In this work, the effectivity of scaife polishing was evaluated for {110}-oriented single-crystal boron-doped diamond (SC-BDD) electrodes with varying boron doping levels, [B] from similar to 3x10(20) to similar to 7x10(20) atoms cm(-3). While the RMS surface roughness of the as-deposited SC-BDD reached up to 137 nm, after polishing it was reduced to <= 1.5 nm. Following scaife polishing, peak potential difference Delta Ep evaluated from cyclic voltammetry for both outer-sphere ([Ru(NH3)(6)](3+/2+), ferrocenemethanol(+/0)) and inner-sphere redox marker [Fe(CN)(6)](3-/4-) became relatively equal regardless of [B]. Notably, heterogenous electron transfer (HET) kinetics of [Fe(CN)(6)](3-)/(4-) improved significantly with the HET rate constant k0 increasing from 45.7x10- 5 to 171x10- 5 cm s- 1 with increasing [B]. These results were confirmed by electrochemical impedance spectroscopy measurements with [Fe(CN)(6)](3-/4-) , as charge transfer resistance (R-CT) significantly decreased after scaife polishing, whereas R-CT values gradually decreased with increasing [B]. Finally, scaife-polished SC-BDD electrodes with varying surface terminations (H- vs. O-termination) were compared with chemically-mechanically polished polycrystalline BDD electrodes in dopamine sensing utilising square-wave voltammetry. The limits of detection achieved on both types of polished surfaces are generally lower than 1 mu mol L-1. Obviously, a smooth BDD surface presumably possesses uniform surface conductivity, which contributes significantly to the improved analytical performance of the BDD electrodes.

Homoepitaxially grown single crystal boron-doped diamond (BDD) electrodes with {100} surface were nano-structured using dip-coated silica nanospheres (400 nm in diameter) as a template for microwave plasma-enhanced chemical vapour deposition. Co-doping of BDD with Si atoms was confirmed as a result of SiO2 etching during the deposition process. Electrochemical properties of the nanostructured electrodes with hemispherical cavities were thoroughly investigated using cyclic voltammetry and electrochemical impedance spectroscopy, and were compared with smooth {100} BDD surfaces. Heterogeneous electron transfer kinetics rates for the [Fe(CN)6]3-/4-redox marker were notably higher than literature-reported values for {100} BDD and were further increased up to two orders of magnitude by the nanostructuring. Similar increase in the electron transfer rate was observed for dopamine. Such enhancement can be caused by exposure of more reactive surfaces with other crystallographic orientations due to nanostructuring. Further, surface area analysis revealed the electroactive surface increase factor up to 2.44 upon nanostructuring, exceeding the theoretical estimate of 1.91 derived from geometrical considerations. This discrepancy may indicate nanoscale roughness of the surface of the hemispherical cavities' walls. Overall, the results demonstrate that the applied nanostructuring approach preserves the spa carbon character of the material while improving its electrochemical properties. These findings uncover the potential of nanostructured BDD surfaces for applications in electrochemical sensors, spatially distributed surface modification, and particle entrapment.

Boron doped diamond has been considered as a fouling-resistive electrode material for in vitro and in vivo detection of neurotransmitters. In this study, its performance in electrochemical detection of dopamine and serotonin in neuron cultivation media NeurobasalTM before and after cultivation of rat neurons was investigated. For differential pulse voltammetry the limits of detection in neat NeurobasalTM medium of 2 mu M and 0.2 mu M for dopamine and serotonin, respectively, were achieved on the polished surface, which is comparable with physiological values. On oxidized surface twofold higher values, but increased repeatabilities of the signals were obtained. However, in NeurobasalTM media with peptides-containing supplements necessary for cell cultivation, the voltammograms were notably worse shaped due to biofouling, especially in the medium isolated after neuron growth. In these complex media, the amperometric detection mode at +0.75 V (vs. Ag/AgCl) allowed to detect portion-wise additions of dopamine and serotonin (as low as 1-2 mu M), mimicking neurotransmitter release from vesicles despite the lower sensitivity in comparison with neat NeurobasalTM. The results indicate substantial differences in detection on boron doped diamond electrode in the presence and absence of proteins, and the necessity of studies in real media for successful implementation to neuron-electrode interfaces.

