| 1. |
- Akpe, Victor, et al.
(författare)
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Understanding the Photochemical Pathway of In Vitro Target Delivery of Aluminium Phthalocyanine : A Mechanistic Approach Using Radical Reaction Chemistry
- 2014
-
Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 79:5, s. 671-679
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Tidskriftsartikel (refereegranskat)abstract
- A classical dye, aluminium phthalocyanine (AlPc), is used to study the photochemical processes involved in the chromophore-assisted laser inactivation technique. Both cell-free and cell-based systems are investigated by novel methods and radical reaction chemistry. Findings on the photochemical pathways in two models representing cell-free and a cell-based systems are reported. In the cell-free system, the unsubstituted, free, fluorescence-active photosensitiser AlPc recovers its fluorescence signal by means of phosphorescence through a reversible photobleaching process. In the cell-based system, photoactivation of substituted AlPc conjugated to an antibody results in the loss of fluorescence signal at the area examined. Reinjection of the AlPc-conjugated antibodies restores the fluorescence signal.
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| 2. |
- Alsaoub, Sabine, et al.
(författare)
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An Intrinsic Self-Charging Biosupercapacitor Comprised of a High-Potential Bioanode and a Low-Potential Biocathode
- 2017
-
Ingår i: ChemPlusChem. - : John Wiley & Sons. - 2192-6506. ; 82:4, s. 576-583
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Tidskriftsartikel (refereegranskat)abstract
- An intrinsic self-charging biosupercapacitor built on a unique concept for the fabrication of biodevices based on redox polymers is presented. The biosupercapacitor consists of a high-potential redox polymer based bioanode and a low-potential redox polymer based biocathode in which the potentials of the electrodes in the discharged state show an apparent potential mismatch E-anode > E-cathode and prevent the use of the device as a conventional biofuel cell. Upon charging, the potentials of the electrodes are shifted to more positive (cathode) and more negative (anode) values because of a change in the a(ox-)to-a(red) ratio within the redox polymer matrix. Hence, a potential inversion occurs in the charged state (E-anode < E-cathode) and an open circuit voltage of >0.4 V is achieved and the bio-device acts as a true biosupercapacitor. The bioanode consists of a novel specifically designed high-potential Os complex modified polymer for the efficient immobilization and electrical wiring of glucose converting enzymes, such as glucose oxidase and flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase. The cathodic side is constructed from a low-potential Os complex modified polymer integrating the O-2 reducing enzyme, bilirubin oxidase. The large potential differences between the redox polymers and the prosthetic groups of the biocatalysts ensure fast and efficient charging of the biodevice.
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| 3. |
- Arja, Katriann, et al.
(författare)
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Self-Assembly of Chiro-Optical Materials from Nonchiral Oligothiophene-Porphyrin Derivatives and Random Coil Synthetic Peptides
- 2023
-
Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 88:1
-
Tidskriftsartikel (refereegranskat)abstract
- Biomimetic chiral optoelectronic materials can be utilized in electronic devices, biosensors and artificial enzymes. Herein, this work reports the chiro-optical properties and architectural arrangement of optoelectronic materials generated from self-assembly of initially nonchiral oligothiophene−porphyrin derivatives and random coil synthetic peptides. The photo-physical- and structural properties of the materials were assessed by absorption-, fluorescence- and circular dichroism spectroscopy, as well as dynamic light scattering, scanning electron microscopy and theoretical calculations. The materials display a three-dimensional ordered helical structure and optical activity that are observed due to an induced chirality of the optoelectronic element upon interaction with the peptide. Both these properties are influenced by the chemical composition of the oligothiophene−porphyrin derivative, as well as the peptide sequence. We foresee that our findings will aid in developing self-assembled optoelectronic materials with dynamic architectonical accuracies, as well as offer the possibility to generate the next generation of materials for a variety of bioelectronic applications.
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| 4. |
- Awad, Doaa, et al.
(författare)
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Halogenated Dodecaborate Clusters as Agents to Trigger Release of Liposomal Contents
- 2015
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Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 80:4, s. 656-664
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Tidskriftsartikel (refereegranskat)abstract
- Halogenated dodecaborates, and especially dodecaiodododecaborate(2−), are found to trigger effectively the release of the contents of phospholipid liposomes, including liposomes containing distearoylphosphatidylcholine and cholesterol, which are used clinically in cancer therapy. The basis of the release is studied through differential scanning calorimetry, cryo-transmission electron microscopy, and atomic force microscopy. Upon administration at high concentrations, drastic morphological changes are induced by the dodecaborates. Their possible use in triggered release is suggested.
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| 5. |
- Berniak, Tomasz, et al.
