An Apatite-Group Praseodymium Carbonate Fluoroxybritholite: Hydrothermal Synthesis, Crystal Structure, and Implications for Natural and Synthetic Britholites.

Britholites are the lanthanide-silica-rich end-members of the apatite group, commonly studied for their optical properties. Here, we show ∼50-100 μm single crystals synthesized hydrothermally at 650-500 °C and 500-300 MPa composed of a solid solution between CaPr(SiO)F-fluorbritholite and CaPr(SiO)O-oxybritholite, with a significant carbonate component substitution, via C replacing Si. Single-crystal X-ray diffraction and density functional theory computations show that a planar carbonate group occupies the face of a now-vacant silica tetrahedron.

Mineral Mimetic Material Sr-Exchanged Sitinakite of Different Crystallinity: Phase Transformations during Heat Treatment and the Strength of SR Fixation in a Ceramic Matrix.

A simple method for the direct transformation of Sr-exchanged titanosilicate with the sitinakite structure (IONSIV) into ceramic material through cold pressing and subsequent sintering at 1100 °C for 4 h is presented. The temperature transformation of Sr-exchanged sitinakite showed the stages of recrystallization of the material with the formation of Sr-Ti phases matsubaraite (SrTi[SiO]O), jeppeite (SrTiO), tausonite (SrTiO), and rutile. Leaching experiments showed the efficiency of fixation of Sr cations in a ceramic matrix; extraction into water does not exceed 0.

The AM-4 Family of Layered Titanosilicates: Single-Crystal-to-Single-Crystal Transformation, Synthesis and Ionic Conductivity.

Flexible crystal() structures, which exhibit() single-crystal()-to-single-crystal() (SCSC) transformations(), are attracting attention() in many applied aspects: magnetic() switches, catalysis, ferroelectrics and sorption. Acid treatment() for titanosilicate material() AM-4 and natural() compounds with the same structures led to SCSC transformation() by loss() Na, Li and Zn cations with large structural() changes (20% of the unit()-cell() volume()). The conservation() of crystallinity through complex() transformation() is possible due() to the formation() of a strong hydrogen bonding() system().

Serpentine Overburden Products-Nature-Inspired Materials for Metal Detoxification in Industrially Polluted Soil.

The possibility of plants growing on serpentine soils and the ability of serpentine minerals to accumulate significant amounts of metals was the basis for developing a method for using serpentine-containing materials to restore vegetation in areas with a high level of metal pollution. Serpentine-containing products obtained from phlogopite mining overburden (Kovdor, Murmansk region, Russia) with and without thermal activation were used in a field experiment on the remediation of industrially polluted peat soil. According to the geochemical mobility of the components, one of four fractions was allocated depending on the acidic (HCl) concentration of the solution used for the material treatment: readily mobile (0.

The role of local heteropolyhedral substitutions in the stoichiometry, topological characteristics and ion-migration paths in the eudialyte-related structures: a quantitative analysis.

Topological analysis of the heteropolyhedral MT framework (where M and T are octahedral and tetrahedral cations, respectively) in the eudialyte-type structure and its derivatives was performed based on a natural tiling analysis of the 3D cation. To analyze the migration paths of sodium cations in these structures, the Voronoi method was used. The parental eudialyte-type MT framework is formed by isolated ZO octahedra, six-membered [M(1)O] rings of edge-sharing M(1)O octahedra, and two kinds of rings of tetrahedra, [SiO] and [SiO].

2 H-Azirines as C-C Annulation Reagents in Cu-Catalyzed Synthesis of Furo[3,2- c]quinolone Derivatives.

A method of furo-annulation of 4-hydroxy-2-oxoquinoline-3-carboxylates with 3-arylazirines under Cu(II) catalysis was developed to synthesize a variety of 2,3-dihydrofuro[3,2- c]quinolones bearing a carbamate group at the C2 position. The reaction involves an azirine ring opening across the N-C2 bond and formation of a dihydrofuran ring with the inclusion of two azirine carbon atoms, accompanied by a shift of the ester group to the nitrogen. The discovered reaction is the first example of the use of 2 H-azirines for furo-annulation.

