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1.
Molecules ; 27(15)2022 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-35956978

RESUMO

A method is proposed for the preparation of stable sols of nanocrystalline cerium dioxide in nonpolar solvents, based on surface modification of CeO2 nanoparticles obtained by thermal hydrolysis of concentrated aqueous solutions of ammonium cerium(IV) nitrate with residues of 2-ethylhexanoic and octanoic acids. The synthesis was carried out at temperatures below 100 °C and did not require the use of expensive and toxic reagents. An assessment of the radical-scavenging properties of the obtained sols using the superoxide anion-radical neutralization model revealed that they demonstrate notable antioxidant activity. The results obtained indicate the potential of the nanoscale cerium dioxide sols in nonpolar solvents to be used for creating nanobiomaterials possessing antioxidant properties.


Assuntos
Cério , Nanopartículas , Antioxidantes/química , Cério/química , Nanopartículas/química , Solventes
2.
Nanomaterials (Basel) ; 11(10)2021 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-34685141

RESUMO

Flexible materials, such as fabric, paper and plastic, with nanoscale particles that possess antimicrobial properties have a significant potential for the use in the healthcare sector and many other areas. The development of new antimicrobial coating formulations is an urgent topic, as such materials could reduce the risk of infection in hospitals and everyday life. To select the optimal composition, a comprehensive analysis that takes into account all the advantages and disadvantages in each specific case must be performed. In this study, we obtained an antimicrobial textile with a 100% suppression of E. coli on its surface. These CeO2 nanocoatings exhibit low toxicity, are easy to manufacture and have a high level of antimicrobial properties even at very low CeO2 concentrations. High-power ultrasonic treatment was used to coat the surface of cotton fabric with CeO2 nanoparticles.

3.
Phys Chem Chem Phys ; 21(24): 13014-13021, 2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31166329

RESUMO

Acetonitrile and the species resulting from its dehydrogenation play an important role in the radiation-induced evolution of organic matter in the space environment. In this work, we report on FTIR spectroscopic studies of the degradation of isolated CH3CN and CD3CN molecules induced by prolonged X-ray irradiation in solid noble gas matrices at 5 K. The principal products observed at high conversion degree of the parent acetonitrile molecules (70-90%) are CCN and CNC radicals, which result from prompt or two-step dehydrogenation of the corresponding precursors, H2CN and CH2NC radicals, respectively. CHCN and CHNC were also found as products of dehydrogenation at high absorbed doses, whereas the fragmentation products (CH3, CN, HCN, and HNC) were detected only in minor amounts over the whole dose range studied. CCN and CNC are produced in nearly equal amounts at high absorbed doses. Selective isomerization of CCN to CNC was observed under the illumination with visible light (460-470 nm), while subsequent action of the UV light (254 nm) induced reverse transformation leading to a photostationary state with the relative population of CNC/CCN being ca. 0.7. The astrochemical implications of the obtained results are discussed in connection with the recent discovery of CCN in extraterrestrial objects.

4.
Phys Chem Chem Phys ; 19(35): 24348-24356, 2017 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-28849816

RESUMO

The HCNCO complex and its X-ray induced transformation to HNCCO in solid noble gas (Ng) matrices (Ng = Ne, Ar, Kr, Xe) was first characterized by matrix isolation FTIR spectroscopy at 5 K. The HCNCO complex was obtained by deposition of HCN/CO/Ng gaseous mixtures. The assignment was based on extensive quantum chemical calculations at the CCSD(T) level of theory. The calculations predicted two computationally stable structures for HCNCO and three stable structures for HNCCO. However, only the most energetically favorable linear structures corresponding to the co-ordination between the H atom of HCN (HNC) and the C atom of CO have been found experimentally. The HCNCO complex demonstrates a considerable red shift of the H-C stretching vibrations (-24 to -38 cm-1, depending on the matrix) and a blue shift of the HCN bending vibrations (+29 to +32 cm-1) with respect to that of the HCN monomer, while the C[double bond, length as m-dash]O stretching mode is blue-shifted by 15 to 20 cm-1 as compared to the CO monomer. The HNCCO complex reveals a strong red shift of the H-N bending (-77 to -118 cm-1) and a strong blue shift of the HNC bending mode (ca. +100 cm-1) as compared to the HNC monomer, whereas the C[double bond, length as m-dash]O stretching is blue-shifted by 24 to 29 cm-1 with respect to that of the CO monomer. The interaction energies were determined to be 1.01 and 1.87 kcal mol-1 for HCNCO and HNCCO, respectively. It was found that the formation of complexes with CO had a remarkable effect on the radiation-induced transformations of HCN. While the dissociation of HCN to H and CN is suppressed in complexes, the isomerization of HCN to HNC is strongly catalyzed by the complexation with CO. The astrochemical implications of the results are discussed.

5.
J Chem Phys ; 145(21): 214309, 2016 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-28799372

RESUMO

Spectroscopic characteristics and X-ray induced transformations of the HCN⋯CO2 complex in solid Ar and Kr matrices were studied by FTIR spectroscopy and ab initio calculations at the CCSD(T) level. The complex was prepared by deposition of the HCN/CO2/Ng gas mixtures (Ng = Ar or Kr). The comparison of the experiment and calculations prove formation of a linear, H-bonded NCH⋯OCO complex with a substantial red shift of the C-H stretching band and a blue shift of the H-C-N bending band in respect to the monomer. This result is in contrast with the previous gas-phase observations, where only T-shape complex was found. Irradiation of deposited matrices leads to formation of CN radicals and HNC molecules and subsequent annealing results in appearance of H2CN and trans-HCNH in both matrices plus HKrCN in the case of Kr. In the presence of CO2, the strongest absorption of trans-HCNH radical demonstrates an additional blue-shifted (by 6.4 cm-1) feature, which was assigned to the N-coordinated complex of this radical with CO2 on the basis of comparison with calculations. To our knowledge, it is the first experimentally observed complex of this radical. No evidence was found for HKrCN⋯CO2 complex, which was explained tentatively by steric hindrance.

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