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Öğe A theoretical evaluation on free radical scavenging activity of 3-styrylchromone derivatives: the DFT study(Springer, 2020) Cakmak, Emre; Isin, Dilara OzbakirChromone (4H-chromen-4-one, 4H-1-benzopyran-4-one) and related compounds are important pharmacophores and privileged structures in medicinal chemistry because of their important biological activities such as anti-tumor, anti-HIV, and antioxidant. In the study, the density functional theory (DFT) calculations were performed for radical scavenging activity evaluation of a series of 3-styrylchromone derivatives. The reaction enthalpies related to the steps in the radical scavenging action mechanisms and several physicochemical descriptors such as global hardness, softness, and electronegativity were computed in gas phase and in water. The solvation effect of water on the antioxidant activity was taken into account by using the conductor-like polarizable continuum model. The calculated results were discussed by considering all physicochemical properties of molecules: thermodynamic, orbital, and structural. The results obtained were consistent with the experimental results.Öğe Computational Investigation of the Substituent Effect on the Intramolecular Proton Transfer Reaction of 3-Hydroxytropolone(CHINESE JOURNAL STRUCTURAL CHEMISTRY, 2014) Gul, Vedat; Isin, Dilara OzbakirThe effects of substituent type and position on the proton transfer reaction of 3-hydroxytropolone (3-OHTRN) have been investigated theoretically by using density functional theory at the level of B3LYP/ 6-31+G** method. The influence of solvent on the proton transfer reactions of substituted 3-OHTRN has been examined using the self-consistent isodensity polarized continuum model (SCI-PCM) in water. As a result, while the proton transfer reaction is kinetically the easiest by substitution on position 3 of -NH2 group in the gas phase, it is kinetically the easiest by substitution on position 5 of the same group in water. In addition, these reactions are either kinetically or thermodynamically easier in the gas phase than that in water, except the reaction of structure with -NH2 group at position 6.Öğe Computational study of the intramolecular proton transfer reactions of 3-hydroxytropolone (2,7-dihydroxycyclohepta-2,4,6-trien-1-one) and its dimers(SPRINGER, 2010) Isin, Dilara Ozbakir; Karakus, NihatThe proton transfer reaction and dimerization processes of 3-hydroxytropolone (3-OHTRN) have been investigated using density functional theory (DFT) at the B3LYP/6-31+G** level. The influence of the solvent on the proton transfer reaction of 3-OHTRN was examined using the self-consistent isodensity polarized continuum model (SCI-PCM) with different dielectric constants (epsilon = 4.9, CHCI(3); epsilon = 32.63, CH(3)OH; epsilon = 78.39, H(2)O). The intramolecular proton transfer reaction occurs more readily in the gas phase than in solution. Results also show that the stability of 3-OHTRN dimers in the gas phase is directly affected by the hydrogen bond length in the dimer structure.Öğe A computational study on corrosion inhibition performances of novel quinoline derivatives against the corrosion of iron(ELSEVIER SCIENCE BV, 2017) Erdogan, Saban; Safi, Zaki S.; Kaya, Savas; Isin, Dilara Ozbakir; Guo, Lei; Kaya, CemalIn this computational study, the adsorption and corrosion inhibition properties of some novel quinoline derivatives namely, 2-amino-7-hydroxy-4-phenyl-1,4-dihydroquinoline-3-carbonitrile (Q1), 2-amino-7-hydroxy-4-(p-toly1)-1,4-dihydroquinoline-3-carbonitrile (Q2), 2-amino-7-hydroxy-4-(4-methoxypheny1)-1,4-dihydroquinoline-3-carbonitrile) (Q3) and 2-amino-4-(4-(dimethylamino)pheny1)-7-hydroxy-1,4-dihydroquinoline-3-carbonitrile (Q4) on the corrosion of iron were investigated using quantum chemical and molecular dynamics simulation approaches. Quantum chemical calculations section of the study provides enough calculation and discussion on the relationship between corrosion inhibition and global reactivity descriptors such as E-HOMO, E-LUMO, HOMO-LUMO energy gap (Delta E), chemical hardness (eta), softness (sigma), electronegativity (chi), chemical potential (mu), electrophilicity (omega), nucleophilicity (epsilon), electrons transferred from inhibitors to metal surface (Delta N), initial molecule-metal interaction energy (Delta Psi), total electronic energy (E), the energy change during electronic back-donation process (Delta Eb-d). The adsorption behaviors of studied compounds on Fe (110) surface were investigated with the help of molecular dynamics simulation approach. The binding energies calculated on Fe (110) surface of mentioned quinoline derivatives followed the order: Q4 > Q3 > Q2 > Q1. It should be noted that the results obtained in the study are in good agreement with experimental inhibition efficiency results earlier reported. (C) 2017 Elsevier B.V. All rights reserved.Öğe Inhibition performances of new pyrazole derivatives against the corrosion of C38 steel in acidic medium: Computational study(Elsevier B.V., 2024) Kaya, Savaş; Siddique, Farhan; Isin, Dilara Ozbakir; Katin, Konstantin P.; Asati, Vivek; Berisha, AvniCorrosion inhibition performances of two new pyrazole derivatives, namely 5-(4-dimethylamino)phenyl)-3-(4-dimethylamino)styryl)-4,5-dihydro-1H-pyrazole-1-carbothio amide (P1) and 5-(4-dimethylamino)phenyl)-3-phenyl-4,5-dihydro-1H-pyrazole-1-carbothio amide (P2) against the corrosion of carbon steel in acidic medium are theoretically investigated by combination of the density functional theory with the molecular dynamics approach. Additionally, the toxicity and solubility of the aforementioned molecules were investigated. Quantum chemical parameters of considered molecules (calculated energy levels of HOMO and LUMO molecular orbitals as well as the gap between them, hardness, softness, chemical potential, electronegativity, electrophilicity index, nucleophilicity, electro donating power, electro accepting power, polarizability, dipole moment, metal-inhibitor interaction energy, the fraction of electrons transferred from inhibitors to metal surface, back-donation energy, Fukui indices) were calculated