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Redox Properties of Fluorinated Derivativers of 1,3-Diphenylisobenzofuran-Chromophores for Singlet Fission
Šimková, Ludmila; Ludvík, Jiří
2018 - English
Derivatives of 1,3-diphenylisobenzofuran attract interest because they should be efficient as the molecules for singlet fission. The understanding of singlet fission in isolated molecules might be advantageous for use as solar cell sensitizers. This study is focused on fluorinated derivatives of 1,3-diphenylisobenzofuran and the effect of the position of fluorine atoms on their redox properties. For characterization of the redox properties standard electrochemical methods, and in situ UV-vis and EPR spectroscopy techniques were used.
Keywords:
1,3-diphenylisobenzofuran; fluorinated derivatives; spectroelectrochemistry
Available on request at various institutes of the ASCR
Redox Properties of Fluorinated Derivativers of 1,3-Diphenylisobenzofuran-Chromophores for Singlet Fission
Derivatives of 1,3-diphenylisobenzofuran attract interest because they should be efficient as the molecules for singlet fission. The understanding of singlet fission in isolated molecules might be ...
Electrochemical Monitoring of the Water Clusters Formation in an Organic Solvent in the Presence of Hydrated Ions
Mareček, Vladimír
2018 - English
An electrochemical method has been developed that makes it possible to monitor the\ndynamics of the co-extraction of water with hydrated chloride ions at the interface between\ntwo immiscible electrolyte solutions (ITIES). The interfacial potential was controlled by the\ndistribution of a common tetralkylammonium (TAA+) ion. Changes in the TAA+\nconcentration at the interface were monitored by measuring the open circuit potential (OCP).\nTransfer of hydrated chloride ions is accompanied by the transfer of TAA+, decreasing its\nconcentration on the aqueous side of the interface. This process involves the co-extraction of\nwater molecules with the hydrated chloride ions and the formation of water clusters in the\norganic solvent phase. The ability to monitor the process from the very beginning of interface\nformation allowed us to obtain important kinetic data.
Keywords:
Liquid/liquid interface; Water co-extraction dynamics; Emulsification
Available on request at various institutes of the ASCR
Electrochemical Monitoring of the Water Clusters Formation in an Organic Solvent in the Presence of Hydrated Ions
An electrochemical method has been developed that makes it possible to monitor the\ndynamics of the co-extraction of water with hydrated chloride ions at the interface between\ntwo immiscible ...
Silver Solid Amalgam Electrodes as Perspective Tools for Sensitive Voltammetric Determinations of Food Azo Dyes Amaranth and Allura Red AC
Tvorynska, S.; Barek, J.; Josypčuk, Bohdan
2018 - English
In this paper, for the first time, the electrochemical behaviours of the food azo dyes Amaranth (E 123) and Allura Red AC (E 129) were investigated on two modifications of silver solid amalgam electrode, namely mercury meniscus modified, polished and compared with hanging mercury drop electrode using differential pulse voltammetry and direct current voltammetry. The effect of adsorption and the reduction mechanism on tested electrodes were described in detail. Measurements with amalgam electrodes showed good reproducibility, stability and high sensitivity. As a result, they were successfully applied for the determination of investigated azo dyes in different commercial drink samples.
Keywords:
voltammetry; azo dyes; amaranth
Available on request at various institutes of the ASCR
Silver Solid Amalgam Electrodes as Perspective Tools for Sensitive Voltammetric Determinations of Food Azo Dyes Amaranth and Allura Red AC
In this paper, for the first time, the electrochemical behaviours of the food azo dyes Amaranth (E 123) and Allura Red AC (E 129) were investigated on two modifications of silver solid amalgam ...
Electrochemical Study of Selected Pyrene Derivatives as Precursors to Organic Semiconductors
Koláčná, Lucie; Tobrman, T.; Ludvík, Jiří
2018 - English
A series of 9 precursors for pyrene based biodegradable organic (semi)conductors having tetrasubstituted double bond as a central organic core and photo- or redox active centers attached at this core were electrochemically investigated in order to determine the influence of individual parts of the molecule on the redox properties, to describe the location of the reduction center and to understand the structure - redox activity relationship of the mentioned compounds.
