Browsing by Author "Demir S."

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A combined experimental and computational study of electrochemical and photophysical properties of new benzophenone derivatives functionalized with N-substituted-phenyl-1,3,4-thiadiazole-2-amine
(2020-03-05) Şener İ.; Şahin Ç.; Demir S.; Şener N.; Gür M.
New benzophenone derivatives with N-substituted-1,3,4-thiadiazole including different substituents were synthesized and characterized by using FTIR, NMR, UV/Visible, and fluorescence spectroscopies and cyclic voltammetry. The effect of –F, -Cl, –OCH3 and –NO2 substitutions at ortho-, meta-, para-positions on the photoluminescence properties of the molecules have been investigated. The results indicate that the electron-donating and electron-withdrawing moieties at the ortho-, meta-, and para-positions have an important effect on the photoluminescence properties of the molecules. The calculated the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels are in the range of (−5.55) to (−5.65) eV and (−2.83) to (−3.02), respectively. The lower LUMO energy levels were observed for the molecules with –OCH3 substituents due to the donor strength of the substituent. Excited states and electrochemical properties of the molecules were also comprehensively and quantitatively studied by Density Functional Theory and Time-Dependent Density Functional Theory calculations. Experimental trends were successfully revealed by calculated data.
Antiproliferative-antimicrobial properties and structural analysis of newly synthesized Schiff bases derived from some 1,3,4-thiadiazole compounds
(2020-11-05) Gür M.; Yerlikaya S.; Şener N.; Özkınalı S.; Baloglu M.C.; Gökçe H.; Altunoglu Y.C.; Demir S.; Şener İ.
The 1,3,4-thiadiazole core has been mainly used as a pharmacological scaffold in medicinal chemistry. A series of Schiff bases derived from 5-substituted-1,3,4-thiadiazole-2-amine were designed and synthesized to investigate their biological activities. Structures of compounds were clarified with FTIR, 1H NMR and elemental analysis. Due to the importance of this core in pharmacology, all these newly synthesized compounds were tested for different biological properties at the same time. Compound 3A ((E)-N-(2,5-dimethoxybenzylidene)-5-(4-methoxyquinolin-2-yl)-1,3,4-thiadiazol-2-amine) and compound 4A ((E)-N-(2,5-dimethoxybenzylidene)-5-(3-methylbenzofuran-2-yl)-1,3,4-thiadiazol-2-amine) possessed high DNA protective ability against oxidative Fenton mixture. Compound 1A ((E)-N-(2,5-dimethoxybenzylidene)-5-(benzo[b]thiophen-2-yl)-1,3,4-thiadiazol-2-amine) and compound 2B ((E)-2-((5-(1H-indol-2-yl)-1,3,4-thiadiazol-2-ylimino)methyl)-6-methoxyphenol) showed strong antimicrobial activity against S. epidermidis. The most effective compound was detected as compound 3A which exhibited cytotoxicity on both PC-3 and MDA-MB-231 cancer cell lines. The IC50 of this compound was calculated as 370.7 μM and 505.1 μM for MDA-MB-231 and PC-3 cells, respectively. Molecular docking studies were also performed to examine the understanding of the mechanism behind the anti-cancer and anti-bacterial properties. For further study, compound 3A has the potential for utilization with chemotherapy drugs to establish a more efficient therapy strategy with minimum cytotoxicity against cancer cells.
New amide based iridium(III) complexes: Synthesis, characterization, photoluminescence and DFT/TD-DFT studies
(2018-01-01) Sahin C.; Goren A.; Demir S.; Cavus M.S.
New iridium(iii) complexes with 2-(3-fluorophenyl)-4-methylpyridine as cyclometalated ligands and 2,2′-bipyridine-4,4′-dicarboxamide derivatives as ancillary ligands were synthesized and characterized by FTIR, NMR, MS, UV/Visible, and fluorescence spectroscopies and cyclic voltammetry. The effects of different solvents and substituents on the photophysical properties of the complexes have been investigated. The complexes show tunable photoluminescence wavelengths depending on solvent polarity in the 548 nm to 610 nm range where the emission colour can change from green to orange-red. The complexes exhibit high photoluminescence quantum yields between 0.41 and 0.75, which may be attributed to the change in the transition dipole moment originating from the amide group upon electronic excitation. The calculated HOMO and LUMO energy levels of complexes 1-7 are in the -5.51 to -5.60 eV and -3.37 to -3.40 eV ranges, respectively. The ground and excited state properties of 1 have been fully investigated by means DFT and TD-DFT methods respectively. The general trends of observed data have been successfully represented and quantified by computational data.
Strongly fluorescing silver(I) complex of a new thiadiazole ligand: X-ray crystallography, close anagostic interactions and TD-DFT emissive states
(2019-09-17) Demir S.; Gür M.; Şener N.; Şener İ.; Alpaslan G.