(författare)
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Covalent bonding of N-hydroxyphthalimide on mesoporous silica for catalytic aerobic oxidation of p-xylene at atmospheric pressure
- 2024
-
Ingår i: ChemPlusChem. - 2192-6506.
-
Tidskriftsartikel (refereegranskat)abstract
- The surface of SBA-15 mesoporous silica was modified by N-hydroxyphthalimide (NHPI) moieties acting as immobilized active species for aerobic oxidation of alkylaromatic hydrocarbons. The incorporation was carried out by four original approaches: the grafting-from and grafting-onto techniques, using the presence of surface silanols enabling the formation of particularly stable O-Si-C bonds between the silica support and the organic modifier. The strategies involving the Heck coupling led to the formation of NHPI groups separated from the SiO2 surface by a vinyl linker, while one of the developed modification paths based on the grafting of an appropriate organosilane coupling agent resulted in the active phase devoid of this structural element. The successful course of the synthesis was verified by FTIR and H-1 NMR measurements. Furthermore, the formed materials were examined in terms of their chemical composition (elemental analysis, thermal analysis), structure of surface groups (C-13 NMR, XPS), porosity (low-temperature N-2 adsorption), and tested as catalysts in the aerobic oxidation of p-xylene at atmospheric pressure. The highest conversion and selectivity to p-toluic acid were achieved using the catalyst with enhanced availability of non-hydrolyzed NHPI groups in the pore system. The catalytic stability of the material was additionally confirmed in several subsequent reaction cycles.
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| 6. |
- Brudvig, G. W., et al.
(författare)
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Catalytic Systems for Water Splitting
- 2016
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Ingår i: ChemPlusChem. - : Wiley-VCH Verlagsgesellschaft. - 2192-6506. ; 81:10, s. 1017-1019
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Denk, C., et al.
(författare)
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Multifunctional Clickable Reagents for Rapid Bioorthogonal Astatination and Radio-Crosslinking
- 2019
-
Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 84:7, s. 775-778
-
Tidskriftsartikel (refereegranskat)abstract
- In the past decade, several developments have expanded the chemical toolbox for astatination and the preparation of 211 At-labeled radiopharmaceuticals. However, there is still a need for advanced methods for the synthesis of astatinated (bio)molecules to address challenges such as limited in vivo stability. Herein, we report the development of multifunctional 211 At-labeled reagents that can be prepared by applying a modular and versatile click approach for rapid assembly. The introduction of tetrazines as bioorthogonal tags enables rapid radiolabeling and radio-crosslinking, which is demonstrated by steric shielding of 211 At to significantly increase label stability in human blood plasma. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
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| 8. |
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| 9. |
- Durbeej, Bo, 1973-, et al.
(författare)
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Molecular Photoswitching Aided by Excited-State Aromaticity
- 2018
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Ingår i: ChemPlusChem. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 2192-6506. ; 83:11, s. 958-967
-
Tidskriftsartikel (refereegranskat)abstract
- Central to the development of optoelectronic devices is the availability of efficient synthetic molecular photoswitches, the design of which is an arena where the evolving concept of excited‐state aromaticity (ESA) is yet to make a big impact. The aim of this minireview is to illustrate the potential of this concept to become a key tool for the future design of photoswitches. The paper starts with a discussion of challenges facing the use of photoswitches for applications and continues with an account of how the ESA concept has progressed since its inception. Then, following some brief remarks on computational modeling of photoswitches and ESA, the paper describes two different approaches to improve the quantum yields and response times of switches driven by E/Z photoisomerization or photoinduced H‐atom/proton transfer reactions through simple ESA considerations. It is our hope that these approaches, verified by quantum chemical calculations and molecular dynamics simulations, will help stimulate the application of the ESA concept as a general tool for designing more efficient photoswitches and other functional molecules used in optoelectronic devices.
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| 10. |
- Erdélyi, Máté, 1975-, et al.
(författare)
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Halogen Bonding : From Fundamentals to Applications
- 2021
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Ingår i: ChemPlusChem. - : John Wiley & Sons. - 2192-6506. ; 86:9, s. 1229-1230
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Guest Editors Maté Erdélyi, Catharine Esterhuysen, and Weilang Zhu introduce the joint Special Collection on Halogen Bonding published by ChemPlusChem and The Chemical Record. This collection is organized in association with the 4th International Symposium on Halogen Bonding (ISXB4) and features top multidisciplinary contributions where halogen bonding plays a pivotal role, including computational, synthetic and catalytic, supramolecular and crystal engineering, and biological investigations and applications.
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| 11. |
- Esfandiarfard, Keyhan, et al.
