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    Electrochemical investigation of a podand type diimine polyether
    (Central Electrochem Res Inst, 2004) Gökmese, E; Gökmese, F; Yildiz, M; Kiliç, Z; Solak, AO
    A podand type diimine polyether, 1,8-di[N-2-oxyphenyl-salicylidene]-3,6-dioxaoctane (DSO), was prepared and its electrochemical behaviour reported. The reduction of the -C=N- bonds in this compound was studied in a 1:5 (v/v) ethyl alcohol-water mixture using sampled current polarography, cyclic voltammetry, chronoamperometry and chronocoulometry. Adsorption characteristics of the compound on the mercury electrode were examined and the amount of adsorption of the molecule was calculated. Considering the adsorption of the compound on the electrode surface, heterogeneous rate constants of the electrode transfer reaction were defermined by cylic voltammetric measurements.
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    Intramolecular hydrogen bonding and tautomerism in N-(3-pyridil)-2-oxo-1-naphthylidenemethylamine
    (Springer/Plenum Publishers, 2001) Ünver, H; Yildiz, M; Zengin, DM; Özbey, S; Kendi, E
    N-(3-pyridil)-2-oxo-1-naphthylidenemethylamine (C16H12N2O) was studied by elemental analysis, IR, H-1 NMR, and UV-visible techniques and X-ray diffraction methods. The UV-visible spectrum of the compound was investigated in solutions effect polarity. The polarity of the some solvents was modifierly the additional (CF3COOH) and [(C2H5)(3)N]. The compound is in tautomeric equilibrium (phenol-imine O-H...N and keto-amine O...H-N forms) in polar and nonpolar solvents. The keto-amine form is observed in basic solutions of DMSO, ethanol, chloroform, benzene, cyclohexane, and in acidic solutions of chloroform and benzene, but not in acidic solutions of DMSO and ethanol. The compound crystallizes in the monoclinic, space group P2(1)/a with a = 7.010(5) Angstrom, b = 13.669(4) Angstrom, c = 12.764(4) Angstrom, beta = 101.23(4)degrees, V = 1199.6(10) Angstrom(3), Z = 4, D-c = 1.375 g/cm(3), mu(MoKalpha) = 0.088 mm(-1), R = 0.045 for 1658 reflections [I > 2sigma(I)]. The title compound is not planar two Schiff base moieties A [C1-C11, O1] and B [N1, C12, C13, N2, C14, C15, C16] are inclined at an angle of 27.4(1)degrees reflecting mainly the twist about C12-N1 [C11-C12-N1-C13, 29.7(2)degrees]. There is a strong intramolecular hydrogen bond (O-H...N) of 2.529(2) Angstrom.
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    Intramolecular hydrogen bonding and tautomerism in Schiff bases.: Structure of N-(2-pyridil)-2-oxo-1-naphthylidenemethylamine
    (Elsevier Science Bv, 2000) Nazir, H; Yildiz, M; Yilmaz, H; Tahir, MN; Ülkü, D
    N-(2-pyridil)-salicylidene (1) and N-(2-pyridil)-2-oxo-1-naphthylidene-methylamine (2) were studied by elemental analysis, IR, H-1 NMR and UV-visible techniques and the structure of compound (2) was examined crystallographically. The UV-visible spectra of 2-hydroxy Schiff bases are investigated in different solvents, acidic and basic media. Compound (2) is in tautomeric equilibrium (phenol-imine, O-H ... N reversible arrow keto-amine, O ... H-N forms) in polar and non-polar solvents. These tautomers are not observed in polar and non-polar solvents for (1) as also supported by H-1 NMR and UV-visible data. The keto-amine form of compound (2) was observed in basic solutions of DMSO, ethanol, chloroform, benzene, cyclohexane and in acidic solutions of chloroform and benzene, but not in acidic solutions of DMSO and ethanol. On the contrary, this form for compound (1) was not observed in the same solutions. The asymmetric unit of compound (2) contains two independent molecules of (C16H12N2O) which constitute a tautomeric pair. The observed differences in the related C=N (1.317(4) and 1.330(4) Angstrom) and C-O (1.279(4) and 1.263(4) Angstrom) bond lengths in the two crystallographically independent molecules indicate that the phenol-imine and the keto-amine forms coexist in the solid state. Intramolecular hydrogen bond lengths (O-H ... N) are 2.586(4) Angstrom and 2.518(4) Angstrom for the two individual tautomers. It crystallizes in the monoclinic space group P2(1)/n with a = 5.837(2), b = 17.476(2), c = 24.295(3) Angstrom, beta = 91.95(4)degrees, V = 2476.9(6) Angstrom(3), Z = 4 and Dx = 1.3315 g cm(-3). (C) 2000 Elsevier Science B.V. All rights reserved.