TfOH-Promoted Reaction of 2,4-Diaryl-1,1,1-Trifluorobut-3-yn-2-oles with Arenes: Synthesis of 1,3-Diaryl-1-CF₃-Indenes and Versatility of the Reaction Mechanisms.

The TfOH-mediated reactions of 2,4-diaryl-1,1,1-trifluorobut-3-yn-2-oles (CF₃-substituted diaryl propargyl alcohols) with arenes in CH₂Cl₂ afford 1,3-diaryl-1-CF₃-indenes in yields up to 84%. This new process for synthesis of such CF₃-indenes is complete at room temperature within one hour. The synthetic potential, scope, and limitations of this reaction were illustrated by more than 70 examples.

Copper(I)-Catalyzed 1,3-Dipolar Cycloaddition of Ketonitrones to Dialkylcyanamides: A Step toward Sustainable Generation of 2,3-Dihydro-1,2,4-oxadiazoles.

Cu-catalyzed cycloaddition (CA) of the ketonitrones, PhC=N(R')O (R' = Me, CHPh), to the disubstituted cyanamides, NCNR (R = Me, Et, (CH), (CH), (CH)O, CH, (CHPh), Ph(Me)), gives the corresponding 5-amino-substituted 2,3-dihydro-1,2,4-oxadiazoles (15 examples) in good to moderate yields. The reaction proceeds under mild conditions (CHCl, RT or 45 °C) and requires 10 mol % of [Cu(NCMe)](BF) as the catalyst. The somewhat reduced yields are due to the individual properties of 2,3-dihydro-1,2,4-oxadiazoles, which easily undergo ring opening via N-O bond splitting.

Towards a revisitation of vesuvianite-group nomenclature: the crystal structure of Ti-rich vesuvianite from Alchuri, Shigar Valley, Pakistan.

Vesuvianite containing 5.85 wt% TiO from an Alpine-cleft-type assemblage outcropped near Alchuri, Shigar Valley, Northern Areas, Pakistan, has been investigated by means of electron microprobe analyses, gas-chromatographic analysis of HO, X-ray powder diffraction, single-crystal X-ray structure refinement, Al NMR, Fe Mössbauer spectroscopy, IR spectroscopy and optical measurements. Tetragonal unit-cell parameters are: a = 15.

Fe(II)/Et3N-Relay-catalyzed domino reaction of isoxazoles with imidazolium salts in the synthesis of methyl 4-imidazolylpyrrole-2-carboxylates, its ylide and betaine derivatives.

A simple approach was developed for the synthesis of methyl 4-imidazolylpyrrole-2-carboxylates from easily available compounds, 5-methoxyisoxazoles and phenacylimidazolium salts under hybrid Fe(II)/Et3N relay catalysis. The products were easily transformed into the corresponding 3-(5-methoxycarbonyl-1H-imidazol-3-ium-3-yl)pyrrol-1-ides, which in turn can be hydrolyzed under basic conditions into the corresponding betaines. A carbene tautomeric form of the 4-methoxycarbonyl-substituted imidazolylpyrrolides was trapped by reaction with sulfur affording the corresponding imidazolethiones under very mild conditions.

Synthesis of natural phaeosphaeride A derivatives and an in vitro evaluation of their anti-cancer potential.

Derivatives of phaeosphaeride A (PPA) were synthesised and characterised; then anti-cancer studies were carried out on the A549 cancer cell line. It was found that the acetyl derivative (compound 3) displayed comparable in vitro cytotoxicity to that of PPA (EC50=49±7 μM and EC50=46±5 μM, respectively), while chloroacetyl derivative 6 (EC50=33±7 μM) was found to have better efficacy towards the A549 cancer cell line.

Crystal structure of natural phaeosphaeride A.

The asymmetric unit of the title compound, C15H23NO5, contains two independent mol-ecules. Phaeosphaeride A contains two primary sections, an alkyl chain consisting of five C atoms and a cyclic system consisting of fused five- and six-membered rings with attached substituents. In the crystal, the mol-ecules form layered structures.