(författare)
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Precursors for the Development of π-Conjugated Low-Coordinate Phosphorus Compounds
- 2023
-
Ingår i: ChemPlusChem. - : Wiley-VCH Verlagsgesellschaft. - 2192-6506. ; 88:6
-
Tidskriftsartikel (refereegranskat)abstract
- The synthesis of a novel monomeric precursor and its butadiyne-bridged dimeric form for the preparation of novel π-conjugated organophosphorus compounds is presented. The precursors are synthesized from commercially available starting materials, and based on a Dmp (2,6-dimesitylphenyl) group for kinetic stabilization of the P-functionality, a bromo substituent for the introduction of the phosphorus center, and an acetylene unit at the para position of the Dmp moiety. Such acetylenic units are synthetically versatile, and can be explored for the construction of larger phosphorus-containing π-conjugates. The precursors are utilized to prepare Dmp-stabilized C,C-dibromophosphaalkenes, and butadiyne-bridged dimeric species thereof. The effect of the low-coordinate phosphorus centers and the extent of π-conjugation on the spectroscopic and electronic properties is evaluated by NMR and UV/Vis spectroscopy, as well as cyclic voltammetry. In addition to the phosphaalkenes, the successful syntheses of two new diphosphenes are presented, indicating a broad applicability of the precursor.
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| 12. |
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| 13. |
- Füchtbauer, Anders Foller, 1984, et al.
(författare)
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Lighting Up DNA with the Environment-Sensitive Bright Adenine Analogue qAN4
- 2020
-
Ingår i: Chempluschem. - : Wiley. - 2192-6506. ; 85:2, s. 319-326
-
Tidskriftsartikel (refereegranskat)abstract
- The fluorescent adenine analogue qAN4 was recently shown to possess promising photophysical properties, including a high brightness as a monomer. Here we report the synthesis of the phosphoramidite of qAN4 and its successful incorporation into DNA oligonucleotides using standard solid-phase synthesis. Circular dichroism and thermal melting studies indicate that the qAN4-modification has a stabilizing effect on the B-form of DNA. Moreover, qAN4 base-pairs selectively with thymine with mismatch penalties similar to those of mismatches of adenine. The low energy absorption band of qAN4 inside DNA has its peak around 358 nm and the emission in duplex DNA is partly quenched and blue-shifted (ca. 410 nm), compared to the monomeric form. The spectral properties of the fluorophore also show sensitivity to pH; a property that may find biological applications. Quantum yields in single-stranded DNA range from 1-29 % and in duplex DNA from 1-7 %. In combination with the absorptive properties, this gives an average brightness inside duplex DNA of 275 M-1 cm(-1), more than five times higher than the most used environment-sensitive fluorescent base analogue, 2-aminopurine. Finally, we show that qAN4 can be used to advantage as a donor for interbase FRET applications in combination with adenine analogue qA(nitro) as an acceptor.
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| 14. |
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| 15. |
- Hoffmann, Christian, et al.
(författare)
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Improved Alkyl Glycoside Synthesis by trans-Glycosylation through Tailored Microenvironments of Immobilized β-Glucosidase
- 2020
-
Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 85:1, s. 137-141
-
Tidskriftsartikel (refereegranskat)abstract
- We present how the microenvironment can directly improve biocatalytic selectivity of immobilized β-glucosidase. β-Glucosidase from Thermotoga neapolitana was immobilized on a variety of functionalized off-stoichiometric thiol-ene (OSTE) particles, where highest activities were observed for thiol and imidazole functional particles. Compared to the soluble enzyme, the selectivity (rs/rh) between trans-glycosylation of p-nitrophenyl β-D-glucopyranoside (pNPG) with 1-propanol over hydrolysis was increased by a factor of 2–3 using particles containing imidazole (rs/rh of 6.7) and carboxylic acid moieties (rs/rh of 9.2), respectively. These results demonstrate clearly that enzyme selectivity depends directly on the local environment of the enzyme with the support.
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| 16. |
- Hogberg, Daniel, et al.
