Browsing by Author "Çavuş M.S."

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A novel series of thiosemicarbazone hybrid scaffolds: Design, synthesis, DFT studies, metabolic enzyme inhibition properties, and molecular docking calculations
(2023-05-15) Yakan H.; Muğlu H.; Türkeş C.; Demir Y.; Erdoğan M.; Çavuş M.S.; Beydemir Ş.
The fourteen new thiosemicarbazone derivatives of Schiff base were synthesized from the condensation reactions of two different aldehydes (3‑hydroxy-4-methoxhybenzaldehyde and 3-ethoxhy-4-hydroxybenzaldehyde) with various substituted-thiosemicarbazides. Structures of the compounds (1-14) were characterized by using FT-IR, 1H NMR, and 13C NMR spectroscopic techniques, and elemental analysis. Furthermore, the enzyme inhibitory effect of the obtained hybrid scaffolds was studied. They exhibited highly potent inhibition effect on acetylcholinesterase (AChE) and carbonic anhydrases (hCAs) (KI values are in the range of 111.00 ± 12.12 to 381.60 ± 38.10 nM, 120.60 ± 20.45 to 338.90 ± 42.18 nM, and 100.60 ± 11.31 to 285.30 ± 45.27 nM for AChE, hCA I, and hCA II, respectively). DFT analyzes were performed to demonstrate the usability of some electronic parameters and nucleophilic-electrophilic attack abilities of the compounds in predicting enzyme inhibition properties. A correlation was seen between the HOMO energy eigenvalues of the compounds and the inhibition reactivity, and revealing that QTAIM calculations could also be used to predict the probability of electrophilic and nucleophilic attacks. Findings supporting that hCA I and AChE enzyme inhibition reactions primarily proceed through electrophilic attack, while hCA II reactions tend to occur via nucleophilic attack have been obtained. Also, molecular docking studies were conducted to confirm the outcomes of studies on binding affinities and the most powerful derivatives. The obtained results showed that the novel thiosemicarbazone derivatives may lead to the development of novel types of pharmacological agents in the treatment of patients with Alzheimer's disease, idiopathic intracranial hypertension, glaucoma, and related conditions.
An analysis of dielectric relaxation using the fractional master equation of the stochastic Ising model
(2011-01-01) Çavuş M.S.; Cavus, MS
In this paper, we begin introducing some basic definitions and mathematical preliminaries of the fractional calculus theory. By using the fractional calculus technique (that is, calculus of derivatives and integrals of any arbitrary real or complex order) a solution of the fractional master equation derived from the stochastic Ising model of Glauber has been obtained and the result is applied to an analysis of the dielectric relaxation processes. From the solution of the equation, the Cole-Cole dispersion relation, KWW (Kohlrausch-William-Watts) equation and algebraic decay relaxation functions are obtained easily. Then these functions are compared with Bozdemir's earlier analysis of the stochastic Ising model. © 2010 Elsevier B.V. All rights reserved.
An analysis of dielectric relaxation using the fractional master equation of the stochastic Ising model
(2011-01-01) Çavuş M.S.
In this paper, we begin introducing some basic definitions and mathematical preliminaries of the fractional calculus theory. By using the fractional calculus technique (that is, calculus of derivatives and integrals of any arbitrary real or complex order) a solution of the fractional master equation derived from the stochastic Ising model of Glauber has been obtained and the result is applied to an analysis of the dielectric relaxation processes. From the solution of the equation, the Cole-Cole dispersion relation, KWW (Kohlrausch-William-Watts) equation and algebraic decay relaxation functions are obtained easily. Then these functions are compared with Bozdemir's earlier analysis of the stochastic Ising model. © 2010 Elsevier B.V. All rights reserved.
Enzyme inhibition, molecular docking, and density functional theory studies of new thiosemicarbazones incorporating the 4-hydroxy-3,5-dimethoxy benzaldehyde motif
(2022-01-01) Demir Y.; Türkeş C.; Çavuş M.S.; Erdoğan M.; Muğlu H.; Yakan H.; Beydemir Ş.
