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    Colorimetric probe and optical behaviours of new azomethine derivatives of sulfonamide
    (Elsevier, 2022) Tekin, Sezen; Karatay, Ahmet; Erdener, Digdem; Yildiz, Elif Akhuseyin; Boyacioglu, Bahadir; Unver, Huseyin; Yıldız, Mustafa
    Syntheses, colorimetric anion probe properties, density functional theory (DFT) studies, and optical properties of the Schiffbases; 4-fluoro-N-(2-hydroxy-5-methylbenzylidene) benzenesulfonamide (1), 4fluoro-N-(2-hydroxy-5-nitrobenzylidene)benzenesulfonamide (2) and 4-fluoro-N-[(2-hydroxynaphthalen1-yl)methylene]benzenesulfonamide (3) were reported. The structure of the compounds was elucidated using MS, FTIR, and UV-visible spectroscopic techniques. Their structures were examined by theoretical calculations using density functional theory (DFT). The colorimetric response of the Schiffbase receptors in DMSO was investigated before and after the addition of an equivalent amount of each anion to evaluate the anion recognition properties. The ultrafast transient absorption spectroscopy measurements were performed to investigate the energy transfer dynamics and decay kinetics of the compounds 1-3. The fluorescence and wavelength-dependent pump-probe measurements of the compounds showed that the excited state lifetime of compound 2 is shorter than compounds 1 and 3. The fluorescence properties of compounds 1-3 were compatible with the pump-probe spectroscopy measurements. The compounds with longer ESA lifetimes showed higher fluorescence. (c) 2021 Published by Elsevier B.V.
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    Öğe
    Colorimetric probing and fluorescent chemosensor features of functionalized sulphonamide-azomethine derivatives
    (Elsevier Science Sa, 2022) Yildiz, Elif Akhuseyin; Erdener, Digdem; Tekin, Sezen; Karatay, Ahmet; Boyacioglu, Bahadir; Unver, Huseyin; Yıldız, Mustafa
    In this work, we have experimentally synthesized bromosulfonamide-based azomethine compounds through the reaction of 4-bromobenzenesulfonamide with 2-hydroxy-5-iodobenzaldehyde, 2-hydroxy-5-nitrobenzaldehyde, and 2-hydroxy-l-naphthaldehyde. We have also characterized the molecular structure of the investigated compounds with MS, H-1 NMR, FTIR and UV-vis spectra. Theoretically, using DFT and TD-DFT methods, we computed frontier molecular orbitals (FMOs) energies and UV-vis spectra as well. We have also obtained the electron localization function (ELF) maps to identify electrophilic substitution sites in the molecules and density of states (DOS) diagrams to show the composition of the fragment orbitals that contribute to the molecular orbitals. We have investigated steady-state absorption, emission features, and excited state dynamics to better understand the photophysical process of bromosulfonamide-based azomethines. It has been demonstrated that by adding a naphthalene unit, the absorption properties of azomethine into two branches. Besides, azomethine, including heavy iodo atoms, presents a slight decrement in the fluorescence intensity. According to thorough calculations of charge transfer dynamics using femtosecond transient absorption spectra, the bromosulfonamidebased azomethines with iodo atoms and incorporating naphthalene units exhibit an intersystem crossing mechanism following photoexcitation. The colorimetric response of the compounds in DMSO to the addition of the equivalent amount of anions (F- , Br- , I-, CN-, SCN-, ClO4-, HSO4-, AcO-, H2PO4- , N-3(-) and OH-) was investigated. In this regard, while the addition of F- ,CN- ,AcO- , H2PO4- and OH(- )anions into the solution containing the compounds resulted in a significant color change, the addition of Br-, I-, SCN-, ClO4- HSO4- and N-3 anions resulted in no color change.
  • [ X ]
    Öğe
    Naked-eye colorimetric anion probing and fluorescent switching features of conjugated Schiff Bases derived from 4-(Trifluoromethyl) benzenesulfonamide
    (Elsevier, 2022) Yildiz, Elif Akhuseyin; Tekin, Sezen; Erdener, Digdem; Karatay, Ahmet; Boyacioglu, Bahadir; Unver, Huseyin; Yıldız, Mustafa
    In this work, synthesis, spectroscopic, density functional theory (DFT) and photophysical studies of the three conjugated benzenesulfonamide Schiff bases were reported. We also calculated the energies of the frontier molecular orbitals (FMOs) and UV-Vis spectra of Schiff bases theoretically using the DFT and TD-DFT methods. Additionally, photophysical properties were investigated by UV-Vis and fluorescence spectroscopy techniques. The ground state interactions show that the absorption band has been separated into two branches and bathochromatically tuned to the visible region, and fluorescence intensity decreased in the case of the Schiff base incorporated naphthalene unit. Furthermore, the charge transfer dynamics of the compounds were analyzed using femtosecond transient absorption spectroscopy measurements proving the triplet-triplet transitions via intersystem crossing mechanism. Based on the ultrafast pump-probe experimental results, as well as decay kinetics of the compounds, the Schiff base with naphthalene unit, showed a fast transition to the triplet state (1.2 ps) as compared to Schiff bases including methyl (4 ps) and chloro (2.7 ps) units. However, upon the addition of various anions, the molecule structure gains anion sensing and fluorescence switching capabilities under daylight and UV light. The obtained experimental results pointed out that the modification of Schiff base molecules with methyl, chlorine and naphthalene units affected its photophysical properties as well as excited-state dynamics significantly.