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Öğe New dye sensitized photocatalysts: Copper(II)-phthalocyanine/TiO2 nanocomposite for water remediation(Elsevier Science Sa, 2016) Albay, Cansu; Koc Kesir, Melek; Altin, Ilknur; Bayrak, Riza; Degirmencioglu, Ismail; Sokmen, MunevverIn this study, a group of novel copper azomethyn-bridged phenolic phtalocyanines (CuPc) were synthesized. These derivatives are completely new, synthesis and characterization studies are first time reported. Four derivatives which have peripheral or non-peripheral substitution on macrocyclic ring were produced and characterized employing various spectroscopic methods. CuPc were immobilized on TiO2 nanoparticles to obtain dye sensitized photoactive nanocomposites (1% of the mass of TiO2). Prepared composites were characterized by SEM, EDX, UV-vis, DRS and XRD analysis. Results revealed that the composites possess anatase structure and phthalocyanine loading on TiO2 exposes strong visible light absorption. Photocatalytic activities of the produced composite materials were tested for reduction of Cr(VI) as a model pollutant and its disinfection properties were investigated using Escherichia coli as a model microorganism employing a near visible UV-A light (365 nm) source. All composite materials exhibited much more photocatalytic activity than bare TiO2 for both pollutants. (C) 2016 Elsevier B.V. All rights reserved.Öğe 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, IsmailIn 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.Öğe Preparation of phthalocyanine/TiO2 nanocomposites for photocatalytic removal of toxic Cr(VI) ions(Elsevier, 2016) Bayrak, Riza; Albay, Cansu; Koc Kesir, Melek; Altin, Ilknur; Degirmencioglu, Ismail; Sokmen, MunevverIn this study, a group of novel metal free azomethine-bridged phenolic phthalocyanines (H2Pc) was synthesized. These derivatives are completely new and first time reported. Four derivatives at peripheral or non-peripheral substitution on macro cyclic ring were synthesized and characterized employing various spectroscopic methods. H2Pc derivatives (defined as H2Pc-1, H2Pc-2, H2Pc-3, H2Pc-4) were immobilized on TiO2 nanoparticles to obtain photoactive nanocomposites (H2Pc/TiO2, 1% of the mass of TiO2). H2Pc derivatives were used as photosensitizer to improve the near visible-light photocatalytic efficiency of TiO2 catalyst in wastewater treatment. Photocatalytic abilities nanocomposites were tested for photocatalytic reduction of chromium (VI) ions (10 mg/L) and compared with neat TiO2. A near UV light source (365 nm) was used for illumination in a batch reactor and Cr(VI) concentration was monitored during 150 min treatment period. It is clear that H2Pc sensitized photocatalyst is effective for the reduction of chromium ions. Removal percentages were between 83.70 and 99.75% indicating almost total reduction of toxic Cr(VI) ions. Neat TiO2 was able to reduce only 55.43% of initial Cr(VI) ions. All phthalocyanine containing TiO2 composites are significantly more effective and reduce more Cr(VI) ions than TiO2 itself. Photocatalytic action of the catalysts is decreased in the following order H2Pc-4/TiO2 > H2Pc-2/TiO2 > H2Pc-1/TiO2 > H2Pc-3/TiO2. (C) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.Öğe Redox-Switchable New Phthalocyanines Containing Hydrazono-Thiazole-Carboxylate Fragments: Synthesis, Electrochemical, Spectroelectrochemical and Electrocolorimetric Investigation(Springer/Plenum Publishers, 2017) Degirmencioglu, Ismail; Er, Mustafa; Bayrak, Riza; Ozkaya, Ali RizaNew phthalonitrile compound with Schiff base, carbothioamide and thiazole moieties as substituents and its corresponding metal-free and metallophthalocyanines (Zn(II), Ni(II), Co(II), and Cu(II)) were synthesized and characterized for the first time. The solubilities of these novel phthalocyanines were high in organic solvents. The redox properties of the compounds have been researched by cyclic voltammetry, square wave voltammetry, controlled-potential coulometry and in situ spectroelectrochemistry in dimethylsulfoxide. The compounds displayed metal and/or phthalocyanine ring-based, generally reversible or quasi-reversible reduction and oxidation processes. The effect of aggregation on the redox behavior of these complexes was also discussed. In general, decreased intensity and broadening in the main Q absorption band and the appearance of a new blue-shifted band confirmed the presence of H-type aggregates in the solutions of the complexes 4, 6 and 8 in DMSO/TBAP. The color changes associated with the redox processes and electrogenerated anionic and cationic redox species were also recorded with in situ electrocolorimetric measurements. In situ UV-vis spectral and associated color changes monitored during the reduction processes of the complexes suggested their applicability in the fields of the electrochemical technologies.