New Schiff base-bearing thiosemicarbazones (1–13) were obtained from 4-hydroxy-3,5-dimethoxy benzaldehyde and various isocyanates. The structures of the synthesized molecules were elucidated in detail. Density functional theory calculations were also performed to determine the spectroscopic properties of the compounds. Moreover, the enzyme inhibition activities of these compounds were investigated. They showed highly potent inhibition effects on acetylcholinesterase (AChE) and human carbonic anhydrases (hCAs) (KI values are in the range of 51.11 ± 6.01 to 278.10 ± 40.55 nM, 60.32 ± 9.78 to 300.00 ± 77.41 nM, and 64.21 ± 9.99 to 307.70 ± 61.35 nM for AChE, hCA I, and hCA II, respectively). In addition, molecular docking studies were performed, confirmed by binding affinities studies of the most potent derivatives.
Exploring of antioxidant and antibacterial properties of novel 1,3,4-thiadiazole derivatives: Facile synthesis, structural elucidation and DFT approach to antioxidant characteristics
(2022-02-01) Muğlu H.; Akın M.; Çavuş M.S.; Yakan H.; Şaki N.; Güzel E.
In recent years, compounds containing thiophene and 1,3,4-thiadiazole skeletons have become important cyclic compounds, especially in medicinal chemistry. In this manner, we synthesized and isolated seven 1,3,4-thiadiazole derivatives with thiophene groups and fully characterized by elemental analysis and general spectroscopic methods such as 1H NMR, 13C NMR, and FT-IR. Antibacterial activities of the title compounds were investigated by using TLC-Dot blot, macro dilution, well diffusion, and growth curve analysis methods. Compounds 1 and 6 showed inhibitory activities against all tested gram-negative and gram-positive bacteria. TLC-DPPH and DPPH assays, on the other hand, were performed to detect the antioxidant activities of the 1,3,4-thiadiazole derivatives and compound 1 exhibited the highest antioxidant activity at all tested concentrations. QTAIM and NCI calculations were performed as well as structural, electronic, and spectral analyzes using density functional theory (DFT). Calculations were carried out at the B3lyp/6–311 + +g(2d,2p) level of theory, and the data were used to examine the antioxidant activity of the compounds.
New 1,3,4-thiadiazole compounds including pyrazine moiety: Synthesis, structural properties and antimicrobial features
(2017-07-05) Gür M.; Şener N.; Muğlu H.; Çavuş M.S.; Özkan O.E.; Kandemirli F.; Şener İ.
In the study, some new 1,3,4-thiadiazole compounds were synthesized and we have reported identification of the structures by using UV-Vis, FT-IR, 1H NMR, 13C NMR and Mass spectroscopic methods. Antimicrobial activities of the compounds against three microorganisms, namely, Candida albicans ATCC 26555, Staphylococcus aureus ATCC 9144, and Escherichia coli ATCC 25922 were investigated by using disk diffusion method. These thiadiazoles exhibited an antimicrobial activity against Staphylococcus aureus and Candida albicans. The experimental data was supported by the quantum chemical calculations. Density functional theory (DFT) calculations were carried out to obtain the ground state optimized geometries of the molecules using the B3LYP, M06 and PBE1PBE methods with 3–21 g, 4–31 g, 6–311++g(2d,2p), cc-pvtz and cc-pvqz basis sets in the different combinations. Frontier molecular orbitals (FMOs) energies, band gap energies and some chemical reactivity parameters were calculated by using the aforementioned methods and basis sets, and the results were also compared with the experimental UV-Vis data.
New N,N'-bis(thioamido)thiocarbohydrazones and carbohydrazones: synthesis, structure characterization, antioxidant activity, corrosion inhibitors and DFT studies
(2022-04-01) Çavuş M.S.; Yakan H.; Özorak C.; Muğlu H.; Bakır T.K.
