On Copper(I) Fluorides,the Cuprophilic Interaction,the Preparation of Copper Nitride at Room Temperature,and the Formation Mechanism at Elevated Temperatures

Our attempts to synthesize the hitherto unknown binary copper(I) fluoride have led to first successes and a serendipitious result: By conproportionation of elemental copper and copper(II) fluoride in anhydrous liquid ammonia, two copper(I) fluorides were obtained as simple NH₃ complexes. One of them presents an example of ligand‐unsupported “cuprophilic” interactions in an infinite [Cu₂(NH₃)₄]²⁺ chain with alternating Cu–Cu distances. We discovered that both copper(I) fluorides can easily be converted into Cu₃N at room temperature, just by applying a vacuum. Additionally, we investigated the formation mechanism of the classical synthesis route of Cu₃N that starts with CuF₂ and flowing NH₃ in the temperature range between ambient and 290 °C by means of thermal analysis and in situ neutron diffraction. The reaction proceeds at elevated temperatures through the formation of a blue and amorphous ammoniate Cu(NH₃)₂F₂, the reformation of CuF₂, and finally the redox reaction to form Cu₃N.     

The [U2F12]2− Anion of Sr[U2F12]

The D_2h‐symmetric dinuclear complex anion [U₂F₁₂]^2? of pastel green Sr[U₂F₁₂] shows a hitherto unknown structural feature: The coordination polyhedra around the U atoms are edge‐linked monocapped trigonal prisms, the U^V atoms are therefore seven‐coordinated. This leads to a U–U distance of 3.8913(6) Å. A weak U^V–U^V interaction is observed for the dinuclear [U₂F₁₂]^2? complex and described by the antiferromagnetic exchange J_exp of circa ?29.9 cm^?1. The crystalline compound can be easily prepared from SrF₂ and β‐UF₅ in anhydrous hydrogen fluoride (aHF) at room temperature. It was studied by means of single crystal X‐ray diffraction, IR, Raman and UV/VIS spectroscopy, magnetic measurements, and by molecular as well as by solid‐state quantum chemical calculations.     

Icosahedral Au(72): a predicted chiral and spherically aromatic golden fullerene

Quantum chemical calculations demonstrate the spherical aromaticity and high thermodynamic stability of Au(72), a predicted I-symmetric golden fullerene.     

Experimental and computational study of HXeY...HX complexes (X, Y = Cl and Br): an example of exceptionally large complexation effect

The complexes of xenon hydrides HXeY (Y = Cl and Br) with hydrogen halides HX (X = Cl and Br) have been studied both computationally and experimentally in a xenon matrix. The experiments revealed three new complexes: HXeBr...HBr, HXeBr...HCl, and HXeCl...HCl. The experimental assignments were done on the basis of the strong H-Xe stretching absorption of HXeY (Y = Cl and Br) molecules and supported by theoretical results. We experimentally obtained monomer-to-complex blue-shifts of this vibrational mode for all the studied systems (up to approximately 150 cm (-1)). The electronic structure calculations revealed three local structures for each HNgY...HX complexes and their computed interaction energies varied between -460 and -2800 cm (-1). The computational estimates of the vibrational shifts were in agreement with the experimental values. We also found possible experimental absorption belonging to HXeBr...(HBr) 2 trimer and its vibrational shift (+245 cm (-1)) is similar to the computational estimate of a cyclic ternary complex (+252 cm (-1)).     

Insulins in equine urine: qualitative analysis by immunoaffinity purification and liquid chromatography/tandem mass spectrometry for doping control purposes in horse-racing

Insulin is a peptide hormone consisting of two peptide chains (A- and B-chain) that are cross-linked by two disulfide bonds. To obtain improved pharmacokinetic onset of action profiles of insulin treatment in diabetic patients, recombinant long-, intermediate-, and rapid-acting insulin analogs are produced, in which the C-terminal end of the B-chain plays an especially important role.A review of the veterinary literature reveals the low prevalence of equine type I diabetes mellitus, which indicates that the therapeutic use of insulin in racing horses is unlikely. Although there is no unequivocal evidence of an overall performance-enhancing effect of insulin, in human sports the misuse of insulin preparations is reported among elite athletes. The desired effects of insulin include the increase of muscular glycogen prior to sports event or during the recovery phase, in addition to a chalonic action, which increases the muscle size by inhibiting protein breakdown.In the present study urinary insulin was detected in equine samples and differences between equine insulin, human insulin, as well as rapidly acting recombinant insulin variants were examined. The method was based on sample purification by solid-phase extraction (SPE) and immunoaffinity chromatography (IAC), and subsequent analysis by microbore liquid chromatography (LC) and tandem mass spectrometry (MS/MS) using top-down sequencing for the determination of various insulins. Product ion scan experiments of intact proteins and B-chains enabled the differentiation between endogenously produced equine insulin, its DesB30 metabolite, human insulin and recombinant insulin analogs, and the assay allowed the assignment of individual product ions, especially those originating from modified C-termini of B-chains.     

Liouville Quantum Gravity on the Riemann Sphere

In this paper, we rigorously construct Liouville Quantum Field Theory on the Riemann sphere introduced in the 1981 seminal work by Polyakov. We establish some of its fundamental properties like conformal covariance under PSL\({_2(\mathbb{C})}\)-action, Seiberg bounds, KPZ scaling laws, KPZ formula and the Weyl anomaly formula. We also make precise conjectures about the relationship of the theory to scaling limits of random planar maps conformally embedded onto the sphere.     

A general screening method for doping agents in human urine by solid phase extraction and liquid chromatography/time-of-flight mass spectrometry

A general screening method based on solid phase extraction (SPE) and liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS) was developed and investigated with 124 different doping agents, including stimulants, -blockers, narcotics, -adrenergic agonists, agents with anti-estrogenic activity, diuretics and cannabinoids. Mixed mode cation exchange/C8 cartridges were applied to SPE, and chromatography was based on gradient elution on a C18 column. Ionization of the analytes was achieved with electrospray ionization in the positive mode. Identification by LC/TOFMS was based on retention time, accurate mass and isotopic pattern. Validation of the method consisted of analysis of specificity, analytical recovery, limit of detection and repeatability. The minimum required performance limit (MRPL), established by World Anti-Doping Agency (WADA), was attained to 97 doping agents. The extraction recoveries varied between 33 and 98% and the median was 58%. Mass accuracy was always better than 5 ppm, corresponding to a maximum mass error of 0.7 mDa. The repeatability of the method for spiked urine samples, expressed as median of relative standard deviations (RSD%) at concentrations of MRPL and 10 times MRPL, were 14% and 9%, respectively. The suitability of the LC/TOFMS method for doping control was demonstrated with authentic urine samples.