Person: KOCA, ATIF
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KOCA
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ATIF
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Publication Metadata only Electrochemistry of novel tetra peripherally and non-peripherally substituted phthalocyanines bearing morpholine groups(ELSEVIER SCIENCE SA, 2020) KOCA, ATIF; Akyuz, Duygu; Demirbas, Umit; Akcay, Hakki Turker; Koca, Atif; Kantekin, HalitMorpholine bearing phthalonitriles (3a and 3b) and peripherally and non-peripherally tetra substituted TiOPc and CuPc complexes (4a-5b) were prepared. Electrochemical responses of metallophthalocyanines were analysed and compared with each other in order to determine the influence of Cu2+ and TiO2+ metal centers and peripherally or non-peripherally substituents of the complexes. While CuPcs illustrated common Pc based reduction processes, TiOPcs showed extraordinary reduction peaks. During the oxidation processes, all complexes were electropolymerizable and metal centers and nonperipherally or peripherally substituents considerably affect electropolymerization processes. However, it was clearly seen that changing the positions of the substituents did not extensively influence the reduction processes. (C) 2020 Elsevier B.V. All rights reserved.Publication Metadata only Photoelectrochemical Performance of Cd0.8Zn0.2SxSe1-x Photoelectrodes Fabricated by Electrodeposition Method(2022-01-25) BUDAK, ÖZLEM; UĞUZ NELİ, ÖZLEM; KOCA, ATIF; Budak Ö., Uğuz Neli Ö., Koca A.Publication Open Access Synthesis, electrochemistry, and electrocatalytic activity of thiazole-substituted phthalocyanine complexes(2022-03-01) KOCA, ATIF; Demir F., Yenilmez H. Y., KOCA A., Bayır Z.We report the synthesis of non-peripheral metallophthalocyanines which carry four 4-(4-methoxyphenyl)-2-thiazole-2-thio units. H-1-NMR, FT-IR, UV-Vis, and MS data were acquired to characterize the synthesized compounds. Voltammetric and in situ spectroelectrochemical measurements shed light on the redox properties of the metallophthalocyanines (MPcs) in order to show the influence of the metal cations and thiazole-bearing substituents. In solution, the redox processes had an influence to the electrochromic responses, which were examined with in situ spectrocolorimetry. Phthalocyanines having cobalt (II), manganese (III), iron (III), and zinc (II) at the center yielded characteristic redox couples which are metal- and/or Pc-based and which are harmonious with the common redox properties of these types of compounds. In situ spectroelectrochemistry provided the information that MPc species underwent distinct color changes during electron transfer reactions. Electropolymerization of all complexes was performed on glassy carbon electrode, and the electropolymerized film of FePc was evaluated as an active electrocatalyst, in the alkaline medium, for oxygen evolution reaction (OER).Publication Metadata only Electrochemistry of Novel Phthalocyanines Bearing 1,2,4 Triazole Groups(WILEY-V C H VERLAG GMBH, 2020) KOCA, ATIF; Akyuz, Duygu; Demirbas, Umit; Akcay, Hakki Turker; Mentese, Emre; Koca, Atif; Kantekin, HalitThe phthalonitrile (3) and triazole substituted metallo phthalocyanines (MPc) (4-7) were prepared. The novel compounds were characterized with spectroscopic data. Electrochemical analyses of metallophthalocyanines (4-7) bearing triazole substituents were performed to investigate redox activity of phthalocyanines (Pcs) ring. While incorporation of Ni(2+)and Cu(2+)cations in the Pc core only influenced peak positions of Pc ring processes, Co(2+)and Cl(1-)Fe(3+)cations of CoPc and FePc gave extra redox couples to the Pc based ones. Releasing the axial Cl(1-)anion on Fe(3+)cation of FePc during the reduction reactions complicated the redox responses. Redox reactions of Co(2+)and Fe(3+)metal centers also considerable influenced spectral and color responses of these complexes.Publication Open Access Electro-stimulated drug release by methacrylated hyaluronic acid-based conductive hydrogel with enhanced mechanical properties(2023-03-15) AYCAN, DİDEM; KARACA ALBAYRAK, FATMA; KOCA, ATIF; ALEMDAR YAYLA, NESLİHAN; AYCAN D., KARACA ALBAYRAK F., KOCA A., Alemdar N.