S?F and S?C Activation of SF6 and SF5 Derivatives at Rhodium: Conversion of SF6 into H2S

The degradation of SF₆ and SF₅ organyls by S F and S C bond‐activation reactions at [{Rh(μ‐H)(dippp)}₂] under mild conditions is reported. Fluorido and thiolato species were identified as products or intermediates, and were characterized by X‐ray diffraction analysis and multinuclear NMR spectroscopy. An unprecedented cyclic process for the conversion of the potent greenhouse gas SF₆ into H₂S was developed.     

Exploring the Association of Electron-Donating Corroles with Phthalocyanines as Electron Acceptors

Electron-donating corroles (Cor) were integrated with electron-accepting phthalocyanines (Pc) to afford two different non-covalent Cor ⋅ Pc systems. At the forefront was the coordination between a 10-meso-pyridine Cor and a ZnPc. The complexation was corroborated in a combination of NMR, absorption, and fluorescence assays, and revealed association with binding constants as high as 10⁶ m ⁻¹. Steady-state and time-resolved spectroscopies evidenced that regardless of exciting Cor or Pc, the charge-separated state evolved efficiently in both cases, followed by a slow charge-recombination to reinstate the ground state. The introduction of non-covalent linkages between Cor and Pc induces sizeable differences in the context of light harvesting and transfer of charges when compared with covalently linked Cor-Pc conjugates.     

Charge renormalization in planar and spherical charged lipidic aqueous interfaces

The charge renormalization in planar and spherical charged lipidic aqueous interfaces has been investigated by means of thermodynamic and electrokinetic measurements. We analyzed the behavior of mixed DOTAP/DOPE monolayers at the air-electrolyte solution interface and DOTAP/DOPE liposomes 100 nm in size dispersed in an aqueous phase of varying ionic strength. For the two systems, we have compared the "effective" surface charge derived from the measurements of surface potential and zeta-potential to the "bare" charge based on the stoichiometry of the lipid mixture investigated. The results confirm that a strong charge renormalization occurs, whose strength depends on the geometry of the mesoscopic system. The dependence of the "effective" charge on the "bare" charge is discussed in light of an analytical approximation based on the Poisson-Boltzmann equation recently proposed.     

Poly(amido‐amine)s Carrying Primary Amino Groups as Side Substituents

Poly(amido‐amine)s carrying primary amino groups as side substituents have been obtained by polyaddition of N‐triphenylmethyl‐monosubstituted 1,2‐diaminoethane (TPHMAE) to 2,2‐bisacrylamido acetic acid or 1,4‐bisacryloylpiperazine and subsequent removal of the protecting triphenylmethyl group by treating the resultant polymers with aqueous hydrochloric acid. Soluble polymers can be also obtained directly by the polyaddition of monoprotonated 1,2‐diaminoethane to 2,2‐bisacrylamido acetic acid in the presence of a limited amount of added acetic or hydrochloric acid. The resultant polymers are of a higher molecular weight than the corresponding ones prepared from TPHMAE. By adding a limited amount of N‐triphenylmethyl‐monosubstituted 1,2‐diaminoethane to the monomer mixtures leading to poly(amido‐amine)s with a recognised potential as nonviral vectors, such as ISA 23 and ISA 1, a controlled number of pendant primary amino groups have been introduced. By this procedure, ISA 23 and ISA 1 become suitable as polymer carriers for carboxylated drugs as well as amenable to the labelling techniques by fluorescent probes commonly employed for proteins.

Formation of monoprotected primary diamines.     

Electron impact mass spectrometry of some geminal bis-sulphones

The behaviour under electron impact of six 1,1-bis(benzenesulphonyl)cyclioalkanes and of 1-phenyl-1-(benzensesulphaonyl)cyclopropane has been studied in detail with the aid of exact mass measurements, linked scans for metastable ion analysis, collisional spectroscopy and kinetic energy release measurements. The molecular ions of these compounds undergo a sulphone-sulphinate rearrangement with alkyl group migration on oxygen, in analogy with what is found for simple monosulphones and, in general, their fragmentation resembles that of mono-sulphonyl compounds. Loss of SO₂ from the molecular ion is observed for all substrates, but only in the case of 1, 1-bis(benzenesulphonyl)cyclopropane is this followed by loss of the second SO₂ unit; the first loss of SO₂ is probably accompanied by rearrangement since the fragmentation pattern of [M ? SO₂]⁺˙ ions from this compound is different than that of the isobaric molecular ions of 1-phenyl-1-(benzenesulphonyl)cyclopropane.     