Keywords:
pyrene; cyclobutene; polarography
Available on request at various institutes of the ASCR
Electrochemical Study of Selected Pyrene Derivatives as Precursors to Organic Semiconductors
A series of 9 precursors for pyrene based biodegradable organic (semi)conductors having tetrasubstituted double bond as a central organic core and photo- or redox active centers attached at this core ...
Supported Liquid Membranes for Hollow-Fibre Based Microextraction and Voltammetric Determination of Neuroblastoma Biomarkers
Hrdlička, Vojtěch; Barek, J.; Navrátil, Tomáš
2018 - English
Novel method of three phase hollow fibre based liquid/liquid/liquid microextraction coupled\nwith voltammetric determination of clinical biomarkers homovanillic and vanillylmandelic\nacid is being developed. Wide variety of water-immiscible supported liquid membranes\n(SLMs) were tested. Highest enrichment factors were obtained using butyl benzoate as SLM.\nEnrichment factors for 30 min HF-LPME were 3. 0.74 for HVA and 5. 0.45 for VMA,\nrespectively. Repeatability of HF-LPME of microM HVA or VMA was 19.0% for HVA and\n7.9 % for VMA (n=5), respectively.
Keywords:
Hollow-fibres; Liquid phase microextraction; Voltammetry
Available on request at various institutes of the ASCR
Supported Liquid Membranes for Hollow-Fibre Based Microextraction and Voltammetric Determination of Neuroblastoma Biomarkers
Novel method of three phase hollow fibre based liquid/liquid/liquid microextraction coupled\nwith voltammetric determination of clinical biomarkers homovanillic and vanillylmandelic\nacid is being ...
Electrochemical Study of the Supported Iron Oxide Catalysts
Gál, M.; Horváth, B.; Navrátil, Tomáš
2018 - English
Propylene oxide (PO) belongs to the group of the most important chemical industrial\nintermediates. It is mainly used for polyurethanes, pharmaceuticals, textile, and detergent\nproduction. In this short contribution we tried to characterize supported iron(III) oxide\ncatalyst with different amount of Fe and to find an optimal iron(III) oxide content for the best\ncatalysts performance. The importance of phase quality on the selectivity of respective\ncatalysts samples is also discussed. Linear sweep voltammetry was chosen for this purpose.\nResults obtained by electrochemical methods are compared with efficiency (selectivity) of\nrespective catalysts.
Keywords:
Catalyst; Linear sweep voltammetry; Propylene oxide
Available on request at various institutes of the ASCR
Electrochemical Study of the Supported Iron Oxide Catalysts
Propylene oxide (PO) belongs to the group of the most important chemical industrial\nintermediates. It is mainly used for polyurethanes, pharmaceuticals, textile, and detergent\nproduction. In this ...
HPLC-ED/UV with Solid Phase Extraction for the Determination of 5-Hydroxyindole-3-acetic Acid
Němečková-Makrlíková, Anna; Dejmková, H.; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
2018 - English
Determination of 5-HIAA in human urine was successfully performed using HPLC-ED/UV with SPE. HPLC-ED is a very sensitive technique, presented method does not need any sample pre-treatment apart from SPE procedure, which replaced filtration of samples of human urine to avoid problems with clogging a HPLC column. The found native\nconcentrations of 5-HIAA in human urine using HPLC-ED with SPE fully corresponds with published normal concentrations in urine (17.8 - 58.3 micromol l-1). The found native concentrations of 5-HIAA were 18.4 micromol L-1 (calculated from peak height). The presented method is fast and could be used for simple\nscreening of human urine, because HPLC-ED/UV allows simultaneous determination of 5-HIAA, HVA, and VMA as important tumour biomarkers.
Keywords:
HPLC; electrochemical detection; spectrophotometric detection
Available on request at various institutes of the ASCR
HPLC-ED/UV with Solid Phase Extraction for the Determination of 5-Hydroxyindole-3-acetic Acid
Determination of 5-HIAA in human urine was successfully performed using HPLC-ED/UV with SPE. HPLC-ED is a very sensitive technique, presented method does not need any sample pre-treatment apart from ...