(författare)
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Self-Assembled Liquid-Crystalline Ion Conductors in Dye-Sensitized Solar Cells : Effects of Molecular Sensitizers on Their Performance
- 2017
-
Ingår i: ChemPlusChem. - : WILEY-V C H VERLAG GMBH. - 2192-6506. ; 82:6, s. 834-840
-
Tidskriftsartikel (refereegranskat)abstract
- Dye-sensitized solar cells employing nonvolatile liquid-crystalline (LC) electrolytes that form nanostructures capable of efficient ion transport are reported. The LC electrolyte consists of a cyclic carbonate-functionalized mesogen and an iodide-based ionic liquid that nanosegregates into lamellar structures exhibiting over four times higher ion conductivities parallel to the layers than perpendicular to the layers. The self-assembled ion pathways allow efficient ion transport in the semi-solid LC state. When used together with organic dyes, DSSCs employing these LC electrolytes show higher power conversion efficiency (PCE) than metal-organic dyes. This behavior is not observed for devices containing standard liquid electrolytes. The higher PCEs of the LC-based devices can be attributed to longer electron lifetimes (t) and higher electron densities in the photoelectrodes. The high concentration of iodide ions in the nanostructured pathways of the LC electrolyte is thought to induce reductive quenching of the ruthenium-based sensitizer, which competes with the electron injection process and lowers the t and electron densities of the TiO2.
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| 17. |
- Hur, Deniz, et al.
(författare)
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3D Micropatterned All-Flexible Microfluidic Platform for Microwave-Assisted Flow Organic Synthesis
- 2018
-
Ingår i: ChemPlusChem. - : WILEY-V C H VERLAG GMBH. - 2192-6506. ; 83:1, s. 42-46
-
Tidskriftsartikel (refereegranskat)abstract
- A large-area, all-flexible, microwaveable polydimethoxysilane microfluidic reactor was fabricated by using a 3D printing system. The sacrificial microchannels were printed on polydimethoxysilane substrates by a direct ink writing method using water-soluble Pluronic F-127 ink and then encapsulated between polydimethoxysilane layers. The structure of micron-sized channels was analyzed by optical and electron microscopy techniques. The fabricated flexible microfluidic reactors were utilized for the acetylation of different amines under microwave irradiation to obtain acetamides in shorter reaction times and good yields by flow organic synthesis.
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| 18. |
- Karlsson, Erik A., et al.
(författare)
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Synthesis and Electron-Transfer Processes in a New Family of Ligands for Coupled Ru-Mn2 Complexes
- 2014
-
Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 79:7, s. 936-950
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Tidskriftsartikel (refereegranskat)abstract
- A series of [Ru(bpy)(3)](2+)-type (bpy= 2,2'-bipyridine) photosensitisers have been coupled to a ligand for Mn, which is expected to give a dinuclear complex that is active as a water oxidation catalyst. Unexpectedly, photophysical studies showed that the assemblies had very short lived excited states and that the decay patterns were complex and strongly dependent on pH. One dyad was prepared that was capable of catalysing chemical water oxidation by using [Ru(bpy)(3)](3+) as an oxidant. However, photochemical water oxidation in the presence of an external electron acceptor failed, presumably because the short excited-state lifetime precluded initial electron transfer to the added acceptor. The photophysical behaviour could be explained by the presence of an intricate excited-state manifold, as also suggested by time-dependent DFT calculations.
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| 19. |
- Keşan, Gürkan, et al.
(författare)
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Time-Resolved Spectroelectrochemical Dynamics of Carotenoid 8’-apo-β-Carotenal
- 2023
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Ingår i: ChemPlusChem. - 2192-6506. ; 88:11
-
Tidskriftsartikel (refereegranskat)abstract
- This work examines the influence of applied external voltage in bulk electrolysis on the excited-state properties of 8′-apo-β-carotenal in acetonitrile by steady-state and ultrafast time-resolved absorption spectroscopy. The data collected under bulk electrolysis were compared with those taken without applied voltage. The steady-state measurements showed that although intensity of the S0-S2 absorption band varies with the applied voltage, the spectral position remain nearly constant. Comparison of transient absorption spectra shows that the magnitude of the ICT-like band decreases during the experiment under applied voltage condition, and is associated with a prolongation of the S1/ICT-like lifetime from 8 ps to 13 ps. Furthermore, switching off the applied voltage resulted in returning to no-voltage data within about 30 min. Our results show that the amplitude of the signal associated with the ICT state can be tuned by applying an external voltage.
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| 20. |
- Kulyk, Kostiantyn, et al.
(författare)
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Dimethylsilanone Generation from Pyrolysis of Polysiloxanes Filled with Nanosized Silica and Ceria/Silica
- 2016
-
Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 81:9, s. 1003-1013
-
Tidskriftsartikel (refereegranskat)abstract
- Temperature-programmed desorption mass spectrometry (TPDMS) was used to study the pyrolysis of PDMS and its composites with nanosized silica and ceria/silica. The results suggest that the elusive organosilicon compound, dimethylsilanone, is generated from PDMS over a broad temperature range (in some cases starting at 70 degrees C). The presence of nano-oxides catalyzes this process. Ions characteristic of the fragmentation of dimethylsilanone under electron ionization are assigned with the aid of DFT structure calculations. Possible reaction mechanisms for dimethylsilanone generation are discussed in the context of the calculated kinetic parameters. Observed accompanying products of PDMS pyrolysis, such as tetramethylcyclodisiloxane and hexamethylcyclotrisiloxane, indicate that multiple channels are involved in the dimethylsilanone release.
