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    Electrochemical and spectroelectrochemical properties of thiadiazole substituted metallo-phthalocyanines
    (Pergamon-Elsevier Science Ltd, 2016) Demirbas, Umit; Akyuz, Duygu; Barut, Burak; Bayrak, Riza; Koca, Atif; Kantekin, Halit
    4-Thiadiazole substituted phthalonitrile and peripherally tetra-substituted phthalocyanine Cu(II), Fe(II) and Ti(IV)O complexes have been synthesized for the first time. Electrochemical properties of these complexes were determined with voltammetric and in situ spectroelectrochemical measurements. CuPc has redox inactive Cu2+ center, therefore it gave three Pc based reduction and two Pc based oxidation processes. TiOPc and FePc complexes gave metal based redox processes in addition to Pc based redox reactions due to the redox activity of Ti4+O and Fe2+ metal centers. Although FePc also gave three reduction and two oxidation reactions, peak potentials of these processes are different than those of CuPc due to the different assignments of the redox reactions. TiOPc went to five reduction and one oxidation reactions. Assignments of the redox processes were carried out with in situ spectroelectrochemical measurements. Spectra and color of the electrogenerated redox species of the complexes were also determined with in situ spectroelectrochemical and in situ electrocolorimetric measurements. Distinct color differences between the electrogenerated redox species were observed, which indicated their possible electrochromic usages. (C) 2015 Elsevier B.V. All rights reserved.
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    Metal-free, zinc(II) and lead(II) phthalocyanines functioning with 3-(2H-benzo[d][1,2,3]triazol-2-yl)-4-hydroxyphenethyl methacrylate groups: Synthesis and investigation of photophysical and photochemical properties
    (Elsevier Science Sa, 2016) Demirbas, Umit; Piskin, Mehmet; Barut, Burak; Bayrak, Riza; Durmus, Mahmut; Kantekin, Halit
    In this study, the synthesis and characterization of 3-(2H-benzo[d][1,2,3]triazol-2-yl)-4-hydroxyphenethyl methacrylate substituted novel phthalonitrile compound and its peripherally substituted zinc(II) lead(II) and metal-free phthalocyanine derivatives were performed for the first time. This novel compounds were characterized by obtained data from general spectroscopic methods such as FT-IR, H-1 NMR, C-13 NMR and mass. The photophysical and photochemical properties of these phthalocyanines were investigated in N,N-dimethylformamide solutions for determination of their photosensitizing abilities in photocatalytic applications such as photodynamic therapy. The lead(II) phthalocyanine complex did not produce any fluorescent in N,N-dimethylformamide because of the heavy atom effect of bigger lead atom. The fluorescence quantum yields of studied zinc(II) and metal-free phthalocyanines were found to quite higher than unsubstituted zinc(II) phthalocyanine due to substitution of the phthalocyanine skeleton. The influence of substituent and variety of the central metal ions on spectroscopic, photophysical and photochemical properties were also determined and compared. (C) 2016 Elsevier B.V. All rights reserved.
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    Novel triazole substituted phthalocyanines showing high singlet oxygen quantum yields
    (Elsevier, 2019) Demirbas, Umit; Bayrak, Riza; Dilber, Gulsev; Mentese, Emre; Akcay, Hakki Turker
    In this study, novel triazole peripherally substituted phthalocyanine zinc(II) complexes 3(a-d) were synthesized from four different phthalonitrile derivative and characterized by FT-IR NMR, MALDI-TOF, UV-Vis methods. Aggregation-concentration relations of the compounds 3(a-d) were investigated by UV-Vis spectroscopy. Fluorescence quenching properties of the phthalocyanines 3(a-d) were studied and fluorescence quantum yields were calculated by comparative method. Photodegradation quantum yields of the compound 3(a-d) were calculated. In addition, singlet oxygen quantum yields of the compounds 3(a-d) were measured by comparative method by using 1,3-diphenylisobenzofuran (DPBF) as singlet oxygen quencher. In this work, it has been observed that the synthesized novel phthalocyanines have higher quantum yield values (the range of 0.8-0.85) compared to the Zn (II) complex of unsubstituted phthalocyanine (0.67). Especially the compound 3d substituted tolyl group has the highest singlet oxygen quantum yield (0.85) seen rarely in literature.
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    Peripherally and non-peripherally tetra-benzothiazole substituted metal-free zinc (II) and lead (II) phthalocyanines: Synthesis, characterization, and investigation of photophysical and photochemical properties
    (Elsevier, 2017) Demirbas, Umit; Gol, Cem; Barut, Burak; Bayrak, Riza; Durmus, Mahmut; Kantekin, Halit; Degirmencioglu, Ismail
    In this study, novel phthalonitrile compounds bearing 2-methylbenzofdlthiazol-5-yloxy groups (4 and 5) and their peripherally and non-peripherally tetra-substituted metal-free (6 and 7), zinc (II) (8 and 9), and lead (II) (10 and 11) phthalocyanine derivatives were synthesized and characterized for the first time. These novel compounds showed extremely good solubility in most common organic solvents. The novel phthalocyanine compounds presented excellent results from photophysical and photochemical examinations in DMF solution. Especially, the singlet oxygen quantum yield (Phi(Delta)) values of the substituted zinc (II) phthalocyanines indicate that these compounds have significant potential as photosensitizers in cancer treatment by the photodynamic therapy (PDT) technique. The fluorescence quenching behaviour of these novel phthalocyanine compounds by 1,4-benzoquinone (BQ) was also examined in DMF solution. (C) 2016 Elsevier B.V. All rights reserved.
