Zeitschrift fur Anorganische und Allgemeine Chemie最新文献

We examine the life, work, and legacy of Clara Haber, nee Immerwahr, who became the first woman to earn a doctorate from the University of Breslau, in 1900. In 1901 she married the chemist Fritz Haber. With no employment available for female scientists, Clara freelanced as an instructor in the continued education of women, mainly housewives, while struggling not to become a housewife herself. Her duties as a designated head of a posh household hardly brought fulfillment to her life. The outbreak of WWI further exacerbated the situation, as Fritz Haber applied himself in extraordinary ways to aid the German war effort. The night that he celebrated the "success" of the first chlorine cloud attack, Clara committed suicide. We found little evidence to support claims that Clara was an outspoken pacifist who took her life because of her disapproval of Fritz Haber's involvement in chemical warfare. We conclude by examining "the myth of Clara Immerwahr" that took root in the 1990s from the perspective offered by the available scholarly sources, including some untapped ones.

A molybdenum L-edge X-ray absorption spectroscopy (XAS) study is presented for native and oxidized MoFe protein of nitrogenase as well as Mo-Fe model compounds. Recently collected data on MoFe protein (in oxidized and reduced forms) is compared to previously published Mo XAS data on the isolated FeMo cofactor in NMF solution and put in context of the recent Mo K-edge XAS study, which showed a Mo^III assignment for the molybdenum atom in FeMoco. The L₃-edge data are interpreted within a simple ligand-field model, from which a time-dependent density functional theory (TDDFT) approach is proposed as a way to provide further insights into the analysis of the molybdenum L₃-edges. The calculated results reproduce well the relative spectral trends that are observed experimentally. Ultimately, these results give further support for the Mo^III assignment in protein-bound FeMoco, as well as isolated FeMoco.

An overview is given on the ways databases can be employed to aid in the prediction of chemical compounds, in particular inorganic crystalline compounds. Methods currently employed and possible future approaches are discussed.

An ionic liquid assisted strategy for the synthesis of zeolitic material is reported. This strategy is a solid state synthetic method and the ionic liquid is employed as structure directing agent. A TON-type zeolite, which contains one-dimensional 10-member-ring, is successfully synthesized with the assistance of the ionic liquid, 1-ethyl-3-methylimidazolium bromide. This finding improves our understanding about the challenge of ionothermally synthesizing siliceous and aluminosilicate zeolites.

Dynamic and static electron densities (EDs) based on the independent spherical atom model (IAM) and multipole (MP) models of crambin were successfully computed, holding no series-termination effects. The densities are compared to EDs of small biological molecules at diverse temperatures. It is outlined that proteins exhibit an intrinsic flexibility, present as frozen disorder at 100 K, in contrast to small molecules. The flexibility of the proteins is reflected by atomic displacement parameters (B-factors), which are considerably larger than for small molecules at 298 K. Thus, an optimal deconvolution of deformation density and thermal motion is not guaranteed, which prevents a free refinement of MP parameters but allows an application of transferable, fixed MP parameters. The analysis of the topological properties, such as the density at bond critical points (BCPs) and the Laplacian, reveals systematic differences between static and dynamic EDs. Zero-point-vibrations, yet present in dynamic EDs at low temperature, affect but marginally the EDs of small molecules. The zero-point-vibrations cause a smearing of the ED, which becomes more pronounced with increasing temperature. Topological properties, primarily the Laplacian, of covalent bonds appear to be more sensitive to effects by temperature and the polarity of the bonds. However, dynamic EDs at ca. 20 K based on MP models provide a good characterization of chemical bonding. Both the density at BCPs and the Laplacian of hydrogen bonds constitute similar values from static and dynamic EDs for all studied temperatures. Deformation densities demonstrate the necessity of the employment of MP parameters in order to comprise the nature of covalent bonds. The character of hydrogen bonds can be roughly pictured by IAM, whereas MP parameters are recommended for a classification of hydrogen bonds beyond a solely interpretation of topological properties.

