Phosphorus-nitrogen compounds : Part 30. Syntheses and structural investigations, antimicrobial a... more Phosphorus-nitrogen compounds : Part 30. Syntheses and structural investigations, antimicrobial and cytotoxic activities and DNA interactions of vanillinato-substituted NN or NO spirocyclic monoferrocenylcyclotriphosphazenes". Solak, "The synthesis of a novel DDPHC diazonium salt: Investigation of its usability in the determination of phenol and chlorophenols using CV, SWV and DPV techniques", Analytical Methods, Submitted March 2015 2014 4. Erdal Dinç and Ali Osman Solak, "A new approach to the characterization of the nano-film structure on modified electrode systems by factor analysis model"
Novel calix[4]pyrrole bearing vic-dioxime ligand (LH 2 ) of the general formula, R 1 R 2 C 2 N 2 ... more Novel calix[4]pyrrole bearing vic-dioxime ligand (LH 2 ) of the general formula, R 1 R 2 C 2 N 2 O 2 H 2 (where, R 1 = C 6 H 5 -and R 2 = C 39 H 50 N 5 -) has been synthesized by the reaction of anti-chlorophenylglyoxime with 3-aminophenylcalix[4]pyrrole at room temperature. The mononuclear Cu(II), Ni(II) and Co(II)complexes of this vic-dioxime ligand were prepared and their structures were confirmed by elemental analysis, FT-IR, TGA and magnetic susceptibility measurements; the HMBC, DEPT, 1 H and 13 C NMR spectra of the LH 2 ligand were also reported. The electrochemical property of the complexes was investigated in DMSO by cyclic voltammetry at 200 mV s À1 scan rate. The cyclic voltammetric measurements clearly indicated that Co(LH) 2 Á2H 2 O complex differs from the Ni(LH) 2 and Cu(LH) 2 complexes upon the exhibition of quasireversible one-electron transfer reduction process in the negative region instead of an irreversible process.
The scope of this study is to modify a Surface Plasmon Resonance (SPR) sensor slide with isophtha... more The scope of this study is to modify a Surface Plasmon Resonance (SPR) sensor slide with isophthalic acid to evaluate the possible application on the detection of copper(II) ions in aqueous media by total internal reflection ellipsometry. A gold sensor surface was modified by an electrochemical diazonium reduction modification method. The modified surfaces are characterized with cyclic voltammetry (CV) and ellipsometry. Isophthalic acid monolayer modified gold slides were used for in situ detection of aqueous Cu 2+ solution with the SPR enhanced total internal reflection ellipsometry (SPRe-TIRE) technique. Layer formation, pH dependency of adsorption, sensor response of the SPRe-TIRE and isothermal kinetic parameters were examined. A high dependency on the number of CV cycles in the monolayer-multiple layer transition was observed. The suggested sensor gave a linear response over a wide range of Cu 2+ concentrations. It was also reported that adsorption on the SPRe-TIRE sensor gave Langmuir adsorption model behavior.
This work describes the synthesis, characterization and electrochemical grafting of N-(4-aminophe... more This work describes the synthesis, characterization and electrochemical grafting of N-(4-aminophenyl)aza-18-crown-6 (4APA18C6). The key step in the synthesis is the reaction of N-phenylaza-18-crown-6 (PA18C6) with sodium nitrite. The compound, N-(4-nitrosophenyl)aza-18-crown-6 (NOPA18C6) could not be isolated purely from the reaction mixture, but a reduction of the residue with SnCl 2 gave the desired azacrown ether, N-(4-aminophenyl)aza-18-crown-6 (4APA18C6). To confirm its proposed structure detailed characterization techniques such as elemental analysis, FT-IR, 1 H NMR, 13 C NMR, DEPT, HETCOR, HMBC and ESI mass-spectrometry were used. Due to the importance of azacrown compounds in the field of analytical chemistry, in the derivatization of dyes, chemical sensors and ionic extraction, as molecular receptors, grafting of 4APA18C6 on the glassy carbon (GC) surface has been investigated by amine oxidation to gain new insight into the modification area. The oxidation mechanism has been established, and the results are in accordance with the attachment of amines to a glassy carbon surface by cyclic voltammetry. The modification of 4APA18C6 molecules onto the glassy carbon surface was verified by cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS) reflection-absorption infrared spectroscopy (RAIRS) and ellipsometry. The film on the GC surface was formed according to the layer-by-layer mechanism and the ellipsometric thickness was obtained around 11.5 ± 1.1 nm.
