Trifluoromethyl Sulfoxides: Reagents for Metal‐Free C−H Trifluoromethylthiolation

Trifluoromethyl sulfoxides are a new class of trifluoromethylthiolating reagent. The sulfoxides engage in metal‐free C?H trifluoromethylthiolation with a range of (hetero)arenes. The method is also applicable to the functionalization of important compound classes, such as ligand derivatives and polyaromatics, and in the late‐stage trifluoromethylthiolation of medicines and agrochemicals. The isolation and characterization of a sulfonium salt intermediate supports an interrupted Pummerer reaction mechanism.     

Tungsten‐183 NMR study of cis‐[W(CO)4(PPh3)(4‐RC5H4N)]; effect of varying the σ donor strength of the pyridine

Tungsten‐183 NMR data are reported for the complexes cis‐[W(CO)₄(PPh₃)(4‐RC₅H₄N)] (R = H, Me, Ph, COMe, COPh, OMe, NMe₂, Cl, NO₂). The ¹⁸³W chemical shift (obtained by indirect detection using ³¹P) is found to correlate with the Hammett σ function for the group R, with ¹⁸³W shielding increasing approximately linearly with the donor strength of the pyridine over a range of 93 ppm. The X‐ray structures of cis‐[W(CO)₄(PPh₃)(4‐MeOC₅H₄N)] and cis‐[W(CO)₄(PPh₃)(4‐PhCOC₅H₄N)] are also reported. Copyright © 2013 John Wiley & Sons, Ltd.     

Soluble perlecan domain i enhances vascular endothelial growth factor-165 activity and receptor phosphorylation in human bone marrow endothelial cells

Background  

Immobilized recombinant perlecan domain I (PlnDI) binds and modulates the activity of heparin-binding growth factors, in vitro. However, activities for PlnDI, in solution, have not been reported. In this study, we assessed the ability of soluble forms to modulate vascular endothelial growth factor-165 (VEGF₁₆₅) enhanced capillary tube-like formation, and VEGF receptor-2 phosphorylation of human bone marrow endothelial cells, in vitro.     

Quantum discord and the geometry of Bell-diagonal states

The set of Bell-diagonal states for two qubits can be depicted as a tetrahedron in three dimensions. We consider the level surfaces of entanglement and quantum discord for Bell-diagonal states. This provides a complete picture of the structure of entanglement and discord for this simple case and, in particular, of their nonanalytic behavior under decoherence. The pictorial approach also indicates how to show that discord is neither convex nor concave.     

SQUID-based measuring systems

A program has been developed and initiated at the Indira Gandhi Centre for Atomic Research (IGCAR) for the utilization of SQUID sensors in various application areas. DC SQUID sensors based on Nb-AlO _x -Nb Josephson junctions have been designed and developed inhouse along with associated flux-locked loop (FLL) electronics. A compact low field SQUID magnetometer insertible in a liquid helium storage dewar has also been developed inhouse and is in use. Efforts to build a high field SQUID magnetometer, SQUID-DAC system, are in progress. A planar gradiometric DC SQUID sensor for non-destructive evaluation (NDE) application to be used in relatively unshielded environment has been designed and developed. An easily portable NDE cryostat with a small lift-off distance, to be used in external locations has been designed and tested. The magnetic field produced by a given two-dimensional current density distribution is inverted using the Fourier transform technique.     

A review on the interrogation of peptide-metal interactions using electrospray ionization-mass spectrometry

Over the years, protein interactions have been studied by many techniques to obtain a wide breadth of information. The large size and complexity of the macromolecules have caused difficulties for studying them by some techniques. In some cases, peptides, smaller and less complex biomolecules, have been found to be suitable models to mimic the interactions of entire proteins. The study of peptide-metal interaction, in particular, has proven to be fruitful to researchers across the science fields. One technique in particular, electrospray ionization-mass spectrometry (ESI-MS), has been shown to provide a great deal of information to these studies. The speed, sensitivity, and selectivity of MS, along with the information that can be interpreted from MS-based experiments, has driven this technique to the forefront for understanding the nature of peptide-metal complexes. MS has allowed researchers to identify the stoichiometry of peptide-metal complexes or even mixtures of complexes. The specific amino acids in which the metal cations are bound and the degree of association in these complexes can also be determined by MS experiments. The following review discusses the ESI process and how it is ideal for studying noncovalent interactions between peptides and metals. An investigation of the qualitative and quantitative information that has been determined by ESI-MS follows for readers to realize the versatility of this technique and the diversity of information that can be obtained by a variety of related methods.     

Constituents of cannabis sativa L. XII—mass spectral fragmentation patterns for some. Cannabinoid acid as their TMS derivatives

Fragmentation schemes for a number of TMS derivatized cannabinoid acids are described. Specific fragmentation pathways and rearrangement mechanisms were determined based on the ion composition of deuterium labeled derivatives. Significant differences in the mode of fragmentation of the two isomeric Δ⁹-tetrahydrocannabinolic acids are described. These results are based on information obtained from deuterium labeling and high resolution data or by the extension of previously reported mechanisms for neutral cannabinoids. Comparisons of the fragmentation schemes between the neutral and acidic cannabinoids are used to confirm many of the fragmentation mechanisms.     

The intramolecular Diels-Alder reaction: Stereocontrol through nonsynchronous bond formation?

Nonsynchronous bond formation in the transition state of the intramolecular Diels-Alder reaction is suggested to be an important determinant of the stereochemical outcome of the cyclization.