© 2023 Elsevier B.V.Recently, the design of stimuli-responsive hydrogels for controlled drug delivery systems has been extensively investigated to meet therapeutic needs and optimize the release pattern of the drug. Being a natural polyelectrolyte, hyaluronic acid (HA) is excellent potential to generate new opportunities for electro-responsive drug carrier applications. In the current study, HA-based electroconductive hydrogel was developed as a novel smart drug carrier for anti-inflammatory drug release by the combination of in-situ and post polymerization mechanisms. HA was modified through methacrylation reaction to introduce photocrosslinkable groups into its structure and then reduced graphene oxide (rGO) was encapsulated into methacrylated HA (HA/MA) hydrogel by using the photopolymerization technique. In the post polymerization process, polyaniline (PANI) was incorporated/loaded into HA/MA-rGO polymeric network produced in previous step. The produced HA/MA-rGO-PANI hydrogel exhibited sufficient electrical conductivity providing the desirable electro-responsive ability for Ibuprofen (IBU) release. Furthermore, it has superior mechanical performance compared to pure (HA/MA) and rGO containing (HA/MA-rGO) hydrogels. IBU release from the hydrogel was successfully triggered by electrical stimulation and the cumulative drug release also enhanced by increasing of the applied voltage. These results highlighted that the novel HA/MA-rGO-PANI hydrogel could be a promising candidate for electrical-stimulated anti-inflammatory release systems in neural implant applications.Publication Metadata only Electrochemical and spectroelectrochemical characterizations of new tetra-substituted metallophthalocyanines bearing 4-(trifluoromethoxy)phenoxy groups on non-peripheral positions(SPRINGER WIEN, 2020) KOCA, ATIF; Farajzadeh, Nazli; Akyuz, Duygu; Koca, Atif; Kocak, Makbule BurkutIn this study, a series of non-peripherally tetra-substituted phthalocyanines [M = Zn(II), Co(II), and In(III)] was successfully prepared by cyclotetramerization of the phthalonitrile derivative bearing 4-(trifluoromethoxy)phenoxy group at 3-position. All newly synthesized compounds were characterized using spectroscopic methods, such as FT-IR, NMR, and UV-Vis spectroscopy. The effect of concentration on aggregation properties of the resulting phthalocyanines was investigated in different concentrations ranging from 4 x 10(-6)to 14 x 10(-6) M in THF. In addition, the spectral properties of the metallophthalocyanines were studied in various organic solvents. Besides, redox responses of metallophthalocyanines and their electro-optical responses were determined. Although {1(4),8(11),15(18),22(25)-tetrakis[4-(trifluoromethoxy)phenoxy]phthalocyaninato}cobalt(II) showed well-resolved reversible redox peaks depicting the anticipated electron transfer reactions, electrochemical investigation of its zinc(II) and indium(III) chloride analogs resulted in complex redox waves, and their chemical reversibility decreased with the aggregation of the complexes. The influence of the redox processes on the optical responses of metallophthalocyanines was studied with in situ spectroelectrochemistry measurements and the peak assignments and optical responses of the electrogenerated species were determined. [GRAPHICS] .Publication Open Access Non-peripheral tetra methoxylated pyrazoline bearing Co-II, Cu-II and (MnCl)-Cl-III phthalocyanines: Syntheses, electrochemistry and spectroelectrochemistry(2022-08-01) BUDAK, ÖZLEM; KOCA, ATIF; Yalazan H., KANTEKİN H., BUDAK Ö., KOCA A.The novel and highly soluble cobalt(II), copper(II) and manganese(III) phthalocyanines ((Pc-Co, Pc-Cu, and