suleyman
    Oligo-2-[(2-hydroxymethylphenylimino) methyl] phenol O-(2-HMPIMP) and oligo-2-[(2-hydroxymethylphenyl imino) methyl]-5-bromo-phenol O-(2-HMPIMBP) were synthesized by the oxidative polycondensation reaction using air as an oxidant in an aqueous alkaline medium at 70 degrees C. They were characterized by H-1-NMR, FT-IR, UV-vis, TC, size exclusion chromatography (SEC) and elemental analysis. According to the SEC analyses, the number-average molecular weight (M-n), weight-average molecular weight (M-w) and polydispersity index (PDI) values of O-2-HMPIMBP and O-2-HMPIMP are 1100, 1600 g mol(-1) and 1.45; and 6000, 6250 g mol(-1) and 1.04, respectively. According to TG analyses, the weight losses of O-2-HMPIMP and O-2-HMPIMBP are 98.31% and 96.91%, respectively, at 900 degrees C.
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    Öğe
    Synthesis, Characterization and Conductivity Properties of Novel Oligomer Schiff Bases Derived from 4-Amino-3-hydrazino-5-mercapto-1, 2, 4-triazole and Their Reactions with VO(IV), Cu(II) Ions
    (Springer, 2014) Kaya, İsmet; Ercag, Ayse; Avci, Ali; Culhaoglu, Suleyman
    A new Schiff base, 4-(4-hydroxysalicylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole (4HSAHMT), and novel Schiff base oligomers of 4-salicylidenamino-3-hydrazino-5-mercapto-1,2,4-triazole (SAHMT), 4-(2-hydroxynaphthylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole (2HNAHMT), 4-(4-hydroxysalicylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole (4HSAHMT) and 4-(5-bromosalicylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole (BrSAHMT) were synthesized via oxidative polymerization using NaOCl as the oxidant. The structures of the oligomers were supported by FT-IR, UV-Vis, H-1-NMR, and C-13-NMR techniques. The compounds were further characterized by solubility tests, TG-DTA, and elemental analysis. The molecular weight distribution parameters of the compounds were determined by the size exclusion chromatography (SEC). According to SEC, the number average molecular weight (M (n) ) values of O-SAHMT, O-BrSAHMT, O-4HSAHMT and O-2HNAHMT were 2,700, 2,100, 2,700 and 1,000 g mol(-1), respectively. The weight losses of O-SAHMT, O-BrSAHMT, O-4HSAHMT and O-2HNAHMT were 73, 76, 80 and 54 %, respectively, at 1,000 A degrees C. TG analyses showed that the synthesized oligomers were stable toward thermal decomposition. The synthesized oligomers were converted to metal complexes with salts of VO(IV) and Cu(II). The doped and undoped electrical properties of oligomers and oligomer-metal complexes were determined by the four-point probe technique at room temperature and atmospheric pressure.
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    Öğe
    The monomers and polymers of azomethine-based thiocarbohydrazones: Fluorescent activities, fluorescence quantum yields of polymers in water and DMF solutions
    (Elsevier, 2022) Kaya, İsmet; Temizkan, Kevser; Kaya, Yeliz; Ercag, Ayse
    In this study, a family of azomethine-based thiocarbohydrazone monomers and polymers prepared and their structurally characterized by FT-IR, 1H-13C NMR and UV-Vis techniques. The electrochemical behaviors, fluorescent activities, thermal characteristics, antioxidant effectiveness of synthesized compounds were determined by cyclic voltammetry (CV), fluorescence (FL) spectroscopy, thermogravimetric-differential thermal analysis (TG-DTA), differential scanning calorimeter (DSC) and CUPRAC techniques, respectively. Fluorescence quantum yields of Poly-SATCH, Poly-BSATCH, Poly-MSATCH, Poly-NATCH were calculated to be 4.1, 9.4, 11.4 and 7.4 % in 0.025 mg mL-1 concentrations in DMF solutions in the range of 3 nm slit at 440, 420, 400 and 340 nm, respectively. The antioxidant values of monomer and polymers were changed between 0.30 +/- 0.029 and 3.54 +/- 0.719 against CUPRAC technique. The glass transition temperatures of Poly-SATCH, Poly-BSATCH, PolyMSATCH and Poly-NATCH were found to be 116, 134, 138 and 139, respectively.