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| 21. |
- Kunz, Anne, et al.
(författare)
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Intermolecular London Dispersion Interactions of Azobenzene Switches for Tuning Molecular Solar Thermal Energy Storage Systems
- 2019
-
Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 84:8, s. 1145-1148
-
Tidskriftsartikel (refereegranskat)abstract
- The performance of molecular solar thermal energy storage systems (MOST) depends amongst others on the amount of energy stored. Azobenzenes have been investigated as high-potential materials for MOST applications. In the present study it could be shown that intermolecular attractive London dispersion interactions stabilize the (E)-isomer in bisazobenzene that is linked by different alkyl bridges. Differential scanning calorimetry (DSC) measurements revealed, that this interaction leads to an increased storage energy per azo-unit of more than 3 kcal/mol compared to the parent azobenzene. The origin of this effect has been supported by computation as well as X-ray analysis. In the solid state structure attractive London dispersion interactions between the C−H of the alkyl bridge and the π-system of the azobenzene could be clearly assigned. This concept will be highly useful in designing more effective MOST systems in the future.
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| 22. |
- Lee, T J, et al.
(författare)
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An accurate quartic force field and fundamental frequencies for the ozonide anion.
- 2003
-
Ingår i: Collection of Czechoslovak Chemical Communications. - : Institute of Organic Chemistry & Biochemistry. - 2192-6506 .- 0010-0765 .- 1212-6950. ; 68:1, s. 189-201
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Tidskriftsartikel (refereegranskat)abstract
- The CCSD(T) method has been used to compute a highly accurate quartic force field and fundamental frequencies for all 16O and 18O isotopomers of the ozonide anion. The CCSD and CASPT2 methods have also been used to verify the reliability of the CCSD(T) fundamental frequencies. The computed fundamental frequencies are in agreement with gas-phase experiments, but disagree with matrix isolation experiments for the antisymmetric stretch, n3. CASPT2 calculations show that the antisymmetric part of the O3- potential surface is sensitive to the external environment. It is concluded that the antisymmetric stretch exhibits a significant matrix shift in the matrix isolation experiments and that the matrix environment is not representative of the gas-phase environment for ozonide anion. It is hoped that the theoretical data provided here will aid in the interpretation of future high-resolution gas-phase experiments.
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| 23. |
- Li, H., et al.
(författare)
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Visible-Light-Driven Water Oxidation on a Photoanode by Supramolecular Assembly of Photosensitizer and Catalyst
- 2016
-
Ingår i: ChemPlusChem. - : Wiley-VCH Verlagsgesellschaft. - 2192-6506. ; 81:10, s. 1056-1059
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Tidskriftsartikel (refereegranskat)abstract
- A ruthenium water oxidation catalyst (WOC) bearing hydrophobic ligands was incorporated on the surface of a dye-sensitized nanostructured TiO2 film by formation of a host–guest adduct with the dye. This provides a new strategy for constructing photocatalytically active electrodes for water oxidation. The resultant photoanode exhibits a photocurrent of 800 μA cm−2 under visible-light illumination (λ>400 nm, 300 mW cm−2) and 240 μA cm−2 under simulated sunlight illumination (AM 1.5G, 100 mW cm−2) with an applied bias of 0.2 V vs. NHE in neutral phosphate buffer.
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| 24. |
- Liang, Yu, et al.
(författare)
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Ultrafast Dynamics of meso-Tetraphenylmetalloporphyrins : The Role of Dark States
- 2013
-
Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 78:10, s. 1244-1251
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Tidskriftsartikel (refereegranskat)abstract
- Studying the relaxation pathways of porphyrins and related structures upon light absorption is crucial to understand the fundamental processes of light harvesting in biosystems and many applications. Herein, we show by means of transient absorption studies, following Q- and Soret-band excitation, and abinitio calculations on meso-tetraphenylporphyrinato magnesium(II) (MgTPP) and meso-tetraphenylporphyrinato cadmium(II) (CdTPP) that electronic relaxation following Soret-band excitation of porphyrins with a heavy central atom is mediated by a hitherto disregarded dark state. This accounts for an increased rate of internal conversion. The dark state originates from an orbital localized at the central nitrogen atoms and its energy continuously decreases along the series from magnesium to zinc to cadmium to below 2.75eV for CdTPP dissolved in tetrahydrofuran. Furthermore, we are able to directly trace fast intersystem crossing in the cadmium derivative, which takes place within (110 +/- 20)ps.
