High-throughput and microwave investigation of rare earth phosphonatoethanesulfonates—Ln(O3P-C2H4-SO3) (Ln=Ho, Er, Tm, Yb, Lu, Y)

Following the strategy of using bifunctional phosphonic acids for the synthesis of new metal phosphonates, the flexible ligand 2-phosphonoethanesulfonic acid, H₂O₃P-C₂H₄-SO₃H (H₃L), was used in a high-throughput (HT) and microwave investigation of rare earth phosphonatoethanesulfonates. The HT-investigation led to six isotypic compounds Ln(O₃P-C₂H₄-SO₃) with Ln=Ho (1), Er (2), Tm (3), Yb (4), Lu (5) and Y (6). The syntheses were scaled-up in glass reactor tubes in order to obtain larger amounts for a detailed characterization. Based on these results all compounds could be also synthesized by microwave-assisted heating and the influence of reaction time and stirring rate during the synthesis was established. For compound 2 the crystal structure was determined by single-crystal X-ray diffraction. The compounds contain isolated slightly distorted LnO₆ octahedra that are connected by the phosphonate and sulfonate groups into a three-dimensional framework. Thermogravimetric investigations demonstrate the high thermal stability of the compounds up to 460 °C.     

Phosphaniminato‐Komplexe des Zirconiums: Die Kristallstrukturen von [ZrCl3(NPPh3)(HNPPh3)2] und [ZrCl2(NPPh3)2(HNPPh3)2]

Phosphoraneiminato Complexes of Zirconium: Crystal Structures of [ZrCl₃(NPPh₃)(HNPPh₃)₂] and [ZrCl₂(NPPh₃)₂(HNPPh₃)₂] The phosphoraneiminato complexes [ZrCl₃(NPPh₃)(HNPPh₃)₂] ( 1 ) and [ZrCl₂(NPPh₃)₂(HNPPh₃)₂] ( 2 ) have been obtained by reaction of [ZrCl₄(THF)₂] with [CsNPPh₃]₄ in THF solution to give colourless moisture sensitive crystals which are characterized by X‐ray structure determinations. [ZrCl₃(NPPh₃)(HNPPh₃)₂] ( 1 ): Space group P 1, Z = 2, lattice dimensions at 193 K: a = 1209.4(2); b = 1480.8(2); c = 1814.2(2) pm; α = 71.203(13)°, β = 71.216(13)°, γ = 74.401(13)°; R = 0.0476. The zirconium atom of 1 is oktahedrally coordinated by the three chlorine atoms in meridional arrangement and by the three nitrogen atoms of the (NPPh₃^–) ligand and of the two phosphane imine molecules HNPPh₃. The ZrN bond distance of the (NPPh₃^–) group (193.5 pm) corresponds with a double bond. [ZrCl₂(NPPh₃)₂(HNPPh₃)₂] ( 2 ): Space group P 1, Z = 4, lattice dimensions at 193 K: a = 1447.6(2); b = 1925.7(2), c = 2457.0(2) pm; α = 67.317(12)°, β = 87.376(12)°, γ = 87.103(13)°; R = 0.0408. The zirconium atom in 2 is octahedrally coordinated by the two chlorine atoms in trans position, and by the nitrogen atoms of the two (NPPh₃^–) groups as well as by the two HNPPh₃ molecules. The ZrN distance of the (NPPh₃^–) ligands (198.9 and 202.0 pm) suggest some π‐interaction between the zirconium and the nitrogen atoms.     

