Reaktionen von tetracarbonylhydridovanadium-verbindungen mit isopren

Disubstituted tetracarbonylhydridovanadium compounds (HV(CO)₄L₂, L₂ = dppm, arphos) react with isoprene to give η³-dimethylallyl complexes of the type (η³-dimethylallyl)V(CO)₃L₂. The compounds have been characterized and the isomers having methyl groups in various positions of the allyl ligand identified by ¹H NMR spectroscopy.     

Importance of REP values when comparing the CALUX bioassay results with chemoanalyses results: Example with spiked vegetable oils

Differences between chemical activated luciferase gene expression (CALUX) bioassay and chemoanalyses results are observed.

This paper shows that calculations of the TEQ values using REP values instead of WHO TEF values give different results. The REP values do affect the results obtained by the CALUX technique. These differences are more marked for the dioxin like PCB compounds (CALUX TEQ values are lower than WHO TEQ values) than for the dioxin compounds (CALUX TEQ values are higher than WHO TEQ values).

The CALUX results were compared with the concentrations of the congeners’ spiked into the oil.     

Synthesis, structures and reactivity of macrocyclic imidazolylboranes

New macrocyclic imidazolylboranes [imidazolylB(R¹)₂]_n, where selected carbon atoms of imidazolyl rings may bear substituents other than hydrogen, and where n=4 or 5, are obtained from 1-trimethysilylimidazoles and haloboranes XB(R¹)₂ by boron/silicon exchange using 2-bromoimidazole and benzimidazole. These macrocycles are formally zwitterionic and contain imidazolyl rings linked through their nitrogen atoms by BH₂, B(R¹)₂ or BR¹X units. Despite the sterical demand of these derivatives tetrameric macrocycles are formed. A new synthetic strategy to macrocyclic imidazolylboranes includes the preparation and cyclization of bis(imidazolyl)boronium chlorides. In addition dihaloboranes have been tested for cyclization to yield halogen-containing macrocycles. The new compounds are spectroscopically characterized and X-ray structure analyses of tetrameric- (2a) and pentameric 1-imidazolylborane (2a′), tetrameric 1-imidazolyldimethylborane (2b), tetrameric 1-(2-bromo)imidazolylborane (2d) and bis(2-bromoimidazolyl)boronium chloride (3d) are reported.     

Photoresponsive molecular tools for emerging applications of light in medicine

Light-based therapeutic and imaging modalities, which emerge in clinical applications, rely on molecular tools, such as photocleavable protecting groups and photoswitches that respond to photonic stimulus and translate it into a biological effect. However, optimisation of their key parameters (activation wavelength, band separation, fatigue resistance and half-life) is necessary to enable application in the medical field. In this perspective, we describe the applications scenarios that can be envisioned in clinical practice and then we use those scenarios to explain the necessary properties that the photoresponsive tools used to control biological function should possess, highlighted by examples from medical imaging, drug delivery and photopharmacology. We then present how the (photo)chemical parameters are currently being optimized and an outlook is given on pharmacological aspects (toxicity, solubility, and stability) of light-responsive molecules. With these interdisciplinary insights, we aim to inspire the future directions for the development of photocontrolled tools that will empower clinical applications of light.

This perspective article explores the current state of light-controlled molecular tools for medical therapy and imaging and offers an outlook on clinical application scenarios and optimisation strategies.     

A spectrophotometric method for the determination of copper ions and its application to the co-precipitation of copper in the crystallization of sodium

The molar absorptivity of the cyanide complexes [Cu(CN)(3)](2-) and [Cu(CN)(4)](3-), at their isosbestic wavelength (235 nm) is 1.13 x 10(3) l.mole(-1)mm.(-1) and can be used for the quantitative determination of micro-amounts of copper in the ppm range. The determination of 1-10 mug of Cu(2+) per g of NaCl, or 0.25-2.5 mug ml , is described in detail. The co-precipitation of copper with NaCl crystallizing from aqueous solutions has been studied by this method.     