Glassy carbon (GC) surfaces modified with monolayers of biphenyl and nitrobiphenyl molecules were... more Glassy carbon (GC) surfaces modified with monolayers of biphenyl and nitrobiphenyl molecules were examined as voltammetric electrodes for ferrocene, benzoquinone, and tetracyanoquinodimethane electrochemistry in acetonitrile. The modified electrodes exhibited slower electron transfer than unmodified GC, by factors that varied with the monolayer and redox system. However, after a negative potential excursion to ∼-2.0 V versus Ag + /Ag, the modified electrodes exhibited much faster electrontransfer kinetics, approaching those observed on unmodified GC. The effect is attributed to an apparently irreversible structural change in the biphenyl or nitrobiphenyl monolayer, which increases the rate of electron tunneling. The transition to the "ON" state is associated with electron injection into the monolayer similar to that observed in previous spectroscopic investigations and causes a significant decrease in the calculated HOMO-LUMO gap for the monolayer molecule. Once the monolayer is switched ON, it supports rapid electron exchange with outer-sphere redox systems, but not with dopamine, which requires adsorption to the GC surface. The increase in electrontransfer rate with electron injection is consistent with an increase in electron tunneling rate through the monolayer, caused by a significant decrease in tunneling barrier height. The ON electrode can reduce biphenyl-or nitrobiphenyldiazonium reagent in solution to permit formation of a second modification layer of biphenyl or nitrobiphenyl molecules. This "double derivatization" procedure was used to prepare tetraphenyl-and nitrotetraphenyl-modified electrodes, which exhibit significantly slower electron transfer than their biphenyl and nitrobiphenyl counterparts. A "switching" electrode may have useful properties for electroanalytical applications and possibly in electrocatalysis. In addition, the ON state represents an "organic electrode" in which electron transfer occurs at an interface between an organic conductor and a solution rather than an interface between a solution and a metal or carbon electrode.
Note to users: The section "Articles in Press" contains peer reviewed accepted articles... more Note to users: The section "Articles in Press" contains peer reviewed accepted articles to be published in this journal. When the final article is assigned to an issue of the journal, the "Article in Press" version will be removed from this section and will appear in the associated ...
... Schiff bases have been used extensively as ligands in metal complexes [1]. This important gro... more ... Schiff bases have been used extensively as ligands in metal complexes [1]. This important group of compounds has also been used to obtain thermotropic liquid crystalline polymers [2]. Metal complexes of hydroxy-substituted Schiff bases show biological activities such as ...
... 2 3 Elif Ece ltera,*, Nuran Asmafilizb, Zeynel K lb, Leyla A kc, Makbule Yavuzc, E. Burcu Bal... more ... 2 3 Elif Ece ltera,*, Nuran Asmafilizb, Zeynel K lb, Leyla A kc, Makbule Yavuzc, E. Burcu Balic, Ali Osman 4 Solakb ... 110 All electrochemical experiments were performed using a BAS-100B electrochemical analyzer 111 (Bioanalytical System Inc., Lafayette, IL, USA) and Gamry ...
A molecular junction formed by a 10-15 Å organic monolayer between carbon and mercury contacts ex... more A molecular junction formed by a 10-15 Å organic monolayer between carbon and mercury contacts exhibited conductance switching for several monolayer structures. When the carbon potential was scanned to a sufficiently negative voltage relative to the mercury, the junction resistance suddenly decreased by at least an order of magnitude, and high resistance could be restored by a positive voltage scan. The high and low conductance states were persistent, and conductance switching was repeatable at least 100 cycles for the case of a terphenyl junction. The switching behavior is consistent with phenyl ring rotation and formation of a planar, quinoid structure as a consequence of electron injection into the monolayer. A unique feature of the junction structure is the strong electronic coupling between the monolayer system and the graphitic carbon through a quinoid double bond. Not only does this interaction lead to high conductivity and possible practical applications as a molecular switch, it also combines the electronic properties of the conjugated monolayer with those of the graphitic substrate. The switching mechanism reported here is an example of ''dry electrochemistry'' in which a redox process appears to occur under the influence of a high electric field in the absence of solvent or electrolyte.