New symmetric N,N'-bis(thioamido)thio/carbohydrazones (1–4) were prepared from thio/carbohydrazide and various isothiocyanates with high yields and characterized the structures of the compounds. The compounds were evaluated as new corrosion inhibitors for corrosion of mild steel in 0.1 M HCl solutions using polarization and electrochemical impedance spectroscopy (EIS) techniques, and all compounds showed effective inhibitory properties. Antioxidant activity values determined using the DPPH method for all compounds showed higher antioxidant activity than the standard Trolox (5.89 µM). The IC50 values of the compounds were obtained between 3.45 and 4.25 µM, and also showed a ranking of 4 > 2 > 3 > 1 > Trolox , with antioxidant activities better than Trolox. Compound 4 (1,5-bis((3-fluorophenyl)carbamothioyl)carbonohydrazide) exhibited the highest activity in terms of both antioxidant and anti-corrosion properties. DFT calculations were also performed to determine the spectroscopic properties of the compounds and to analyze the structure–activity relationship for their antioxidant characteristics. It was investigated how DPPH reactions are affected by the dependence of delocalization indices and charge densities of N–H bonds on intramolecular interactions. As well as the calculations of intramolecular interactions and some QTAIM parameters, Laplacian bond order and bond polarity index (BPI) analysis were also performed to examine the electronic properties of reactive N–H bonds. Graphical abstract: New symmetric N,N'-bis(thioamido)thio/carbohydrazones were obtained. Structures of all compounds were elucidated using spectroscopic approaches. Antioxidant activities of the compounds were determined by DPPH method. QTAIM analyses were used to examine the relationship between the electronic properties and antioxidant activity. The compounds were evaluated as new corrosion inhibitors for corrosion of mild steel in 0.1 M HCl.[Figure not available: see fulltext.].
New Schiff bases based on isatin and (thio)/carbohydrazone: preparation, experimental–theoretical spectroscopic characterization, and DFT approach to antioxidant characteristics
(2023-04-01) Muğlu H.; Sönmez F.; Çavuş M.S.; Kurt B.Z.; Yakan H.
In this study, synthesis, spectroscopic elucidation, and investigation of antioxidant properties of new Schiff bases based on isatin and (thio)/carbohydrazone derivatives have been reported for the first time. The structures of the synthesized compounds were elucidated by FT-IR, 1H-NMR, and 13C-NMR spectroscopic methods and elemental analysis. Their DPPH, ABTS, and CUPRAC activities were evaluated as antioxidant properties. Electronic and spectral data of the compounds were obtained by DFT calculations at the B3LYP/6–311+ +G(2d,2p) level of theory. Intramolecular interactions and charge densities on the bonds were analyzed by QTAIM and IRI calculations. In addition to parameters such as frontier molecular orbital energy eigenvalues, electronegativity, nucleophilicity index, and electrodonating power, the changes in the enthalpy of the compounds for the reactions realized through the SET mechanism were calculated to elucidate the antioxidant reactions of the compounds. Most of synthesized compounds exhibited antioxidant activities with the IC50 values ranging from 27.13 to 43.35 µM for DPPH, from 6.47 to 24.96 µM for ABTS and with the A0.50 values ranging from 9.04 to 47.52 µM for CUPRAC. Among them, compound 3, containing two hydroxyl groups, showed the strongest antioxidant activity for each assay (IC50 = 27.13 µM for DPPH, 6.47 µM for ABTS, and A0.50 = 9.04 µM for CUPRAC). The antioxidant activities of compound 3 were almost two or threefold weaker than that of BHA (IC50 = 9.55 µM for DPPH, 3.42 µM for ABTS, and A0.50 = 2.24 µM for CUPRAC), used as a standard. In addition, thiocarbohydrazone compounds exhibited higher antioxidant activity than carbohydrazones. Electron donating ability and single electron transfer enthalpy calculations predicted that thiocarbohydrazone compounds can perform SET reactions more easily than carbohydrazones.
New β-isatin aldehyde-N,N′-thiocarbohydrazones: preparation, spectroscopic studies and DFT approach to antioxidant characteristics
(2020-12-01) Yakan H.; Bakır T.K.; Çavuş M.S.; Muğlu H.
