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Abstract Metal-organic frameworks (MOFs) have emerged as highly promising materials for hosting functional biomolecules. Here, a 1,2,4-benzenetricarboxylate ligand with a flat asymmetric shape is applied to infuse an unusual behavior to a 3D europium MOF (SLU-1). Solvent addition results in the 3D MOF splitting into a 2D one (SLU-2), and in the presence of excess water, gets cross-linked into a different 3D MOF (SLU-3) prone to spontaneous exfoliation. SLU-3 features a combination of highly hydrophilic and hydrophobic spots and serves as an attractive host for incorporating large active species. As a representative demonstration, horseradish peroxidase (HRP) is incorporated into the exfoliated 3D-layered structure by simple mixing, and secured by an outer silica layer in the form of core-shell structures. The resulting HRP-based biocatalyst exhibited enhanced stability and reusability, effectively degrading phenol. This work showcases the potential of reconfigurable MOFs, offering upheld applications through the controlled uptake and retention of biocatalytic agents.

Abstract Yttrium doping-stabilized γ-Fe2O3 nanoparticles were studied for its potential to serve as a plant fertilizer and, through enzymatic activity, support drought stress management. Levels of both hydrogen peroxide and lipid peroxidation, after drought, were reduced when γ-Fe2O3 nanoparticles were delivered by irrigation in a nutrient solution to Brassica napus plants grown in soil. Hydrogen peroxide was reduced from 151 to 83 μM g−1 compared to control, and the malondialdehyde formation was reduced from 36 to 26 mM g−1. Growth rate of leaves was enhanced from 33 to 50% growth compared to fully fertilized plants and SPAD-measurements of chlorophyll increased from 47 to 52 suggesting improved agronomic properties by use of γ-Fe2O3 nanoparticles as fertilizer as compared to chelated iron.

Spherical silica particles with bifunctional (≡Si(CH2)3NH2/≡SiCH3, ≡Si(CH2)3NH2/≡Si(CH2)2(CF2)5CF3) surface layers were produced by a one-step approach using a modified Stöber method in three-component alkoxysilane systems, resulting in greatly increased contents of functional components. The content of functional groups and thermal stability of the surface layers were analyzed by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and 13C and 29Si solid-state NMR spectroscopy revealing their composition and organization. The fine chemical structure of the surface in the produced hybrid adsorbent particles and the ligand distribution were further investigated by electron paramagnetic resonance (EPR) and electron spectroscopy of diffuse reflectance (ESDR) spectroscopy using Cu2+ ion coordination as a probe. The composition and structure of the emerging surface complexes were determined and used to provide an insight into the molecular structure of the surfaces. It was demonstrated that the introduction of short hydrophobic (methyl) groups improves the kinetic characteristics of the samples during the sorption of copper(II) ions and promotes fixation of aminopropyl groups on the surface of silica microspheres. The introduction of long hydrophobic (perfluoroctyl) groups changes the nature of the surface, where they are arranged in alternately hydrophobic/hydrophilic patches. This makes the aminopropyl groups huddled and less active in the sorption of metal cations. The size and aggregation/morphology of obtained particles was optimized controlling the synthesis conditions, such as concentrations of reactants, basicity of the medium, and the process temperature.

In order to develop a new type of improved wound dressing, we combined the wound healing properties of nanotitania with the advantageous dressing properties of nanocellulose to create three different hybrid materials. The hemocompatibility of the synthesized hybrid materials was evaluated in an in vitro human whole blood model. To our knowledge, this is the first study of the molecular interaction between hybrid nanotitania and blood proteins. Two of the hybrid materials prepared with 3 nm colloidal titania and 10 nm hydrothermally synthesized titania induced strong coagulation and platelet activation but negligible complement activation. Hence, they have great potential as a new dressing for promoting wound healing. Unlike the other two, the third hybrid material using molecular ammonium oxo-lactato titanate as a titania source inhibited platelet consumption, TAT generation, and complement activation, apparently via lowered pH at the surface interface. It is therefore suitable for applications where a passivating surface is desired, such as drug delivery systems and extracorporeal circuits. This opens the possibility for a tailored blood response through the surface functionalization of titania.