Öğe Substituted phthalocyanines and their electropolymerization properties(Elsevier Science Sa, 2016) Bayrak, Riza; Akcay, Hakki Turker; Biyiklioglu, Zekeriya; Degirmencioglu, IsmailIn this study, new metal-free and metallo-phthalocyanine complexes (Co, TiO) were synthesized using a piperazine-substituted phthalonitrile derivative. All proposed structures were supported by instrumental methods. Electrochemical studies of H-2-Pc, (TiOPc)-O-IV, and (COPc)-Pc-II were examined using cyclic voltammetry (CV) and square-wave voltammetry (SWV) techniques. Voltammetric analyses of phthalocyanines supported the proposed structure of the synthesized complexes. All studied phthalocyanines were oxidatively electropolymerized on the working electrode during the repetitive anodic potential scans. (C) 2016 Elsevier B.V. All rights reserved.Öğe Synthesis and Spectro-Electrochemical Properties of New Metallophthalocyanines Having High Electron Transfer Capability(Elsevier, 2021) Bayrak, Riza; Atasen, Secil Kirlangic; Yilmaz, Ismail; Yalcin, Izzet; Erman, Murat; Unver, Yasemin; Degirmencioglu, IsmailIt is important to synthesis and examine the redox properties of phthalocyanines and related macrocycles in order to reveal their possible applications. In this paper, new Zn2+, Co2+ and Mn2+ phthalocyanine complexes containing substituted 1,2,4-triazole groups on peripheral positions have been prepared and characterized by classical methods and electrochemistry in detail. The use of triethylamine and acetone combination in the synthesis of nitrile structures 3a and 3b , the starting compounds for phthalocyanines, both increased yield of products and shortened reaction time compared to classical synthesis of nitrile structures. The electron transfer capability of new metallophthalocyanines (ZnPcs, CoPcs and MnPcs) was investigated in detail via cyclic voltammetry (CV), square wave voltammetry (SWV) and in situ UV-vis spectroelectrochemistry. For ZnPcs, these experiments demonstrated that the complexes exhibited three well-defined reductions and two oxidations waves based on the Pc ring electroinactive nature of the Zn metal coordinated to the macrocycle. For CoPcs showed three reductions and one oxidation based on both the Pc ring and electroactive nature of Co center. Furthermore, MnPcs displayed three well-defined reductions and two oxidations waves based on either the Pc ring or electroactive Mn center. (C) 2020 Elsevier B.V. All rights reserved.Öğe Synthesis of axially disubstituted silicon phthalocyanines and investigation of photodynamic effects on HCT-116 colorectal cancer cell line(Elsevier, 2018) Sari, Ceren; Eyupoglu, Figen Celep; Degirmencioglu, Ismail; Bayrak, RizaPhotodynamic therapy is one of the hot topics in cancer studies. Photosensitizing chemical substrates are stimulated by light having a specific wavelength to cause fatal effect on different kinds of targets. In this study, axially 4-{[(1E)-2-furylmethylene]aminol}phenol, 4-{[(1E)-2-thienylmethylene]aminol}phenol and 4-{[(1E)-(4-nitro-2-thienyl)methylene]amino}phenol disubstituted silicon phthalocyanines were synthesized as Photosensitizers for photodynamic therapy in cancer treatment. The structural characterizations of these novel compounds were performed by a combination of FT-IR, H-1-NMR, UV-vis and mass. All these newly prepared compounds did not show aggregation at the concentration range of 2 x 10(-6) - 12 x 10(-6) M in tetrahydrofurane and also did not show aggregation in different organic solvents at 2 x 10(-6) M concentration. Phthalocyanines synthesized in this study were tested on HCT-116 colorectal cancer cells and stimulated by light has wavelength of 680 nm. The toxic effects on cancer cells which are caused by different concentrations of photosensitizing molecules have been examined and compared with the toxic effects on cancer cells that were kept in the dark. It is confirmed that these molecules caused toxic effects on colorectal cancer cells when they were stimulated by light but there was no toxic effect in the dark.Öğe 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, IsmailIn 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.Öğe Use of azomethine-bridged phenolic metallophthalocyanines for sensitization of TiO2(Desalination Publ, 2017) Koc Kesir, Melek; Albay, Cansu; Altin, Ilknur; Bayrak, Riza; Gokce, Halil; Degirmencioglu, Ismail; Sokmen, MunevverA group of novel azomethine-bridged phenolic metallophtalocyanines (substituted at -nonperipheral position, MPc) were synthesized, characterized and used as sensitizer. Phthalocyanine derivatives (containing TiO(II), Fe(II), Co(II), Ni(II) and Zn(II) ions in the center of phtalocyanine) were immobilized on TiO2 photocatalyst using a wet deposition method. MPc/TiO2 nanocomposites have been tested for their photocatalytic reduction ability of Cr(VI) ions in aqueous solution under near visible light irradiation. The results demonstrated that the presence of the sensitizer is certainly beneficial for the photocatalytic activity of TiO2, confirming the significant role of substitution and metal-co-ordination in the center of the phthalocyanine ring. Photoreduction results show that the all composite materials exposed significantly higher Cr(VI) removal performance than bare TiO2-Consequently, MPc sensitized TiO2 nanocomposites may be good alternatives for efficient photocatalysis that can be used for wastewater treatment processes.