Abstract: Five new Schiff bases of isatin and its derivatives were prepared from monothiocarbohydrazides and 5-chloro isatin. The chemical structures of the synthesized compounds were performed by 1H NMR, 13C NMR, and FT-IR spectroscopic techniques and elemental analysis. The in vitro antioxidant activities of all the products were determined by 1,1-Diphenyl-2-Picryl Hydrazyl free radical scavenging method. It also examined the antioxidant properties of the compounds based on quantum chemical calculations as well as supporting experimental spectroscopic data. Theoretical calculations carried out at B3LYP correlation functional with 6-311++g(2d,2p) basis set. Some chemical reactivity descriptors obtained from AIM, NCI, and ELF analysis were used to reveal the relationship between the electronic and antioxidant properties of the compounds. Furthermore, the bond lengths, charge densities, potential energy densities, inter-atomic dipole moments, and delocalization indices of the active phenolic hydrogen bonds of the compounds were shown to be parameters that can be used to determine the antioxidant properties of compounds. Graphic Abstract: New β-isatin aldehyde-N,N′-thiocarbohydrazones were synthesized. Structures of synthesized molecules were clarified using spectroscopic methods. Antioxidant activities of the compounds were tested by the DPPH method. AIM, NCI, and ELF analysis were performed to investigate the relationship between the electronic properties and antioxidant activity.[Figure not available: see fulltext.]
Novel carbohydrazones including 5-substituted isatin: Synthesis, characterization, and quantum-chemical studies on the relationship between electronic and antioxidant properties
(2020-05-01) Çavuş M.S.; Yakan H.; Muğlu H.; Bakır T.
1-(5-Chloro-2-oxoindolin-3-ylidene)carbohydrazone (1), 1-(5-fluoro-2-oxoindolin-3-ylidene)carbohydrazone (2), 1-(5-methoxy-2-oxoindolin-3-ylidene)thiocarbohydrazone (3), and 1-(5-methoxy-2-oxoindolin-3-ylidene)carbohydrazone (4) were synthesized from 5-substituted isatins and thiocarbohydrazide/carbohydrazide under reflux in absolute ethanol. Fourier transform-IR, 1H NMR, and 13C NMR spectroscopy and elemental analysis were used to characterize the structures of the compounds. Experimental spectroscopic data were supported by theoretical data obtained with the Becke three-parameter Lee–Yang–Parr (B3LYP) correlation functional with cc-pvtz and 6–311++g(2d,2p) basis sets. The antioxidant properties of the compounds were examined on the basis of the quantum-chemical calculations. Analysis by quantum theory of atoms in molecules (QTAIM), density of states analysis (DOS), frontier molecular orbital eigenvalues (FMO), and other chemical reactivity descriptors were used to elucidate the relationship between electronic and antioxidant characteristics of the compounds. The in vitro antioxidant activity of all the compounds were evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical scavenging method. Antioxidant activity was in the following order: 3 > 4 > butylated hydroxytoluene (BHT) > 2 > 1. Theoretical investigations of the structural and antioxidant properties were performed.
Preparation, antioxidant activity, and theoretical studies on the relationship between antioxidant and electronic properties of bis(thio/carbohydrazone) derivatives
(2022-05-01) Muğlu H.; Kurt B.Z.; Sönmez F.; Güzel E.; Çavuş M.S.; Yakan H.
A series of novel bis(thio/carbohydrazone) compounds has been prepared from (thio)/carbohydrazide and various aldehyde derivatives. FTIR, 1H and 13C NMR spectroscopy, and elemental analysis have been used to elucidate the structures of synthesized compounds. Their antioxidant properties have been assessed using the DPPH, ABTS, and CUPRAC methods. Most of the synthesized compounds exhibited antioxidant activity in each assay. The effects of the electronic and structural properties of urea/thiourea groups on the antioxidant properties of the compounds have been investigated, and it was observed that thiourea-based compounds showed better antioxidant activity than structurally similar urea-based compounds. Among them, N′,N‴-1,4-phenylene-bis(methaneylylidene)-bis(N′-2-hydroxybenzylidene)methane-bis(thiohydrazide) (9) and N′,N‴-(1,4-phenylene-bis(methaneylylidene)-bis(N′-2,4-dihydroxybenzylidene)methane-bis(thiohydrazide) (11) showed higher ABTS activity (IC50 = 2.69 μM and 3.24 μM, respectively) than the reference butylated hydroxyanisole (BHA, IC50 = 3.42 μM). Moreover, compound 11 showed the strongest DPPH activity with an IC50 value of 5.77 μM, almost twofold higher than that of BHA (IC50 = 9.55 μM). Structural, spectral, and electronic analyses of the compounds have also been performed by DFT calculations at the B3LYP/6–311++g(2d,2p) level of theory. EDR, NCI, DOS, and QTAIM calculations have been carried out to analyze the bond properties of electronegative atoms and to investigate intramolecular interactions. DFT simulations have also been carried out in order to study the relationship between electronic characteristics and antioxidant activity.
