Halil Berber

Synthesis, characterization, tautomerism and theoretical study of some new Schiff base derivatives

New Schiff base derivatives were prepared by the condensation of 5-chloro and 5-bromo salicylaldehyde with bis(o-aminophenol)ethers. Five bis(o-nitrophenol)ether compounds were synthesized using some ditosylate, 1,3-dibromopropane and 1,4-dibromobuthane with o-nitrophenol. These compounds were reduced to bis(o-aminophenol)ethers. The products have been characterized by elemental analysis, FTIR, 1H, 13C NMR, HETCOR and HMBC spectroscopic techniques. The tautomerisms of all of the Schiff bases compounds were determined in DMSO, CHCl3, C2H5OH and C6H12 solvents and in both acidic and basic media using the UV-vis spectrophotometric method. The heat of formation (ΔHf), enthalpy (ΔH), entropy (ΔS), Gibbs free energy (ΔGf and ΔG), stable isomers, conformations and tautomers of the synthesized compounds are calculated using the MOPAC2009 (PM6) program.

A theoretical search on metal–ligand interaction mechanism in corrosion of some imidazolidine derivatives

Abstract The interaction mechanism of some imidazolidine derivatives with metallic Zn in gas phase, using semiempirical methods, was studied at elevated temperature and the obtained data were used to search a possible correlation between the computed and experimental results obtained for Fe in the literature. It was concluded that the interaction between the metallic Zn and the protonated imidazolidine molecules occurs as physical adsorption via electrostatic interaction between Zn surface which covered by negatively charged Cl− ions in acidic media (i.e. 0.1N HCl). However, chemical adsorption may also take place via two possible ways by forming coordinate covalent bond; one possible way is giving one pair of electrons (i.e. lone pair) from pyrrole type nitrogen atom to the Zn and the second possible way is giving one pair of electron (i.e. lone pair) from pyridine type nitrogen atom which already released the proton as hydrogen gas at the cathode becoming a neutral sp2 hybridized nitrogen atom.

Synthesis, crystal structure, optical and electrochemical properties of novel diphenylether-based formazan derivatives

In this study, formazans 5a–5h were synthesized by coupling the reactions of substituted phenylhydrazone compounds 3a–3h with diazonium salt of 4-chloro-2-phenoxybenzenamine (4). The substituted phenylhydrazones 3a–3h were obtained from the condensation of substituted phenylhydrazines 1a–1h with 4-methoxybenzaldehyde (2). The structures of the formazans were characterized by using elemental analysis, FTIR, 1H NMR, 13C NMR, LC-MS and the crystal structure of compound 5e was determined by X-ray crystallography. The absorption spectra of all compounds were investigated in various solvents. Although their absorption bands are only slightly dependent on the polarities of solvents, the significant change was observed by altering the electronic characteristics of the substituents. The fluorescence quantum yield properties and Stokes shifts of compounds 5a–5h in DMSO were also explored. Electrochemical properties of the new products were studied by CV measurements. In addition, computational studies were conducted at the PBE1PBE/6-311g (2d,2p) level to shed light on the structures of possible tautomers and intramolecular H-bonds.

Novel formazan derivatives containing phenylsulfanyl and carbonyl units: synthesis, optical and electrochemical properties

A series of phenylsulfanyl and aryl carbonyl containing formazan derivatives 4a–4h and 5a–5h were synthesized by coupling of substituted phenylhydrazones with diazonium salts of 2-(phenylthio)benzenamine and 5-chloro-2-benzoylbenzenamine in pyridine. The electronic properties of the new formazans were studied by cyclic voltammetry and UV-vis spectroscopy. Fluorescence emission wavelengths were measured in solution, and fluorescence quantum yields and Stokes shifts were calculated. Computational studies were carried out on the tautomer structures formed through intramolecular proton transfer in the formazan backbone, and their HOMO–LUMO energy values were estimated. In addition, the influences emerging from ether, thioether and carbonyl groups on the properties of formazans were elaborated.

