Number of found documents: 244
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Charge Transport in Single Oligophenylene Molecular Wires with Different Anchoring Groups
Hromadová, Magdaléna; Kolivoška, Viliam; Šebera, Jakub; Sebechlebská, Táňa; Gasior, Jindřich; Nováková Lachmanová, Štěpánka; Mészáros, G.; Lindner, M.; Mayor, M.; Valášek, M.
2019 - English
This work compares single molecule conductance measurements of selected organic systems containing identical oligophenylene molecular wires and different tripodal anchoring groups. Single molecule conductance G was obtained by a scanning tunneling microscopy break junction technique complemented by theoretical calculations based on the density functional theory and non-equilibrium Green’s function formalism. Two molecules were compared where the same oligophenylene wire is connected to one of the electrodes via a tripod substituted on each leg by a thiol group either in the meta or para position. By combined experimental and theoretical analysis it was possible to confirm that single molecule conductance in the metal-molecule-metal junction of both molecules corresponds to a fully extended molecular wire, which is attached to one of the electrodes by all three thiolate bonds of the tripod. Experimental results confirmed that G value of meta-connected molecules is lower than that of para, whereas junction formation probability was higher for meta functionalization. Keywords: STM break junction; Tetraphenylmethane Tripodal anchor; Single molecule conductance Available at various institutes of the ASCR
Charge Transport in Single Oligophenylene Molecular Wires with Different Anchoring Groups

This work compares single molecule conductance measurements of selected organic systems containing identical oligophenylene molecular wires and different tripodal anchoring groups. Single molecule ...

Hromadová, Magdaléna; Kolivoška, Viliam; Šebera, Jakub; Sebechlebská, Táňa; Gasior, Jindřich; Nováková Lachmanová, Štěpánka; Mészáros, G.; Lindner, M.; Mayor, M.; Valášek, M.
Ústav fyzikální chemie J. Heyrovského, 2019

Electrochemical Enzymatic Biosensors for Determination of Catecholamines in Flow Systems\n
Josypčuk, Bohdan; Barek, J.; Josypčuk, Oksana
2019 - English
Several biosensors (BS) based on flow enzymatic mini-reactors containing a mesoporous silica powder covered by enzyme laccase or tyrosinase were used for determination of L-DOPA, dopamine, noradrenaline, and adrenaline. The silica powder of MCM-41 with covalently bonded laccase was found to be the best reactor filling for the detection of catecholamines. Relative current response of such BS was 100 % for dopamine, 32.1 % for L-DOPA, 26.2 % for noradrenaline, and 0.71 % for adrenaline. The practical applicability of Lac-MCM41 biosensor was successfully verified by the determination of dopamine and noradrenaline in medical solutions for infusions. Keywords: Enzymatic biosensor; Catecholamines; Flow analysis Available at various institutes of the ASCR
Electrochemical Enzymatic Biosensors for Determination of Catecholamines in Flow Systems\n

Several biosensors (BS) based on flow enzymatic mini-reactors containing a mesoporous silica powder covered by enzyme laccase or tyrosinase were used for determination of L-DOPA, dopamine, ...

Josypčuk, Bohdan; Barek, J.; Josypčuk, Oksana
Ústav fyzikální chemie J. Heyrovského, 2019

On UV-Vis Spectroelectrochemistry of Luteolin-7-O-Glucoside
Castano, A.; Sokolová, Romana; Degano, I.
2019 - English
The UV-Vis spectroelectrochemical cell containing an optically transparent platinum net used as the working electrode was tested in two regimes of electrochemical measurement, cyclic voltammetry and chronoamperometry, respectively. A three electrode setup used silver quasi reference electrode and platinum electrode serving as a counter electrode. The calibration of the spectroelectrochemical cell was performed for one-electron oxidation processes as well as for two-electron oxidations. The spectral changes during the oxidation of luteolin-7-O-Glucoside gave the information about the electroactive chromophores in molecule. Resulted spectra were compared with luteolin. The identification of products of oxidation was done by complementary analytical techniques HPLC-DAD and HPLC-ESI-MS/MS. Keywords: spectroelectrochemistry; oxidation; luteolin; antioxidants Available at various institutes of the ASCR
On UV-Vis Spectroelectrochemistry of Luteolin-7-O-Glucoside

The UV-Vis spectroelectrochemical cell containing an optically transparent platinum net used as the working electrode was tested in two regimes of electrochemical measurement, cyclic voltammetry and ...

