Person: KOCA, ATIF
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KOCA
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ATIF
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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 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 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 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.Publication Open Access Improved photoelectrochemical hydrogen production performance of reduced graphene oxide-cadmium zinc sulfoselenide photoelectrodes prepared by a Facile In-situ Electrosynthesis method(2023-08-01) BUDAK, ÖZLEM; KOCA, ATIF; NELİ Ö. U., BUDAK Ö., KOCA A.Cadmium zinc sulfoselenide, CdZnSSe, and reduced graphene oxide-cadmium zinc sulfoselenide (RGO)-CdZnSSe composite-based photoelectrodes are fabricated using a facile, simultaneous co-electrodeposition by repetitive cyclic voltammetric (rCV) for the first time in literature. With this method, CdZnSSe particles are homogeneously decorated among the RGO sheets by controlling the composition of the composite structure and the film thickness with rCV. Photoelectrochemical, optical, and structural properties of photoelectrodes are evaluated to investigate their usability in photoelectrochemical hydrogen evolution. Decorating Cd0.8Zn0.2S0.2Se0.8 among RGO sheets leads to a slight red-shift of the absorption edge because of the less transparency of fabricated photoelectrode which decreases the band gap of composites. Among all Cd0.8Zn0.2SxSe1-x (x = 0.0, 0.2, 0.5, 0.8, 1.0) photoelectrodes, Cd0.8Zn0.2S0.2Se0.8 demonstrates the sharp rise in photocurrent density (4.08 mA cm−2). Decorating Cd0.8Zn0.2S0.2Se0.8 with RGO at an optimum composition jumps the photocurrent density up to 5.00 mA cm−2 in addition to the improved stability. The long-term stability of RGO(0.25)-Cd0.8Zn0.2S0.2Se0.8 is reported as 89.8% at the end of the 48th hour. The applied bias photon to current efficiency (ABPE) and Faradaic efficiency are obtained as 3.07% and 89.9%. Enhanced photoelectrochemical performance indicates the superiority of the proposed rCV technique for the fabrication of well-controlled photoelectrodes consisting of RGO[sbnd]CdZnSSe composites.Publication Open Access Novel silicon phthalocyanine photosensitizers containing carboxylic acid based axial anchoring groups: Electrochemistry, spectroelectrochemistry, and dye sensitized solar cell performance(2022-11-01) ERDAĞ MADEN, YAREN; KOCA, ATIF; GÜMRÜKÇÜ KÖSE G., KESER KARAOĞLAN G., ERDAĞ MADEN Y., KOCA A.In this study, two novel silicon phthalocyanines (SiPc) having axial anchoring groups (3: SiPc carrying bis-dibutyl phenoxy acrylic acid and 5: SiPc carrying bis-dibutyl phenoxy carboxylic acid) are synthesized as the photosensitizers of dye sensitized solar cells (DSSCs). The obtained novel photosensitizers are elucidated by using 1H NMR, MALDI-TOF, FT-IR, UV-Vis spectroscopy, and elemental analysis. Moreover, the electrochemistry of SiPcs is investigated with voltametric and in-situ spectroelectrochemical analysis. Both SiPcs illustrate similar two reductions and one oxidation Pc based redox processes. In-situ spectroelectrochemical results support the Pc based characters of the voltametric responses. The chromaticity diagrams and optical responses of the anionic and cationic moieties are recorded with the in-situ spectroelectrochemistry to determine the viability of them for various photoelectrochemical usage. Finally, SiPcs are investigated as dyes in DSSCs in order to investigate the influence of bis-dibutyl phenoxy acrylic acid and bis-dibutyl phenoxy carboxylic acid anchoring groups to the photovoltaic performance of SiPcs. DSSCs sensitized with SiPc (3) and SiPc (5) illustrate good photovoltaic performance with 1.48 and 1.99 mA/cm2 short circuit current density, 0.751 and 0.657 V open circuit potential, 0.52 and 0.57 fill factor, and 0.57% and 0.75% power conversion efficiency respectively.Publication Open Access A detailed experimental and computational study of Cd complexes with pyridyl-based thiazolyl hydrazones(2022-11-01) UĞUZ NELİ, ÖZLEM; KOCA, ATIF; Kokanov S. B. , Filipovic N. R. , Visnjevac A., Nikolic M., Novakovic I., Janjic G., Hollo B. B. , Ramotowska S., Nowicka P., Makowski M., et al.Interest in Cd complexes has been growing in recent years. Cd complexes are considered a potential solution in the search for novel antibiotics that can fight antimicrobial resistance. In addition, Cd complexes draw attention to material chemistry. The main objective of this work was to prepare the first Cd(II) complexes with anionic forms of pyridine-based thiazolyl hydrazone (THs) ligands HLS2 [(E)-4-(4-methoxyphenyl)-2-(2-[pyridine-2-ylmethylene]hydrazinyl)thiazole] and HLS3 [(E)-2-(2-[pyridine-2-ylmethylene]hydrazinyl)-4-(p-tolyl)thiazole] and perform their structural and spectroscopic characterization, as well as stability in solution and upon heating. Studies related to their