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    Spectroscopic studies, antimicrobial activities and crystal structures of N-(2-hydroxy-3-methoxybenzalidene) 1-aminonaphthalene
    (Elsevier, 2005) Ünver, H; Yildiz, M; Dülger, B; Özgen, Ö; Kendi, E; Durlu, TN
    Schiff base N-(2-hydroxy-3-methoxybenzalidene)1-aminonaphthalene has been synthesized from the reaction of 2-hydroxy-3-methoxybenzaldehyde with 1-aminonaphthalene. The compound were characterized by elemental analysis, FT-IR, H-1 NMR, C-13 NMR and UV-visible techniques. The UV-visible spectra of the Schiff base were studied in polar and nonpolar solvents in acidic and basic media. The structure of the compound has been examined cyrstallographically. There are two independent molecules in the asymmetric unit. It crystallizes in the monoclinic space group P2(l)/c, with unit cell parameters: a=14,602(2), b=5,800(1), c= 16,899(1) Angstrom, V= 1394.4(2) Angstrom(3) D-x=1.321 g cm(-3) and Z = 4. The crystal structure was solved by direct methods and refined by full-matrix least squares to a find R = 0.041 of for 1179 observed reflections. The title compound's antimicrobial activities also have been studied. The antimicrobial activities of the ligand has been screened in vitro against the organisms Escherichia coli ATCC 11230, Staphylococcus aureus ATCC 6538, Klebsiella pneumoniae UC57, Micrococcus luteus La 2971, Proteus vulgaris ATCC 8427, Pseudomonas aeruginosa ATCC 27853, Mycobacterium smegmatis CCM 2067, Bacillus cereus ATCC 7064 and Listeria monocytogenes ATCC 15313, the yeast cultures Candida albicans ATCC 1023 1, Kluyveromyces fragilis NRRL 2415, Rhodotorula rubra DSM 70403, Debaryomyces hansenii DSM 70238 and Hanseniaspora guilliemodii DSM 3432. (C) 2004 Elsevier B.V. All rights reserved.
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    Synthesis and antimicrobial activity of bis(imido) Schiff bases derived from thiosemicarbazide with some 2-hydroxyaldehydes and metal complexes
    (Scientific Publ-India, 2004) Yildiz, M; Dülger, B; Koyuncu, SY; Yapici, BM
    Schiff bases have been synthesised by the reaction of salicylaldhyde, 5-bromosalicylaldehyde, 5-nitrosalicylaldehyde and naphthaldehyde with thiosemicarbazide. The ligands of N,N'-bis(salicylidene)thiosemicarbazide (1) react with Mn-II, Co-II, Ni-II, Cu-II, Zn-II and Hg-II metals to yield 1 : 1 metal-ligand complexes. The structures of ligands and complexes have been investigated by elemental analyses, magnetic susceptibility measurements, H-1 NMR, IR and UV-visible spectral data. The pentadentate nature of the ligands is inferred from IR spectra. The UV-visible spectral data suggest octahedral geometry for Mu(II), Co-II, Ni-II, Cu-II, square-pyramidal geometry for Zn-II and Hg-II The antimicrobial activities of the ligands and metals complexes have been screened in vitro against the organisms Escherichia coli ATCC 11230, Staphylococcus aureus ATCC 6538 P, Bacillus cereus ATCC 7064, Proteus vulgaris ATCC 8427, Salmonella typhimurium DSM 554, Corynebacterium xerosis ATCC 373 and Hanseniaspora guilliermondii DSM 3432, Rhodotorula rubra DSM 70403 and Kluyveromyces fragilis ATCC 8608. It is observed that the coordination of metal ions has pronounced effect on the microbial activities of the ligands. The metal complexes have higher antimicrobial effect than the free ligand.