Synthesis of new bis(thiosemicarbazone) derivatives and DFT analysis of antioxidant characteristics in relation to HAT and SET reactions
(2022-12-01) Muğlu H.; Çavuş M.S.; Bakır T.K.; Yakan H.
A series of new bis(thiosemicarbazones) have been synthesized from terephthalaldehyde and various thiosemicarbazides. IR, 1H NMR, 13C NMR spectroscopic methods, and elemental analysis were used to characterize the identification of the synthesized compounds. The in vitro antioxidant activity determinations were made using the 1,1-Diphenyl-2-Picryl Hydrazil (DPPH) method. The compounds exhibited very different inhibition activities with the change of groups attached to the bis(thiosemicarbazone) structure. The spectral and electronic properties of the compounds were investigated by DFT calculation. Intramolecular interactions were analyzed by QTAIM and IRI calculations. Intrinsic bond strength index values of the N–H bonds, Fukui indices and the local electron affinities of the compounds were calculated, and the relationships between the compounds and their antioxidant activity properties were investigated. The SET and HAT mechanisms in the reactions of the compounds with DPPH were affected by the concentration of the compounds, and the possible effects of the parameters supporting the dominant characteristics in these reactions were examined using theoretical data.
Synthesis, Characterization, and Theoretical Calculation of New Azo Dyes Derived from [1,5-a]Pyrimidine-5-one Having Solvatochromic Properties
(2019-03-01) Şener N.; Gür M.; Çavuş M.S.; Zurnaci M.; Şener İ.
7-Amino-3-phenylazo-2-methyl-4H-pyrazolo[1,5-a]pyrimidine-5-one (3) was synthesized by the reaction of 5-amino-3-methyl-4-phenylazo-1H-pyrazole and 2-aminobenzothiazole with ethyl cyanoacetate in acetic acid at 150°C. Four novel heterocyclic azo disperse dyes were obtained by the coupling of heterocyclic amines-based diazonium chloride with compound 3. They were purified and characterized by elemental analysis, FTIR, and 1 H NMR. Furthermore, solvatochromic behaviors of related dyes were studied in detail by using ultraviolet–visible absorption spectrometer. The experimental data were supported by density functional theory using b3lyp/cc-pvtz level calculations, and a detailed analysis of predicted tautomeric structures was made.
Synthesis, characterization, quantum chemical calculations and evaluation of antioxidant properties of 1,3,4-thiadiazole derivatives including 2- and 3-methoxy cinnamic acids
(2017-04-15) Gür M.; Muğlu H.; Çavuş M.S.; Güder A.; Sayıner H.S.; Kandemirli F.
A series of 1,3,4-thiadiazole derivatives including 2- and 3-methoxy cinnamic acids were synthesized, and their structures were elucidated by the UV, IR, 1H NMR, 13C NMR spectroscopies and elemental analysis. The UV and IR calculations of the molecules were performed by using B3LYP, HF and MP2 methods with selected 6-311++G(2d,2p), 6-311++G(3df,3pd) and cc-pvtz basis sets. Dipole moment, polarizability, chemical hardness/softness and electronegativity were also calculated and analyzed. Experimental FT-IR spectra and UV–Vis spectrum of the compounds were compared with theoretical data. Furthermore, antioxidant activities of the compounds were practised via different test methods such as 2,2-diphenyl-1-picryl-hydrazyl (DPPH[rad]), N,N-dimethyl-p-phenylenediamine (DMPD[rad]+), and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS[rad]+) scavenging activity assays. When compared with standards (BHA-Butylated hydroxyanisole, RUT-Rutin, and TRO-Trolox), it was observed that especially XIII and XIV which include methoxy groups at the o- and m-positions, respectively, had effective activities.
