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  • Küçük Resim
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    Synthesis, characterization, DFT study, conductivity and effects of humidity on CO2 sensing properties of the novel tetrakis- [2-(dibenzylamino)ethoxyl] substituted metallophthalocyanines
    (Elsevier Science Sa, 2020) Senoglu, Sema; Ozer, Metin; Dumludag, Fatih; Acar, Nursel; Salih, Bekir; Bekaroğlu, Özer
    Novel tetrakis[2-(dibenzylamino)ethoxyll substituted nickel (II), cobalt (II) and manganese (II) phthalocyanines were synthesized by using 4-(2-(dibenzylamino)ethoxy)phthalonitrile with corresponding metal salts in 2-N, N-dimethylaminoethanol. New phthalonitrile ligand was prepared from 2-(dibenzylamino)ethan-l-ol and 4-nitrophthalonitrile in acetonitrile at reflux temperature using potassium carbonate as catalyst. The compounds was characterized by elemental analysis, infrared, ultraviolet-visible and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopic methods. Density functional theory calculations were performed for structural and electronic properties. Direct current and alternating current conductivity properties of the metallophthalocyanine films were investigated between 293 - 523 K and frequencies 40 -100 kHz. The direct current conductivity values were calculated as 5.29 x 10(-10 )S/cm, 2.39 x 10(-9)S/cm, and 3.04 x 10(-10) S/cm, for nickel, cobalt and manganese complexes (293 K) films, respectively. Activation energies of the films were 0.50-0.70 eV for T < 478 K. Alternating current conductivity results suggest that hopping model explains dominant charge transport mechanisms. Carbon dioxide sensing properties (1000-8000 ppm) of the metallophthalocyanine films were investigated at room temperature (293 K) in air as background. Additionally, effects of the relative humidity on carbon dioxide sensing properties were also investigated for relative humidity between 0-80 % RH in air. Response and response time values of the films were reported. Newly synthesized phthalocyanine complexes in this study were found to be reversible and sensitive to the carbon dioxide gas in humid air. Carbon dioxide sensing measurements revealed that sensitivity of the sensors increased with increasing carbon dioxide concentration and relative humidity. It is found that manganese phthalocyanine showed greater sensitivity than nickel- and cobalt phthalocyanine complexes.
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    Synthesis, conductivity, and ımpedance studies on metallophthalocyanines formed across adjacent rings
    (Wiley-V C H Verlag Gmbh, 2019) Sener, Sevil; Selcuki, Nursel Acar; Dumludag, Fatih; Salih, Bekir; Bekaroğlu, Özer
    The synthesis and characterization of Co-II, Zn-II, and Ni-II phthalocyanines (Pcs) 4, 5, and 6, respectively, containing two bis[2-(4-hydroxyphenyl)-2-propyl]benzene groups formed across adjacent rings at the peripheral positions are described. The Pcs were synthesized by cyclotetramerization of the previously prepared precursor 4,4 '-bis[1,3-propylbenzene-2-p-phenoxy]phthalonitrile (3) in the presence of metal salt in boiling dry DMF under a dry nitrogen atmosphere. Elemental analysis, UV-Vis, FT-IR, and H-1-NMR spectroscopy, as well as MALDI-TOF mass spectrometry techniques were used for the characterization of 4. Conductivity (dc and ac) and impedance spectroscopy (IS) measurements were performed on the films of 5 and 6 between the temperatures 293 and 523 K and frequencies 40 and100 kHz. The dc conductivity values were calculated as 2.11 x 10-(10), 3.48 x 10-(10), and 1.90 x 10-(10) S/cm for the films of 4, 5, and 6, respectively, at room temperature. Activation energy values of the films were also calculated. Conductivity (ac) results suggest that the dominant charge transport mechanisms can be explained by the hopping model depending on temperature and frequency range. From impedance spectra and Cole-Cole plots, the relaxation time in the Debye dispersion relation is considered as a distribution of relaxation time values rather than as a single relaxation time. To elucidate the structural, spectroscopic, and bonding properties of the obtained compounds, DFT/TD-DFT calculations were performed.