Novel Copper(I)‐Thioantimonates(III): Solvothermal Synthesis,Crystal Structures,Thermal Stability and Magnetic Properties of (C2N2H10)0.5Cu2SbS3, (C3N2H12)0.5Cu2SbS3, and (C4N2H14)0.5Cu2SbS3

The novel copper(I)‐thioantimonates(III) (enH₂²⁺)_0.5Cu₂SbS₃ ( I ) (en = ethylendiamine), (1, 3‐DAPH₂²⁺)_0.5Cu₂SbS₃ ( II ) (1, 3‐DAP = 1, 3 diaminopropane) and (1, 4‐DABH₂²⁺)_0.5Cu₂SbS₃ ( III ) (1, 4‐DAB = 1, 4‐diaminobutane) were synthesized under solvothermal conditions reacting Sb₂S₃, CuCl₂·2H₂O, S with the amines. The compounds crystallize in the monoclinic space group P2₁/n. The primary building units are a SbS₃ trigonal pyramid and two distorted CuS₃ units. In the structures the SbS₃ pyramid is connected to six CuS₃ moieties and every S atom has bonds to one Sb atom and to two Cu atoms. Further interconnection leads to the formation of ten‐membered (10 MR) Cu₃Sb₂S₅ and six‐membered (6 MR) Cu₂SbS₃ rings. Every 10 MR is condensed to four 10 MR and four 6 MR to form a single layer within the (010) plane. Two such single layers are connected to a double layer thus forming the final [Cu₂SbS₃]^— layered anion. The [CuSbS₃]^— protonated amines are located between the layers and the interlayer spacing depends on the size and orientation of these amines. Between the Sb atom and one Cu atom a remarkable short distance of about 2.7Å is observed. At elevated temperatures the compounds decompose into CuSbS₂ and Cu₃SbS₄ suggesting a complex redox reaction. Diamagnetic susceptibilities indicate the copper(I) in the metal sulfide frameworks. All three compounds are semiconductors with intermediate band gaps of about 2 eV.     

Differential Contribution of Albumin and Lipids to the Hydrophobic Extraction of Bis-(2-ethylhexyl) Phthalate from Hemodialysis Tubing by Human Serum: Analysis by Gas Chromatography - Stable Isotope Dilution Mass Spectrometry

Abstract

A method is presented which allows quantitative assignment of hydrophobic human serum components to the extraction of bis-(2-ethylhexyl) phthalate (DEHP) from medical tubing. Under optimized conditions (sample pH 5.5; fluid-fluid extraction with ethyl acetate + tert-butyl methyl ether 1 + 1 v/v; DEHP-ring-D4 as internal standard with ratios of endogenous (m/z = 149) and added deuterated DEHP (m/z = 153) adjusted to around 1.0; equilibration of added internal standard with the hydrophobic sample for 24 hours), a high precision can be achieved with an intra-assay coefficient of variation of 1.5% (n = 7) for sample DEHP quantification. Phthalate migration from hemodialysis tubing was quantified by use of a peristaltic pump and recirculation (200 minutes) of serum with different degrces of hypertriglyceridemia (range from 2.26 to 14.5 g/L) or solutions of human albumin (10 to 50 g/L). Only DEHP, but no other phthalates are detected in the extracts. There exist linear relations between DEHP extraction and triglyceride content (increase by 1.01 μg DEHP/g tubing material per g triglyceride/L serum) as well as between DEHP extraction and albumin content (0.59 μg DEHP/g tubing material per g albumin/L). Under physiological conditions, the total amount of albumin extracts 17.7-fold more DEHP than the total triglyceride amount in human serum. The suitability of the proposed method as a candidate reference method as well as consequences for dyslipidemic and hypalbuminemic patients on hemodialysis schemes are discussed.     

Dimers of heptapnictide anions: As14 4- and P14 4- in the crystal structures of [Rb(18-crown-6)]4As14.6NH3 and [Li(NH3)4]4P14.NH3

Compounds [Rb(18-crown-6)]4As14.6NH3 (1) and [Li(NH3)4]4P14.NH3 (2) were prepared by the reaction of Rb4As6 with SbPh3 and 18-crown-6 and by the reduction of white phosphorus with elemental lithium in liquid ammonia, respectively. Both were characterized by low-temperature single-crystal X-ray structure analysis. They were found to contain the Ci symmetrical Pn14(4-) anion (Pn = P, As), which consists of two nortricyclane-like Pn7-cages connected by a single bond. Molecular complexes of [Rb(18-crown-6)(NH3)]2[Rb(18-crown-6)]2As14 are formed in 1, which are connected to fanfold sheets via N-H...O bonds. The anion is isolated in 2, and N-H...N bonds result in the formation of {[Li(NH3)4](mu-NH3)2[Li(NH3)4]}2+ cationic complexes.     

Neutral and ionic dissociation patterns in hexacoordinate silicon chelates: a model nucleophilic substitution at pentacoordinate silicon

A model nucleophilic-displacement reaction coordinate at pentacoordinate silicon is demonstrated by neutral and ionic dissociation equilibria through a stable hexacoordinate complex.     

