Electrochemical joint oxidation of diphenylphosphine oxide with acetylenes in the presence of silver acetate (10%) as a catalyst yields benzo
b
phosphole oxide derivatives under mild conditions at ...room temperature without additional oxidants or initiators and with yields up to 100%. The redox properties of the key intermediate of the catalytic cycle have been investigated by cyclic voltammetry and EPR spectroscopy. The Ph
2
P(O)Ag intermediate oxidizes easier (+0.05 V
vs.
Fc
+
/Fc) than all reaction precursors to form the phosphinyl radical Ph
2
P(&z.dbd;O)&z.rad;, fixed as a spin-adduct by ESR. Thus, a radical mechanism type through the Ag
+
/Ag
0
couple was developed for electrocatalytic conditions.
Electrochemical oxidation synthesis of benzo
b
phosphole oxides has been performed at room temperature with catalytic amounts of AgOAc.
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Nickel (I) complexes of 1,5-diaza-3,7-diphosphacyclooctane PPh2NR2 ligands were obtained from precursor Ni(II) by exhaustive electrolysis of Ni(PPh2NR2)22+ precursors at the Ni(II/I) ...couple potential and characterized by several techniques. Paramagnetic Ni(I) complexes were investigated by cyclic voltammetry, spectroelectrochemistry UV/Vis and ESR methods at room temperature and in a frozen solution. Catalytic behavior of Ni(I) complex in different ligand environment for hydrogen evolution from acid depends from the ligand nature. The two possible catalytic cycles were proposed depending on the nitrogen substituents in 1,5-diaza-3,7-diphosphacyclooctane.
Transition-metal complexes are candidates for replacing platinum and its combinations with other metals as catalysts for the hydrogen oxidation reaction (HOR) in proton-exchange membrane fuel cells ...(PEMFCs). The results of catalytic tests of bis(diphosphine) coordination complexes of nickel Ni(P
Ph
2
N
Ph
2
)
2
·2BF
4
and Ni(P
Ph
2
N
Bn
2
)
2
·2BF
4
in liquid-phase oxidation of hydrogen and as components of catalysts for the HOR in PEMFC are analyzed. It was found that the latter complex is a much more efficient catalyst for the HOR in PEMFC than the former. ESR studies demonstrated an increase in the difference between the hyperfine coupling constants on phosphorus nuclei on going from Ni(P
Ph
2
N
Ph
2
)
2
· 2BF
4
to Ni(P
Ph
2
N
Bn
2
)
2
·2BF
4
. Significant morphological differences between the complexes on the atomically smooth surface of pyrolytic graphite were revealed by atomic force microscopy.
Joined electrolysis of arenes (benzene or coumarin derivatives) and diethyl-
H
-phosphonate (EtO)
2
P(O)H in the presence of CoCl
2
(bpy) catalyst (5%) in an ethanol-aqueous solution in reductive ...conditions allows obtaining the desired products in a single step by aromatic C–H bonds phosphonation with yields up to 70%. The only by-product is hydrogen; the reaction proceeds at room temperature and does not require specially added reducing agents and oxidants or other initiators. Radical mechanism has been confirmed for the catalytic reaction proceeding via bicobalt phosphonates with Co–P bond, the structure of which also has been identified.
Abstract
This study is part of the work on the creation of a transparent conductive coating based on oriented nanonetwork and submicron nickel fibres. It is devoted to finding the optimal values of ...electrical conductivity and optical transparency of the developed coating. In this work, we study the transmission spectra of oriented nickel networks on a glass substrate in the UV, visible and near-IR regions at different amounts of deposited metal. An exciting feature of the coating was discovered: in the range of 950 nm and above, there is a "bend" of the transmission spectrum downward. This bend (increased absorption of radiation in the near-IR region) is observed only in the presence of nickel nanonetwork and is not typical for a pure submicron network.
The C4F8 ligand was shown to support well-defined terpyridyl nickel complexes in the +2 and +3 oxidation states. Notably, a cyclic voltammetry study of the nickel(iii) species indicates that an ...additional oxidation is accessible, providing a family of related fluoroalkyl nickel complexes spanning the +2 to +4 oxidation states.
Searching for new ways of converting carbon dioxide into value-added products, such as fuels, is a relevant task of our time. Electrochemical reduction of carbon dioxide to carbon monoxide, ...hydrocarbons and alcohols is considered as one of the main approaches in this area. One of the most advanced approaches is the use of coordination polymers for homogeneous and heterogeneous catalysis of carbon dioxide reduction. We obtained coordination pectin biopolymers with different nickel ions contents (PG-NaNi). The structure and composition of the obtained biopolymers were characterized by such physicochemical methods as IR and ICP-AE spectroscopy. Morphology of PG-NaNi on a glassy carbon surface provides very high surface to volume ratio. Cyclic voltammetry on the modified glassy carbon working electrode in water solution saturated with carbon dioxide shows catalytic properties of PG-NaNi for CO2 reduction reaction.
Abstract
The paper investigates the optical transparency dependence of a coating based on an oriented network of platinum nanowires on the amount of metal used. Oriented platinum nanowires on a glass ...surface are produced by chemical deposition from an aqueous hexachloroplatinic acid solution. The topography of the deposited metal layer on glass is visualized using atomic force microscopy. Optical transparency was investigated with a spectrophotometer. In almost the entire region of optical radiation, the transparency is approximately 98%. The absorption spectrum shows that the absorption coefficient increases sharply in the near UV region.
Multitarget ligands (MTL) based on sterically hindered phenol and containing a quaternary ammonium moiety (SHP-n-Q) were synthesized. These compounds are inhibitors of cholinesterases with ...antioxidant properties. The inhibitory selectivity is 10-fold potent for BChE than for AChE. IC50 of SHP-n-Q for BChE is 20 μM. SHP-n-Q and their nanosystems exhibit more pronounced antioxidant properties than the synthetic antioxidant (hindered phenol, butylated hydroxytoluene). These compounds display a low hemolytic activity against human red blood cells. The nanotechnological approach was used to increase the bioavailability of SHP-n-Q derivatives. For water soluble SHP-n-Q derivative, the self-assembled structures have a size close to 100 nm at critical association concentration (0.01 M). Mixed cationic liposomes based on l-α-phosphatidylcholine and SHP-n-Q of 100 nm diameter were prepared. The stability, encapsulation efficacy and release from liposomes of a model drug, Rhodamine B, depend on the structure of SHP-n-Q. Cationic liposomes based on l-α-phosphatidylcholine and SHP-3-Q show a good stability in time (1year) and a sustained release (>65 h). They are promising templates for the development of anti-Alzheimer MT-drug delivery systems.
•Sterically hindered phenol containing quaternary ammonium moiety were synthesized.•The inhibitory selectivity is 10-fold higher for BuChE than for AChE.•Sterically hindered phenol self-assembled 100 nm structures were observed.•Sterically hindered phenol-loaded liposomes show a good stability and sustained release.•Sterically hindered phenols are promising templates for multitarget-drug delivery systems.
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