Люминесцентный хемосенсор для детектирования паров диметиламина и аммиака

The interaction of tris-dibenzoylmethanate Eu(III) with dimethylamine and ammonia vapors was investigated. It was found that when vapors of aqueous solutions of analytes are exposed to tris-dibenzoylmethanate Eu(III) impregnated into the SiO2 matrix, an optical response is observed in the form of an increase in the luminescence intensity of Eu(III). Changes in the luminescence spectra and luminescence excitation of this sensor are analyzed, both under the quenching action of water vapor and under the sensitizing action of analyte vapors. The main points recorded in the excitation spectra are noted, which are important for understanding the processes occurring in the near environment of the lanthanide center. The luminescent chemosensor is promising for creating sensors for detecting ammonia and amines in food safety control and environmental monitoring. Shishov A.S., Mirochnik A.G.

Development of Efficient One-Pot Methods for the Synthesis of Luminescent Dyes and Sol–Gel Hybrid Materials

This paper presents a comparison of the simultaneous preparation of di-O-alkylated and ether–ester derivatives of fluorescein using different methods (conventional or microwave heating). Shortening of the reaction time and increased efficiency were observed when using a microwave reactor. Moreover, described here for the first time is the application of a fast, simple, and eco-friendly ball-assisted method to exclusively obtain ether–ester derivatives. We also demonstrate that fluorescein can be effectively functionalized by O-alkylation carried out under microwave or ball-milling conditions, saving time and energy and affording the desired products with good yields and minimal byproduct formation. All the synthesized products as well as pH-dependent (prototropic) forms trapped in the SiO2 matrix were examined using UV–Vis and fluorescence spectroscopy.

Sol-Gel Synthesis, Structure, Morphology and Magnetic Properties of Ni0.6Mn0.4Fe2O4 Nanoparticles Embedded in SiO2 Matrix

The structure, morphology and magnetic properties of (Ni0.6Mn0.4Fe2O4)α(SiO2)100−α (α = 0–100%) nanocomposites (NCs) produced by sol-gel synthesis were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM) and vibrating sample magnetometry (VSM). At low calcination temperatures (300 °C), poorly crystallized Ni0.6Mn0.4Fe2O4, while at high calcination temperatures, well-crystallized Ni0.6Mn0.4Fe2O4 was obtained along with α-Fe2O3, quartz, cristobalite or iron silicate secondary phase, depending on the Ni0.6Mn0.4Fe2O4 content in the NCs. The average crystallite size increases from 2.6 to 74.5 nm with the increase of calcination temperature and ferrite content embedded in the SiO2 matrix. The saturation magnetization (Ms) enhances from 2.5 to 80.5 emu/g, the remanent magnetization (MR) from 0.68 to 12.6 emu/g and the coercive field (HC) from 126 to 260 Oe with increasing of Ni0.6Mn0.4Fe2O4 content in the NCs. The SiO2 matrix has a diamagnetic behavior with a minor ferromagnetic fraction, Ni0.6Mn0.4Fe2O4 embedded in SiO2 matrix displays superparamagnetic behavior, while unembedded Ni0.6Mn0.4Fe2O4 has a high-quality ferromagnetic behavior.

Synthesis and Characteristics of Multifunctional Magneto-luminescent Nanoparticles by an Ultrasonic Wave-assisted Stӧber Method

Multifunctional magneto-luminescent nanoparticles (NPs) were synthesised by an ultrasonic wave-assisted Stöber method. The multifunctional NPs are composed of magnetic NPs (Fe3O4) and photoluminescent quantum dots (QDs) (ZnS:Mn) in amorphous silica (SiO2) matrix, which was confirmed by X-ray diffraction, Raman scattering spectroscopy, and transmission electron microscopy (TEM). The multifunctional NPs have high saturation magnetisation at room temperature simultaneously with strong photoluminescence (PL) in visible light, which is promising for biomedical applications.

Catalytic Hydrocracking of Fresh and Waste Frying Oil over Ni- and Mo-Based Catalysts Supported on Sulfated Silica for Biogasoline Production

The synthesis of a sulfated silica catalyst and its modification with Ni and/or Mo metal, along with its application for the hydrocracking of fresh and waste frying oil into biogasoline, were conducted. Synthesis of the catalysts was initiated with the sulfation of silica (SiO2) material by H2SO4 using the sol-gel method. Ni and/or Mo metal were impregnated into the SO4/SiO2 matrix with concentration variations of 1, 2, and 3 wt%. The sulfation process and promotion by Molybdenum (Mo) metal in the modified catalyst successfully increased the catalytic activity and selectivity. Among the catalysts investigated, Ni-SS2 exhibited the best performance for the hydrocracking reaction with waste frying oil. This catalyst was able to achieve a conversion of the liquid product of 71.47% and a selectivity of 58.73% for the gasoline fraction (C5-C12). NiMo-SS3 showed the highest percentage of activity and selectivity in the hydrocracking of fresh frying oil at 51.50 and 43.22 wt%, respectively.

Исследование фотофизических свойств нанокомпозита HgI-=SUB=-2-=/SUB=-@mSiO-=SUB=-2-=/SUB=-

The luminescent properties of a composite consisting of mesoporous silica and mercury diiodide nanoparticles formed in silica nanopores have been investigated. The formation of nanoparticles was carried out by evaporation of a HgI2 solution introduced into the SiO2 nanopores. It was found that photoluminescence of the HgI2@mSiO2 composite was due to emission of mercury diiodide, with the emission spectrum being significantly shifted towards shorter wavelengths with respect to the emission spectrum of bulk HgI2 crystals. The shift of the HgI2 emission spectrum to the short-wavelength side is explained by quantum-size effects in the electronic spectra of HgI2 nanoparticles included in the composite. The significant width of the spectrum is explained by its inhomogeneous broadening due to the dependence of the band gap of the nanodots on their size d. The shape of the size distribution function of HgI2 nanodots was estimated and it was shown that it was characterized by a rather narrow maximum at dM = 2.2 nm, which is 2/3 of the diameter of the nanopores in the SiO2 matrix (~3 nm).