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    Synthesis and characterization of new crown ethers of Schiff base type and their complexes
    (Indian Chemical Soc, 2005) Yildiz, M; Dülger, B; Çinar, A
    New crown ether ligands of Schiff base type (4-11) have been synthesised by the reaction of two equivalents, of benzaldehyde, 2-hydroxybenzaldehyde, 2,3-dihydroxybenzaldehyde, 5-methoxy-2-hydroxybenzaldehyde, 5-bromo-2-hydroxybenzaldehyde, 5-nitro-2-hydroxybenzaldehyde, 4-hydroxybenzaldehyde or 2-hydroxy-l-naphthaldehyde with 2,3,5,6-di[4-aminobenzo]-1,7,10,13-tetraoxacyclopentadeca-2,5-dien (3). The ligand 2,3,5,6 -di[4-N-(salicylidene)benzo]-1,7,10,13-tetraoxacyclopentadeca-2,5-dien (5) (5) reacts with Mn-II, Fe-II, Co-II, Ni-II, Cu-II and Zn-II to yield 1 : 1 metal-ligand complexes. The structures of ligands and complexes have been investigated by elemental analysis, IR, UV-visible, (1)(H) NMR and C-13 NMR data. The tetradentate nature of the ligands is inferred from IR spectra. The UV-visible spectral data suggest octahedral geometry for metal complexes. The antimicrobial activities and yeast cultures of the ligands and metal complexes have been screened in vitro against the organisms Escherichia coli ATCC 11230, Staphylococcus aureus ATCC 6538 P, Bacillus cereus ATCC 7064, Proteus vulgaris ATCC 8427, Salmonella typhimurium DSM 554, Corynebacterium xerosis ATCC 373 and Hanseniaspora guilliermondii DSM 3432, Rhodotorula rubra DSM 70403 and Kluyveromyces fragilis ATCC 8608. The metal complexes are more fungitoxic than the free ligand.
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    Synthesis and characterization of phenoxyphosphazenes. Structure of 2,2-[2,2?-metheylenebis(4-chlorophenoxy)]-4,4,6,6-tetrachlorocyclo-2?5,4?5,6?5-triphosphazatriene (spiro)
    (Elsevier, 2005) Yildiz, M; Erdener, D; Ünver, H; Iskeleli, NO
    The reactions of trimericphosphazenes with sodium [2, 2'-methylenebis(4-chlorophenoxide)] have been investigated. Experimental studies were carried out in argon atmosphere. The sodium aryloxides were prepared from methylenebis (4-chlorophenol) and sodium. The phosphazene and phenolate were reacted at -20 degrees C and then refluxed. After the reaction products (I and 2) were separated by column chromatography, the structures of the compounds were characterized by elemental analysis, IR, H-1-, C-13-, P-31-NMR, and mass spectroscopy. The compound I (spiro) crystallizes in the monoclinic space group Cm with unit cell parameters: a = 8.231(1), b = 16.242(2), c = 7.731(1) angstrom, beta = 103.31(1)degrees, V= 1005.8(2) angstrom(3), D-x = 1.796 g cm(-3) respectively. The crystal structures were solved by direct methods and refined by full-matrix least squares. (c) 2005 Elsevier B.V. All rights reserved.
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    Synthesis and spectroscopic studies of some new polyether ligands of the Schiff base type
    (Taylor & Francis Inc, 2004) Yildiz, M
    New polyether ligands of Schiff base type (3-13) were synthesized from the reaction of diethylene glycol bis(2-aminophenyl)ether and triethylene glycol bis(2-aminophenyl)ether with salicylaldehyde, 5-methoxysalicylaldehyde, 5-bromosalicylaldehyde, 5-nitro salicylaldehyde, and 2-hydroxy-1-naphthaldehyde. The products were characterized by elemental analysis, IR, H-1, C-13 NMR, and UV-VIS techniques. The UV-VIS spectra of those Schiff bases with an OH group in the ortho position to the imino group were studied in polar and nonpolar solvents in acidic and basic media. The compounds are in tautomeric equilibrium (enol-imine, O-(HN)-N-... reversible arrow keto-amine, (OH)-H-...-N forms) in solvents, acidic chloroform, and benzene solutions and basic DMSO, chloroform, and benzene solutions. These tautomers were not observed in polar and non-polar solvents and in basic solutions of DMSO, chloroform, and benzene for the Schiff bases 5-10. Tautomer proportions, which were obtained from H-1 NMR and UV-VIS data in DMSO, were compared for compounds 3, 4, 11, and 12.