biological activities and possible electrochromic applications are also being conducted. Complexes [Cd(HLS2)(2)] (1) and [Cd(HLS3)(2)] (2) have been characterized by a single-crystal X-ray diffraction and computational analysis of intermolecular interactions responsible for their solid-state structures was performed. Thermal stability of 1 and 2 in the solid-state was analyzed by TGA/MS, where as their solution stability was determined by the spectrophotometric titration method. Electrochemical and in situ UV-Vis spectroelectrochemical analyses of 1 and 2 were carried out to determine redox mechanisms and the influence of the substituents and electrolytes on their redox responses. The antioxidant capacity of both complexes was tested in antioxidant assays, while their antimicrobial activity was tested against five Gram-positive and four Gram-negative bacteria, as well as against three fungi. The obtained results indicate their potent antioxidant capacity. The antimicrobial activity of investigated compounds on almost all tested bacterial strains was stronger than that of the standard antibiotic erythromycin. The results of docking studies indicate that the minor groove DNA is the possible biological target of 1 and 2.Publication Open Access Synthesis, characterization, electrochemical, spectroelectrochemical and dye-sensitized solar cell properties of Phthalocyanines Containing Carboxylic Acid Anchoring Groups as photosensitizer(2022-08-01) ERDAĞ MADEN, YAREN; KOCA, ATIF; Karaoglan G. K., Hisir A., ERDAĞ MADEN Y., Karakus M. O., KOCA A.Peripherally tetra-4-carboxyethylphenoxy substituted oxotitanium (IV), cobalt(II), zinc(II) and metal free phthalocyanines were synthesized to research the sensitizing abilities of these dye molecules in standard dye sensitized solar cells (DSSCs). All the synthesized phthalocyanine complexes have been characterized by using elemental analyses, UV-Vis, FT-IR, H-1 NMR and MALDI-TOF MS spectroscopic techniques. Electrochemistry of metallo phthalocyanines (MPcs) were studied with electrochemical and in-situ spectroelectrochemical measurements. H2Pc (7) and ZnPc (5) illustrated similar Pc based electron transfer reactions. Differently, CoPc (6) and TiOPc (4) illustrated metal based redox reactions, which enhanced the redox functionality of these complexes. Metal based reductions for CoPc (6) and TiOPc (4) were recorded in addition to the Pc based one. In-situ spectroelectrochemical measurements supported the proposed voltametric mechanism. Moreover, the color and spectra of the electrogenerated species were determined with the in-situ spectroelectrochemical analyses to predict possible optoelectrochemical application of the complexes. Pronounced optical and color changes during the electrolysis of the complexes indicated electrooptical and possible solid state electrochemical functionality of the complexes. TiO2 semiconductor on the fluoride doped indium tin oxide coated glass electrode (FTO) was decorated with H2Pc (7) and TiOPc (4) bearing four carboxyl anchoring groups and they were first of all tested as possible dye for the DSSC. H2Pc (7), TiOPc (4), CoPc (6) and ZnPc (5) dyes used in DSSCs showed 2.9%, 3.3%, 1.02% and 2.2% of power conversion efficiencies respectively.Publication Open Access Utilization of pyrazole-perimidine hybrids bearing different substituents as corrosion inhibitors for 304 stainless steel in acidic media(2022-08-15) UĞUZ NELİ, ÖZLEM; KOCA, ATIF; Ugus Ö., GÜMÜŞ M., SERT Y., KOCA İ., KOCA A.© 2022Water soluble Pyrazole-Perimidine (PYR-PER) hybrids bearing various anchoring groups has been synthesized and their corrosion inhibitive efficiencies for the 304 stainless steel in 1.0 M hydrochloric acid has been investigated by the electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), open circuit potential (OCP) measurements, and Density Functional Theory (DFT) B3LYP functional combined with 6-311++G(d,p) basis set. The analyses show that all PYR-PER hybrids effectively reduced the corrosion current density, increased corrosion resistance and inhibited the corrosion of the 304 stainless steel in 1.0 M hydrochloric acid at 298 K. The results indicated that the hybrids functioned as a mixed type inhibitors with anodic suppression outweighing the cathodic one. Multi-functional heteroatoms and methyl, fluoride, chloride, and bromide substituents of pyrazole derivatives considerably enhanced the inhibition efficiencies of the hybrids. The highest corrosion inhibitive efficiency (as 97.45%) was achieved with PYR-PER3 bearing methyl and bromide anchoring groups on the benzene group of the main PYR-PER structure. Some quantum chemical parameters, EHOMO, ELUMO, ΔE, electronegativity, chemical hardness, chemical softness, electrophilicity index, proton affinity and ΔN electron transfer were also discussed. Additionally non-linear optical properties (NLO) were investigated. The results in the B3LYP technique supported by experimental results.