Gold nanoparticles (AuNPs) with about 6 nm size were produced and stabilized with mercaptopropion... more Gold nanoparticles (AuNPs) with about 6 nm size were produced and stabilized with mercaptopropionic acid (MPA) film to produce a monolayer protected cluster (MPC) of AuS(CH(2))(2)COOH. 4-Aminothiophenol (ATP) molecules were introduced to the activated carboxylic acid ends of the film surrounding the AuNPs to produce AuS(CH(2))(2)CONHPhSH MPC. These modified AuNPs were again self-assembled with Au@Ag core-shell bimetallic nanoparticles via the -SH groups to produce an organic bridge between Au and Au@Ag metallic nanoparticles. An unusually strong enhancement of the Raman signals was observed and assigned to the plasmon coupling between the AuNPs and Au@Ag NPs bridged assembly. Formation of AuS(CH(2))(2)COOH and AuS(CH(2))(2)CONHPhSH clusters and AuS(CH(2))(2)CONHPhS(Au@Ag) assembly is confirmed by UV-Vis, reflection-absorption IR spectroscopy (RAIRS) and X-ray photoelectron spectroscopy (XPS), as well as by TEM analysis. The SERS activity of the AuNPs and Au@Ag NPs was tested using the HS(CH(2))(2)CONHPhSH molecule as a probe to compare the effectiveness of monometallic and bimetallic systems. SERS spectra show that Au@Ag bimetallic nanoparticles are very effective SERS-active substrates.
A single compartment biofuel cell (BFC) based on an anode and a cathode powered by the same fuel ... more A single compartment biofuel cell (BFC) based on an anode and a cathode powered by the same fuel glucose is reported. Glucose oxidase (GOx) from Aspergillus niger was applied as a glucose consuming biocatalyst for both anode and cathode of the BFC. The 5-amino-1,10-phenanthroline modified graphite rod electrode (GRE) with cross-linked GOx was used as the bioanode, and the GRE with co-immobilised horseradish peroxidase and GOx was exploited as the biocathode of the BFC. The open-circuit voltage of the designed BFC exceeded 450 mV and a maximal power density of 3.5 mW/cm 2 was registered at a cell voltage of 300 mV.
Phosphorus-nitrogen compounds : Part 30. Syntheses and structural investigations, antimicrobial a... more Phosphorus-nitrogen compounds : Part 30. Syntheses and structural investigations, antimicrobial and cytotoxic activities and DNA interactions of vanillinato-substituted NN or NO spirocyclic monoferrocenylcyclotriphosphazenes". Solak, "The synthesis of a novel DDPHC diazonium salt: Investigation of its usability in the determination of phenol and chlorophenols using CV, SWV and DPV techniques", Analytical Methods, Submitted March 2015 2014 4. Erdal Dinç and Ali Osman Solak, "A new approach to the characterization of the nano-film structure on modified electrode systems by factor analysis model"
Novel calix[4]pyrrole bearing vic-dioxime ligand (LH 2 ) of the general formula, R 1 R 2 C 2 N 2 ... more Novel calix[4]pyrrole bearing vic-dioxime ligand (LH 2 ) of the general formula, R 1 R 2 C 2 N 2 O 2 H 2 (where, R 1 = C 6 H 5 -and R 2 = C 39 H 50 N 5 -) has been synthesized by the reaction of anti-chlorophenylglyoxime with 3-aminophenylcalix[4]pyrrole at room temperature. The mononuclear Cu(II), Ni(II) and Co(II)complexes of this vic-dioxime ligand were prepared and their structures were confirmed by elemental analysis, FT-IR, TGA and magnetic susceptibility measurements; the HMBC, DEPT, 1 H and 13 C NMR spectra of the LH 2 ligand were also reported. The electrochemical property of the complexes was investigated in DMSO by cyclic voltammetry at 200 mV s À1 scan rate. The cyclic voltammetric measurements clearly indicated that Co(LH) 2 Á2H 2 O complex differs from the Ni(LH) 2 and Cu(LH) 2 complexes upon the exhibition of quasireversible one-electron transfer reduction process in the negative region instead of an irreversible process.
