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  • Küçük Resim
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    Chromogenic sensing, biological, and optical properties of Schiff bases of 2-amino-6-methoxybenzothiazole
    (Elsevier B.V., 2024) Akhüseyin Yıldız, Elif; Pepe, Yasemin; Erdener, Diğdem; Karatay, Ahmet; Boyacıoğlu, Bahadır; Ünver, Hüseyin; Yapar, Gönül; Demir, Neslihan; Yıldız, Mustafa
    In this study, a new series of Schiff base benzothiazole derivatives were synthesized and their structures were characterized by elemental analysis, FTIR, UV–VIS and NMR spectroscopy. The biological, sensory and photophysical properties of the benzothiazole derivatives were investigated. The sensing properties of the compounds were investigated UV–VIS spectroscopically, calorimetrically and theoretically. All compounds showed colorimetric, fluorometric and spectroscopic sensor properties for F−, CN−, AcO−, H2PO4− and OH− anions. Furthermore, DNA binding, DNA cleavage and antioxidant activities of compounds 1-4 were investigated. All compounds affected pBR322 DNA both hydrolytically and oxidatively, interacted with DNA in electrostatic mode, and also compounds 1 and 2 exhibited antioxidant activity close to standard BHT. In addition, the effects of electron donating and accepting substituents on the emission properties and charge transfer dynamics were investigated by fluorescence and femtosecond transient absorption spectroscopy measurements, respectively. According to fluorescence measurements, compounds 3 and 4 showed emission signal, while compounds 1 and 2 showed fluorescence quenching and weaker emission signal.
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    Öğe
    Effect of group electronegativity on spectroscopic, biological, chromogenic sensing and optical properties of 2-formyl-benzene sulfonic acid sodium salt-based Schiff bases
    (Elsevier B.V., 2023) Akhüseyin Yıldız, Elif; Pepe, Yasemin; Erdener, Diğdem; Karatay, Ahmet; Boyacıoğlu, Bahadır; Ünver, Hüseyin; Yapar, Gönül; Demir, Neslihan; Yıldız, Mustafa; Elmalı, Ayhan
    In this study, 2-formylbenzenesulfonic acid sodium salt-based Schiff bases were synthesized from the reactions of 2-formylbenzenesulfonic acid sodium salt with 2-amino-4-chlorophenol and 2-amino-4-methylphenol. The structure of the compounds was determined by FTIR, UV–Vis and NMR spectroscopy methods using both experimental and DFT methods. The anion sensor properties of the compounds were investigated both UV–Vis spectroscopically and calorimetrically. In addition, the antimicrobial activities, interactions with DNA, DNA cleavage and antioxidant activities of Schiff bases were investigated. Additionally, the effects of group electronegativity on the spectroscopic, biological, chromogenic sensing and optical properties of chlorine and methyl side groups and sodium 2-sulfobenzalidene-aminophenol-based Schiff bases were investigated.
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    Spectroscopic studies, antimicrobial activities, and crystal structure of N-[2-hydroxy-1-naphthylidene]3,5-bis(trifluoromethyl)aniline
    (Springer/Plenum Publishers, 2006) Ünver, Hüseyin; Yıldız, Mustafa; Kiraz, Aşkın; İskeleli, Nazan Ocak; Erdönmez, Ahmet; Dülger, Başaran; Durlu, Tahsin Nuri
    A new Schiff base compound has been synthesized by the reaction of 2-hydroxy-1-naphthaldehyde with 3,5-bis(trifluoromethyl)aniline.The title compound was characterized by elemental analysis, IR, H-1 NMR, C-13 NMR, and UV-Visible techniques.Its UV-Vis spectra was examined in polar and nonpolar solvents and in acidic and basic media. The crystal structure of the compound showed the OH group to be ortho to the imine group. It crystallizes in the monoclinic space group P2(1) with a = 11.328(2), b = 6.125(1), c = 11.937(2) angstrom, V = 825.1(2) angstrom(3), D (x) = 1.543 g cm(-3) and Z = 2. An intramolecular O1- H center dot center dot center dot N1 [2.558(7) angstrom] hydrogen bond stabilizes the molecule. The compound has also been characterized by its antimicrobial activities. 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 10231, Kluyveromyces fragilis NRRL 2415, Rhodotorula rubra DSM 70403, Debaryomyces hansenii DSM 70238, and Hanseniaspora guilliermondii DSM 3432.
