Studying complex processes in solid phases such as adsorption or phase transitions in situ is the best way to obtain detailed and realistic insights on a molecular level. Besides in situ X-ray diffraction techniques, magic angle spinning (MAS) solid-state NMR spectroscopy is one of the most powerful analytical techniques. The implementation of in situ and operando MAS NMR is however challenging and requires dedicated hardware. We introduce here a new 4.0 mm wide-bore probe that allows for a continuous and well-distributed flow of gaseous adsorbates or reactants through the packed sample, as well as uniform heating of the sample and spinning of the rotor at the magic angle. The combination of both in situ MAS NMR and in situ powder X-ray diffraction allowed us to obtain new insights into two phase transformation mechanisms in crystalline, porous materials, viz. that of aluminophosphate VPI-5 into AlPO4-8 and that of metal-organic frameworks from the MIL-53 family during water adsorption and desorption.

Monometallic (CuO and FeOx) and bimetallic (CuFeOx) entities on different supports are promising transition-metal low-cost catalysts for catalytic oxidation of volatile organic compounds (VOC) from industrial air alternatively to noble-metal catalysts which are currently in use. In this work we report for the first time that the promotion of catalytic oxidation of toluene as a model VOC is due to the cooperative redox effect between CuO nanocrystals and finely dispersed Cu-oxo-Fe clusters on mesoporous silica with defined Fe/Cu molar ratio. This increases the number and reactivity of adsorbed electrophilic (O- and O-2(-)) as well as nucleophilic lattice oxygen (O-2) species at the CuO crystal and and Cu-oxo-Fe cluster interface, thus providing up to twofold enhancement in catalytic activity for total oxidation of toluene. Catalysts were prepared via direct synthesis of Fefunctionalized disordered mesoporous silica containing only isolated iron sites followed by copper addition via impregnation.

SO3H-functionalised mesoporous materials with different pore structures (SBA-15 and SBA-16) were prepared by the post-synthesis surface modification. The materials were thoroughly characterized by X-ray powder diffraction, nitrogen physisorption, temperature-gravimetric analysis, elemental analysis and solid state NMR spectroscopy. The acidic properties were investigated by the temperature-programed desorption of ammonia. The catalytic performance of SO3H-functionalised mesoporous materials was studied in glycerol esterification with acetic acid.The different amount of silanol groups in the initial SBA-15 and SBA-16 silicas predetermined the different amount of propylsulfonic groups which are formed in them and therefore significantly influenced the acidity and the catalytic performance in glycerol esterification. Much higher amount of Br?nsted acid sites was generated in SO3H modified SBA-15 catalyst, which exhibited higher activity to value-added triacetyl glycerol.

Two different quaternary ammonium cations, methyltriethyl- (MTEA) and tetraethylammonium cations (TEA) were used as templates in the synthesis of pure-silica as well as aluminosilicate ZSM-12 (MTW-type) frameworks. The distribution of the template cations in the 12-membered rings channels in the 1-dimensional framework topology was studied; thus the as-prepared products were characterized by means of X-ray powder diffraction, Raman, transmission FTIR, solid-state NMR spectroscopy, thermogravimetric and elemental analyses and SEM. It was shown that in pure-silica (PS) ZSM-12, TEA cations are well ordered - a superstructure with three-times longer b edge (in comparison to unit cell of empty framework) along the channel is formed, which can be seen by virtue of a few additional peaks in the X-ray powder pattern. Herein we describe that its aluminosilicate counterpart with TEA also contains ordered TEA cations and is isostructural to PS-ZSM-12. Conversely, in both pure-silica and aluminosilicate ZSM-12 frameworks with MTEA, the cations are disordered and no superstructure is formed.

The instantaneous formation of cerium vanadium oxide gels starting from polyoxovanadates is reported together with their application in pollutant removal and controlled acid release.

Nickel and magnesium acetylacetonate molecular complexes were post-synthetically incorporated into microporous zirconium-based MOF (UiO-66-NH2) in order to introduce active open-metal sites for hydrogen sorption. Elemental analysis, nitrogen physisorption and DFT calculations revealed that 5 molecules of Ni(acac)2 or 2 molecules of Mg(acac)2 were incorporated into one unit cell of UiO-66-NH2. 1H–13C CPMAS and 1H MAS NMR spectroscopy showed that, although embedded within the pores, both Ni- and Mg-complexes interacted with the UiO-66-NH2 framework only through weak van der Waals bonds. Inclusion of metal complexes led to the decrease of hydrogen sorption capacities in Ni-modified as well as in Mg-modified samples in comparison with the parent UiO-66-NH2. The isosteric hydrogen adsorption enthalpy slightly increased in the case of Ni-modified material, but not in the case of Mg-modified analogue.