The scope of this study is to modify a Surface Plasmon Resonance (SPR) sensor slide with isophtha... more The scope of this study is to modify a Surface Plasmon Resonance (SPR) sensor slide with isophthalic acid to evaluate the possible application on the detection of copper(II) ions in aqueous media by total internal reflection ellipsometry. A gold sensor surface was modified by an electrochemical diazonium reduction modification method. The modified surfaces are characterized with cyclic voltammetry (CV) and ellipsometry. Isophthalic acid monolayer modified gold slides were used for in situ detection of aqueous Cu 2+ solution with the SPR enhanced total internal reflection ellipsometry (SPRe-TIRE) technique. Layer formation, pH dependency of adsorption, sensor response of the SPRe-TIRE and isothermal kinetic parameters were examined. A high dependency on the number of CV cycles in the monolayer-multiple layer transition was observed. The suggested sensor gave a linear response over a wide range of Cu 2+ concentrations. It was also reported that adsorption on the SPRe-TIRE sensor gave Langmuir adsorption model behavior.
This work describes the synthesis, characterization and electrochemical grafting of N-(4-aminophe... more This work describes the synthesis, characterization and electrochemical grafting of N-(4-aminophenyl)aza-18-crown-6 (4APA18C6). The key step in the synthesis is the reaction of N-phenylaza-18-crown-6 (PA18C6) with sodium nitrite. The compound, N-(4-nitrosophenyl)aza-18-crown-6 (NOPA18C6) could not be isolated purely from the reaction mixture, but a reduction of the residue with SnCl 2 gave the desired azacrown ether, N-(4-aminophenyl)aza-18-crown-6 (4APA18C6). To confirm its proposed structure detailed characterization techniques such as elemental analysis, FT-IR, 1 H NMR, 13 C NMR, DEPT, HETCOR, HMBC and ESI mass-spectrometry were used. Due to the importance of azacrown compounds in the field of analytical chemistry, in the derivatization of dyes, chemical sensors and ionic extraction, as molecular receptors, grafting of 4APA18C6 on the glassy carbon (GC) surface has been investigated by amine oxidation to gain new insight into the modification area. The oxidation mechanism has been established, and the results are in accordance with the attachment of amines to a glassy carbon surface by cyclic voltammetry. The modification of 4APA18C6 molecules onto the glassy carbon surface was verified by cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS) reflection-absorption infrared spectroscopy (RAIRS) and ellipsometry. The film on the GC surface was formed according to the layer-by-layer mechanism and the ellipsometric thickness was obtained around 11.5 ± 1.1 nm.
Glassy carbon (GC) surfaces modified with monolayers of biphenyl and nitrobiphenyl molecules were... more Glassy carbon (GC) surfaces modified with monolayers of biphenyl and nitrobiphenyl molecules were examined as voltammetric electrodes for ferrocene, benzoquinone, and tetracyanoquinodimethane electrochemistry in acetonitrile. The modified electrodes exhibited slower electron transfer than unmodified GC, by factors that varied with the monolayer and redox system. However, after a negative potential excursion to ∼-2.0 V versus Ag + /Ag, the modified electrodes exhibited much faster electrontransfer kinetics, approaching those observed on unmodified GC. The effect is attributed to an apparently irreversible structural change in the biphenyl or nitrobiphenyl monolayer, which increases the rate of electron tunneling. The transition to the "ON" state is associated with electron injection into the monolayer similar to that observed in previous spectroscopic investigations and causes a significant decrease in the calculated HOMO-LUMO gap for the monolayer molecule. Once the monolayer is switched ON, it supports rapid electron exchange with outer-sphere redox systems, but not with dopamine, which requires adsorption to the GC surface. The increase in electrontransfer rate with electron injection is consistent with an increase in electron tunneling rate through the monolayer, caused by a significant decrease in tunneling barrier height. The ON electrode can reduce biphenyl-or nitrobiphenyldiazonium reagent in solution to permit formation of a second modification layer of biphenyl or nitrobiphenyl molecules. This "double derivatization" procedure was used to prepare tetraphenyl-and nitrotetraphenyl-modified electrodes, which exhibit significantly slower electron transfer than their biphenyl and nitrobiphenyl counterparts. A "switching" electrode may have useful properties for electroanalytical applications and possibly in electrocatalysis. In addition, the ON state represents an "organic electrode" in which electron transfer occurs at an interface between an organic conductor and a solution rather than an interface between a solution and a metal or carbon electrode.
