Cinnamate-Intercalated Layered Yttrium Hydroxide: UV Light-Responsive Switchable Material

In recent years, there has been an increasing interest in stimuli-responsive host–guest materials due to the high potential for their application in switchable devices. Light is the most convenient stimulus for operating these materials; a light-responsive guest affects the host structure and the functional characteristics of the entire material. UV-transparent layered rare earth hydroxides intercalated with UV-switchable anions are promising candidates as stimuli-responsive host–guest materials. The interlayer distance in the layered rare earth hydroxides depends on the size of the intercalated anions, which could be changed in situ, e.g., via anion isomerisation. Nevertheless, for layered rare earth hydroxides, the possibility of such changes has not been reported yet. A good candidate anion that is capable of intercalating into the interlayer space is the cinnamate anion, which undergoes UV-assisted irreversible trans–cis isomerisation. In this work, both trans- and cis-cinnamate anions were intercalated in layered yttrium hydroxide (LYH). Upon UV-irradiation, the interlayer distance of trans-cinnamate-intercalated layered yttrium hydroxide suspended in isopropanol changed from 21.9 to 20.6 Å. For the first time, the results obtained demonstrate the possibility of using layered rare earth hydroxides as stimuli-responsive materials

Layered Gadolinium-Europium-Terbium Hydroxides Sensitised with 4-Sulfobenzoate as All Solid-State Luminescent Thermometers

Ternary layered gadolinium-europium-terbium basic chlorides were synthesised using a facile hydrothermal-microwave technique. A continuous series of solid solutions was obtained in a full range of rare earth concentrations. To sensitise the luminescence of Eu3+ and Tb3+, a 4-sulfobenzoate anion was intercalated in the ternary layered rare earth hydroxides using one of two methods—a high-temperature ion exchange or a single-stage synthesis. The luminescent colour of the materials was governed by the gadolinium content: at low and medium gadolinium concentrations (0–70%), layered Gd-Eu-Tb basic sulfobenzoate exhibited a bright red europium luminescence; at high gadolinium content (70–90%), a bright green terbium luminescence was observed. The colour coordinates of layered Gd-Eu-Tb basic sulfobenzoate luminescence depended on the temperature in the physiological range (20–50 °C). The relative thermal sensitivity of the obtained materials was up to 2.9%·K−1

Combined SANS and SAXS study of the action of ultrasound on the structure of amorphous zirconia gels

In the present work, we have studied for the first time the combined effect of both sonication and precipitation pH on the structure of amorphous zirconia gels synthesized from zirconium(IV) propoxide. The techniques of small-angle neutron and X-ray scattering (SANS and SAXS) and low temperature nitrogen adsorption provided the integral data on the changes in the microstructure and mesostructure of these materials caused by ultrasonic (US) treatment. Amorphous ZrO2·xH2O synthesized under ultrasonic treatment was found to possess a very structured surface, characterized by the surface fractal dimension 2.9–3.0, compared to 2.3–2.5 for the non US-assisted synthesis, and it was also found to possess a higher specific surface area, while the sizes of the primary particles remain unchanged

Switchable Nanozyme Activity of Porphyrins Intercalated in Layered Gadolinium Hydroxide

In this study, organo-inorganic nanohybrids LHGd-MTSPP with enzyme-like activity were prepared by in situ intercalation of anionic 5,10,15,20-tetrakis-(4-sulfonatophenyl)porphyrin and its complexes with Zn(II) and Pd(II) (MTSPP, M = 2H, Zn(II) and Pd(II)) into gadolinium layered hydroxide (LHGd). The combination of powder XRD, CHNS analysis, FT-IR, EDX, and TG confirmed the layered structure of the reaction products. The basal interplanar distances in LHGd-MTSPP samples were 22.3–22.6 Å, corresponding to the size of an intercalated tetrapyrrole molecule. According to SEM data, LHGd-MTSPP hybrids consisted of individual lamellar nanoparticles 20–50 nm in thickness. The enzyme-like activity of individual constituents, LHGd-Cl and sulfoporphyrins TSPP, ZnTSPP and PdTSPP, and hybrid LHGd-MTSPP materials, was studied by chemiluminescence analysis using the ABAP/luminol system in phosphate buffer solution. All the individual porphyrins exhibited dose-dependent antioxidant properties with respect to alkylperoxyl radicals at pH 7.4. The intercalation of free base TSPP porphyrin into the LHGd preserved the radical scavenging properties of the product. Conversely, in LHGd-MTSPP samples containing Zn(II) and Pd(II) complexes, the antioxidant properties of the porphyrins changed to dose-dependent prooxidant activity. Thus, an efficient approach to the design and synthesis of advanced LHGd-MTSPP materials with switchable enzyme-like activity was developed