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| 25. |
- Olsson, Sandra K., 1987-, et al.
(författare)
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Exciton-Coupled Circular Dichroism Characterization of Monotopically Binding Guests in Host-Guest Complexes with a Bis(zinc porphyrin) Tweezer
- 2018
-
Ingår i: ChemPlusChem. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 2192-6506. ; 83, s. 1169-1178
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Tidskriftsartikel (refereegranskat)abstract
- A stiff-stilbene-linked bisporphyrin tweezer with inherent helicity was used for exciton-coupled circular dichroism (ECCD) characterization of a series of monotopically binding amine guest molecules. CD signals were observed for a variety of monoamines at relatively low tweezer/amine (host/guest) ratios between 1 :10 to 1: 70. For the amines producing the most intense CD signals, a binding stoichiometry of 1:2 was found. A likely explanation is the presence of guest-guest interactions in the complexes. This is supported by the correlation observed between CD signal intensity and magnitude of possible noncovalent binding between the guests, which can be divided into three groups showing no, moderate and strong response, respectively. Further support for this rationalization comes from molecular modelling.
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| 26. |
- Roos, Björn
(författare)
-
The ground state potential for the chromium dimer revisited.
- 2003
-
Ingår i: Collection of Czechoslovak Chemical Communications. - : Institute of Organic Chemistry & Biochemistry. - 2192-6506 .- 0010-0765 .- 1212-6950. ; 68:2, s. 265-274
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Tidskriftsartikel (refereegranskat)abstract
- Results are presented from a new theoretical study of the ground state potential curve of the chromium dimer using multiconfiguration second-order perturbation theory. A new basis set of the atomic natural orbital type is used where the construction includes correlation of the semi-core 3p orbitals and scalar relativistic effects are added using the Douglas-Kroll Hamiltonian. The active space used in the CASSCF/CASPT2 calculations comprised 16 orbitals with 12 active electrons. The resulting ground state potential is in agreement with experiment. Computed spectroscopic constants are (with experimental values within parentheses): Re = 1.66 (1.68) Å, D0 = 1.65 (1.53 ± 0.06) eV, ∆G1/2 = 413 (452) cm-1. Higher vibrational frequencies are also well reproduced.
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| 27. |
- Rönnholm, Petra, 1969, et al.
(författare)
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Aggregation and Solvation of Chiral N,P-Amide Ligands in Coordinating Solvents: A Computational and NMR Spectroscopic Study
- 2012
-
Ingår i: Chempluschem. - : Wiley. - 2192-6506. ; 77:9, s. 799-806
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Tidskriftsartikel (refereegranskat)abstract
- The lithium amides of a series of chiral N,P ligands were studied in solution. This ligand class had been shown previously to give good selectivities in asymmetric alkylation of benzaldehyde. These lithium amides were found to aggregate into dimers with surprisingly strong coordination of phosphorus to lithium. The equilibrium between dimeric forms was found to depend strongly on non-bonded interactions within the solute and between solute and solvent. Only if dispersion and free-energy contributions were scaled to approximately 20?% of the gas-phase values was it possible to reproduce the experimentally observed aggregation preferences. NMR spectroscopic shieldings were calculated and found to correlate well with the experimentally observed shifts. Calculated Li,P couplings were shown to be a sensitive measure of the Li?P distance.
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| 28. |
- Serra, Immacolata, et al.
(författare)
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Developing a Collection of Immobilized Nucleoside Phosphorylases for the Preparation of Nucleoside Analogues: Enzymatic Synthesis of Arabinosyladenine and 2,3-Dideoxyinosine
- 2013
-
Ingår i: Collection of Czechoslovak Chemical Communications. - : Wiley. - 2192-6506. ; 78:2, s. 157-165
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Tidskriftsartikel (refereegranskat)abstract
- The use of nucleoside phosphorylases (NPs; EC 2.4.2.n) represents a convenient alternative to the chemical route for the synthesis of natural and modified nucleosides. We purified four recombinantly expressed nucleoside phosphorylases from the bacterial pathogens Citrobacter koseri, Clostridium perfringens, and Streptococcus pyogenes (CkPNPI, CkPNPII, CpUP, SpUP) and their substrate specificity was investigated towards either natural pyrimidine or purine nucleosides and some analogues, namely, arabinosyladenine (araA) and 2,3-dideoxyinosine (ddI). A 23% activity towards these latter compounds (compared to the natural substrates) was observed. Enzyme activities were compared to the specificities obtained for the enzymes pyrimidine nucleoside phosphorylase from Bacillus subtilis (BsPyNP) and purine nucleoside phosphorylase from Aeromonas hydrophila (AhPNPII) previously reported by some of the authors. The enzymes displaying the suitable specificity for the synthesis of araA and ddI were immobilized on aldehydeagarose. The immobilized preparations were highly stable at alkaline pH and in the presence of methanol or acetonitrile as cosolvent. They were used in the synthesis of araA and ddI by a one-pot, bienzymatic transglycosylation achieving 74 and 44% conversion, respectively.