Note to users: The section "Articles in Press" contains peer reviewed accepted articles... more Note to users: The section "Articles in Press" contains peer reviewed accepted articles to be published in this journal. When the final article is assigned to an issue of the journal, the "Article in Press" version will be removed from this section and will appear in the associated ...
... Schiff bases have been used extensively as ligands in metal complexes [1]. This important gro... more ... Schiff bases have been used extensively as ligands in metal complexes [1]. This important group of compounds has also been used to obtain thermotropic liquid crystalline polymers [2]. Metal complexes of hydroxy-substituted Schiff bases show biological activities such as ...
... 2 3 Elif Ece ltera,*, Nuran Asmafilizb, Zeynel K lb, Leyla A kc, Makbule Yavuzc, E. Burcu Bal... more ... 2 3 Elif Ece ltera,*, Nuran Asmafilizb, Zeynel K lb, Leyla A kc, Makbule Yavuzc, E. Burcu Balic, Ali Osman 4 Solakb ... 110 All electrochemical experiments were performed using a BAS-100B electrochemical analyzer 111 (Bioanalytical System Inc., Lafayette, IL, USA) and Gamry ...
A molecular junction formed by a 10-15 Å organic monolayer between carbon and mercury contacts ex... more A molecular junction formed by a 10-15 Å organic monolayer between carbon and mercury contacts exhibited conductance switching for several monolayer structures. When the carbon potential was scanned to a sufficiently negative voltage relative to the mercury, the junction resistance suddenly decreased by at least an order of magnitude, and high resistance could be restored by a positive voltage scan. The high and low conductance states were persistent, and conductance switching was repeatable at least 100 cycles for the case of a terphenyl junction. The switching behavior is consistent with phenyl ring rotation and formation of a planar, quinoid structure as a consequence of electron injection into the monolayer. A unique feature of the junction structure is the strong electronic coupling between the monolayer system and the graphitic carbon through a quinoid double bond. Not only does this interaction lead to high conductivity and possible practical applications as a molecular switch, it also combines the electronic properties of the conjugated monolayer with those of the graphitic substrate. The switching mechanism reported here is an example of ''dry electrochemistry'' in which a redox process appears to occur under the influence of a high electric field in the absence of solvent or electrolyte.
Gold nanoparticles (AuNPs) with about 6 nm size were produced and stabilized with mercaptopropion... more Gold nanoparticles (AuNPs) with about 6 nm size were produced and stabilized with mercaptopropionic acid (MPA) film to produce a monolayer protected cluster (MPC) of AuS(CH(2))(2)COOH. 4-Aminothiophenol (ATP) molecules were introduced to the activated carboxylic acid ends of the film surrounding the AuNPs to produce AuS(CH(2))(2)CONHPhSH MPC. These modified AuNPs were again self-assembled with Au@Ag core-shell bimetallic nanoparticles via the -SH groups to produce an organic bridge between Au and Au@Ag metallic nanoparticles. An unusually strong enhancement of the Raman signals was observed and assigned to the plasmon coupling between the AuNPs and Au@Ag NPs bridged assembly. Formation of AuS(CH(2))(2)COOH and AuS(CH(2))(2)CONHPhSH clusters and AuS(CH(2))(2)CONHPhS(Au@Ag) assembly is confirmed by UV-Vis, reflection-absorption IR spectroscopy (RAIRS) and X-ray photoelectron spectroscopy (XPS), as well as by TEM analysis. The SERS activity of the AuNPs and Au@Ag NPs was tested using the HS(CH(2))(2)CONHPhSH molecule as a probe to compare the effectiveness of monometallic and bimetallic systems. SERS spectra show that Au@Ag bimetallic nanoparticles are very effective SERS-active substrates.
A single compartment biofuel cell (BFC) based on an anode and a cathode powered by the same fuel ... more A single compartment biofuel cell (BFC) based on an anode and a cathode powered by the same fuel glucose is reported. Glucose oxidase (GOx) from Aspergillus niger was applied as a glucose consuming biocatalyst for both anode and cathode of the BFC. The 5-amino-1,10-phenanthroline modified graphite rod electrode (GRE) with cross-linked GOx was used as the bioanode, and the GRE with co-immobilised horseradish peroxidase and GOx was exploited as the biocathode of the BFC. The open-circuit voltage of the designed BFC exceeded 450 mV and a maximal power density of 3.5 mW/cm 2 was registered at a cell voltage of 300 mV.
Uploads
Papers by Ali Solak