Titania (anatase) nanoparticles were anisotropically functionalized in water-toluene Pickering emulsions to self-assemble into nanoshells with diameters from 500 nm to 3 μm as candidates for encapsulation of drugs and other compounds. The water-phase contained a hydrophilic ligand, glucose-6-phosphate, while the toluene-phase contained a hydrophobic ligand, n-dodecylphosphonic acid. The addition of a dilute sodium alginate suspension that provided electrostatic charge was essential for the self-limited assembly of the nanoshells. The self-assembled spheres were characterized by scanning electron microscopy, elemental mapping, and atomic force microscopy. Drug release studies using tetracycline suggest a rapid release dominated by surface desorption.

Sustainable and green synthesis of nanocomposites for degradation of pharmaceuticals was developed via immobilization and stabilization of the biological strong oxidizing agents, peroxidase enzymes, on a solid support. Sol−gel encapsulated enzyme composites were characterized using electron microscopy (TEM, SEM), atomic force microscopy, FTIR spectroscopy, and thermogravimetric analysis. Horseradish peroxidase (HRP) and lignin peroxidase (LiP) were adsorbed onto magnetite nanoparticles and sol−gel encapsulated in a surface silica layer. Encapsulation enhanced the stability of the biocatalysts over time and thermal stability. The biocatalysts showed appreciable selectivity in oxidation of the organic drinking water pollutants diclofenac, carbamazepine, and paracetamol with improved activity being pharmaceutical specific for each enzyme. In particular, sol−gel encapsulated LiP- and HRP-based nanocomposites were active over 20 consecutive cycles for 20 days at 55 °C (24 h/cycle). The stability of the sol−gel encapsulated catalysts in acidic medium was also improved compared to native enzymes. Carbamazepine and diclofenac were degraded to 68% and 64% by sol−gel LiP composites respectively at pH 5 under elevated temperature. Total destruction of carbamazepine and diclofenac was achieved at pH 3 (55 °C) within 3 days, in the case of both immobilized HRP and LiP. Using NMR spectroscopy, characterization of the drug decomposition products, and decomposition pathways by the peroxidase enzymes suggested.

Here, we show that wet impregnation of ZrO2 nanoparticles with 10% and 20% Eu oxide followed by thermal anneal in air above 500 °C produces full stabilization of the tetragonal phase of ZrO2 without evidencing any phase separation. The bare ZrO2 nanoparticles were obtained using three synthetic methods: oil in water microemulsion, rapid hydrothermal, and citrate complexation methods. The homogeneity of the solid solutions was assessed using X-ray diffraction, Raman spectroscopy, high resolution transmission electron microscopy, and advanced luminescence spectroscopy. Our findings show that wet impregnation, which is a recognized method for obtaining surface doped oxides, can be successfully used for obtaining doped oxides in the bulk with good homogeneity at the atomic scale. The limits of characterization technique in detecting minor phases and the roles of dopant concentration and host structure in formation of phase stabilized solid solutions are also analyzed and discussed.

The review presents synthetic approaches to modern rhenium-based catalysts. Creation of an active center is considered as a process of obtaining a nanoparticle or a molecule, immobilized within a matrix of the substrate. Selective chemical routes to preparation of particles of rhenium alloys, rhenium oxides and the molecules of alkyltrioxorhenium, and their insertion into porous structure of zeolites, ordered mesoporous MCM matrices, anodic mesoporous alumina, and porous transition metal oxides are considered. Structure-property relationships are traced for these catalysts in relation to such processes as alkylation and isomerization, olefin metathesis, selective oxidation of olefins, methanol to formaldehyde conversion, etc.

Nano α-MnO2 is usually synthesized under hydrothermal conditions in acidic medium, which results in materials easily undergoing thermal reduction and offers single crystals often over 100 nm in size. In this study, α-MnO2 built up of inter-grown ultra-small nanoflakes with 10 nm thickness was produced in a rapid two-step procedure starting via partial reduction in solution in basic medium subsequently followed by co-proportionation in thermal treatment. This approach offers phase-pure α-MnO2 doped with potassium (cryptomelane type K0.25Mn8O16 structure) demonstrating considerable chemical and thermal stability. The reaction pathways leading to this new morphology and structure have been discussed. The MnO2 electrodes produced from obtained nanostructures were tested as electrodes of lithium ion batteries delivering initial discharge capacities of 968 mAh g−1 for anode (0 to 2.0 V) and 317 mAh g−1 for cathode (1.5 to 3.5 V) at 20 mA g−1 current density. At constant current of 100 mA g−1, stable cycling of anode achieving 660 mAh g−1 and 145 mAh g−1 for cathode after 200 cycles is recorded. Post diagnostic analysis of cycled electrodes confirmed the electrode materials stability and structural properties.