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    Synthesis and electrochemical characterization of tetra-(5-chloro-2-(2,4-dichlorophenoxy)phenol) substituted Ni(II), Fe(II) and Cu(II) metallophthalocyanines
    (Elsevier Science Sa, 2016) Demirbas, Umit; Kobak, Rabia Zeynep Uslu; Barut, Burak; Bayrak, Riza; Koca, Atif; Kantekin, Halit
    The synthesis and characterization of novel nitrile compound (3) and peripherally tetra 5-chloro-2-(2,4-dichlorophenoxy)phenol substituted nickel(II) (4), iron(II) (5) and copper(II) (6) phthalocyanines were accomplished for the first time in this study. Electrochemical characterizations of the complexes were carried out with voltammetric and in situ spectroelectrochemical measurements. CuPc and NiPc showed common Pc based electron transfer reactions. Small potential differences were observed between the redox responses of these complexes due to the different effective nuclear charges of the metal centers. [Cl1--(FePc2-)-Pc-III] complex gave metal and Pc based electron transfer reactions. While [Cl-1-Fe(III)pc(2-)] reduced to [Cl1--(FePc2-)-Pc-II](1-), [Cl1--(FePc2-)-Pc-I](2-), and [Cl1--(FePc3-)-Pc-I](3-) during reduction reactions, a metal based ([Cl1--(FePc2-)-Pc-III]/[Cl1--(FePc2-)-Pc-IV](1+)) and then a Pc based ([Cl1--(FePc2-)-Pc-IV](1+)/[Cl1--(FePc1-)-Pc-IV](2+)) oxidation reaction was observed the cathodic potential scans. Determination of the spectra, color of the electrogenerated MPc species and peak assignments of the complexes were determinated with in situ spectroelectrochemical measurements. (C) 2016 Elsevier B.V. All rights reserved.
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    Synthesis of some new Methoxy Bridged Benzimidazolyl-Substituted phthalocyanines as potent inhibitors of urease
    (Elsevier Science Sa, 2018) Demirbas, Umit; Mentese, Emre; Sokmen, Bahar Bilgin; Bayrak, Riza; Akcay, Hakki Turker
    In this study, the novel peripherally 4-[(2-methyl-1H-benzimidazol-1-yl)methoxy] substituted Zn(II) (3) Cu(II) (4), Co(II) (5) phthalocyanines were prepared and their structures were characterized spectro-scopically. The light absorption behaviors of the synthesized compounds (3-6) were studied by UV-Vis spectroscopy in the different concentration and different solvents were studied also. In addition, the urease inhibition activities of the synthesized compounds were also investigated. Among the synthesized molecules, compound 5 showed the best inhibitory effect against jack bean urease with IC50 values of 0.0034 +/- 0.0010 mu M. (C) 2018 Elsevier B.V. All rights reserved.
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    Synthesis, aggregation and spectroscopic studies of novel water soluble metal free, zinc, copper and magnesium phthalocyanines and investigation of their anti-bacterial properties
    (Pergamon-Elsevier Science Ltd, 2014) Bayrak, Riza; Akcay, Hakki Turker; Beris, Fatih Saban; Sahin, Ertan; Bayrak, Hacer; Demirbas, Umit
    In this study, novel phthalonitrile derivative (3) was synthesized by the reaction between 4-nitrophthalonitrile (2) and a triazole derivative (1) containing pyridine moiety. Crystal structure of compound (3) was characterized by X-ray diffraction. New metal free and metallo-phthalocyanine complexes (Zn, Cu, and Mg) were synthesized using the phthalonitrile derivative (3). Cationic derivatives of these phthalocyanines (5, 7, 9, and 11) were prepared from the non-ionic phthalocyanines (4, 6, 8, and 10). All proposed structures were supported by instrumental methods. The aggregation behaviors of the phthalocyanines (4-11) were investigated in different solvents such as dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), chloroform and water. Water soluble cationic Pcs (5, 7, 9, and 11) aggregated in water and sodium dodecyl sulfate was used to prevent the aggregation. The second derivatives of the UV-Vis spectra of aggregated Pcs were used for analyzing the Q and B bands of aggregated species. Thermal behaviors of the phthalocyanines were also studied. In addition, anti-bacterial properties of the phthalocyanines were investigated. We used four gram negative and two gram positive bacteria to determine antibacterial activity of these compounds. Compound 7 has the best activity against the all bacteria with 125 mu g/mL of MIC value. Compounds 4, 6, and 10 have the similar effect on the bacteria with 250 mu g/mL of MIC value. (C) 2014 Elsevier B.V. All rights reserved.