Introducing Functionality by Graphene Covalent Grafting
Kovaříček, Petr; Kalbáč, Martin
2018 - English
Graphene is a material of great potential in a broad range of applications, for each of which specific tuning of the material’s properties is required. This can be achieved, for example, by covalent functionalization. We have exploited protocols for surface grafting by diazonium salts, by nucleophilic and electrophilic substitution to perform graphene covalent modification of graphene on substrates. The painstaking analysis problem of monolayered materials was addressed using Raman spectroscopy, SERS, SEIRA, MS, AFM, XPS and SEM/EDX. The covalent grafting was shown to tolerate the transfer process, thus allowing ex post transfer from copper to other substrates. Functional devices often require combination of several materials with specific functions, such as graphene-polymer hybrid heterostructures. We have used the developed methodology of chemical functionalization for preparation of PEDOT:Graphene bilayers by selective in situ polymerization of EDOT on covalently functionalized graphene. The polymerization proceeds exclusively on the grafted graphene, and patterned structures with high spatial resolution down to 3 μm could have been prepared. The composite exhibits enhanced efficiency of electrochemical doping compared to pristine graphene, unsymmetrical transport characteristic with very good hole-transporting properties and efficient electronic communication between the two materials. The covalent functionalization of graphene thus introduces advanced functionality to the material, broadening its scope of applications.
Keywords:
graphene; covalent functionalization; PEDOT
Available at various institutes of the ASCR
Introducing Functionality by Graphene Covalent Grafting
Graphene is a material of great potential in a broad range of applications, for each of which specific tuning of the material’s properties is required. This can be achieved, for example, by covalent ...
HPLC-ED/UV for determination of vanillylmandelic acid in human urine after solid phase extraction
Němečková-Makrlíková, Anna; Dejmková, H.; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
2018 - English
HPLC with electrochemical and spectrophotometric detection (ED/UV) after solid phase extraction (SPE) was used for determination of vanillylmandelic acid in human urine. HPLC-ED was performed at a glassy carbon electrode in a “wall-jet” arrangement in acetate-phosphate buffer at pH = 2.5 and gradient elution (increasing content of\nacetonitrile from 5 to 25% in 10 minutes) was used. Optimized parameters were following: flow rate of mobile phase 1 mL min−1, detection potential +1.1 V, detection wavelength 279 nm, injected volume 20 μL. Dependence of the peak current on the analyte concentration was linear in the concentration range from 10 to 150 μmol L−1, with obtained limits of detection 2.6 μmol L−1 (calculated from peak height) and 1.9 μmol L−1 (calculated from peak area) for HPLC-ED, and 11.0 μmol L−1 (calculated from peak height) and 9.8 μmol L−1 (calculated from peak area) for HPLC-UV.
Keywords:
HPLC; solid phase extraction; tumor biomarker
Available on request at various institutes of the ASCR
HPLC-ED/UV for determination of vanillylmandelic acid in human urine after solid phase extraction
HPLC with electrochemical and spectrophotometric detection (ED/UV) after solid phase extraction (SPE) was used for determination of vanillylmandelic acid in human urine. HPLC-ED was performed at a ...
Investigation of Single Molecule Charge Transport Properties and Geometrical Arrangement in Terpyridine Architectures Supported by the Tetraphenylmethane Tripod
Kolivoška, Viliam; Sebechlebská, Táňa; Šebera, Jakub; Gasior, Jindřich; Lindner, M.; Lukášek, J.; Valášek, M.; Mayor, M.; Mészáros, G.; Hromadová, Magdaléna
2018 - English
Tripodal platforms were engineered recently to realize a well-defined directional contact between metallic electrodes and molecular architectures dedicated to serve as working elements for electronic applications. In this work we employ cyclic voltammetry, scanning tunneling microscopy break junction technique and theoretical approaches based on the combination of density functional theory and non-equilibrium Green´s function to investigate the geometrical arrangement and single molecule charge transport in terpyridine-based architectures supported by tetraphenylmethane tripod. We demonstrate that this architecture adopts a favorable geometrical arrangement capable of forming highly conductive molecular junctions and is thus suitable to serve as a basis for working molecular switches.
Keywords:
molecular electronics; Molecular conductors and switches; Tripodal platforms
Available on request at various institutes of the ASCR
Investigation of Single Molecule Charge Transport Properties and Geometrical Arrangement in Terpyridine Architectures Supported by the Tetraphenylmethane Tripod
Tripodal platforms were engineered recently to realize a well-defined directional contact between metallic electrodes and molecular architectures dedicated to serve as working elements for electronic ...
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