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    Synthesis, characterization and applications of (E)-3- ((5-bromo-2-hydroxy-3-methoxycyclohexa-1,3-dienyl) methyleneamino)-6-(hydroxymethyl)-tetrahydro-2hpyran-2,4,5-triol
    (Open Access House of Science and Technology, 2016) Tadesse, Solomon; Alpaslan, Yelda Bingöl; Yıldız, Mustafa; Ünver, Hüseyin; Aslan, Kadir
    We present the synthesis, characterization, biological and sensing applications of a Schiff base, (E)- 3-((5-bromo-2-hydroxy-3-methoxycyclohexa-1, 3-dienyl)methyleneamino)-6-(hydroxymethyl)- tetrahydro-2H-pyran-2,4,5-triol. Characterization of the title compound was carried out using theoretical quantum-mechanical calculations and experimental spectroscopic methods. The molecular structure of the title compound was confirmed using NMR and FTIR, which was in good agreement with the structure predicted by the theoretical calculations. The title compound was evaluated for its ability to detect anions in DMSO and on a solid surface and for its antimicrobial activity against several common microorganisms. © 2016 Solomon Tadesse, Yelda Bingöl Alpaslan, Mustafa Yildiz, Hüseyin ünver and Kadir Aslan.
  • Küçük Resim
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    Synthesis, characterization, and application of a novel water-soluble polyethyleneimine-based Schiff base colorimetric chemosensor for metal cations and biological activity
    (Elsevier Science Sa, 2017) Yıldız, Mustafa; Demir, Neslihan; Ünver, Hüseyin; Şahiner, Nurettin
    A novel colorimetric cation sensor based on polyethyleneiminehydrochloride (PEI.HCl) as Schiff base was synthesized. The molecular structure of the PEI.HCl-Schiff base was characterized via FT-IR, H-1 NMR, C-13 NMR, LC-MS and UV-vis spectroscopic methods The chromogenic sensing ability of PEI.HCl-Schiff base was investigated with colorimetric and UV-vis spectroscopy. The designed sensor exhibited highly selective recognition for Fe2+, Co2+, Cu2+, Cr3+, and Fe3+ amongst a wide range of metal ions tested in water. In the presence of these cations, the sensor underwent a dramatic colour change from yellow to green, while the presence of other metal cations such as Mn2+, Ni2+, Zn2+, Cd2+, Hg2+ and Pb2+ produced no effect on the colour. The absorption spectral changes were observed upon the addition of Fe2+, Co2+, Cu2+, Cr3+, and Fe3+ with impressive naked eye detectable colour change from yellow to dark-gray, light-brown, green, light-green and brown, respectively. The most discernable colour change in the PEI.HCl-Schiff base was caused by Fe2+, Co2+, Cu2+, Cr3+, and Fe3+ suggesting the selective detection of these metal cations. Surprisingly, PEI.HCl-Schiff base behaves as highly selective chemical sensor for the oxidation of Fe2+ to Fe3+ cations. Moreover, the antimicrobial activity of PEI.HCl-Schiff base was tested for its minimum inhibitory concentration (MIC), and the interaction with calf thymus DNA (CT-DNA) was investigated using UV-vis spectroscopy. DNA cleavage study showed that PEI.HCl-Schiff base can successfully cleave DNA without any external agents. (C) 2017 Elsevier B.V. All rights reserved.
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    Synthesis, spectroscopic studies and structure of 2-[(Benzo[d]thiazol-2- ylamino)methyl]phenol
    (Springer New York LLC, 2010) Yıldız, Mustafa; Özay, Hava; Ünver, Hüseyin; İskeleli, Nazan Ocak; Mehmet Zengin, D.; Durlu, Tahsin Nuri
    Schiff base (E)-2-[(benzo[d]thiazol-2-ylimino)methyl]phenol (1) has been synthesized from the reaction of 2-hydroxy-benzaldehyde with 2-aminobenzothiazole. The 2-[(benzo[d]thiazol-2-ylamino)methyl]phenol (2) was prepared reduction of the Schiff base 1 with sodium borohydride. The compounds 1 and 2 have been characterized by elemental analysis, FT-IR, 1 H-NMR, 13 C-NMR and UV-visible spectroscopic techniques. The structure of the compound 2 has also been examined crystallographically. The compound 2 crystallizes in the monoclinic space group P2/c. The unit cell parameters were found as a = 10.017(1), b = 11.725(1), c = 10.341(1) Å, V = 1208.1(1) Å 3 , D x = 1.409 g cm -3 and Z = 4. The crystal structure was solved by direct methods and refined by the full-matrix least squares method and found as R 1 = 0.0308 and wR 2 = 0.0818 for 2032 for the observed reflections [I > 2?(I)]. Graphical Abstract: Crystal and molecular structure of the compound 2-[(benzo[d]thiazol-2- ylamino)methyl]phenol have been studied in order to reveal the presence of either the enol-imine or keto-amine forms related with hydrogen bonding by using FT-IR, 1 H-NMR, 13 C-NMR, UV-visible spectroscopic and X-ray crystallographic techniques.[Figure not available: see fulltext.] © 2010 Springer Science+Business Media, LLC.