at B3LYP/SVP, CAM-B3lyp/TZVP and ?B97XD/Def2-TZVP levels of theory. Comparative calculations were performed in the gaseous phase and in the aqueous solutions. The adsorption behavior of the mentioned molecules on the Fe (110) surface was investigated with the molecular dynamics. Both considered molecules demonstrates high adsorption energies on steel surface, low toxicity and high solubility. P1 is found to be more efficient in hydrochloric acid, whereas P2 molecule is found to be more efficient in sulfuric acid. © 2024Öğe Kaya's composite descriptor and Maximum Composite Hardness Rule for chemical reactions(Elsevier, 2022) Kaya, Savas; Isin, Dilara Ozbakir; Karakus, NihatWithin the framework of Maximum Hardness and Minimum Polarizability Principles and as compatible with Jenkins Volume Based Thermodynamics approach, Kaya and coworkers calculated the lattice energies of inorganic ionic crystals using their eta(M)/V-m(1/3) ratio (here eta(M) and V-m represent the chemical hardness and molar volume of any molecule, respectively). This ratio is called as Kaya's composite descriptor. It is apparent that Kaya's composite descriptor can be considered in the analysis of the chemical stability of compounds and the directions of chemical reactions. In a recent paper, Szentpaly, Kaya and Karakus proposed Maximum Composite Hardness Rule for solid state double exchange reactions. To see the validity in other reaction types also of Kaya's composite descriptor and Maximum Composite Hardness Rule, twenty-eight chemical reactions including especially organic molecules were investigated. Reactivity descriptors such as chemical hardness, molar volume, polarizability regarding reactants and products putting in an appearance were calculated at B3LYP/6-31thornthorng (d, p) calculation level with the help of computational chemistry tools. The result showed that instead of using separately the chemical hardness, polarizability and molar volume concepts, the use of Kaya chemical reactivity approach will be more useful to predict whether the reactions are exothermic or endothermic. It can be concluded from here that new composite descriptors should be derived and used for the accurate prediction of the reactivities of the chemical systems.Öğe Quantum chemical study on the inhibition efficiencies of some sym-triazines as inhibitors for mild steel in acidic medium(ELSEVIER SCIENCE BV, 2015) Isin, Dilara Ozbakir; Karakus, NihatQuantum chemical calculations using density functional theory (DFT) at the B3LYP/6-31++G(d,p) basis set level were performed on five sym-triazines used as corrosion inhibitors for mild steel in acidic medium to determine the relationship between molecular structure and their percentage inhibition efficiencies. The results of the calculations and experimental IE% were subjected to correlation analysis and indicate that their inhibition effect are closely related to EHOMO, ELUMO, energy gap, hardness, softness, electronegativity and the fraction of electrons transferred were calculated. The theoretically obtained results were found to be consistent with the experimental data reported. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.Öğe Spectral analysis and detailed quantum mechanical investigation of some acetanilide analogues and their self-assemblies with graphene and fullerene(Springer, 2020) Almuqrin, Aljawhara H.; Al-Otaibi, Jamelah S.; Mary, Y. Sheena; Thomas, Renjith; Kaya, Savas; Isin, Dilara OzbakirSpectroscopic analysis and different quantum mechanical studies of four pharmaceutically active compounds phenacetin, p-acetanisidide, 4 '-butoxyacetanilide, and 4 '-(3-chloropropoxy)acetanilide are reported in this manuscript. Simulated IR spectrum of these compounds was compared with experimentally available data, and essential functional group assignments were made. We also report the frontier orbital properties and other derived local energy descriptors which talks about the relative stability and reactivity. Photovoltaic efficiency of the compounds was studied from the simulated electronic spectra. The compound was found to interact with graphene and fullerene, to form molecular self-assembly. These self-assemblies showed tremendous enhancement in various physicochemical properties when compared with its constituents. The nature of the interactions between studied chemical species was discussed with the help of chemical reactivity principles. Biological activity of the compounds was predicted using molecular docking studies. It is interesting to see that on adsorption with a graphene/fullerene surface, all adsorbed complex shows enhancement in the Raman activity giving surface enhanced Raman spectra (SERS). This can be used for the detection of these drugs in a pharmacological or biological sample. Interestingly the graphene/fullerene drug molecular assembly shows enhanced biological activity when compared with individual drug molecules.Öğe Theoretical study on the investigation of antioxidant properties of some hydroxyanthraquinones(TAYLOR & FRANCIS LTD, 2016) Isin, Dilara OzbakirAnthraquinones are located in an important class of natural compounds having antioxidant properties. Quantum chemical calculations based on the density functional theory were employed to study the relationship between the structure and the antioxidant activity of four hydroxyanthraquinones. The solvation effects on the antioxidant activity were taken into account by using the conductor-like polarisable continuum model with different dielectric constants (epsilon = 2.25, C6H6; epsilon = 78.39, H2O). The three antioxidant action mechanisms, hydrogen atom transfer (HAT), single electron transfer-proton transfer and sequential proton loss electron transfer (SPLET) were elucidated. The reaction enthalpies related to the steps in these mechanisms were computed in gas phase and solvents. The calculated results are in line with experimental values. The results showed that HAT was the most favourable mechanism for describing the antioxidant activity of hydroxyanthraquinones in the gas phase and in benzene, whereas in aqueous solution, SPLET represented the most thermodynamically plausible reaction pathway. [GRAPHICS] .