Considering the simulation of cyclic voltammetry response in the case of porous electrodes that exhibit fractal properties, we propose a numerical technique to solve parameters’ identification problem for the corresponding fractional differential model and study the properties of its implementations in multi-threaded and GPU environments. The one-dimensional model consists of a space-fractional differential equation that describes diffusion and electrochemical reaction processes in a porous electrode and an integer-order diffusion equation for modeling solute transport towards an electrode. Using the L1-approximation of the Caputo derivative, we solve the problem by a finite-difference scheme on a non-uniform grid. Several variants of the particle swarm optimization (PSO) algorithm are applied to reconstruct the values of structural parameters of an electrode—its thickness, roughness, and fractional derivative’s order. Taking into account significantly different solution time for direct problems when the values of parameters vary, we consider an asynchronous and memetic variants of PSO. Testing was performed reconstructing parameters’ values based on the noised solution of the direct problem. Testing results show that memetic PSO algorithm is characterized by the most stable convergence while asynchronous versions of PSO allow the most even loading of CPU cores. Involvement of GPU in the computation process yields its acceleration only on grids with more than 1600 nodes allowing up to 10% performance gain. Successful testing of the developed technique shows its ability to be used for the analysis of real-world observations and for the prediction of the corresponding processes’ dynamics.

In this research, the oxidation of a series of benzoins, R-C(=O)-CH(OH)-R, where R = phenyl, 4-methoxyphenyl, 4-bromophenyl, and 2-naphthyl, by hydrogen peroxide in the presence of nanostructured HKUST-1 (suspension in acetonitrile/water mixture) was studied. The respective benzoic acids were the only products of the reactions. The initial average reaction rates were experimentally determined at different concentrations of benzoin, H2O2 and an effective concentration of HKUST-1. The sorption of the isotherms of benzoin, dimethoxybenzoin and benzoic acid on HKUST-1, as well as their sorption kinetic curves, were measured. The increase in H2O2 concentration expectedly led to an acceleration of the reaction. The dependencies of the benzoin oxidation rates on the concentrations of both benzoin and HKUST-1 passed through the maxima. This finding could be explained by a counterplay between the increasing reaction rate and increasing benzoin sorption on the catalyst with the increase in the concentration. The electronic effect of the substituent in benzoin had a significant influence on the reaction rate, while no relation between the size of the substrate molecule and the rate of its oxidation was found. It was confirmed by DFT modeling that the reaction could pass through the Baeyer–Villiger mechanism, involving an attack by the HOO− anion on the C atom of the activated C=O group.

Catalytic activity in arylzinc compound formation was studied for eight Co complexes with phosphines along with their redox properties for implementing the idea of rational design. It was found that Co(XantPhos)Cl2 and Co(N-XantPhos)Cl2 demonstrated distinct reversible CoII/CoI redox processes and acted as efficient catalysts of arylzinc compound formation. Meanwhile, for Co(DPEphos)Cl2, Co(dppf)Cl2, Co(dppb)Cl2, Co(PPh3)2Cl2, and Co(XantPhos)(Piv)2 (the latter one without the addition of LiCl), reversible redox processes were not observed. These catalysts did not act efficiently for the model process of organozinc compound formation. Co4(dppe)5Cl8 was the only exception, explained by a completely different structure (CoP4Cl and CoPCl3) of donor sets instead of CoP2X2 (X = Cl or O). The stability of complexes in tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) solutions was studied by UV-vis spectroscopy. Previously unknown X-ray structures for Co(XantPhos)(Piv)2, Co(N-XantPhos)Cl2, and {Co(DMF)6}{(CoCl3)2(dppb)} were determined. The use of pivalate counterions instead of chloride for Co(XantPhos)2+ led to a significant (ca. 20 times) increase of the kinetic solubility in THF compared to Co(XantPhos)Cl2, preserving high catalytic productivity upon the addition of LiCl. This allowed the latter to be efficiently used in combination with LiCl as the catalyst for arylzinc compound formation on a 2 g scale. The data obtained in this work can be regarded as experimental confirmation of the first and last stages of the plausible reaction pathway of arylzinc compound formation, involving CoII → CoI and CoI → CoII transformations, which could be a significant framework for further mechanistic investigations.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Electrochemical generation of nanowire arrays by one-step anodic oxidation of Zn in carbonate-based electro-lytes of different pH values is described. Zn foil was anodized in a mixture containing 5 mM Na2CO3 and 5 mM NaHCO3, as well as in pure Na2CO3 and NaHCO3 (both 10 mM). The morphology of anodic films was verified by FE-SEM. A special emphasis was put on the analysis of the composition of as-received nanomaterials by various techniques including XRD, XPS, UV-Vis, and Raman spectroscopy. Contrary to previous reports, we confirmed that the unknown phase of zinc carbonate with a formula of ZnCO3.H2O or Zn(HCO3)(OH) is formed at the Zn surface during anodization. The formation of ZnO resulting in more evident electrode passivation was also observed in the electrolytes containing sodium carbonates. The changes occurring during the thermal treatment of as-received materials were described based on TG, XPS, XRD, Raman, and nitrogen adsorption-desorption measurements. It was verified that, except for a several-fold increase in the active surface area, no significant changes in the wire-like morphology of the anodically generated product occur during its thermal conversion to ZnO. Finally, no noticeable differences in the photoelectrochemical performance of ZnO nanostructures formed in different electrolytes were observed.