Spherical cellulose nanocrystal-based hybrids grafted with titania nanoparticles were successfully produced for topical drug delivery. The conventional analytical filter paper was used as a precursor material for cellulose nanocrystals (CNC) production. Cellulose nanocrystals were extracted via a simple and quick two-step process based on first the complexation with Cu(II) solution in aqueous ammonia followed by acid hydrolysis with diluted H2SO4. Triclosan was selected as a model drug for complexation with titania and further introduction into the nanocellulose based composite. Obtained materials were characterized by a broad variety of microscopic, spectroscopic, and thermal analysis methods. The drug release studies showed long-term release profiles of triclosan from the titania based nanocomposite that agreed with Higuchi model. The bacterial susceptibility tests demonstrated that released triclosan retained its antibacterial activity against Escherichia coli and Staphylococcus aureus. It was found that a small amount of titania significantly improved the antibacterial activity of obtained nanocomposites, even without immobilization of model drug. Thus, the developed hybrid patches are highly promising candidates for potential application as antibacterial agents.

Modification of different zirconium propoxide precursors with H2dea was investigated by characterization of the isolated modified species. Upon modification of zirconium n-propoxide and [Zr(OnPr)(OiPr)3(iPrOH)]2 with ½ a mol equivalent of H2dea the complexes [Zr2(OnPr)6(OCH2CH2)2NH]2 (1) and [Zr2(OnPr)2(OiPr)4(OCH2CH2)2NH]2 (2) were obtained. However, 1H-NMR studies of these tetranuclear compounds showed that these are not time-stable either in solution or solid form. The effect of this time instability on material properties is demonstrated by light scattering and TEM experiments. Modification of zirconium isopropoxide with either ½ or 1 equivalent mol of H2dea results in formation of the trinuclear complex, Zr{η3μ2-NH(C2H4O)2}3[Zr(OiPr)3]2(iPrOH)2 (3) countering a unique nona-coordinated central zirconium atom. This complex 3 is one of the first modified zirconium propoxide precursors shown to be stable in solution for long periods of time. The particle size and morphology of the products of sol-gel synthesis are strongly dependent on the time factor and eventual heat treatment of the precursor solution. Reproducible sol-gel synthesis requires the use of solution stable precursors.

Sol-gel technology is a versatile tool for preparation of complex silica-based materials with targeting functions for use as adsorbents in water purification. Most efficient removal of organic pollutants is achieved by using enzymatic reagents grafted on nano-carriers. However, enzymes are easily deactivated in the presence of heavy metal cations. In this work, we avoided inactivation of immobilized urease by Cu (II) and Cd (II) ions using magnetic nanoparticles provided with additional complexonate (diethylene triamine pentaacetic acid or DTPA) functions. Obtained nanomaterials were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). According to TGA, the obtained Fe3O4/SiO2-NH2-DTPA nanoadsorbents contained up to 0.401 mmol/g of DTPA groups. In the concentration range Ceq = 0–50 mmol/L, maximum adsorption capacities towards Cu (II) and Cd (II) ions were 1.1 mmol/g and 1.7 mmol/g, respectively. Langmuir adsorption model fits experimental data in concentration range Ceq = 0–10 mmol/L. The adsorption mechanisms have been evaluated for both of cations. Crosslinking of 5 wt % of immobilized urease with glutaraldehyde prevented the loss of the enzyme in repeated use of the adsorbent and improved the stability of the enzymatic function leading to unchanged activity in at least 18 cycles. Crosslinking of 10 wt % urease on the surface of the particles allowed a decrease in urea concentration in 20 mmol/L model solutions to 2 mmol/L in up to 10 consequent decomposition cycles. Due to the presence of DTPA groups, Cu2+ ions in concentration 1 µmol/L did not significantly affect the urease activity. Obtained magnetic Fe3O4/SiO2-NH2-DTPA-Urease nanocomposite sorbents revealed a high potential for urease decomposition, even in presence of heavy metal ions.

