Browsing by Author "Sarac K."

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    Experimental and Theoretical Investigations Regarding the Thione–Thiol Tautomerism in 4-Benzyl-5-(thiophene-2-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione
    (2021-01-01) Sarac K.; Orek C.; Koparir P.
    Abstract: The title compound was synthesized by ring-closure reaction of thiophene-2-carbohydrazide with benzyl isothiocyanate and characterized using spectroscopic methods (NMR and FT-IR). Quantum chemical calculations at the B3LYP/6-311++G(d,p) level were carried out to examine its molecular and spectroscopic properties, thione–thiol tautomerism, and proton transfer reaction. The structural and spectroscopic results were well consistent with the experimental data. The solvent effect on the proton transfer reaction was examined using three solvents (acetone, ethanol, and dimethyl sulfoxide) through the polarizable continuum model (PCM) approximation (direct solvent effect) and solvent-assisted mechanism. A high energy barrier was determined for the interconversion of the thione and thiol forms in both gas and solution phases. Even though the presence of solvent molecules significantly reduced the barrier to proton transfer, it was insufficient for the reaction to occur. The corresponding thermodynamic parameters and the energy difference between the HOMO and LUMO of the thione and thiol tautomers were calculated.
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    Synthesis, structure, cytotoxic and antioxidant properties of 6-ethoxy-4-methylcoumarin
    (2020-04-05) Celikezen F.C.; Orek C.; Parlak A.E.; Sarac K.; Turkez H.; Tozlu Ö.Ö.
    Coumarins have a wide usage area in medicinal applications. It is known that the design and synthesis of new coumarin derivatives are performed to prepare new drugs in many laboratories. The aim of the study was to synthesize 6-ethoxy-4-methylcoumarin and detect its chemical and biological properties for the first time. 6-ethoxy-4-methylcoumarin was synthesized using Pechmann method. Atomic orbital (GIAO) 1H and 13C NMR chemical shift values in the ground state were calculated and Density Functional Method (DFT) was applied with the 6–311++G (d, p) basis set to determine chemical properties. 6-ethoxy-4-methylcoumarin was applied to cultured blood samples at various concentrations (10–400 mg/L) for determining biological activity. 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) release assays were used to evaluate cytotoxic effect. In addition, total antioxidant capacity (TAC) and total oxidative status (TOS) were examined to determine antioxidant properties. The results showed that theoretical vibrational frequencies and chemical shift values were close to experimental values. Moreover, 6-ethoxy-4-methylcoumarin showed a slight cytotoxic effect at dose of 200 mg/L and exhibited an antioxidant activity at 25 mg/L concentration without changing oxidative status at all of doses.