Silver nanofoams were obtained on silver surface via electrodeposition from acidic aqueous electrolyte (AgNO3 + HBF4) under high current densities. The nanofoams consist of irregularly shaped Ag filaments (mean width 100-450 nm) arranged in walls surrounding void craters (mean diameter 7-40 mu m). Synthesis parameters (AgNO3 and HBF4 concentrations, deposition time, current density) were varied, and it was found that the higher the value of any synthesis parameter, the higher the observed mean crater diameter. An increase in the deposition time and current density also resulted in higher surface roughness. The higher Ag+ concentration led to higher mean filament width as well. The electrocatalytic performance of the nanofoams was studied via cyclic voltammetry by comparing potentials and currents of the peak corresponding to the bromobenzene reduction. All nanofoams were notably more electrocatalytically active in the reaction than bulk silver (potentials were at least 200 mV less negative), but, unexpectedly, the significant changes in their structure resulted only in moderate adjustment of their activity (the peak potentials varied within 60 mV). These observations allowed us to choose the explanation of the superior nanofoams activity among several suppositions, namely, the presence of some kind of active sites on the facets of the nanofoam forming particles.

A Cu-catalyzed, easily scalable one-pot synthesis of fused pyridines by the reaction of cyclic ketones with propargylamine is described. The protocol was optimized based on the results of more than 30 experiments. The highest product yields were achieved in i-PrOH as a solvent in the presence of 5.0 mol % CuCl2 in air. In contrast to the well-known Au-catalyzed protocol, our procedure is "laboratory friendly", cost-effective, and suitable for preparing dozens of grams of fused pyridine-based building blocks and does not require a high-pressure autoclave technique. Decreasing the catalyst amount in the reaction to 1.25 mol % CuCl2 provided a yield comparable to that achieved with 5 mol % catalyst, though a longer reaction time was required. A plausible reaction mechanism was proposed. The scope and limitation of the reaction were studied using 24 different cyclic ketones as starting materials. The fused pyridine yield decreased among cyclic ketones in the following order: six-membered ≫ eight-membered > five-membered ∼ seven-membered. The elaborated reaction conditions demonstrated tolerance to a number of protective functional groups in ketone such as ester, tert-butoxycarbonyl (Boc)-protected amine, and acetal moieties.

Reaction of 2,2′-bipyridine (2,2′-bipy) or 1,10-phenantroline (phen) with [Mn(Piv)2(EtOH)]n led to the formation of binuclear complexes [Mn2(Piv)4L2] (L = 2,2′-bipy (1), phen (2); Piv− is the anion of pivalic acid). Oxidation of 1 or 2 by air oxygen resulted in the formation of tetranuclear MnII/III complexes [Mn4O2(Piv)6L2] (L = 2,2′-bipy (3), phen (4)). The hexanuclear complex [Mn6(OH)2(Piv)10(pym)4] (5) was formed in the reaction of [Mn(Piv)2(EtOH)]n with pyrimidine (pym), while oxidation of 5 produced the coordination polymer [Mn6O2(Piv)10(pym)2]n (6). Use of pyrazine (pz) instead of pyrimidine led to the 2D-coordination polymer [Mn4(OH)(Piv)7(µ2-pz)2]n (7). Interaction of [Mn(Piv)2(EtOH)]n with FeCl3 resulted in the formation of the hexanuclear complex [MnII4FeIII2O2(Piv)10(MeCN)2(HPiv)2] (8). The reactions of [MnFe2O(OAc)6(H2O)3] with 4,4′-bipyridine (4,4′-bipy) or trans-1,2-(4-pyridyl)ethylene (bpe) led to the formation of 1D-polymers [MnFe2O(OAc)6L2]n·2nDMF, where L = 4,4′-bipy (9·2DMF), bpe (10·2DMF) and [MnFe2O(OAc)6(bpe)(DMF)]n·3.5nDMF (11·3.5DMF). All complexes were characterized by single-crystal X-ray diffraction. Desolvation of 11·3.5DMF led to a collapse of the porous crystal lattice that was confirmed by PXRD and N2 sorption measurements, while alcohol adsorption led to porous structure restoration. Weak antiferromagnetic exchange was found in the case of binuclear MnII complexes (JMn-Mn = −1.03 cm−1 for 1 and 2). According to magnetic data analysis (JMn-Mn = −(2.69 ÷ 0.42) cm−1) and DFT calculations (JMn-Mn = −(6.9 ÷ 0.9) cm−1) weak antiferromagnetic coupling between MnII ions also occurred in the tetranuclear {Mn4(OH)(Piv)7} unit of the 2D polymer 7. In contrast, strong antiferromagnetic coupling was found in oxo-bridged trinuclear fragment {MnFe2O(OAc)6} in 11·3.5DMF (JFe-Fe = −57.8 cm−1, JFe-Mn = −20.12 cm−1).

