Vergleichende Untersuchung zur Gewinnung von Antik?rpern gegen verschiedene Verbindungen des Katecholaminstoffwechsels

Ohne Zusammenfassung

---

Comparative investigation on the preparation of antibodies to different compounds of catecholamine metabolism

     

The generation of gem-difluoroallyllithium by the transmetalation reaction

3,3-Difluoroallyltrimethyltin was prepared by reaction of chlorodifluoromethane with the ylide reagent Ph₃PCHCH₂SnMe₃$\text{gem}$-Difluoroallyllithium, which was generated by the reaction of $\text{n}$-butyllithium with 3,3-difluoroallyltrimethyltin in THF at ?95°, was of very limited stability at that temperature. However, $\text{in}$$\text{situ}$ procedures and alternate incremental addition procedures allowed its application in the synthesis of 1,1-difluoroallylsilanes from chlorosilanes and of CH₂CHCF₂C(OH)-Et₂ from 3-pentanone.     

Ultrasonic imaging of sheet metal forming

With sheet metal hydroforming, a sheet metal is formed by a liquid medium under high pressure (up to 1000 bar) and a cavity contour (die). As the exact state of forming is of interest, an ultrasonic imaging system is under development. The task is to determine the geometry of a sheet metal contour with respect to the original (before forming) and the final (die) state of the sheet metal. For this purpose, two different contour reconstruction algorithms were designed, tested and compared. With the reconstruction results it will be possible to determine the optimal distribution of transmitters and receivers in the ultrasonic transducer matrix. Experiments were conducted with one pair of transducers (unfocussed, center frequency 2 MHz) and a three axis stepper motor set-up. For each experimental set of data, the contour was reconstructed with both SAFT reconstruction algorithms. Both algorithms incorporate a priori information such as original and final contour and maximal axial dislocation of the sheet metal. The results for both algorithms are compared and the relative mean error in axial direction is 0.30% and 0.48%.     

Alkali Metal Based Triimidosulfite Cages as Versatile Precursors for Single-Molecule Magnets

Based on the potassium [{S(tBuN)₂(tBuNH)}₂K₃(tmeda)-K₃{(HNtBu)(NtBu)₂S}₂] ( 1 ) and sodium precursors [S(tBuN)₃(thf)₃-Na₃SNa₃(thf)₃(NtBu)₃S] ( 2 ), [S(tBuN)₃(thf)₃Na₃{(HNtBu)(NtBu)₂S}] ( 3 ) and [(tmeda)₃S-{Na₃(NtBu)₃S}₂] ( 4 ) the syntheses and magnetic properties of three mixed metal triimidosulfite based alkali-lanthanide-metal-cages [(tBuNH)Dy{K(0.5tmeda)}₂{(NtBu)₃S}₂]_n ( 5 ) and [ClLn{Na(thf)}₂{(NtBu)₃S}₂] with Ln=Dy ( 6 ), Er ( 7 ) are reported. The corresponding potassium ( 1 ) and sodium ( 2 – 4 ) based cages are characterized through XRD and NMR experiments. Preventing lithium chloride co-complexation led to a significant increase of SMM performance to previously reported sulfur-nitrogen ligands. The subsequent Dy^III-complexes 5 and 6 display slow relaxation of magnetization at zero field, with relaxation barriers U=77.0 cm⁻¹ for 5 , 512.9 and 316.3 cm⁻¹ for 6 , respectively. Significantly, the latter complex 6 also exhibits a butterfly-shaped hysteresis up to 7 K.     

A Stable Dimer of SiS2 Arranged between Two Carbene Molecules

The Me‐cAAC:‐stabilized dimer of silicon disulfide (SiS₂) has been isolated in the molecular form as (Me‐cAAC:)₂Si₂S₄ ( 2 ) at room temperature [Me‐cAAC:=cyclic alkyl(amino) carbene]. Compound 2 has been synthesized from the reaction of (Me‐cAAC:)₂Si₂ with elemental sulfur in a 1:4 molar ratio under oxidative addition. This is the smallest molecular unit of silicon disulfide characterized by X‐ray crystallography, electron ionization mass spectrometry, and NMR spectroscopy. Structures with three sulfur atoms arranged around a silicon atom are known; however, 2 is the first structurally characterized silicon–sulfur compound containing one terminal and two bridging sulfur atoms at each silicon atom. Compound 2 shows no decomposition after storing for three months in an inert atmosphere at ambient temperature. The bonding of 2 has been further studied by theoretical calculations.     

Triimidosulfonates as Acute Bite‐Angle Chelates: Slow Relaxation of the Magnetization in Zero Field and Hysteresis Loop of a CoII Complex

Starting from a polyimido sulfonate the four‐coordinate, N,N′‐chelated Co^II complex [Co{(NtBu)₃SMe}₂] ( 1 ) was synthesized, and its molecular structure was elucidated by single‐crystal X‐ray structural analysis. The acute N‐Co‐N bite angle imposed by the N,N′‐chelating ligand (NtBu)₃SMe^? leads to pronounced C_2v distortion of the tetrahedral coordination environment and thus to high anisotropy of the Co^II ion (D≈?58 cm^?1), favorable for single‐molecule‐magnet (SMM) properties. Magnetic measurements revealed a high barrier to spin reversal (U_eff=75 cm^?1) that gives rise to the observation of slow relaxation of the magnetization in zero field and a hysteresis loop at 2 K for this unique complex.     

Sample preparation with solid phase microextraction and exhaustive extraction approaches: Comparison for challenging cases

In chemical analysis, sample preparation is frequently considered the bottleneck of the entire analytical method. The success of the final method strongly depends on understanding the entire process of analysis of a particular type of analyte in a sample, namely: the physicochemical properties of the analytes (solubility, volatility, polarity etc.), the environmental conditions, and the matrix components of the sample. Various sample preparation strategies have been developed based on exhaustive or non-exhaustive extraction of analytes from matrices. Undoubtedly, amongst all sample preparation approaches, liquid extraction, including liquid–liquid (LLE) and solid phase extraction (SPE), are the most well-known, widely used, and commonly accepted methods by many international organizations and accredited laboratories. Both methods are well documented and there are many well defined procedures, which make them, at first sight, the methods of choice. However, many challenging tasks, such as complex matrix applications, on-site and in vivo applications, and determination of matrix-bound and free concentrations of analytes, are not easily attainable with these classical approaches for sample preparation.