A sulfide-bridged diiron(II) complex bearing a cis-N₂H₄ (hydrazine) ligand has been prepared by reaction of LFe^II(μ-S)Fe^IIL (1; L = sterically encumbered βdiketiminate ligand) with 2 molar equivalents of N₂H₄. The metastable diiron(II) hydrazine complex LFe^II(μ-S)(μH N-NH₂)Fe^II (3) is formed, as shown by crystallography, and NMR, vibrational, and electronic absorption spectroscopies. Compound 3 has been crystallographically characterized as its DBU (1,8-diazabicyclo[5.4.0]undec-7$ene) adduct, which exhibits weak N-H···DBU hydrogen bonding. The synthetic process evolves roughly 2 equivalents of NH₃. The cis-N₂H₄ bridge in 3 may be relevant to the structure and function of intermediates on the FeMoco of nitrogenase.

This report describes the dimerisation of glutathione, and by extension, other cysteine-containing peptides or protein fragments, with a 5, 5'-disubstituted-2, 2'-bipyridine or 6, 6"-disubstituted-2, 2':6',2"-terpyridine unit. The resulting bipy-GS₂ and terpy-GS₂ were investigated as potential metal ion dependent switches in aqueous solution, and were found to predominantly adopt the transoïd conformation at physiological pH. Metal complexation with Cu^II and Zn^II at this pH has been studied by UV/Vis, CD, NMR and ion-mobility mass spectrometry. Zn^II titrations are consistent with the formation of a 1:1 Zn^II:terpy-GS₂ complex at pH 7.4, but bipy-GS₂ was shown to form both 1:1 and 1:2 complexes with the former being predominant under dilute micromolar conditions. Formation constants for the resulting 1:1 complexes were determined to be log K_M 6.86 (bipy-GS₂ ) and 6.22 (terpy-GS₂ ), consistent with a higher affinity for the unconstrained bipyridine, compared to the strained terpyridine. Cu^II coordination involves the initial formation of 1:1 complexes, followed by 1.5Cu:1bipy-GS₂ and 2Cu:1terpy-GS₂ complexes at micromolar concentrations. Binding constants for formation of the 1:1 complexes (log K_M 12.5 (bipy-GS₂ ); 8.04 and 7.14 (terpy-GS₂ )) indicate a higher affinity for Cu^II than Zn^II. Finally, ion-mobility MS studies detected the free ligands in their protonated form, and were consistent with the formation of two different Cu adducts with different conformations in the gas-phase. We illustrate that the bipyridine and terpyridine dimerisation units can behave like conformational switches in response to Cu/Zn complexation, and propose that in future these can be employed in synthetic biology with larger peptide or protein fragments, to control large scale folding and related biological function.

Ce₄B₁₄O₂₇ was synthesized under conditions of 2.6 GPa and 750 °C in a Walker-type multianvil apparatus. The crystal structure was determined on the basis of single-crystal X-ray diffraction data, collected at room temperature, revealing that Ce₄B₁₄O₂₇ is isotypic to La₄B₁₄O₂₇. Ce₄B₁₄O₂₇ crystallizes monoclinically with four formula units in the space group C2/c (No. 15) and the lattice parameters a = 1117.8(2), b = 640.9(2), c = 2531.7(5) pm, and β = 100.2(1)°. The three-dimensional boron-oxygen framework consists of [BO₄]^5- tetrahedra and trigonal-planar [BO₃]^3- groups. The structure contains two crystallographically different cerium ions. Furthermore, Raman spectroscopy was performed on single crystals of Ce₄B₁₄O₂₇.

An alternative synthesis of C-monoacetylenic phosphaalkenes trans-Mes*P=C(Me)(C≡CR) (Mes* = 2, 4, 6-^tBu₃Ph, R = Ph, SiMe₃) from C-bromophosphaalkenes cis-Mes*P=C(Me)Br using standard Sonogashira coupling conditions is described. Crystallographic studies confirm cis-trans isomerization of the P=C double bond during Pd-catalyzed cross coupling, leading exclusively to trans-acetylenic phosphaalkenes. Crystallographic studies of all synthesized compounds reveal the extend of π-conjugation over the acetylene and P=C π-systems.