Über die Kronenetherkomplexe [K(15-Krone-5)2]3[Sb3I12], [TeCl3(15-Krone-5)][TeCl5] und [TeCl3(15-Krone-5)]2[TeCl6]

On the Crown Ether Complexes [K(15-Crown-5)₂]₃[Sb₃I₁₂], [TeCl₃(15-Crown-5)][TeCl₅], and [TeCl₃(15-Crown-5)]₂[TeCl₆] Orange-coloured crystals of [K(15-crown-5)₂]₃[Sb₃I₁₂] are formed in the reaction of potassium iodide with antimony triiodide and 15-crown-5 in acetonitrile solution. An X-ray structure determination reveals severe disorder of the crown ether molecules, which coordinate to the potassium atoms in a sandwich array; so only the [Sb₃I₁₂]^3? ion and the potassium positions were ascertained. The anion is a centrosymmetric trimer (symmetry C_2h), which can be understood as central SbI₆^3? ion, coordinated by two SbI₃ molecules. (Space group C2/m), Z = 2, 3263 observed, independent reflections, R = 0.06, lattice dimensions at 20°C: a = 2541.1 pm, b = 1441.7 pm, c = 1588.4 pm, β = 113.33°. The tellurium complexes [TeCl₃(15-crown-5)] [TeCl₅] and [TeCl₃(15-crown-5)]₂[TeCl₆] are prepared by reaction of TeCl₄ with 15-crown-5 in acetonitrile solution, forming yellow-green crystals sensitive to moisture. They are characterized by their i.r. spectra.     

Kristall- und Molekülstruktur von 6-Ethoxy-12,12-dimethyldibenzo[d,g]-1,3,2,6-dioxaphosphasilocin-6-oxid

Synthesis and Crystal Structure of the Bis(amidinatochelate) Complex ClSb[Ph? C(NSiMe₃)₂]₂ The antimony(III) amidinato complex ClSb[Ph? C(NSiMe₃)₂]₂ was obtained by the reaction of antimony trichloride and N,N,N′-tris(trimethylsilyl)benzamidine in dichloromethane in form of pale-yellow, moisture sensitive crystals. X-ray crystal structure determinations were performed at 20°C and at ?93°C. Crystal data at 20°C: space group P1 , Z = 2, a = 1160.3(2), b = 1305.4(2), c = 1336.5(2) pm, α = 68.32(1), β = 79.79(1), γ = 71.47(1)°; at ?93°C the lattice vectors are 1.20 to 0.85% shorter. In the molecule two Ph? C(NSiMe₃)₂ groups are attached with their N atoms in a chelate manner to the Sb atom. Together with the Cl atom they form an irregular coordination polyhedron about the Sb atom with a stereochemically strongly effective lone electron pair. The SiMe₃ groups show considerable twisting vibrations about the N? Si axes even at ?93°C.     

End‐group modified poly(methyl vinyl ether): Characterization and LCST demixing behavior in water

A range of hydrophilic poly(methyl vinyl ether) (PMVE) polymers was synthesized by living cationic polymerization of methyl vinyl ether (MVE), having different hydrophilic or hydrophobic chain‐end functionalities. The dissimilar end‐groups were either introduced by end‐capping of the growing polymer chain with LiBH₄, methanol, and water or by functional initiation with 2‐bromo‐(3,3‐diethoxy‐propyl)‐2‐methylpropanoate. The synthesized PMVEs were characterized by ¹H NMR, size exclusion chromatography, and matrix‐assisted laser desorption ionization time of flight, displaying a narrow polydispersity. Modulated temperature DSC was applied to study the influence of the nature of the end‐groups on the solubility behavior of PMVE in water. Terminal‐modification with a hydroxyl function improves the solubility, whereas a Br‐containing end‐group causes the polymer to be insoluble in water at room temperature; however, the special type III lower critical solution temperature demixing behavior being maintained. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 461–469, 2006     

A comparison of two-particle rapidity correlations in antiproton-proton and proton-proton interactions at 31 GeV centre-of-mass energy

We investigated correlations between pairs of charged secondaries produced in antiproton-proton and proton-proton interactions at a centre-of-mass energy of 31 GeV using the pseudorapidity variable η=?ln (tanθ/2). Positive, short-range correlations were observed in both reactions. In the antiproton-proton case, however, there is a stronger correlation at very short range when both particles are produced in the central region and when the charged multiplicity of the event is about 30% higher than the mean. A simple Monte Carlo calculation indicates that quark-antiquark annihilation into two hadronic jets could account for the observed effect.     

High-frequency properties of thin amorphous ribbons

Magnetic energy losses have been investigated in Co-based near-zero-magnetostriction amorphous ribbons from DC to 10 MHz. Attention has been devoted to the properties of field-annealed ribbons thinned down to 5.8 μm and their behavior at high frequencies. A rationale is provided for the frequency dependence of the magnetic losses over the investigated many-decade range through analysis of the loss components. Ribbons annealed under transverse field benefit by limited irreversible domain wall activity and correspondingly reduced hysteresis and excess losses. Based on the near-linear response of the material and the permeability–energy loss relationship, the separate contributions of domain wall displacements and rotations to the magnetization process and the related dissipation effects are singled out at all frequencies. Very thin amorphous ribbons are shown to display lower loss and higher permeability (i.e. higher Snoek's product) than Mn–Zn ferrites at all frequencies.