A HF Loaded Lewis-Acidic Aluminium Chlorofluoride for Hydrofluorination Reactions.

The very strong Lewis acid aluminium chlorofluoride (ACF) was loaded with anhydrous HF. The interaction between the surface of the catalyst and HF was investigated using a variety of characterization methods, which revealed the formation of polyfluorides. Moreover, the reactivity of the HF-loaded ACF towards the hydrofluorination of alkynes was studied.

F-doping of nanostructured ZnO: a way to modify structural, electronic, and surface properties.

Polycrystalline ZnO is a material often used in heterogeneous catalysis. Its properties can be altered by the addition of dopants. We used gaseous fluorine (F) as direct way to incorporate fluoride in ZnO as anionic dopants.

Insight into the Structure and Properties of Novel Imidazole-Based Salts of Salicylic Acid.

The preparation of new active pharmaceutical ingredient (API) multicomponent crystal forms, especially co-crystals and salts, is being considered as a reliable strategy to improve API solubility and bioavailability. In this study, three novel imidazole-based salts of the poorly water-soluble salicylic acid (SA) are reported exhibiting a remarkable improvement in solubility and dissolution rate properties. All structures were solved by powder X-ray diffraction.

Nb-doped variants of high surface aluminium fluoride: a very strong bi-acidic solid catalyst.

A niobium doped high surface aluminium fluoride (HS-AlF3) catalyst was prepared, using an approach in which niobium doped aluminium hydroxide fluoride obtained via reaction of aqueous HF with the respective metal alkoxides in isopropanol is further fluorinated under flow of CHClF2 at 200 °C. A comparable procedure was used to synthesize a Nb-free variant for comparison. Both catalysts exhibit very strong Lewis acidic surface sites which are capable to activate strong carbon-halogen bonds at room temperature, just as the classical high-surface AlF3 (HS-AlF3), obtained by reacting aluminium isopropoxide with anhydrous HF, does.

Ca-, Sr-, and Ba-Coordination polymers based on anthranilic acid via mechanochemistry.

Ca-, Sr-, and Ba-Based coordination polymers (CPs) were prepared mechanochemically by milling metal-hydroxide samples with anthranilic acid (oABAH). {[Ca(oABA)2(H2O)3]}n (1) consists of one-dimensional polymeric chains that are further connected by a hydrogen-bonding network. {[Sr(oABA)2(H2O)2]·H2O}n (2) is a one-dimensional CP in which water molecules bridge Sr2+ ions and increase the dimensionality by building an extended network.

A Silylene-Borane Lewis Pair as a Tool for Trapping a Water Molecule: Silanol Formation and Dehydrogenation.

The Lewis acid B(C F ) and the cyclic silane (Ar Si) (1) (Ar =o-(CH ) NCH C H ) are useful precursors to access the silylene(II)-borane adduct Ar Si-B(C F ) (2). Treatment of 2 with water led to coordination and gave the Lewis pair (Ar H O)Si-B(C F ) (3) that exhibits a hydrogen-bond-stabilized silanol unit. It can be converted into the siloxane [(HAr ) SiOB(C F ) ] O (6) by dehydrogenation in the presence of a base.

Comparative study of the strongest solid Lewis acids known: ACF and HS-AlF.

Aluminium chlorofluoride (ACF) and high-surface aluminium fluoride (HS-AlF3) were analyzed by a set of characterization methods to assess their acidic properties: NH3-TPD, CO adsorption followed by DRIFTS, CD3CN-PAS-FTIR and MAS NMR spectroscopy after 15N-pyridine adsorption. Both catalysts contain very strong and medium-strong Lewis acid sites as confirmed by CO adsorption, in which small differences arise from the morphological properties of each catalyst, with ACF being microporous and HS-AlF3 mesoporous. Shifts of the CO vibration band of up to 77 cm-1 were observed, which account for very strong Lewis acid sites.

A Combined Mg Solid-State NMR and Ab Initio DFT Approach to Probe the Local Structural Differences in Magnesium Acetate Phases Mg(CH COO) ⋅ nH O (n=0, 1, 4).

Multinuclear ( H, C, Mg) solid-state NMR data is reported for a series of magnesium acetate phases Mg(CH COO)  ⋅ nH O (n=0 (two polymorphs), 1, 4). The central focus here is Mg as this set of compounds provides an expanded range of local magnesium coordinations compared to what has previously been reported in the literature using NMR. These four compounds provide 10 distinct magnesium sites with varying NMR interaction parameters.

Ca-Tetrafluorophthalate and Sr-isophthalate: mechanochemical synthesis and characterization in comparison with other Ca-and Sr-coordination polymers.

New Ca- and Sr-based coordination polymers (CPs) were mechanochemically synthesized by milling metal hydroxide samples (M = Ca, Sr) with tetrafluorophthalic acid (H2oBDC-F4) and isophthalic acid (H2mBDC). [Ca(oBDC-F4)(H2O)2] (1) exhibits a small surface area which is slightly increased after removing the crystal water. On the other hand, the hydrated sample of the nonfluorinated [Sr(mBDC)(H2O)3.

Sol-Gel-Synthesis of Nanoscopic Complex Metal Fluorides.