A new thiadiazole ligand, N-ethyl-5- (benzo[b]thien-2-yl-)-1,3,4-thiadiazol-2-amine (BTH), was prepared from 3-methyl-1-benzofuran-2-carboxylic acid and N-ethylhydrazinecarbothioamide precursors. Corresponding silver(I) complex, tetrakis(N-ethyl-5-(benzo[b]thien-2-yl-)-1,3,4-thiadiazol-2-amine)silver(I) nitrate [Ag2(BTH)4](NO3)2 (1), was prepared. The structures of BTH and 1 were characterized by 1H-NMR, 13C-NMR, FT-IR, elemental analysis and HR-MS techniques. Furthermore, molecular structure of 1 was illuminated by X-ray crystallography. Owing to strong anagsotic interaction, crystal structure of the complex revealed an intriguing asymmetric monomer unit even with two same ligands in 2:1 metal-to-ligand stoichiometry. Photoluminescence properties of the complex were investigated by solid and solution media emission measurements. Excited and emissive state behavior of the complex was further analyzed by quantum chemical TD-DFT calculations and natural transition orbital (NTO) analyses.
Surface chemistry dependent toxicity of inorganic nanostructure glycoconjugates on bacterial cells and cancer cell lines
(2023-01-01) Sancak S.; Yazgan İ.; Bayarslan A.U.; Ayna A.; Evecen S.; Taşdelen Z.; Gümüş A.; Sönmez H.A.; Demir M.A.; Demir S.; Bakar F.; Dilek-Tepe H.; Kasemets K.; Otsus M.; Çeter T.
Surface functionalized nanostructures have outstanding potential in biological applications owing to their target-specific design. In this study, we utilized laboratory synthesized carbohydrate-derivatives (i.e., galactose, mannose, lactose, and cellobiose derivatives) for aqueous one-pot synthesis of gold (Au) and silver (Ag) nanostructure glycoconjugates (NSs), and iron metal-organic framework glycoconjugates (FeMOFs). This work aims to test whether differences in the surface chemistry of the inorganic nanostructures play roles in revealing their toxicities towards bacterial cells and cancerous cell lines. As of the first step, biological activity of AuNSs, AgNSs, and FeMOFs were tested against a variety of gram (−) and gram (+) bacterial strains, where AgNSs possessed moderate to high antibacterial activities against all the tested bacterial strains, while AuNSs and FeMOFs showed their bacterial toxicity mostly depending on the strain. Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) determination studies were performed for the nanostructure glycoconjugates, for which μg/mL MBC values were obtained such as (Cellobiose p-aminobenzoic acid_AgNS) CBpAB_AgNS gave 50 μg/mL MBC value for P.aeruginosa and S.kentucy. The activity of selected sugar ligands and corresponding glycoconjugates were further tested on MDA-MB-231 breast cancer and A549 lung cancer cell lines, where selective anticancer activity was observed depending on the surface chemistry as well. Besides, D-penicillamine was introduced to galectin specific sugar ligand coated AuNS glycoconjugates, which showed very strong anticancer activities even at low doses. Overall, the importance of this work is that the surface chemistry of the inorganic nanostructures can be critical to reveal their toxicity towards bacterial cells and cancerous cell lines.
Synthesis of a new 1,3,4-thiadiazole-substituted phenanthroimidazole derivative, its growth on glass/ITO as a thin film and analysis of some surface and optoelectronic properties
(2021-12-28) Zurnaci M.; Ünal F.; Demir S.; Gür M.; Şener N.; Şener İ.
A new phenanthroimidazole derivative (PMItz) bearing a 1,3,4-thiadiazole moiety was prepared and deposited as a thin film on a previously prepared glass/ITO substrate via the physical vapor deposition (PVD) method. The optical and surface morphological properties of the fabricated thin film, glass/ITO/PMItz, were investigated via UV-Vis spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Subsequently, metal/ITO/PMItz/metal (metal: In and Ag) devices were fabricated and their electrical properties were investigated. The optical measurements revealed the reasonably high optical conductivities of the thin films. The energy band gap was calculated to be 2.96 eV, the absorption coefficient was calculated to be 1.3 × 106 m-1 and the optical conductivity was calculated to be 3.14 × 1014. The typical diode characteristics of the devices were demonstrated by electrical measurements. The current-voltage (I-V) measurements revealed that the devices exhibited photo-sensitivity, the photovoltaic effect and strong negative differential resistance (NDR) effect at certain voltage values. The ideality factors in the dark were calculated to be 2.4 and 2.54 for the In/ITO/PMItz/In and Ag/ITO/PMItz/Ag devices, respectively. According to the Hall effect measurements, the conductivity of PMItz was found to be p-type with high carrier mobility and concentration and low specific resistance. This journal is