In situ reduction of NiCl2 incorporated in porous coordination polymer MIL-101(Cr) by NaBH4 or reduction of PdCl2 incorporated in MIL-101(Cr) by H-2 led to formation of NixB/MIL-101(Cr) and Pd/MIL-101(Cr) composites, respectively. Hydrogenation of quinoline at presence of these composites led to formation of 1,2,3,4-tetra-hydroquinoline in more than 90% yield, but in the case of Ni-containing catalyst 8 times higher metal loading in the reaction mixture was required to achieve this result (in the same conditions). The composites after the reaction were characterized by TEM and powder XRD.

Представлено результати розробки магнітної та магнітно-люмінесцентної рідини на основі нанорозмірних частинок CoFe 2 O 4 , а також композитів магнітних наночастинок CoFe 2 O 4 та Fe 3 O 4 з органічними полімерами.Показано, що використання рідини на основі CoFe 2 O 4 для магнітної дефектоскопії дозволяє візуалізувати дефекти з шириною розкриття щонайменше 1,2 мкм.Додавання люмінесцентного барвника до магнітної рідини дає можливість одержати магнітно-люмінесцентний матеріал, використання якого дозволяє проявляти дефекти завдяки втягуванню усієї рідини в магнітне поле.Запропоновано простий спосіб приготування композицій для одержання реплік для методу магнітно-порошкової дефектоскопії, який полягає у створенні магнітних рідин Fe 3 O 4

A simple two-step electrochemical method for the fabrication of a new type of hierarchical Sn/SnOx micro/nanostructures is proposed for the very first time. Firstly, porous metallic Sn foams are grown on Sn foil via hydrogen bubble-assisted electrodeposition from an acidulated tin chloride electrolyte. As-obtained metallic foams consist of randomly distributed dendrites grown uniformly on the entire metal surface. The estimated value of pore diameter near the surface is ~35 µm, while voids with a diameter of ~15 µm appear in a deeper part of the deposit. Secondly, a layer of amorphous nanoporous tin oxide (with a pore diameter of ~60 nm) is generated on the metal surface by its anodic oxidation in an alkaline electrolyte (1 M NaOH) at the potential of 4 V for various durations. It is confirmed that if only optimal conditions are applied, the dendritic morphology of the metal foam does not change significantly, and an open-porous structure is still preserved after anodization. Such kinds of hierarchical nanoporous Sn/SnOx systems are superhydrophilic, contrary to those obtained by thermal oxidation of metal foams which are hydrophobic. Finally, the photoelectrochemical activity of the nanostructured metal/metal oxide electrodes is also presented.

The possibility of the chromatographic separation of isomeric nitroanilines and fluorine-substituted analogues using porous coordination polymers [Al(OH)(Fum)] n ( I ) (Fum 2– is trans -1,2-ethylenedicarboxylic acid anion), [Al(OH)(Bdc)] n ( II ) (Bdc 2– is 1,4-benzenedicarboxylic acid anion), [Cu 3 (Btc) 2 (H 2 O) 3 ] ( III ) (Btc 3– is 1,3,5-benzenetricarboxylic acid anion), and [Cr 3 (O)(OH)(H 2 O) 2 (Bdc) 3 ] ( IV ) as stationary phases in a mixture of nonpolar solvents is studied. The separation of the amines is achieved only in the case of [Al(OH)(Fum)] n . Possible relationships of the separation factors of the amines to the sizes of the molecules, polarity, and lipophilicity are examined. Among the factors considered, only the difference between the values of lipophilicity exerts a noticeable effect on the efficiency.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.