Quantum chemical studies on some 1,2,4-triarylsubstituted imidazoles

The geometries, proton affinities and thermodynamic properties of some 1,2,4-triarylsubstituted imidazole derivatives were calculated with full geometry optimization using AM1 and PM3 methods in aqueous phase. A possible correlation between experimentally obtained results and the computed data was searched.

Quantum Chemical and Experimental Studies on the Mechanism of Alkylation of β-Dicarbonyl Compounds. The Synthesis of Five and Six Membered Heterocyclic Spiro Derivatives

The alkylation of beta-dicarbonyl compounds in a K2CO3/DMSO system was found to afford O- and C-alkylated derivatives, depending on the type of the beta-dicarbonyl compound involved. The alkyl derivatives obtained were used in the synthesis of some new spiro barbituric acid derivatives. Quantum chemical calculations were carried out to elucidate the reaction mechanisms for some typical synthesis.

Theoretical study: Non-small cell lung cancer drugs

M wild plants commonly used in folk medicine, such as different species from the genus Lathyrus, may represent new sources of biologically active compounds. Therefore, the study of the composition and (bio)chemical behaviour of extracts from these plants may provide valuable information. Several Lathyrus species have been studied: L. aureus, L. pratensis, L. czeczottianus and L. nissolia. Extracts from these plants were analyzed by high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI-MSn) to determine their phenolic profile. The in vitro antioxidant activity and enzyme inhibitory evaluation were also investigated. The main phenolic compounds (flavonoids and saponins, mainly) and the antioxidant and enzyme inhibition results are here reported. The phenolic contents and the (bio)chemical properties of the analyzed extracts presented significant variations in the different Lathyrus species. However, the high number of phenolic compounds and the antioxidant and enzyme assays suggest that these plants may be further used in phytopharmaceutical or food industry applications.

Theoretical study on a newly approved pharmaceutical formulation active components-Indacaterol and Roflumilast

M wild plants commonly used in folk medicine, such as different species from the genus Lathyrus, may represent new sources of biologically active compounds. Therefore, the study of the composition and (bio)chemical behaviour of extracts from these plants may provide valuable information. Several Lathyrus species have been studied: L. aureus, L. pratensis, L. czeczottianus and L. nissolia. Extracts from these plants were analyzed by high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI-MSn) to determine their phenolic profile. The in vitro antioxidant activity and enzyme inhibitory evaluation were also investigated. The main phenolic compounds (flavonoids and saponins, mainly) and the antioxidant and enzyme inhibition results are here reported. The phenolic contents and the (bio)chemical properties of the analyzed extracts presented significant variations in the different Lathyrus species. However, the high number of phenolic compounds and the antioxidant and enzyme assays suggest that these plants may be further used in phytopharmaceutical or food industry applications.

Theoretical Study on the Stability, Acidity Constants and Molecular Electronic Properties of Certain o-Hydroxy Schiff Bases and their Tautomers

In the present work, certain novel o-hydroxy Schiff bases and possible tautomer forms, which were previously synthesized by our group and their structures elucidated, have been calculated by DFT/6-311g(2d,2p) in both vacuum and polar solvents and the most stable tautomeric forms have been determined. The acidity constants of the Schiff bases have been calculated with the PM6 method by MOPAC2016. HOMO-LUMO values of the studied Schiff bases were calculated with DFT/6-311g(2d,2p) and their possible molecular electronic properties were searched. The results were compared with those experimental values.

Acidity constant determination of novel drug precursor benzothiazolon derivatives including acyl and piperazine moieties

In this study, protonation and deprotonation behaviors of eight new drug precursor benzothiazolon derivatives in all of acidic and basic scale (super acidic, pH, super basic regions) are analyzed by using UV-visible spectrophotometric technique. Acidity constants (pKa), elucidation of the structure and protonation mechanisms of the studied molecules are obtained. Substituent effect on acidity constant values is discussed. These molecules are protonated from oxygen atom of acetamide group in the keto form. The protonation is found to be considerably contributed by the keto form.