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| 29. |
- Shameem, Muhammad Anwar, et al.
(författare)
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1-Phospha-Butadienes and 1H-Phospholes via Alkynylation of Acetylenic Phosphaalkenes
- 2023
-
Ingår i: ChemPlusChem. - : Wiley-Blackwell. - 2192-6506. ; 88:4
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Tidskriftsartikel (refereegranskat)abstract
- Carbon-rich motifs are important building blocks for the fabrication of functional and opto-electronic materials. Electronic tuning can be achieved by alteration of bonding topologies but also via incorporation of heteroelements, for example phosphorus. Herein we present the palladium/copper mediated formation of branched 1-phospha-butadiene derivatives through an unusual alkynylation of a phospha-enyne fragment. Structural and NMR studies provide mechanistic insights into this alkynylation. Furthermore, we disclose a complex cyclisation of the thus obtained 3-yne-1-phosphabutadiene motifs to give highly substituted phosphole derivatives identified by 2D NMR and SC-XRD analysis.
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| 30. |
- Sharma, Pratigya, et al.
(författare)
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Activation-Induced Surface Modulation of Biowaste-Derived Hierarchical Porous Carbon for Supercapacitors
- 2022
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Ingår i: ChemPlusChem. - : John Wiley & Sons. - 2192-6506. ; 87:6
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Tidskriftsartikel (refereegranskat)abstract
- Wheat straw-derived carbon from the Wheatbelt region in Western Australia was subjected to chemical activation in an electrolyte containing either acid or base treatment. The findings showed an increase in electron/hole mobility towards the interfaces due to the presence of different surface functional groups such as C-SOx-C and S=C in the carbon framework for acid activation. Likewise, the galvanostatic capacitance measured at a current density of 2 mA cm(-2) in a three-electrode configuration for acid-activated wheat straw exhibited 162 F g(-1), while that for base-activated wheat straw exhibited 106 F g(-1). An increase of 34.5 % more capacitance was achieved for acid-treated wheat straw. This improvement is attributed to the synergistic effects between surface functional groups and electrolyte ions, as well as the electronic structure of the porous electrode.
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| 31. |
- Shleev, Sergey
(författare)
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Quo Vadis, Implanted Fuel Cell?
- 2017
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Ingår i: ChemPlusChem. - : John Wiley & Sons. - 2192-6506. ; 82:4, s. 522-539
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Forskningsöversikt (refereegranskat)abstract
- The road to safe and effective implantable electrical power devices has been long-and the goal has not been reached yet, although a certain amount of scientific and technological progress has been made. This brief review is focused on highlighting the stages of development of implanted fuel cells capable of providing electrical power for running implanted "personal electronics". The paper starts with early efforts to implant glucose-burning fuel cells in dogs, and ends with realistic attempts at interfacing a more sophisticated enzymatic glucose/oxygen fuel cell in an actual human blood stream. However, before that, the review deals with thermodynamic aspects of fuel cells, emphasizing the general advantages of these devices. Further steps, which are needed to realize the potential of this technology and which somehow differ from generally accepted ideas, are presented. These next steps are evaluated in the context of theoretically achievable abilities of implantable chemical power sources, which are not as great as many researchers might expect.
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| 32. |
- Tavahodi, Mojtaba, et al.
(författare)
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Direct Electron Transfer of Cellobiose Dehydrogenase on Positively Charged Polyethyleneimine Gold Nanoparticles
- 2017
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Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 82:4, s. 546-552
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Tidskriftsartikel (refereegranskat)abstract
- Efficient conjugation between biomolecules and electrode materials is one of the main challenges in the field of biosensors. Cellobiose dehydrogenase (CDH) is a monomeric enzyme, which consists of two separate domains: one catalytic dehydrogenase domain (DHCDH) carrying strongly bound flavin adenine dinucleotide (FAD) in the active site and a cytochrome domain (CYTCDH) carrying a b-type heme connected by a flexible linker region. Herein, we report on the development of a lactose biosensor, based on direct electron transfer (DET) from CDH from Phanerochaete sordida (PsCDH) electrostatically attached onto polyethyleneimine-stabilized gold nanoparticles (PEI@AuNPs) used to cover a conventional polycrystalline solid gold disk electrode. PEI@AuNPs were synthesized in aqueous solution using PEI as reducing agent for AuIII and as stabilizer for the nanoparticles. The heterogeneous electron-transfer (ET) rate (ks) for the redox reaction of immobilized PsCDH at the modified electrodes was calculated based on the Laviron theory and was found to be (39.6±2.5)s-1. The proposed lactose biosensor exhibits good long term stability as well as high and reproducible sensitivity to lactose with a response time less than 5s and a linear range from 1 to 100μm.