The fluorolytic sol-gel synthesis for binary metal fluorides (AlF₃, CaF₂, MgF₂) has been extended to ternary and quaternary alkaline earth metal fluorides (CaAlF₅, Ca₂AlF₇, LiMgAlF₆). The formation and crystallization of nanoscopic ternary CaAlF₅ and Ca₂AlF₇ sols in ethanol were studied by F liquid and solid state NMR (nuclear magnetic resonance) spectroscopy, as well as transmission electron microscopy (TEM). The crystalline phases of the annealed CaAlF₅, Ca₂AlF₇, and LiMgAlF₆ xerogels between 500 and 700 °C could be determined by X-ray powder diffraction (XRD) and F solid state NMR spectroscopy.

Strontium-coordination polymers based on tetrafluorophthalic and phthalic acids: mechanochemical synthesis, ab initio structures determination, and spectroscopic characterization.

Two strontium-based dicarboxylate systems [Sr(oBDC-F)(HO)] (1) and [{Sr(oBDC)(HO)}·HO] (2) were synthesized mechanochemically via milling of Sr(OH)·8HO with tetrafluorophthalic acid (HoBDC-F) or phthalic acid (HoBDC), respectively. The new structures were determined ab initio from the powder X-ray diffraction (PXRD) data. Both compounds 1 and 2 crystallize in the monoclinic space group P2/c as two-dimensional coordination polymers (2D-CPs).

Ca- and Sr-tetrafluoroisophthalates: mechanochemical synthesis, characterization, and ab initio structure determination.

New fluorinated coordination polymers were prepared mechanochemically by milling the alkaline earth metal hydroxides M(OH)·xHO (M: Ca, Sr) with tetrafluoroisophthalic acid (HmBDC-F). The structures of [{Ca(mBDC-F)(HO)}·HO] (1) and [{Sr(mBDC-F)(HO)}·HO] (2) were determined based on ab initio calculations and their powder X-ray diffraction (PXRD) data. The compounds are isomorphous and crystallize in the orthorhombic space group P222.

Is Geometric Frustration-Induced Disorder a Recipe for High Ionic Conductivity?

Ionic conductivity is ubiquitous to many industrially important applications such as fuel cells, batteries, sensors, and catalysis. Tunable conductivity in these systems is therefore key to their commercial viability. Here, we show that geometric frustration can be exploited as a vehicle for conductivity tuning.

Novel and easy access to highly luminescent Eu and Tb doped ultra-small CaF, SrF and BaF nanoparticles - structure and luminescence.

A universal fast and easy access at room temperature to transparent sols of nanoscopic Eu and Tb doped CaF, SrF and BaF particles via the fluorolytic sol-gel synthesis route is presented. Monodisperse quasi-spherical nanoparticles with sizes of 3-20 nm are obtained with up to 40% rare earth doping showing red or green luminescence. In the beginning luminescence quenching effects are only observed for the highest content, which demonstrates the unique and outstanding properties of these materials.

Investigation of the fluorolysis of magnesium methoxide.

The structures of magnesium methoxide and magnesium methoxide fluoride obtained via the reaction of Mg(OCH(3))(2) with HF were investigated by single-crystal structure analysis and multinuclear solid-state NMR ((13)C and (19)F). The fluorolysis of magnesium methoxide transforms the cubane structure units in hexanuclear dicubane units containing micro(4)-fluorine atoms. The resulting Mg(6)F(2)(OCH(3))(10)(CH(3)OH)(14) compound crystallizes in two different crystalline modifications.

Novel sol-gel synthesis of acidic MgF(2-x)(OH)(x) materials.

Novel magnesium fluorides have been prepared by a new fluorolytic sol-gel synthesis for fluoride materials based on aqueous HF. By changing the amount of water at constant stoichiometric amount of HF, it is possible to tune the surface acidity of the resulting partly hydroxylated magnesium fluorides. These materials possess medium-strength Lewis acid sites and, by increasing the amount of water, Brønsted acid sites as well.

Tunable porosity in bridged organosilicas using self-organizing precursors.

Functionalized, mesoporous organosilicas with tunable porosity were prepared by a direct and simple approach from rationally designed precursors, combining the function of a network builder and a porogen in one molecule. The precursors are synthesized using a dual hydroboration reaction, fulfilling the criteria of "click-chemistry", first on an ethylene-bridged organosilica and then on a long-chain alkene. Thus, in the final molecule the boron atom connects the sol-gel precursor (the bridged organosilica) with the porogen (the long-chain alkene).

Structure of (NH4)3GaF6 investigated by multinuclear magic-angle spinning NMR spectroscopy in comparison with rietveld refinement.

The structure of ammonium gallium cryolite (NH(4))(3)GaF(6) was investigated by (19)F and (69,71)Ga magic-angle spinning (MAS) NMR in comparison with X-ray powder diffraction followed by Rietveld refinement. In agreement with previous thermodynamic measurements, NMR experiments on (NH(4))(3)GaF(6) support the model of rigid GaF(6) octahedra. At high spinning speeds (30 kHz), the scalar coupling between the six equivalent (19)F nuclei and (69,71)Ga can be directly observed in the powder spectra.

Structural insights into aluminum chlorofluoride (ACF).

The structure of the very strong solid Lewis acid aluminum chlorofluoride (ACF, AlCl(x)F(3-x), x = 0.05-0.3) was studied by IR, ESR, Cl K XANES, (19)F MAS NMR, and (27)Al SATRAS NMR spectroscopic methods and compared with amorphous aluminum fluoride conventionally prepared by dehydration of alpha-AlF(3) x 3H(2)O.