Metall-Schwefelstickstoff-Verbindungen. 19. Neue Komplexe von CuI mit dem S3N−-Chelatliganden Darstellung und Struktur von [Ph4As][Cu(S3N)(CN)], [(Ph3P)2N][Cu(S3N)(S7N)] und [Ph4As]2[(S3N)Cu(S2O3)Cu(S3N)]

Metal Sulfur-Nitrogen Compounds. 19. Novel Complexes of Cu^I with the S₃N^? Chelate Ligand. Preparation and Structure of [Ph₄As][Cu(S₃N)(CN)], [(Ph₃P)₂N][Cu(S₃N)(S₇N)], and [Ph₄As]₂[(S₃N)Cu(S₂O₃)Cu(S₃N)] In alkaline media S₇NH reacts with Cu salts to yield different products. With Cu(CN) the ion [Cu(S₃N)(CN)]^? is formed, which was isolated as the [Ph₄As]⁺ salt. The crystals are monoclinic, space group P2₁/c, a = 10.499(5), b = 13.418(6), c = 18.032(8) Å, β = 91.84°(3), Z = 4. Besides the known complex ions [Cu(S₃N)₂]^? and [Cu(S₃N)Cl]^? still some more may be obtained when CuCl₂ is reacted with S₇NH: Under special conditions the S₇N ring is partly preserved, and [Cu(S₃N)(S₇N)]^? is formed. Its sparingly soluble [(Ph₃P)₂N]⁺ salt is monoclinic, space group P2₁/n, a = 9.335(6), b = 30.984(11), c = 15.108(8) Å, β = 102.87°(4), Z = 4. Using a longer reaction time a dinuclear complex [(S₃N)Cu(S₂O₃)Cu(S₃N)]^{? ?} results from the reaction of CuCl₂ with S₇NH. The two Cu atoms are bridged by an S atom of the S₂O₃^{? ?} anion. The [Ph₄As]⁺ salt of the dinuclear complex anion is triclinic, space group P1 , a = 11.226(6), b = 12.423(6), c = 19.000(10) Å, β = 76.47°(4), β = 83.98°(4), γ = 84.71°(4), Z = 2. In all these compounds the coordination of Cu^I is trigonal-planar, the S₃N^? chelate group coordinates the Cu in the usual way by two S atoms.     

Die Cardenolide der Samen von Mansonia altissima A. CHEV. 2. Mitteilung Die Struktur von Mansonin und Strophothevosid Glykoside und Aglykone, 287. Mitteilung

Mansonin is the 2,3-di-O-methyl-6-deoxy-β-D-glucopyranoside of strophanthidin, and strophothevoside the corresponding 3-O-methyl-6-deoxy-β-D-glucopyranoside.     

Thermal enhancement of the quantum decay rate in a dissipative system

The quantum decay of a metastable system which interacts with an environment at temperatureT is considered. A general formula for the decay rate at finite temperatures is obtained by a method which is based on the framework recently described by Caldeira and Leggett. The thermal enhancement of the tunnelling rate at low temperatures is discussed for arbitrary metastable potentials, and it is found that the exponent of the rate obeys a power law in a dissipative system. The power law exponent is shown to be a characteristic feature of the dissipative mechanism. Finally, a universally valid formula for the thermal enhancement factor is given, where the form of the potential enters only through the frequency of small oscillations about the metastable minimum and the length of the zero temperature bounce trajectory.     

Use of a five-channel multiplexed electrospray quadrupole time-of-flight hybrid mass spectrometer for metabolite identification

Metabolism data provided with reduced cycle time has become of increasing importance for the early evaluation of DMPK properties of drugs in discovery. In this regard, quadrupole time-of-flight hybrid mass spectrometers (Q-TOF) can provide very reliable metabolite identification via accurate mass measurement of ions and the consequent access to the elemental composition of the metabolite. However, due to their cost, they are often used for drug metabolism studies on later stage drug candidates or to address challenging metabolism questions. A new prototype, consisting of a five-channel multiplexed electrospray ionization (ESI) source on a Q-TOF with one channel used for lock-mass compound infusion, was evaluated for metabolite identification. The goal was to increase the sample throughput of a single ESI-MS system by a factor of 4, while maintaining efficient metabolite separation in high-performance liquid chromatography (HPLC) as well as adequate sensitivity and mass accuracy, and ultimately improve the speed and quality of metabolism studies supporting drug discovery. The analytical performance of the system was assessed by evaluating the sensitivity and mass accuracy (using real in vitro and in vivo samples), inter-channel differences in retention times, MS/UV response, and cross-talk among channels. The sensitivity using the multiplexed ESI source was on average 2-fold lower than with single ESI, correlating well with previous literature data. The mass accuracy was comparable to that obtained using single ESI in both MS and MS/MS modes, making the metabolite identification process using the multiplexed ESI source as reliable as with single ESI. Compound-dependent differences in ionization efficiencies were observed among channels, and were minimized by analyzing related samples on the same channel. Finally, the level of cross-talk among channels was acceptable (around 0.3%) and comparable to levels previously published for quantitative applications using multiplexed ESI. The paper also focuses on the advantages and disadvantages of this new approach compared to other approaches in the literature in the field of metabolite identification.