The exploration of the NiX2/py2CO/Et3N (X = F, Cl, Br, I; py2CO = di-2-pyridyl ketone; Et3N = triethylamine) reaction system led to the tetranuclear [Ni4Cl2{py2C(OH)O}2{py2C(OMe)O}2(MeOH)2]Cl2·2Et2O (1·2Et2O) and [Ni4Br2{py2C(OH)O}2{py2C(OMe)O}2(MeOH)2]Br2·2Et2O (2·2Et2O) and the trinuclear [Ni3{py2C(OMe)O}4]I2·2.5MeOH (3·2.6MeOH), [Ni3{py2C(OMe)O}4](NO3)0.65I1.35·2MeOH (4·2MeOH) and [Ni3{py2C(OMe)O}4](SiF6)0.8F0.4·3.5MeOH (5·3.5MeOH) aggregates. The presence of the intermediate size Cl−and Br−anions resulted in planar tetranuclear complexes with a dense hexagonal packing of cations and donor atoms (tetramolybdate topology) where the X−anions participate in the core acting as bridging ligands. The F−and I−anions do not favour the above arrangement resulting in triangular complexes with an isosceles topology. The magnetic properties of 1–3have been studied by variable-temperature dc, variable-temperature and variable-field ac magnetic susceptibility techniques and magnetization measurements. All complexes are high-spin with ground states S = 4 for 1and 2and S = 3 for 3. [ABSTRACT FROM AUTHOR]

Interaction of M(acac)2with Ti(OEt)4associated with hydrolysis or thermolysis provides with high yields, through the decomposition of the initially formed M2Ti2(acac)4(OEt)8, M = Ni (1), Co (2), poorly soluble Lindqvist-type products with the formula M5TiO(acac)6(OEt)6, M = Ni (3), Co (4), Mg (5). The compounds 3–5are isostructural and display a perfect statistical disorder between the OEt groups and 1/2 of the β-diketonate, acac, ligand. The metal atoms constitute a regular octahedron, centered by the oxo-oxygen atom. There is only one symmetrically independent metal site, which imposes it to contain 1/6 of titanium and 5/6 of the divalent metal atom. The oxygen atoms on the surface of the octahedron are doubly bridging and are located above the twelve edges of the octahedron, as is usual for the Lindqvist-type structures. The coordination of the metal atoms is completed by a single terminal oxygen atom. The complexes 3–5are volatile with decomposition, releasing only homometallic products into the gas phase in the case of 3and 4, but with a considerable contribution of molecular evaporation in the case of 5. The intermediates 1and 2belong to the tetramolybdate, M4O16, structure type. Highly soluble 1and 2can be considered as attractive molecular precursors for the incorporation of 3and 4into porous matrices for the preparation of combustion catalysts. Application of the same synthetic approach to n-propoxide complexes offers in a Co–Ti system a derivative with a different composition and resolved metal and ligand disorder, Co4Ti2O(acac)4(OnPr)10(6), which, however, still follows the Lindquist type and displays high (tetragonal) symmetry for both the molecule and the crystal structure. [ABSTRACT FROM AUTHOR]

An attempt to utilize a Co(II) cubane cluster as a building block to create extended frameworks results instead in the transformation of the cube into a dimer of dimers. [ABSTRACT FROM AUTHOR]

Systematic structural study of the molecules, resulting from microhydrolysis of heterometallic β-diketonate alkoxides of barium and strontium (single-source precursors of perovskite oxide materials), demonstrates that the structures of these products result from a thermodynamically driven self-assembly of metal cations and ligands directed towards the most densely packed cores. The ratio between metal cations, and of the cations to bidentate heteroligands, is easily changed to enable the highest packing density. The key to the application of single-source precursors appears to be the use of stoichiometric or superstoichiometric water amounts together with solvents preventing diffusion of possible homometallic intermediates. Eu-doped BaTiO3 nanoparticles have been successfully obtained and characterized. [ABSTRACT FROM AUTHOR]

Abstract The article describes the principles of the Single Source Precursor approach to inorganic materials and introduces the Geometrical Molecular Structure Design Concept (MSDC) based on the choice of a proper molecular structure type for the desired precursor and completing it with ligands providing both the necessary number of donor atoms and the sterical protection of the chosen core. Application of MSDC is illustrated with examples taken from development of new approaches in the synthesis of oxide and sulfide catalysts and ferroelectric oxide materials. [ABSTRACT FROM AUTHOR]