Zinc oxide nanoparticles (NPs) with an average crystallite size of 22 nm and a bandgap energy of 3.26 eV have been obtained using neem (Azadirachta indica) leaf extract as a natural green stabilizing agent. Significant reduction of 2,2-diphenyl-1-picrylhydrazyl (DPPH) quantity by ZnO NPs in dark has been found in the result of DPPH scavenging studies. This effect is explained by reductive action of the compounds from neem extract, immobilized on ZnO NPs, and it is an indicator of their antioxidant activity. It is shown that ZnO NPs demonstrate strong antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida albicans.
The influence of the preparation method (impregnation of γ-Al2O3 vs. sol–gel method) on the physicochemical and catalytic properties of Ni-Mo-Al oxide systems in the CO2-mediated oxidative dehydrogenation of n-butane into C4 alkenes/dienes has been analyzed. It is shown that the catalyst obtained by a sol–gel method is characterized by a prevalence of the crystalline Al2(MoO4)3 phase in the composition and a lower acidity/basicity ratio. These features ensure higher selectivity and specific productivity toward the target buta-1,3-diene.
The effect of the polarity and volume fraction of organic solvents (n-heptane, isopropylacetate, ethylacetate, dichloromethane, and 1,2-dichloroethane) on the catalytic benzoylation of alanine, serine, and glutamic acid in a water–organic solvent two-phase system in the presence of pyridine N-oxide derivatives has been studied. It is found that the reaction occurs in a kinetic region, the effective rate constants increase with increasing solvent polarity. The possibility of replacing chlorine-containing solvents with ethyl acetate and isopropyl acetate was demonstrated, resulting in only a minor decrease in reaction rate ( 10
X-ray amorphous zirconium dioxide samples have been obtained by calcination of a mixture of zirconium oxychloride with sodium bicarbonate, sodium carbonate, or potassium oxalate. It is established that the efficiency of phosphate anion removal from Ringer’s solution by zirconium dioxide synthesized using sodium carbonate is higher (91.2
Micellization in a solution of sodium dodecyl sulfate (SDS) containing the antibiotic ofloxacin (OFX) in the presence of glucose or urea in the temperature range of 293-323 K has been studied by conductometry. It is shown that the critical micelle concentration (CMC) of SDS increases in the presence of OFX. The addition of urea increases the CMC in the SDS-OFX mixture, while in the presence of glucose the CMC decreases. The thermodynamic parameters of micellization, ∆ G_m^0 , ∆ H_m^0 , and ∆ S_m^0 , have been determined and it is proved that the SDS-OFX mixture undergoes spontaneous micellization both in pure water and in an aqueous solution of glucose or urea.
It is shown that the formation of nanosized MoS(2–x)Ox under hydrothermal conditions with an increased thiourea content leads to a decrease in the oxygen content in the resulting material and doesn’t significantly affect its morphology. It has been established that in quinoline hydrogenation over MoS(2–x)Ox samples with an increased sulfur content, the yield of 1,2,3,4-tetrahydroquinoline increases. The obtained MoS(2–x)Ox oxysulfides catalyze the hydrogenation of isomeric bromoquinolines bearing a Br atom in the carbocyclic ring to form the corresponding bromine-containing 1,2,3,4-tetrahydroquinolines; in this case, the yields of these products generally decrease with increasing sulfur content in the catalyst.
It has been established that during the hydrothermal sol–gel synthesis of sulfuric acid-modified TiO2 nanostructures (S-TiO2 nanostructures), a crystalline anatase phase is formed, which remains stable up to 800°C, and the anatase to rutile phase transition begins at 850°C. Increasing the calcination temperature of S-TiO2 nanostructures gradually leads to the densification of loosely agglomerated anatase crystallites and, finally, their sintering, which leads to a decrease in the specific surface area. As a result, the photocatalytic activity of such nanostructures in the process of doxycycline photodegradation under visible light irradiation and hydrogen release from water–alcohol mixtures under ultraviolet light irradiation increases with elevating calcination temperature, but decreases exceeding after 470°C.
A novel non-conjugated aromatic polymer that contains azo-linked moieties of diphenylmethane and 2,5-bis-4-(hydroxyphenyl)-1,4-dimethoxybenzene ((MeO)2AzoPhO) has been obtained. The structure of the polymer is corroborated using IR spectroscopy, 1H, 13C NMR, and CP-MAS NMR spectroscopy. With the use of thermogravimetry, it is shown that the compound is thermally stable up to 150°C. Based on the analysis of the electron spectra, it is established that the band gap width (Eg) of (MeO)2AzoPhO equals 3.0-3.4 eV. This value is higher than Eg for the polymeric analogue with a conjugated linker (≈2.9 eV) and consistent with the size of the electron density delocalization regions.
A stable colloid of Zn- and Ag-doped CuO nanoparticles has been synthesized using a co-precipitation method in the presence of sodium dodecyl sulfate. The synthesis parameters that significantly affect the stability of the final product have been optimized. The nanoparticles in the stable suspension exhibit a rod-like morphology with an average size of 40-60 nm. It is shown that the obtained colloidal system has higher antimicrobial activity of against M. fortuitum, M. bovis, and M. avium in comparison with undoped analogues.
A new multifunctional magneto-responsive composite polymer material with an increased content of β-cyclodextrin was synthesized using nanoscale magnetite and a copolymerization reaction between β-cyclodextrin and hexamethylene diisocyanate. The structure and physicochemical properties of the surface functional groups of the resulting nanocomposite were characterized by IR spectroscopy, thermogravimetry, low-temperature nitrogen adsorption–desorption, X-ray phase analysis, chemical analysis, and scanning electron microscopy. The composite demonstrated a pronounced ability for the selective extraction of strontium(II) ions from a mildly acidic aqueous medium.