Castano, A.; Sokolová, Romana; Degano, I.
Ústav fyzikální chemie J. Heyrovského, 2019

Charge Transport in Single Oligophenylene Molecular Wires with Different Anchoring Groups
Hromadová, Magdaléna; Kolivoška, Viliam; Šebera, Jakub; Sebechlebská, Táňa; Gasior, Jindřich; Nováková Lachmanová, Štěpánka; Mészáros, G.; Lindner, M.; Mayor, M.; Valášek, M.
2019 - English
This work compares single molecule conductance measurements of selected organic systems containing identical oligophenylene molecular wires and different tripodal anchoring groups. Single molecule conductance G was obtained by a scanning tunneling microscopy break junction technique complemented by theoretical calculations based on the density functional theory and non-equilibrium Green’s function formalism. Two molecules were compared where the same oligophenylene wire is connected to one of the electrodes via a tripod substituted on each leg by a thiol group either in the meta or para position. By combined experimental and theoretical analysis it was possible to confirm that single molecule conductance in the metal-molecule-metal junction of both molecules corresponds to a fully extended molecular wire, which is attached to one of the electrodes by all three thiolate bonds of the tripod. Experimental results confirmed that G value of meta-connected molecules is lower than that of para, whereas junction formation probability was higher for meta functionalization. Keywords: STM break junction; Tetraphenylmethane Tripodal anchor; Single molecule conductance Available at various institutes of the ASCR
Charge Transport in Single Oligophenylene Molecular Wires with Different Anchoring Groups

This work compares single molecule conductance measurements of selected organic systems containing identical oligophenylene molecular wires and different tripodal anchoring groups. Single molecule ...

Hromadová, Magdaléna; Kolivoška, Viliam; Šebera, Jakub; Sebechlebská, Táňa; Gasior, Jindřich; Nováková Lachmanová, Štěpánka; Mészáros, G.; Lindner, M.; Mayor, M.; Valášek, M.
Ústav fyzikální chemie J. Heyrovského, 2019

Oxidation and Reduction of Selected 1,10-Phenantrolines
Wantulok, J.; Sokolová, Romana; Nycz, J. E.; Degano, I.
2019 - English
Derivatives of 1,10-phenanthroline (Phen) are well-known bident ligands which had a lot of interesting applications thanks to their coordination abilities. Selected 1,10-phenanthroline compounds were studied by electrochemical methods. Depending on their different substituents were observed several oxidation and reduction voltammetric peaks. The study involves also in situ spectroeletrochemistry, infrared spectroscopy and identification of products by HPLC-DAD and HPLC-ESI MS/MS. Keywords: electrochemistry; oxidation mechanism; reduction mechanism Available at various institutes of the ASCR
Oxidation and Reduction of Selected 1,10-Phenantrolines

Derivatives of 1,10-phenanthroline (Phen) are well-known bident ligands which had a lot of interesting applications thanks to their coordination abilities. Selected 1,10-phenanthroline compounds were ...

Wantulok, J.; Sokolová, Romana; Nycz, J. E.; Degano, I.
Ústav fyzikální chemie J. Heyrovského, 2019

Chronopotentiometry of Papain Modified by Ruthenium Complexes
Nováková Lachmanová, Štěpánka; Pospíšil, Lubomír; Talbi, B.; Salmain, M.; Hromadová, Magdaléna
2019 - English
Catalytic hydrogen evolution reaction is one of known effects observed during the electrochemical studies of proteins. Constant current chronopotentiometric stripping technique is suitable tool for the study of catalytic hydrogen evolution reaction due to the formation of peak H. This contribution compares the catalytic behaviour of nonmodified papain and its artificial derivatives prepared by the interaction of organometallic complexes of ruthenium with free sulfhydryl group of protein. The comparison of the chronopotentiometric behaviour of papain and its derivatives would help to better understand the catalytic hydrogen evolution reaction in these derivatives. Keywords: papain; ruthenium organometallic complexes; artificial metalloproteins; catalytic hydrogen evolution reaction Available at various institutes of the ASCR
Chronopotentiometry of Papain Modified by Ruthenium Complexes

Catalytic hydrogen evolution reaction is one of known effects observed during the electrochemical studies of proteins. Constant current chronopotentiometric stripping technique is suitable tool for ...

Nováková Lachmanová, Štěpánka; Pospíšil, Lubomír; Talbi, B.; Salmain, M.; Hromadová, Magdaléna
Ústav fyzikální chemie J. Heyrovského, 2019

Charge Transport in Single Oligophenylene Molecular Wires with Different Anchoring Groups
Hromadová, Magdaléna; Kolivoška, Viliam; Šebera, Jakub; Sebechlebská, Táňa; Gasior, Jindřich; Nováková Lachmanová, Štěpánka; Mészáros, G.; Lindner, M.; Mayor, M.; Valášek, M.
2019 - English
This work compares single molecule conductance measurements of selected organic systems containing identical oligophenylene molecular wires and different tripodal anchoring groups. Single molecule conductance G was obtained by a scanning tunneling microscopy break junction technique complemented by theoretical calculations based on the density functional theory and non-equilibrium Green’s function formalism. Two molecules were compared where the same oligophenylene wire is connected to one of the electrodes via a tripod substituted on each leg by a thiol group either in the meta or para position. By combined experimental and theoretical analysis it was possible to confirm that single molecule conductance in the metal-molecule-metal junction of both molecules corresponds to a fully extended molecular wire, which is attached to one of the electrodes by all three thiolate bonds of the tripod. Experimental results confirmed that G value of meta-connected molecules is lower than that of para, whereas junction formation probability was higher for meta functionalization. Keywords: STM break junction; Tetraphenylmethane Tripodal anchor; Single molecule conductance Available at various institutes of the ASCR
Charge Transport in Single Oligophenylene Molecular Wires with Different Anchoring Groups

This work compares single molecule conductance measurements of selected organic systems containing identical oligophenylene molecular wires and different tripodal anchoring groups. Single molecule ...