Pc-Mn) bearing 3-(5-(3,5-dimethoxyphenyl)-1-phenyl-4,5-dihydro-1H-pyrazol-3-yl)phenol have been synthesized and characterized by FT-IR, NMR, UV-Vis and mass spectroscopic methods. Additionally, electrochemical and spectroelectrochemical properties of these phthalocyanine compounds were investigated. Due to the redox inactivity of the Cu2+ central cation of (Pc-Cu), Pc based reductions and oxidation processes are recorded. [(CoPc2-)-Pc-II]/[(CoPc2-)-Pc-I](1-) and [(CoPc2-)-Pc-II]/[(CoPc2-)-Pc-III](1+) couples for the central metal redox reactions, and [(CoPc2-)-Pc-I](1-)/[(CoPc3-)-Pc-I](2-), [(CoPc3-)-Pc-I](2-)/[(CoPc4-)-Pc-I](3-) and [(CoPc2-)-Pc-III](1+)/[(CoPc1-)-Pc-III](2+) couples for the Pc based reduction and oxidation are observed respectively with (Pc-Co). Like (Pc-Co), (Pc-Mn) also illustrated metal-based reduction processes, [Cl1--(MnPc2-)-Pc-III]/[Cl1--(MnPc2-)-Pc-II](1-) and [Cl1--(MnPc2-)-Pc-II](1-)/[Cl1--(MnPc2-)-Pc-I](2-) in addition to the Pc based [Cl1--(MnPc2-)-Pc-I](2-)/[Cl1--(MnPc3-)-Pc-I](3-), [Cl1--(MnPc3-)-Pc-I](3-) /[Cl1--(MnPc4-)-Pc-I](4-) and [Cl1--(MnPc2-)-Pc-III]/[Cl1--(MnPc1-)-Pc-III](1+) redox couples were also recorded. These redox mechanisms were supported with the characteristic spectral changes observed during the in-situ spectroelectrochemical measurements. Especially metal-based electron transfer changes caused distinct spectral and color changes, which are the desired properties of the complexes for the possible opto-electrochemical applications. (C) 2022 Elsevier B.V. All rights reserved.Publication Open Access Influence of 2-naphthoic acid anchoring groups to the photovoltaic performance of zinc phthalocyanine-based photosensitizers in dye-sensitized solar cell(2023-09-15) KOCA, ATIF; Köse G. G., Karaoğlan G. K., Maden Y. E., KOCA A.Two different zinc phthalocyanines bearing different numbers of 2-naphthoic acid anchoring groups at the peripheral positions were synthesized and characterized with UV–Vis, proton nuclear magnetic resonance (1H NMR), fouirer transform infrared (FT-IR), and matrix-assisted laser desorption/ionization mass (MALDI-TOF MS) spectroscopy. Then their electrochemical, and spectroelectrochemical performances were investigated to predict their suitability of them as photosensitizers in dye-sensitized solar cells (DSSC). In the voltammetric analysis results, [2,9,16-Tri-(4-carboxyethylphenoxy)-23-(4-[6-carboxy-2-naphtoxy]) substituted zinc(II) phthalocyanine (ZnPc(3)) and [2,9,16,23-tetra-(4-(6-carboxy-2-naphthoxy) substituted zinc(II) phthalocyanine (ZnPc(4)) illustrate similar electron transfer processes. The substituent environments of the complexes slightly influenced the position and reversibility of the redox couples. Redox processes of ZnPc(3) bearing unsymmetrical carboxyethylphenoxy and 2-naphthoic acid anchoring groups slightly shift towards the positive potentials concerning ZnPc(4) bearing symmetrical 2-naphthoic acid substituents. Peak positions of both complexes reflecting the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) positions indicate the suitability of the complexes for the efficient charge carrier transferring from these photosensitizers to the semiconductor and redox mediator in the DSSC. Pc-based spectroelectrochemical responses of the complexes supported the HOMO and LUMO positions for both neutral and electrogenerated ZnPc species. DSSC responses indicated that ZnPc(3), which has the asymmetric carboxyethylphenoxy and 2-naphthoic acid substituents, gave higher DSSC efficiency with short-circuit photocurrent density (JSC) (9.54 mA cm−2), open circuit potential (VOC) (697 mV), fill factor (FF) (51%), incident monochromatic photon-to-current conversion efficiency (IPCE) (51%), and power conversion efficiency (ƞ) (3.4%) parameters concerning ZnPc(4) bearing symmetric 2-naphthoic acid anchoring groups.Publication Metadata only New asymmetric bisthiocarbohydrazones and their mixed ligand nickel(II) complexes: Synthesis, characterization, crystal structure, electrochemical-spectroelectrochemical property, antimicrobial and antioxidant activity(PERGAMON-ELSEVIER SCIENCE LTD, 2021) KOCA, ATIF; Kaya, Yeliz; Ercag, Ayse; Uguz, Ozlem; Koca, Atif; Zorlu, Yunus; Hacioglu, Mayram; Tan, Ayse Seher BirteksozNew asymmetric isatin bisthiocarbohydrazone ligands were synthesized by the condensation of 3,5-dibromosalicylaldehyde, 3,5-dichlorosalicylaldehyde and 3-bromo-5-chlorosalicylaldehyde with isatin monothiocarbohydrazone. New mixed ligand Ni(II) complexes were synthesized from these ligands using triphenylphosphine (PPh3) as a secondary ligand. The synthesized ligands and complexes were characterized by elemental analysis, FT-IR, H-1 NMR, UV-Vis spectroscopy and mass spectrometry techniques, along with conductivity measurements. The ligands bind to the Ni(II) ion as ONS donors. The fourth coordination site is completed by the secondary ligand PPh3. The single crystal structures of one ligand and one complex were also resolved by X-ray crystallography. The electrochemical responses of the ligands and their complexes were determined and the results were evaluated to illustrate the influence of the substitution of different groups on the ligands. While the free ligands only give one oxidation peak, two oxidation peaks are observed for the Ni(II) complexes. Complexation of the ligands with the Ni(II) ion considerably affected the in-situ spectroelectrochemical responses of the ligands. Finally, the in vitro antioxidant and antimicrobial activities of the synthesized compounds were determined.Publication Open Access Crystal structures, antioxidant, electrochemical and in-situ spectroelectrochemical properties of new bisthiocarbohydrazones and their Ni(II) complexes(2023-05-01) UĞUZ NELİ, ÖZLEM; KOCA, ATIF; KAYA Y., ERÇAĞ A., Uğuz Ö., Zorlu Y., KOCA A.© 2023 Elsevier B.V.Four new isatin bisthiocarbohydrazone ligands (H2L1, H2L2, H2L3, H2L4) were synthesized by the condensation of salicylaldehyde, 5-bromosalicylaldehyde, 5-chlorosalicylaldehyde and 5-nitrosalicylaldehyde with isatin monothiocarbohydrazone, respectively. The mixed ligand Ni(II) complexes {[NiL1(P)], [NiL2(P)], [NiL3(P)] and [NiL4(P)]} containing triphenylphosphine (P: triphenylphosphine, PPh3) of these bisthiocarbohydrazone ligands were synthesized. The synthesized compounds were characterized by elemental analysis, FT-IR, 1H NMR, UV–Vis spectroscopy techniques and conductivity measurements. In the complexes, the bisthiocarbohydrazone ligands coordinate to nickel through ONS mode. The complexes are diamagnetic and exhibit square planar geometry. The crystal structures of two ligands, H2L1 and H2L3, and two complexes, [NiL1(P)] and [Ni3(L3)2(P)2], whose single crystals were obtained, were determined by single crystal X-ray diffraction technique. The crystal structure of [NiL1(P)] complex is monomeric and compatible with the structure of the solid complex. A new trinuclear Ni(II) complex, [Ni3(L3)2(P)2], was obtained by the crystallization of monomeric solid [NiL3(P)] complex in a different solvent mixture. Redox properties of bisthiocarbohydrazone ligands (H2L1-H2L4) bearing S1 or S2 substituents and their nickel(II) complexes {[NiL1(P)]-[NiL4(P)]} were investigated with cyclic voltammetry and in situ spectroelectrochemistry. Voltammetric analyses indicated that all ligands exhibited four quasi-reversible reduction and one irreversible oxidation process. Complexation of the ligands with Ni(II) cation decreased the number of the reduction processes and caused these processes to have more negative potentials. Significant spectral changes were also observed in the in situ spectroelectrochemical analysis due to electron transfer reactions. In addition, electrochemical responses of monosubstituted salicylaldehyde derivative isatin bisthiocarbohydrazone ligands and their nickel(II) complexes were compared with their disubstituted derivatives.