Synthesis, structure characterization and quantum chemical study on relationship between structure and antioxidant properties of novel Schiff bases bearing (thio)/carbohydrazones
(2021-12-01) Muğlu H.; Yakan H.; Misbah A.G.A.; Çavuş M.S.; Bakır T.K.
A series of novel isatin-based Schiff base derivatives, namely β-isatin aldehyde-N,N′-(thio)/carbohydrazone derivatives (1–8), have been synthesized. All of the compounds were purified, and IR, 1H NMR and 13C NMR spectroscopic methods and elemental analysis were used to characterize the compounds. Moreover, the in vitro antioxidant activity of the compounds was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging method and compared with standard natural antioxidant, gallic acid. Experimental data were supported by density functional theory (DFT) calculations. B3LYP hybrid functional with 6–311 + + g(2d,2p) basis set was used to calculate ground-state geometries, FMO energies and related chemical reactivity parameters of the compounds. In addition to the structural and spectral analysis calculations of the compounds, NBO, QTAIM, NCI, Fukui and DOS analyses were also performed at the same level of theory, and the data were used to determine the effects of conformational and electronic properties of substitute groups in the reactive regions of the compounds on the reaction with DPPH and to analyze the antioxidant behavior of the compounds. Graphic abstract: New Schiff bases bearing (thio)/carbohydrazone and isatin were synthesized. Structures of synthesized compounds were elucidated using spectroscopic techniques. Antioxidant activities of the compounds were measured by DPPH method. FMO energies, NBO, QTAIM, NCI, Fukui and DOS analyses were used to examine the relationship between the electronic properties and antioxidant activity. [Figure not available: see fulltext.]
Thio/carbohydrazone derivatives from iso(thio)/cyanates: preparation, structure elucidation, DFT studies, antimicrobial activity and DNA interactions
(2023-01-01) Çavuş M.S.; Yakan H.; Başkan C.; Erdoğan M.; Muğlu H.
New thio/carbohydrazone derivatives (1–10) have been synthesized from various iso(thio)/cyanates. The chemical structures of synthesized compounds were elucidated with UV–Vis, IR, 1H NMR, 13C NMR spectroscopic methods, and elemental analysis. Antimicrobial activities of all synthesized compounds against Gram-positive, Gram-negative mold and yeast were screened by disc diffusion and microdilution methods. Ground state structures were obtained with the DFT approach, and also, experimental data were supported by spectroscopy calculations. In addition to calculating the reactivity parameters, intramolecular interactions and electron density distributions were analyzed and approaches to the antimicrobial properties of the compounds were presented. Furthermore, the interaction between the compounds and pBR322 plasmid DNA was investigated by gel electrophoresis. In this study to investigate the antibacterial and antifungal activity of new thio/carbohydrazone derivatives (1–10), it was determined that compound 7 has a remarkable inhibitory effect on S. aureus (12.66 ± 1.52 mm) and compound 10 on S. aureus (20.33 ± 0.57 mm), S. mutans (16.33 ± 0.57 mm) and A. niger (15.33 ± 0.57 mm). The interaction results of compounds 1–10 with plasmid pBR322 DNA showed that compounds 1, 8, and 10 caused a reduction in the densities of form I and form II DNA. Compounds 2–7, 9 caused a double-stranded break of plasmid DNA (Form III). Graphical abstract: New thio/carbohydrazone derivatives have been synthesized. Structures of all compounds have been elucidated with spectroscopic approaches. Antimicrobial activities of all synthesized compounds were determined. The interaction between the compounds and pBR322 plasmid DNA was investigated by gel electrophoresis. DFT studies were performed about reactivity parameters, intramolecular interactions and electron density distributions. [Figure not available: see fulltext.].