The reaction of the group-13 alkyls ER3 (E = Al, Ga, In; R = CH2t-Bu, CH2 SiMe3) with the platinum-complex [(dcpe)Pt(H)(CH2t-Bu)]

The reactions of the sterically demanding group-13 alkyls ER₃ (E = Al, Ga, In; R = CH₂t-Bu, CH₂SiMe₃) with the platinum-complex [(dcpe)Pt(H)(CH₂t-Bu)] were re-investigated. The bimetallic compounds [(dcpe)Pt(ER₂)(R)] (3: E = Ga, R = CH₂SiMe₃; 5: E = In, R = CH₂t-Bu; dcpe = bis(dicyclohexylphosphino)ethane) with direct σ(Pt-E) bonds were obtained by oxidative addition of an E-C bond to the coordinatively unsaturated fragment [(dcpe)Pt] produced in situ by thermolysis of the starting complex [(dcpe)Pt(CH₂t-Bu)(H)]. The single crystal structure determination reveals a Pt-Ga bond length of 2.376(2) Å and a Pt-In bond length of 2.608(1) Å. All new compounds were characterised by elemental analysis, ³¹P and ¹⁹⁵Pt NMR spectroscopy. Interestingly, the Pt-Ga compound 3 slowly transforms into the platinum alkyl/hydride isomer {(dcpe)Pt(μ₂-H)[CH₂Si(CH₃)₂ CH₂Ga(CH₂SiMe₃)₂]} (4) during crystallization from solution at room temperature. The X-ray single crystal structure analysis revealed both complexes 3 and 4 coexisting in the unit cell in a 1:1 relation. The inaccessibility of analytically pure samples of the Pt-Al complex {(dcpe)Pt[Al(CH₂t-Bu)₂](CH₂t-Bu)} (6), postulated as intermediate of the reaction of [(dcpe)Pt(H)(CH₂t-Bu)] with Al(CH₂t-Bu) on the basis of ³¹P and ¹⁹⁵Pt NMR data, is attributed to an enhanced tendency to isomerisation into the alkyl/hydride Pt/Al congener of 4. A brief DFT analysis of the bonding situation of the model complex [(dhpe)Pt(GaMe₂)(Me)] (1M) revealed, that the contribution of π(Pt-Ga) back-bonding is negligible.     

An isolated cyclo-tetraarsendiide: low temperature synthesis and crystal structure of bis-pentaamminesodium tetraarsendiide-ammonia (1/3) [Na(NH3)5]2As(4).3NH3

Reduction of an excess of arsenic with a solution of sodium in liquid ammonia yields the thermally unstable title compound [Na(NH3)5]2As(4).3NH3, which contains isolated square-planar As4(2-) ions with a mean As-As bond length of 2,345 A.     

Entrance effects at nanopores of nanocapsules functionalized with poly(ethylene glycol) and their flow through nanochannels

We studied the effect of poly(ethylene glycol) (PEG) on the extrusion of large, multilamellar nanocapsules (also called liposomes or vesicles) through nanochannels with a length of 6 microm. For the generation of the nanocapsules, we used a lipid mixture with lecithin consisting of saturated and unsaturated fatty acids (dipalmitoylphosphatidylcholine (DPPC) and dioleoylphosphatidylcholine (DOPC)), cholesterol, and 2-8 mol % PEG linked to a lipid anchor (distearoylphosphatidylethanolamine (DSPE)) or the plain lipid anchor without PEG. An increase in PEG leads to a decrease of the critical tension for nanocapsule rupture (lysis tension) between 20-30%, whereas the pure lipid anchor does not produce any differences. We interpret these findings to be produced by a partial intrusion of the polymeric chain into the phospholipid bilayer of the nanocapsule which weakens its tensile strength. We evaluate statistically the discrepancies of lysis tensions found for different channels widths (50-100 nm) and two or four channels in series. Comparing our results on the flow resistance of either nanocapsules or pure water with lubrication theory, we find that the calculated viscous forces are not sufficient to account for the measured friction of nanocapsules. This shows that the nanocapsules are decelerated in the nanochannels by van der Waals interactions between channel and capsule walls and the intermediate water layer. The strength of these forces is 24 times higher for PEG and 94 times higher for the pure lipid anchor than the respective calculated viscous forces alone, showing that nanocapsule flow in nanochannels cannot be considered under the classical continuum assumption of the intermediate water layer.     

Actions of Solvable Algebraic Groups on Central Simple Algebras

Let k be an algebraically closed base field of arbitrary characteristic. In this paper, we study actions of a connected solvable linear algebraic group G on a central simple algebra Q. The main result is the following: Q can be split G-equivariantly by a finite-dimensional splitting field, provided that G acts “algebraically,” i.e., provided that Q contains a G-stable order on which the action is rational. As an application, it is shown that rational torus actions on prime PI-algebras are induced by actions on commutative domains. Presented by Paul Smith.     

Coordination preferences of the alkali cations sodium and caesium in the mixed‐cationic Zintl ammoniate Cs3.2Na0.8Ge9·5.3NH3

The involvement of two different alkali cations in the nonagermanide ammoniate Cs_3.2Na_0.8Ge₉·5.3NH₃ [tricaesium sodium nonagermanide–ammonia (1/5.3)] provides insights into the coordination behaviour of ammonia towards sodium and caesium cations within one compound and represents the first mixed‐cationic solvate structure of nonagermanide tetraanions. The compound crystallizes in the monoclinic space group P2₁/m and, with the presence of pseudomerohedral twinning, mixed‐cation sites and disordering of the nonagermanide cage anions, features a combination of crystallographic challenges which could all be resolved during the refinement.