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    Spectroscopic Studies and Crystal Structure of 4-(2-Hydroxy-3-Methoxybenzylideneamino)-N-(5-Methylisoxazol-3-yl) Benzenesulfonamide
    (Springer/Plenum Publishers, 2010) Yıldız, Mustafa; Unver, Hueseyin; Erdener, Digdem; Iskeleli, Nazan Ocak
    Schiff base 4-[(2-hydroxy-3-methoxybenzylideneamino)-N-(5-methylisoxazol-3-yl)benzene-sulfonamidehas been synthesized from the reaction of 4-amino-N-(5-methylisoxazol-3-yl)benzenesulfonamide(sulfamethoxazole) with 2-hydroxy-3-methoxybenzaldehyde. It has been characterized by elemental analysis, MS, IR, H-1 NMR, C-13 NMR, HET-COR and UV-Visible techniques. The structure of it also has been examined crystallographically. For the compound exist as dominant form of enol-imines in both the solid state and the solutions. It crystallizes in the monoclinic space group P2(1)/c with a = 8.2694(7), b = 8.3453( 5), c = 26.260( 2) angstrom, beta = 97.142(7)degrees, V = 1798.1(2) angstrom(3) , D-x = 1.431 g cm(-3), R-1 = 0.0529 and wR(2) = 0.1370 [ I > 2 sigma(I)], respectively.
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    Öğe
    Spectroscopic study and structure of (E)-2-[(2-chlorobenzylimino)methyl]methoxyphenol
    (Pergamon-Elsevier Science Ltd, 2009) Unver, Hueseyin; Yıldız, Mustafa; Ozay, Hava; Durlu, Tahsin Nuri
    (E)-2-[(2-Chlorobenzylimino)methyl]methoxyphenol has been synthesized from the reaction of 2-hydroxy-3-methoxy-1-benzaldehyde(o-vanillin) with 2-chlorobenzylamine. The title compound has been characterized by using elemental analysis, FT-IR, H-1 NMR, C-13 NMR and UV-vis spectroscopic techniques. The crystal structure of the title compound has also been examined cyrstallographically. It crystallizes in the orthorhombic space group Pbca with unit cell parameters: a = 7.208(1)angstrom, b = 13.726(2)angstrom, c= 27.858(4) angstrom, V= 2756.0(1) angstrom(3), D, = 1.18 g cm(-3) and Z= 8. The crystal structure was solved by direct methods and refined by full-matrix least squares to a find R=0.046 for 2773 observed reflections. (C) 2009 Elsevier B.V. All rights reserved.
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    Öğe
    Tautomerism in Solution and Solid State, Spectroscopic Studies and Crystal Structure of (Z)-1-[(4-amino-2,3,5,6-tetramethylphenylamino)methylene]-1,8a-dihydronaphthalen-2(3H)-one
    (Taylor & Francis Inc, 2010) Unver, Hueseyin; Yıldız, Mustafa
    A new Schiff base compound(Z)-1-[(4-amino-2,3,5,6-tetramethylphenylamino)methylene]-1,8a-dihydronaphthalen-2(3H)-onewas synthesized by the reaction of 2-hydroxy-1-naphthaldehyde with 2,3,5,6-tetramethyl-p-phenylenediamine. It was investigated by using elemental analysis, IR, 1H-NMR, 13C-NMR, UV-Visible-spectroscopy, and X-ray-crystallography techniques. Its UV-Visible spectra were examined in polar and nonpolar solvents. The Schiff base studied exists in enol-imine keto-amine form in DMSO ethanol, chloroform, and benzene solution. The keto-amine tautomer was found to be dominant in both the phases. The (Z)-1-[(4-amino-2,3,5,6-tetramethylphenylamino)methylene]-1,8a-dihydronaphthalen-2(3H)-one molecule is not planar. It contains a strong intramolecular N-H...O hydrogen bond between the amine and oxo group [N1 and O1=2.591(2) angstrom], the H atom being essentially bonded to the N1 and O1 atoms.
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    Öğe
    UV-Vis spectroscopic and colorimetric anion detection and fluorescence properties of new 3-amino-4-hydroxybenzenesulfonic acid-based Schiff bases depending on the strength and position of the electron donor substitution
    (Iop Publishing Ltd, 2023) Yildiz, Elif Akhuseyin; Pepe, Yasemin; Erdener, Digdem; Karatay, Ahmet; Boyacioglu, Bahadir; Unver, Hueseyin; Yapar, Gonul
    In this study, 3-amino-4-hydroxybenzenesulfonic acid-based imine compounds; 3-(2,5-dihydroxybenzylideneamino)-4-hydroxybenzenesulfonic acid (1), 3-(2,4-dihydroxybenzylideneamino)-4-hydroxybenzenesulfonic acid (2) and 4-hydroxy-3-(2-hydroxy-3-methoxybenzylideneamino)-4-hydroxybenzenesulfonic acid (3) was synthesized. The compounds were analyzed using various spectroscopy methods, and the experimental UV-vis data matched the theoretical predictions. The compound 1 displayed lower stability, higher reactivity, and easier photoexcitation due to a smaller HOMO-LUMO energy gap. The investigated compounds 1-3 showed promise as chemosensors for anions, providing visible detection in daylight conditions. The compound 3 exhibited selective fluorescence at specific wavelengths. The compounds 1-3 interacted with DNA through electrostatic interactions. Also, compounds 1-3 showed higher antioxidant activity than BHT. However, fluorescence measurements indicated that the emission signals were strongly influenced by the position and strength of the electron-donating group. Adding a hydroxy or methoxy moiety near the -OH group on the phenyl ring decreased the fluorescence signal due to intersystem crossing and intramolecular charge transfer mechanisms, respectively. These findings were supported by femtosecond transient absorption spectroscopy measurements. The results emphasize the significance of substituents in imines derived from 3-amino-4-hydroxybenzenesulfonic acid in determining their biological activities, as well as their optical and sensor properties.