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| 33. |
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| 34. |
- Toldo, Josene, et al.
(författare)
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Is Excited-State Aromaticity a Driving Force for Planarization of Dibenzannelated 8 Π-Electron Heterocycles?
- 2019
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Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 84:6, s. 712-721
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Tidskriftsartikel (refereegranskat)abstract
- Compounds with dibenzannelated heterocycles with eight pi-electrons are found in a range of applications. These molecules often adopt a bent structure in the ground state (S-0) but can become planar in the first excited states (S-1 and T-1) because of the cyclically conjugated 4n pi central ring, which fulfils the requirements for excited state aromaticity. We report on a quantum chemical investigation of the aromatic character in the S-1 and T-1 states of dibenzannelated seven- and six-membered heterocycles with one, two, or three heteroatoms in the 8 pi-electron ring. These states could have pi pi* or n pi* character. We find that compounds with one or two heteroatoms in the central ring have pi pi* states as their S-1 and T-1 states. They are to a significant degree influenced by excited state aromaticity, and their optimal structures are planar or nearly planar. Among the heteroatoms, nitrogen provides for the strongest excited state aromaticity whereas oxygen provides for the weakest, following the established trend of the S-0 state. Yet, dibenzannelated seven-membered-ring compounds with N=N bonds have non-aromatic n pi* states with strongly puckered structures as their S-1 and T-1 states.
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| 35. |
- Xu, Chao, et al.
(författare)
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Hydrophobic Porous Polyketimines for the Capture of CO2
- 2016
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Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 81:1, s. 58-63
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Tidskriftsartikel (refereegranskat)abstract
- A new type of porous polymers is presented. Polyketimines (PPKs) were synthesized by condensing 1,3,5-tris(4-aminophenyl)benzene with aromatic diketones usingp-toluenesulfonic acid catalyst. They were characterized by infrared spectroscopy and solid-state 13C{1H} nuclear magnetic resonance spectroscopy, and their porosities were probed through the adsorption of N2 and CO2. The PPKs had low uptakes of N2 (at −196 °C), which was attributed to diffusion limitations and/or a shrinking of the polymer. They had relatively high uptakes of CO2 (at 0 °C; up to 1.26 mmol g−1 at 0.15 bar and 2.99 mmol g−1 at 1 bar), which was related to ultramicropores (6–9 Å). The PPKs had high estimated CO2-over-N2 selectivities (30–40 at 0 °C). Studies on the vapor adsorption of water and ethanol showed the PPKs to be moderately hydrophobic and had a high uptake of ethanol at low partial pressures.
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| 36. |
- Ye, Qilun, et al.
(författare)
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Urchin-Like Cobalt-Copper (Hydr)oxides as an Efficient Water Oxidation Electrocatalyst
- 2020
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Ingår i: ChemPlusChem. - : Wiley. - 2192-6506. ; 85:6, s. 1339-1346
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Tidskriftsartikel (refereegranskat)abstract
- The development of e & xfb03;cient and low-cost oxygen evolution reaction (OER) catalysts is essential for the generation of clean hydrogen energy from water splitting. Herein, a novel hierarchical urchin-like cobalt-copper (hydr)oxide in situ grown on copper foam (CoCuOxHy(S)/CF) was synthesized through the electrochemical transformation of cobalt-copper sulfides (Co9S8-Cu1.81S) via anodization process. This CoCuOxHy(S)/CF anode exhibited a low overpotential (eta) of 274 mV at a current density of 100 mA cm(-2)with a robust durability over a period of 40 h when operated at 10 mA cm(-2). Further investigations imply that the unique nanowires aggregated urchin-like structure of CoCuOxHy(S) derived from the in situ anion exchange process could facilitate the exposure of active sites and accelerate electron transfer. More importantly, the incorporation of copper resulted in an electronic delocalization around the cobalt species, which contributed to reach a high-valent catalytically active cobalt species and further improved the OER performance.
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