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    Synthesis, characterization and investigation of electrochemical and spectroelectrochemical properties of peripherally and non-peripherally tetra 2-methyl-5-benzothiazole substituted nickel(II), copper(II) and cobalt(II) phthalocyanines
    (Elsevier Science Sa, 2017) Demirbas, Umit; Akyuz, Duygu; Bayrak, Riza; Barut, Burak; Koca, Atif; Kantekin, Halit; Degirmencioglu, Ismail
    In this study novel tetra 2-methyl-5-benzothiazole substituted peripherally nickel(II) (6), copper(II) (8), cobalt(II) (10) and non-peripherally nickel(II) (7), copper(II) (9), cobalt(II) (11) phthalocyanines were synthesized. These novel compounds were characterized by a combination of FT-IR, H-1 NMR and UVvis and MALDI-TOF mass spectroscopic techniques. Electrochemical measurements gave well illustrated redox responses for the Pc ring and/or metal center of the complexes. While MPc bearing redox inactive metal centers underwent [(MPc-2)-Pc-II]/[(MPc-3)-Pc-II](1-), [(MPc-3)-Pc-II](1-)/[M(II)Pc(-)4](2-), [(MPc-4)-Pc-II](2-)/[(MPc-5)-Pc-II](3-) and [(MPc-2)-Pc-II](1-)/[(MPc-1)-Pc-II](1+) redox couples. (CoPc)-Pc-II illustrated [(CoPc-2)-Pc-II]/[(CoPc-2)-Pc-I](1-), [(CoPc-2)-Pc-I](1-)/[(CoPc-3)-Pc-I](2-), [(CoPc-3)-Pc-I](2-)/[(CoPc-4)-Pc-I](3-) and [(CoPc-2)-Pc-II]/[(CoPc-2)-Pc-II](1+) redox couples respectively during reduction and oxidation processes respectively. Position of the substituents altered the chemical and electrochemical reversibility of the redox processes. While the substituents were non-peripheral position, the complexes aggregated and both of the redox processes of the aggregated and nonaggregated species were observed, incorporation of the substituents to peripheral position decreased aggregations of the complexes, therefore MPcs substituted at peripheral positions illustrated well resolved reversible redox reactions. In situ spectroelectrochemical results illustrated that electrogenerated MPc species had distinct color differences.
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    The determination of photophysical and photochemical parameters of novel metal-free, zinc(II) and lead(II) phthalocyanines bearing 1,2,4-triazole groups
    (Elsevier Science Sa, 2016) Demirbas, Umit; Piskin, Mehmet; Bayrak, Riza; Unluer, Dilek; Dugdu, Esra; Durmus, Mahmut; Kantekin, Halit
    In this study the synthesis and characterization of novel phthalonitrile compound (3) and its metal-free (4), zinc(II) (5), and lead(II) (6) phthalocyanines bearing four 4-(4-methoxyphenylethyl)-5-propyl-2,4-dihydro-3H-1,2,4-triazol-3-one groups at peripheral positions were synthesized for the first time. These novel compounds were fully characterized by FT-FT-IR, H-1 NMR, UV-vis and MALDI-TOF mass spectroscopic techniques. Their photochemical and photophysical properties were also investigated in N, N-dimethylformamide solutions. In addition, the effect of 4(4-methoxyphenylethyl)-5-propyl-2,4dihydro-3H-1,2,4-triazol-3-one groups as substituents and central metal ions (without metal, zinc(II) or lead(II)) in the phthalocyanine cavity on these properties were also compared. The studied zinc(II) or lead (II) phthalocyanines can be potential Type II photosensitizers for photodynamic therapy in cancer applications because these phthalocyanines showed good singlet oxygen generation and appropriate photodegradation. (C) 2016 Elsevier B.V. All rights reserved.
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    Zinc(II) and lead(II) phthalocyanines bearing thiadiazole substituents: Synthesis, characterization, photophysical and photochemical properties
    (Elsevier, 2019) Demirbas, Umit; Piskin, Mehmet; Bayrak, Riza; Durmus, Mahmut; Kantekin, Halit
    In this study; phthalonitrile compounds 4-((5-methyl-1,3,4-thiadiazol-2-yl)thio)phthalonitrile (4) and 3-((5-methyl-1,3,4-thiadiazol-2-yl)thio)phthalonitrile (5) were synthesized. These compounds were converted to their respective peripherally and non-peripherally tetra-substituted zinc(II) (6 and 7) and lead(II) (8 and 9) phthalocyanine derivatives. The novel phthalocyanine complexes were characterized by using different spectroscopic techniques including FT-IR, UV-Vis, H-1 NMR and mass. The spectroscopic, photochemical and photophysical properties of the phthalocyanines were investigated for determination of their potential as photosensitizers for photodynamic therapy. In addition, the effects of the substituent, binding position and the variety of central metal ions in phthalocyanine core on photochemical and photophysical properties were determined. (C) 2019 Elsevier B.V. All rights reserved.