Combined SANS and SAXS study of the action of ultrasound on the structure of amorphous zirconia gels

In the present work, we have studied for the first time the combined effect of both sonication and precipitation pH on the structure of amorphous zirconia gels synthesized from zirconium(IV) propoxide. The techniques of small-angle neutron and X-ray scattering (SANS and SAXS) and low temperature nitrogen adsorption provided the integral data on the changes in the microstructure and mesostructure of these materials caused by ultrasonic (US) treatment. Amorphous ZrO2·xH2O synthesized under ultrasonic treatment was found to possess a very structured surface, characterized by the surface fractal dimension 2.9–3.0, compared to 2.3–2.5 for the non US-assisted synthesis, and it was also found to possess a higher specific surface area, while the sizes of the primary particles remain unchanged

High-yield microwave synthesis of layered Y2(OH)5NO3xH2O materials

A novel, facile, and versatile microwave-assisted method of high-yield synthesis of layered rare earth hydroxo compounds (LRHs) is proposed. Layered yttrium hydroxonitrates synthesized by the microwave-assisted technique crystallize in the form of thin hexagonal plates aggregated into spheroidal particles. Depending on the conditions of microwave-assisted hydrothermal synthesis, the formation of several phases differing in interplanar spacing along the [00l] direction is possible. The materials obtained are shown to possess good anion-exchange properties. This work provides a route to large-scale synthesis of LRH-based advanced materials

High-yield microwave synthesis of layered Y2(OH)5NO3xH2O materials

A novel, facile, and versatile microwave-assisted method of high-yield synthesis of layered rare earth hydroxo compounds (LRHs) is proposed. Layered yttrium hydroxonitrates synthesized by the microwave-assisted technique crystallize in the form of thin hexagonal plates aggregated into spheroidal particles. Depending on the conditions of microwave-assisted hydrothermal synthesis, the formation of several phases differing in interplanar spacing along the [00l] direction is possible. The materials obtained are shown to possess good anion-exchange properties. This work provides a route to large-scale synthesis of LRH-based advanced materials

Mesostructure of yttrium and aluminum basic salts coprecipitated from aqueous solutions under ultrasonic treatment

The influence of ultrasonic treatment on the micro and mesostructures and fractal characteristics of amorphous powders of yttrium and aluminum basic salts (precursors for the synthesis of neodymiumacti vated yttrium–aluminum garnet, Nd:YAG, which were coprecipitated from aqueous solutions by different precipitants, namely, aqueous solutions of ammonia and ammonium bicarbonate) is studied. It is established that ultrasonication applied during the precipitation of the aforementioned powders does not significantly change the structure of the obtained materials but always leads to the formation of structures with a less homogeneous nuclear density, i.e., a more developed surface area. Moreover, the ultrasoundassisted precip itation of the hydroxocompounds by ammonium hydrocarbonate results in a certain increase in the surface fractal dimension and the degree of aggregation for massfractal aggregates of particles

Mesostructure of yttrium and aluminum basic salts coprecipitated from aqueous solutions under ultrasonic treatment

The influence of ultrasonic treatment on the micro and mesostructures and fractal characteristics of amorphous powders of yttrium and aluminum basic salts (precursors for the synthesis of neodymiumacti vated yttrium–aluminum garnet, Nd:YAG, which were coprecipitated from aqueous solutions by different precipitants, namely, aqueous solutions of ammonia and ammonium bicarbonate) is studied. It is established that ultrasonication applied during the precipitation of the aforementioned powders does not significantly change the structure of the obtained materials but always leads to the formation of structures with a less homogeneous nuclear density, i.e., a more developed surface area. Moreover, the ultrasoundassisted precip itation of the hydroxocompounds by ammonium hydrocarbonate results in a certain increase in the surface fractal dimension and the degree of aggregation for massfractal aggregates of particles