Spontaneous transformation paths of nanomaterials point to guiding principles for synthesis. We describe the room temperature transformation of MgO nanocubes into Mg3(OH)5Cl·4H2O nanofibers in air and investigated the underlying formation mechanism using electron microscopy, X-ray diffraction, and solid-state NMR spectroscopy. Upon contact with water vapor, the magnesium hydroxide needles were found to grow out of agglomerates of highly dispersed MgO nanocubes with preadsorbed SiCl4. Corresponding one-dimensional nanostructures do not form on low surface area materials. The presented growth approach is potentially extendable to other hydrolyzable metal oxides at ultrafine dispersion.

Iron-functionalized disordered mesoporous silica (FeKIL-2) is a promising, environmentally friendly, cost-effective and highly efficient catalyst for the elimination of volatile organic compounds (VOCs) from polluted air via catalytic oxidation. In this study, we investigated the type of catalytically active iron sites for different iron concentrations in FeKIL-2 catalysts using advanced characterization of the local environment of iron atoms by a combination of X-ray Absorption Spectroscopy Techniques (XANES, EXAFS) and Atomic-Resolution Scanning Transmission Electron Microscopy (AR STEM). We found that the molar ratio Fe/Si ≤ 0.01 leads to the formation of stable, mostly isolated Fe3+ sites in the silica matrix, while higher iron content Fe/Si > 0.01 leads to the formation of oligonuclear iron clusters. STEM imaging and EELS techniques confirmed the existence of these clusters. Their size ranges from one to a few nanometers, and they are unevenly distributed throughout the material. The size of the clusters was also found to be similar, regardless of the nominal concentration of iron (Fe/Si = 0.02 and Fe/Si = 0.05). From the results obtained from sample characterization and model catalytic tests, we established that the enhanced activity of FeKIL-2 with the optimal Fe/Si = 0.01 ratio can be attributed to: (1) the optimal concentration of stable isolated Fe3+ in the silica support; and (2) accelerated diffusion of the reactants in disordered mesoporous silica (FeKIL-2) when compared to ordered mesoporous silica materials (FeSBA-15, FeMCM-41).

Four new magnesium 1,3,5-benzenetricarboxylate metal-organic framework materials (NICS-n; n = 3-6) were synthesized solvothermally in the presence of solvents with different EtOH/H2O ratios. We showed that the crystallization process of the Mg-1,3,5-benzentricarboxylate system strongly depends on the solvent composition, and that dimensionality of their structures can be tuned by changing the EtOH/water ratios in the reaction mixture. The presence of only water as a solvent yields the zero-dimensional molecular structure of Mg(H2BTC)(2)(H2O)(4) (NICS-3). One-dimensional (1D) chainlike Mg-3(BTC)(2)(H2O)(12) (NICS-4) and two-dimensional (2D) layered Mg-2(BTC)(OH)(H2O)(4)center dot 2H(2)O (NICS-5) structures were crystallized from EtOH/H2O mixtures with molar ratios of 0.3 and 0.4-0.7, respectively. The crystallization in pure ethanol yields Mg-3(BTC)(2) material (NICS-6) with three-dimensional structure. Nuclear magnetic resonance investigations indicated that builder dusters of Mg species are formed in ethanol-rich solutions, even in the absence of the BTC ligand, and that the starting precursors formed with the reaction of Mg species and the BTC ligand at room temperature does not represent the final structures obtained by solvothermal reactions. NICS-4 and NICS-5 are formed from similar starting precursors but slightly different EtOH/H2O ratios causing the crystallization to go in two different directions. Systematic investigation of phase formation using different EtOH/H2O ratios, times, and temperatures of the synthesis along with the computational DFT studies confirmed that the 2D NICS-5 structure represents a thermodynamically more stable phase than 1D chainlike NICS-4. We showed that solvothermal reaction between Mg-precursors and the BTC ligand in EtOH/water mixture represents a complex and sensitive thermodynamic process.

New heterogeneous, reusable catalysts for olefin metathesis have been prepared by immobilizing the Hoveyda–Grubbs first generation type alkylidene (commercially available as the Zhan catalyst-1C) on siliceous mesoporous molecular sieves with different pore sizes and architectures (SBA-15, SBA-16, MCM-41 and MCM-48) having the surface modified with molecules bearing dicyclohexylphosphine (PCy2) end groups. Resulting novel heterogenized catalysts proved high activity in ring-closing metathesis (RCM) of 1,7-octadiene, diethyl diallylmalonate, tert-butyl N,N-diallylcarbamate and N,N-diallyl-2,2,2-trifluoroacetamide, in homometathesis of 1-decene, 5-hexenyl acetate and methyl 10-undecenoate, and in cross-metathesis (CM) of allylbenzene with cis-1,4-diacetoxy-2-butene. The catalytic activity decreased with decreasing pore size of supports in the order SBA-15 > MCM-48 > SBA-16 and MCM-41. Filtration test suggested that the solid catalyst was responsible for the catalytic activity. Catalysts were easily separated from the reaction mixtures and products of low levels of Ru concentration were obtained.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

In this contribution we present the study of Ca- and Mg-based MOF materials from rational design to application opportunities. In the case of Mg-benzene-1, 3, 5-tricarboxylate system we demonstrate how the solvent composition involved in the synthesis procedure plays the crucial role for the dimensionality of the final crystal structure. In the case of Ca-benzene-1, 4-dicarboxylate we present the detailed spectroscopic study of its structural dynamics upon heating and elucidated the mechanism of crystal-to-crystal transformation. Finally, we show the degradation study of Ca- and Mg-based aliphatic dicarboxylates (succinates, glutarates and pimelates) in body fluid conditions and discuss the possibility employ those materials for bio-applications.