Hromadová, Magdaléna; Kolivoška, Viliam; Šebera, Jakub; Sebechlebská, Táňa; Gasior, Jindřich; Nováková Lachmanová, Štěpánka; Mészáros, G.; Lindner, M.; Mayor, M.; Valášek, M.
Ústav fyzikální chemie J. Heyrovského, 2019

Electrochemical Investigation of Polylactic Acid/Carbon Black Composite Filament for the Manufacture of 3D Printed Electrodes
Sebechlebská, Táňa; Vaněčková, Eva; Shestivska, Violetta; Kolivoška, Viliam
2019 - English
Fused deposition modeling 3D printing has recently attracted increasing attention as an inexpensive, fast, reliable, adaptable and environmentally friendly tool to fabricate electrodes and electrochemical cells from composites of thermoplastics and carbon nanostructures. In this work, we use electric conductance measurements and cyclic voltammetry employing Ru(acac)30/1- as an electroactive probe to demonstrate that commercial polylactic acid(PLA)/carbon black composite filaments may be readily used as functional working electrodes in aqueous electrolytes. We further devise a procedure that leads to an improvement of their electrochemical performance. Characteristics of composite filaments treated by the optimized procedure approach those of classical metallic electrodes. Keywords: 3D printed electrodes; Fused deposition modeling; Polylactic acid; Carbon black Available at various institutes of the ASCR
Electrochemical Investigation of Polylactic Acid/Carbon Black Composite Filament for the Manufacture of 3D Printed Electrodes

Fused deposition modeling 3D printing has recently attracted increasing attention as an inexpensive, fast, reliable, adaptable and environmentally friendly tool to fabricate electrodes and ...

Sebechlebská, Táňa; Vaněčková, Eva; Shestivska, Violetta; Kolivoška, Viliam
Ústav fyzikální chemie J. Heyrovského, 2019

Mechanism of the Water Clusters Formation in the Organic Phase in the Presence of Hydrated Ions
Holub, Karel; Samec, Zdeněk; Mareček, Vladimír
2019 - English
A two-electrode cell comprising a liquid/liquid interface is used to study the water clusters formation in the organic solvent phase following the extraction of tetraalkylammonium chloride (TAACl) from the aqueous phase. The change in the concentration of the common TAA+ ion on the aqueous side of the interface is monitored by the open circuit potential measurements. It is shown that the amount of TAACl extracted into the organic phase exceeds considerably the limit determined by the concentration of Cl- in the organic phase at a given interfacial potential difference and the electroneutrality condition. A mechanism is proposed including an accumulation of the excess TAACl in the water clusters formed from the hydration shell of the Cl- ions, water already dissolved in the organic phase, and additional water extracted from the aqueous phase. At higher concentration of TAACl in the aqueous phase this process leads to the formation of emulsion in the organic phase. Keywords: liquid/liquid interface; water co-extraction dynemics; emulsification Available at various institutes of the ASCR
Mechanism of the Water Clusters Formation in the Organic Phase in the Presence of Hydrated Ions

A two-electrode cell comprising a liquid/liquid interface is used to study the water clusters formation in the organic solvent phase following the extraction of tetraalkylammonium chloride (TAACl) ...

Holub, Karel; Samec, Zdeněk; Mareček, Vladimír
Ústav fyzikální chemie J. Heyrovského, 2019

Construction and Application of Flow Amperometric Biosensor Based on Enzymatic Reactor for Determination of Choline
Tvorynska, Sofiia; Barek, J.; Josypčuk, Bohdan
2019 - English
In this contribution, a novel fast, simple and stable biosensor with the enzymatic reactor based on choline oxidase (ChOx) was developed and applied for the determination of choline using flow injection analysis with amperometric detection. The preparation of the reactor is based on the covalent immobilization of ChOx with glutaraldehyde to mesoporous silica powder (SBA-15) previously covered by NH2-groups. The experimental parameters affecting the sensitivity and stability of the biosensor were optimized. The proposed biosensor with the newly developed ChOx-based reactor possesses good repeatability, reproducibility, long-term stability, and reusability. It was successfully applied for the determination of choline in commercial pharmaceuticals. Keywords: choline; choline oxidase; Flow analysis; enzymatic reactor Available at various institutes of the ASCR
Construction and Application of Flow Amperometric Biosensor Based on Enzymatic Reactor for Determination of Choline

In this contribution, a novel fast, simple and stable biosensor with the enzymatic reactor based on choline oxidase (ChOx) was developed and applied for the determination of choline using flow ...

Tvorynska, Sofiia; Barek, J.; Josypčuk, Bohdan
Ústav fyzikální chemie J. Heyrovského, 2019

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