Pt@MOF-177: synthesis, room-temperature hydrogen storage and oxidation catalysis

The gas-phase loading of [Zn(4)O(btb)(2)](8) (MOF-177; H(3)btb=1,3,5-benzenetribenzoic acid) with the volatile platinum precursor [Me(3)PtCp'] (Cp'=methylcyclopentadienyl) was confirmed by solid state (13)C magic angle spinning (MAS)-NMR spectroscopy. Subsequent reduction of the inclusion compound [Me(3)PtCp'](4)@MOF-177 by hydrogen at 100 bar and 100 degrees C for 24 h was carried out and gave rise to the formation of platinum nanoparticles in a size regime of 2-5 nm embedded in the unchanged MOF-177 host lattice as confirmed by transmission electron microscopy (TEM) micrographs and powder X-ray diffraction (PXRD). The room-temperature hydrogen adsorption of Pt@MOF-177 has been followed in a gravimetric fashion (magnetic suspension balance) and shows almost 2.5 wt % in the first cycle, but is decreased down to 0.5 wt % in consecutive cycles. The catalytic activity of Pt@MOF-177 towards the solvent- and base-free room temperature oxidation of alcohols in air has been tested and shows Pt@MOF-177 to be an efficient catalyst in the oxidation of alcohols.     

Towards perfunctionalized dodecahedranes--en route to C20 fullerene

“One‐pot” substitution of the twenty hydrogen atoms in pentagonal dodecahedrane (C₂₀H₂₀) by OH, F, Cl, and Br atoms is explored. Electrophilic insertion of oxygen atoms with DMDO and TFMDO as oxidizing reagents ended, far off the desired C₂₀(OH)₂₀, in complex polyol mixtures (up to C₂₀H₁₀(OH)₁₀ decols, a trace of C₂₀H(OH)₁₉?). Perfluorination was successful in a NaF matrix but (nearly pure) C₂₀F₂₀ could be secured only in very low yield. “Brute‐force” photochlorination (heat, light, pressure, time) provided a mixture of hydrogen‐free, barely soluble C₂₀Cl₁₆ dienes in high yield and C₂₀Cl₂₀ as a trace component. Upon electron‐impact ionization of the C₂₀Cl₁₆ material sequential loss of the chlorine atoms was the major fragmentation pathway furnishing, however, only minor amounts of chlorine‐free C₂₀⁺ ions. “Brute‐force” photobrominations delivered an extremely complex mixture of polybromides with C₂₀HBr₁₃ trienes as the highest masses. The MS spectra exhibited exclusive loss of the Br substituents ending in rather intense singly, doubly, and triply charged C₂₀H_4–0^+(2+)(3+) ions. The insoluble ～C₂₀HBr₁₃ fraction (C₂₀Br₁₄ trienes as highest masses) obtained along a modified bromination protocol, ultimately allowed the neat mass selection of C₂₀^? ions. The C₂₀Cl₁₆ dienes and C₂₀H_0–3Br_14–12 tri‐/tetraenes, in spite of their very high olefinic pyramidalization, proved resistant to oxygen and dimerization (polymerization) but added CH₂N₂ smoothly. Dehalogenation of the respective cycloaddition products through electron‐impact ionization resulted in C_22–24H_4–8⁺⁽²⁺⁾ ions possibly constituting bis‐/tris‐/tetrakis‐methano‐C₂₀ fullerenes or partly hydrogenated C₂₂, C₂₃, and C₂₄ cages.     

Synthesis and self-assembly of "tree-like" amphiphilic glycopolypeptides

Novel synthetic tree-like oligosaccharides-grafted-polypeptides were prepared by using Huisgen 1,3-dipolar cycloaddition between poly(γ-benzyl-L-glutamate)-block-poly(propargylglycine) and two different oligosaccharides, dextran or hyaluronan. By direct solubilisation in water, these tree-like glycopeptides spontaneously form very small assemblies with sizes below 50 nm and low polydispersity.     

Modelling of the Phase Separation Behaviour of Semiflexible Diblock Copolymers

Silver salts are dissolved in poly(butyl methacrylate) to derive polymer electrolytes via coordinative interaction between the silver ion and the carbonyl oxygen atom. The dissolved silver ions react subsequently with propylene to form reversible silver/olefin complexes that can be utilized as olefin carriers for facilitated olefin transport. The complexation behavior and its effects on propylene transport were investigated by means of Raman and FT‐IR spectroscopy, as well as dielectric thermal analysis.