It has been shown that the thermal decomposition of Co(II) oxalate in a hydrogen atmosphere leads to a mixture of cobalt nanoparticles of hexagonal and cubic modification. The decomposition of heterometallic oxalates obtained as a result of partial substitution of Co(II) by Mg(II) or Mn(II) causes a significant decrease in the average size of the formed Co nanoparticles and an increase in the content of its cubic modification. In the hydrogenation of quinoline on Co and Co-Mg catalysts, a higher yield of 1,2,3,4-tetrahydroquinoline is achieved with an increase of the hexagonal cobalt modification content. In the case of Co-Mn systems, a high yield of 1,2,3,4-tetrahydroquinoline is observed when the content of cubic Co modification is prevailing, which is explained by the promoting effect of Mn.
It has been shown that in the presence of Ag(I) ions, the rate of the oxidation reaction of isoleucine (ILe) by potassium permanganate in an acidic aqueous medium increases by 5.4 times, and in the presence of sodium lauryl sulfate (SLS) micelles does by 4.2 times. The combined action of Ag(I) and SLS micelles leads to a 9.6-fold acceleration of the reaction, which is a manifestation of the cooperative effect. The oxidation process is accelerated due to the electrostatic interaction between permanganate and the negatively charged micelle.
The possibility of obtaining Fe-N-C and Fe,Co-N-C electrocatalysts for the oxygen reduction reaction (ORR) by pyrolysis of Vulcan XC72R carbon black suspension in deep eutectic solvents (DESs) based on 1-butyl-3-methylimidazolium chloride and iron(III) chloride, or a mixture of iron(III), cobalt(II), and zinc(II) chlorides, has been demonstrated. The influence of the DES type on the composition, structure, morphology, and electrocatalytic properties of the obtained materials has been found. It is established that the Fe-N-C catalyst obtained without the involvement of Co- or Zn-containing DES is the most effective in ORR and is characterized in an alkaline electrolyte by Eonset (964 mV vs. RHE) and E1/2 (891 mV vs. RHE) potentials, which exceed those of most analogues obtained using ionic liquids, ensures the ORR proceeds mainly by a 4-electron mechanism, and also does not require additional heat treatment to achieve high ORR characteristics.
It has been shown than the catalysts obtained by depositing cobalt and cobalt boride nanoparticles on Aerosil, exhibit higher performance in the hydrogenation of quinoline and substituted quinolines compared to a catalyst containing cobalt nanoparticles and carbonaceous particles formed via the pyrolysis of cobalt(II) complex with 1,2-diaminobenzene on Aerosil. The enhanced productivity of these systems may be associated with higher dispersion of cobalt-containing particles, the presence of cobalt boride Co2B, and hexagonal modification of Co in contrast to cubic one.
The current state of research on heterogeneous systems based on chiral materials for the photocatalytic transformation of organic and inorganic substances is examined. Examples are provided illustrating methods for obtaining photoactive chiral covalent organic frameworks, coordination polymers, inorganic semiconductors, plasmonic catalysts, as well as complex systems integrating achiral photoactive components and chiral cocatalysts. Their application is demonstrated in initiating photocatalytic asymmetric synthesis of valuable organic stereoisomers, degradation of aquatic pollutants, and enhancing photocatalytic water splitting, CO2 and N2 reduction, and H2O2 production. Potential directions for further research in this field are outlined.
Iron(III) complexes with potentially hexa- and heptadentate oligothioether salicylaldiminates were synthesized. Electron spin resonance and Mössbauer spectra reveal the existence of spin crossover effects between 77 and 300 K. The compounds exhibit solvatochromic behaviour. Their cyclic voltammetry shows reversible one-electron electrochemical processes attributed to the iron(III)/iron(II) couple, while insertion of the additional (ether or thioether) donor atom into the ligand structure causes an anodic shift of the E1/2, the thioether sulfur-atom substantially so. Evidence is presented for heptacoordination in the unique complex entailing the unusual heptadentate N2O2S3 donor set.
The formation, structure, and luminescent properties of LiBi1–xEux(MoO4)2 (x = 0,01-1,00) solid solutions synthesized by solid-state sintering have been studied. X-ray diffraction confirmed the formation of a single-phase tetragonal scheelite-type structure (I41/a) corresponding to the isovalent substitution Bi3+→Eu3+. All samples exhibit red luminescence arising from the 5D0→7Fj (j = 1-4) transitions of Eu3+ ions, with the maximum intensity observed for LiBi0.7Eu0.3(MoO4)2. Th. The obtained results highlight the potential of these solid solutions as promising red phosphors for optoelectronic applications.
It is shown that aminoethylaminopropylisobutyl polyhedral oligomeric silsesquioxane (AEAPIB-POSS) reveals a catalytic effect on the rate of the polycyanurate network (PCN) formation, namely with an increase in its content from 0.05 to 1.0 wt.
It has been shown that sonochemical treatment in the process of Lidocaine oxidation leads to an increase in the yield of Lidocaine N-oxide (LNO) while reducing the reaction time. An ADME (absorption, distribution, metabolism, and excretion) analysis of Lidocaine and LNO was performed. According to in silico calculated ADME profile, LNO is characterized by high bioavailability, efficient absorption in the gastrointestinal tract, and slight inhibition of cytochrome P450, which is a sign of low interaction with other drugs. According to the results of the analysis of LNO interaction with the mutant p53 protein by the molecular docking method, the anticancer activity of this substance can be expected.
Binary heterostructures based on Co3O4 and red phosphorus have been synthesized, and their morphology and spectral characteristics have been analyzed. According to SEM data, the formation of heterostructures is accompanied by the localization of an amorphous phase of red phosphorus (Pred) on the surface of cobalt oxide. It is determined that the incorporation of 15 wt.