Zinc trimesate material with high hydrothermal stability was studied for water adsorption/desorption dynamics, and we explained the reason for material's stability in water. A zinc trimesate Zn-2(BTC)(OH)-(H2O)center dot 1.67H(2)O with the three-dimensional framework contains [Zn2O6(OH)(H2O)] chains with ZnO2(OH)(2) tetrahedra and ZnO4(OH)-(H2O) octahedra corner-shared through mu 3-OH group. Inorganic chains are linked with 1,3,5-benzenetricarboxylates forming two types of parallel channels (open and closed) containing adsorbed water in different environments. Closed channels are occupied by free water molecules connected through strong hydrogen-bonds with coordinated water, whereas open-type channels contain water molecules with partially occupied oxygen atom sites. The dynamics of water adsorption/desorption was evaluated by complementary techniques of thermogravimetric (TG), infrared (IR), water sorption, and different magic-angle spinning nuclear magnetic resonance (MAS NMR) techniques. The removal of water from open channels occurs below 100 degrees C, whereas hydrogen-bonded water molecules and coordinated water are expelled at higher temperatures. H-2 MAS NMR was employed to prove that the removal of water from closed channels is not entirely simultaneous and that adsorbed water begins to diffuse at slightly lower temperatures than the coordinated one. The investigated material shows high hydrothermal stability and withstands 40-cycle hydrothermal-stability test without any significant loss of the structure integrity. It also shows complete structural reversibility upon dehydration/rehydration process at 200 degrees C. The reason for high stability in water mainly lies in the stabilization of the inorganic chains established by the interaction between the adsorbed water molecules and coordinated ones (framework water) via hydrogen bonds. The material also exhibits notable sorption capacity for water (208 mg.g(-1)) adsorbed in a stepwise process.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Structural dynamics of Ca(BDC)(DMF)(H(2)0) with rhombic-shaped channels and 4(4) net topology upon heating and hydration were elucidated by using complementary methods of diffraction (XRD) and spectroscopy (FT-IR, MAS NMR, EXAFS, XANES). During heating the Ca(BDC)(DMF)(H2O) framework underwent structural changes in two steps. The first change at 150 degrees C includes breaking of Ca-O bonds with H2O and DMF molecules. In this step, DMF is removed from the surface or near the surface of the crystals. The affected parts of the crystals are transformed to a new nonporous Ca-BDC(400) phase that prevents the diffusion of DMF from the cores of the crystals. Second transition at 400 degrees C led to the complete transformation to Ca-BDC(400). This phase is reversibly transformed to a pseudo-3-D framework Ca(BDC)(H2O)(3) upon exposure to humid environment We proposed mechanisms of Ca-BDC(RT) -> Ca-BDC(400) and Ca-BDC(400) -> Ca(BDC)(H2O)(3) transformations, which include breaking of the bonds between Ca2+ and carboxylate groups, rotating of BDC ligand, and recoordination of COO- groups to Ca2+ centers. The crystal-to-crystal transformations are driven by the tendencies to change the bonding modes between COO- and Ca2+ with the change of Ca2+ coordination number. Thus the decrease in Ca2+ coordination number, which is usually a consequence of activation, does not lead to the expansion or contraction of the pores, but it leads to pronounced structural rearrangement. Such behavior can explain the lack of porosity in Ca-MOF systems.

Wet hydrogen peroxide catalytic oxidation (WHPCO) is one of the most important industrially applicable advanced oxidation processes (AOPs) for the decomposition of organic pollutants in water. It is demonstrated that manganese functionalized silicate nanoparticles with interparticle porosity act as a superior Fenton‐type nanocatalyst in WHPCO as they can decompose 80% of a test organic compound in 30 minutes at neutral pH and room temperature. By using X‐ray absorption spectroscopic techniques it is also shown that the superior activity of the nanocatalyst can be attributed uniquely to framework manganese, which decomposes H 2 O 2 to reactive hydroxyls and, unlike manganese in Mn 3 O 4 or Mn 2 O 3 nanoparticles, does not promote the simultaneous decomposition of hydrogen peroxide. The presented material thus introduces a new family of Fenton nanocatalysts, which are environmentally friendly, cost‐effective, and possess superior efficiency for the decomposition of H 2 O 2 to reactive hydroxyls (AOP), which in turn readily decompose organic pollutants dissolved in water.