Palladium(II) and platinum(II) tetrakisthiourea dichloride bis(7-hydroxy-5-methyl[1,2,4]triazolo[1,5a]pyrimidine) dihydrate solvates

The title compounds palladium(II) and platinum(II) tetrakisthiourea dichloride bis(7-hydroxy-5-methyl[1,2,4]triazolo[1,5a]pyrimidine (Hmtpo)) dihydrate solvates, have been synthesized by reacting thecis-[MCl₂(Hmtpo)₂] (where M=Pt(II), Pd(II)) complexes with an excess of thiourea (tu) and the structure of the palladium compound was solved by X-ray diffraction. Crystals of [Pd(tu)₄]Cl₂·2Hmtpo·2H₂O are triclinic with space groupP and unit cell dimensionsa=7.972(1),b=9.049(1),c=11.808(2)Å, =88.20(1), =75.15(1), =76.54(1)^o. The cation [Pd(tu)₄]²⁺ is centrosymmetric involving four sulfur thiourea atoms in a near square planar environment. The triazolopyrimidine molecules, chloride anions and water molecules do not take part in the metal center coordination but interact by hydrogen bonding between them and the thiourea moieties. A comparison between powder diffraction data of palladium(II) and platinum(II) compounds clearly indicates that both compounds are isomorphous.     

Synthesis of Renewable meta‐Xylylenediamine from Biomass‐Derived Furfural

We report the synthesis of biomass‐derived functionalized aromatic chemicals from furfural, a building block nowadays available in large scale from low‐cost biomass. The scientific strategy relies on a Diels–Alder/aromatization sequence. By controlling the rate of each step, it was possible to produce exclusively the meta aromatic isomer. In particular, through this route, we describe the synthesis of renewably sourced meta‐xylylenediamine (MXD). Transposition of this work to other furfural‐derived chemicals is also discussed and reveals that functionalized biomass‐derived aromatics (benzaldehyde, benzylamine, etc.) can be potentially produced, according to this route.     

Crystal and molecular structure of four compounds resulting from nucleophilic addition of 2H-pyrroles to dimethyl acetylene-dicarboxylate,methyl propiolate and phenyl isocyanate

Journal of Chemical Crystallography -     

Synthesis and crystal structure of 1-acetyl-3-bromo-3-phenylazetidine and 1-phenyl-2-(N-acetyl-N-formyl)-aminoethanone

1-Acetyl-3-bromo-3-phenylazetidine (1), C₁₁H₁₂BrNO, has been synthesized and characterized by spectroscopic methods and single crystal X-ray analysis. It crystallizes in the space group P2 ₁/c with a = 8.633(1), b = 7.461(1), c = 17.204(1) Å, = 98.403(7)°, V = 1096.2(2) ų, Z = 4, D _calc = 1.540 g cm^–3. The azetidine ring is nearly planar since the four atoms are within ±0.039(5) Å of the mean square plane calculated for the heterocycle. The attempt to obtain a highly strained 2-azetine derivative from the above compound gave, surprisingly, 1-phenyl-2-(N-acetyl-N-formyl)-aminoethanone (2), C₁₁H₁₁NO₃. This compound has been also characterized by spectroscopic methods and single crystal X-ray analysis. It crystallizes in the space group P2₁2₁2₁, with a = 5.4719(3), b = 8.3205(6), c = 23.298(3) Å, V = 1060.7(2) ų, Z = 4, D _calc = 1.286 g cm^–3. The aminoethanone residue is in a near planar conformation where the torsion angles are 7(2)° for N–C–C–=O and –173(2)° for N–C–C–C(Ph).     

Crystal structure of a silver(I) complex with the 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid)

The reaction between freshly precipitated silver oxide Ag₂O and an aqueous solution of tetrabenzenecarboxylic acid H₄L leads to the anhydrous Ag₂H₂L complex. It crystallizes in the space groupP2₁/c, witha=6.457(1),b=8.180(1),c=9.982(1) Å, β=97.83(1)°,V=522.3(1) ų,Z=2,d=2.976 g cm^?3. This structure is a three dimensional polymeric network polymer without any silver...silver interaction. The silver environment is a bipyramid trigonal polyhedron with three short bond distances in the equatorial plane (Ag?O=2.255(2), 2.295(2), and 2.499(2) Å) and two longer bond distances in axial positions (Ag?O=2.558(2) and 2.617(2) Å). Thus, the silver polyhedron involves five different ligands. It is noteworthy that the (H₂L₂)^2? ligand is located around an inversion centre.     

Cyclic beta-peptoids

The first synthesis of functionalized beta-peptoid macrocycles is reported. X-ray crystallographic structure of tetramer 9 reveals a C2-symmetrical derivative with unexpected all-cis-amide bonds and spatial disposition of the appendages toward the two opposite faces of the ring. Quantum calculations suggest that 9 is locked in this layout. These macrocycles constitute novel promising templates for multimeric ligation of biologically active ligands. The concept was exemplified by chemical decoration of tetramer 9 via "click" reactions.     

The diphyllosilicate Rb2(VO)2[Si8O19]

Dirubidium divanadyl phyllooctasilicate, Rb₂(VO)₂[Si₈O₁₉], is the first known anhydrous diphyllosilicate containing V^IV. The structure consists of silicate double layers which are separated by [V₂O₈]⁸⁻ dimers and is related to that of the compounds A₂Cu₂[Si₈O₁₉] (A = Rb or Cs), although the title compound crystallizes in a noncentrosymmetric orthorhombic space group. The silicate double layers contain four tetrahedrally coordinated Si sites in general positions and 12 O sites, nine in general positions and the other three on mirror planes. The vanadyl dimers have two square‐pyramidally coordinated V sites (site symmetry m). There are two different 10‐ and 12‐fold coordinated Rb sites with site symmetry m, one of which is a split position located between the dimers in the interlayer space, while the other is in a channel within the silicate layer.     

On a chip demonstration of a functional role for Odorant Binding Protein in the preservation of olfactory receptor activity at high odorant concentration

The molecular mechanisms underlying odorant detection have been investigated using the chip based SPR technique by focusing on the dynamic interactions between transmembrane Olfactory Receptor OR1740, odorant ligands and soluble Odorant-Binding Protein (OBP-1F). The OR1740 present in the lipid bilayer of nanosomes derived from transformed yeasts specifically bound OBP-1F. The receptor preferential odorant ligand helional released bound OBP-1F from the OR-OBP complex, while unrelated odorants failed to do so. OBP-1F modified the functional OR1740 dose-response to helional, from a bell-shaped to a saturation curve, thus preserving OR activity at high ligand concentration. This unravels an active role for OBPs in olfaction, in addition to passive transport or a scavenger role. This sensorchip technology was applied to assessing native OBP-1F in a biological sample: rat olfactory mucus also displayed significant binding to OR1740 nanosomes, and the addition of helional yielded the dissociation of mucus OBP from the receptor.     

Separation of chitosan oligomers by immobilized metal affinity chromatography

A novel approach for chitosan oligosaccharide (COS) separation by immobilized metal affinity chromatography (IMAC) based on the differences in the interactions of chelated copper (II) ions with various COS (dimers, trimers, tetramers) is described. Polyhydroxylic chromatographic supports (agarose CL-6B and silica) were functionalized with various chelating functions such as iminodiacetate (IDA), carboxymethyl-aspartate (CM-Asp) and tris(carboxymethyl)ethylenediamine (TED). The COS retention capacities of the columns were between 2 and 6 mg/cm(3), depending on the chelating group. The COS were separated and/or enriched up to 95% for dimer and trimer and 90% for the tetramer, with yields of 60-95%.