Nuclear shielding and magnetic hyperfine structure of hydrogen cyanide

A millimeter-wave molecular beam maser has been used to resolve the magnetic hyperfine structure of hydrogen cyanide. The spin-rotation interaction constants have been measured for the three nuclei ¹⁴N, ¹³C, and H. The paramagnetic nuclear shielding factors have been calculated for the three nuclear sites. The spin-rotation constants for ¹⁴N in H¹²C¹⁴N, for H in H¹²C¹⁴N and for ¹³C in D¹³C¹⁴N are + 10.4 kHz, −3.7 kHz, and +15.0 kHz, respectively. The respective paramagnetic shielding factors are −408.98 × 10⁻⁶, −73.40 × 10⁻⁶, and −249.52 × 10⁻⁶.     

Nickel-Catalyzed C-Br/C-H Bis-phenylation of Methyl 4-Bromocrotonate: A Stereoselective Entry to Methyl (E)-3,4-Diphenylbut-2-enoate

A method for C-Br/C-H bis-phenylation of methyl 4-bromocrotonate via nickel-catalyzed cross-coupling reaction has been developed. This protocol involves commercially available catalyst components and furnishes a suitable doubly phenylated building block.     

Advances in Palladium-Catalyzed Carboxylation Reactions

In this short review, we highlight the advancements in the field of palladium-catalyzed carbon dioxide utilization for the synthesis of high value added organic molecules. The review is structured on the basis of the kind of substrate undergoing the Pd-catalyzed carboxylation process. Accordingly, after the introductory section, the main sections of the review will illustrate Pd-catalyzed carboxylation of olefinic substrates, acetylenic substrates, and other substrates (aryl halides and triflates).     

Fluorescent Flavin/PVP-Coated Silver Nanoparticles: Design and Biological Performance

A red-emitting fluorescent Riboflavin (RF)/Polyvinylpyrrolidone (PVP)-coated silver nanoparticles system, λ_em?=?527 nm, Φ?=?0.242, with a diameter of the metallic core of 27.33 nm and a zeta potential of ? 25.05 mV was prepared and investigated regarding its biological activity. We found that PVP has a key role in RF adsorption around the SNPs surface leading to an enhancement of antioxidant properties (～70%), low cytotoxicity (> 90% cell viability, at 50 µL/mL, after 48 h of incubation) as well as to an efficient process of its cellular uptake (～ 60%, after 24 h of incubation) in L929 cells. The results are relevant concerning the involvement of RF and its coenzymes forms in SNPs - based systems, in cellular respiration as well as for future studies as antioxidant marker system on tumoral cells for viewing and monitoring them, by cellular imaging.

     

Evaluation of Co and Zn competitive sorption by zeolitic material synthesized from fly ash using 60Co and 65Zn as radioindicators

Journal of Radioanalytical and Nuclear Chemistry - Zeolitic material prepared by hydrothermal treatment of brown coal fly ash was used for sorption separation of Co2+ and Zn2+ ions from single and...     

Directed Electron Delivery from a Pb-Free Halide Perovskite to a Co(II) Molecular Catalyst Boosts CO2 Photoreduction Coupled with Water Oxidation

The development of high-performance photocatalytic systems for CO₂ reduction is appealing to address energy and environmental issues, while it is challenging to avoid using toxic metals and organic sacrificial reagents. We here immobilize a family of cobalt phthalocyanine catalysts on Pb-free halide perovskite Cs₂AgBiBr₆ nanosheets with delicate control on the anchors of the cobalt catalysts. Among them, the molecular hybrid photocatalyst assembled by carboxyl anchors achieves the optimal performance with an electron consumption rate of 300±13 μmol g⁻¹ h⁻¹ for visible-light-driven CO₂-to-CO conversion coupled with water oxidation to O₂, over 8 times of the unmodified Cs₂AgBiBr₆ (36±8 μmol g⁻¹ h⁻¹), also far surpassing the documented systems (<150 μmol g⁻¹ h⁻¹). Besides the improved intrinsic activity, electrochemical, computational, ex-/in situ X-ray photoelectron and X-ray absorption spectroscopic results indicate that the electrons photogenerated at the Bi atoms of Cs₂AgBiBr₆ can be directionally transferred to the cobalt catalyst via the carboxyl anchors which strongly bind to the Bi atoms, substantially facilitating the interfacial electron transfer kinetics and thereby the photocatalysis.     

Synthesis and characterization of chromium(I) bis(η-toluene) derivatives containing sterically demanding anions

The reaction of Cr(η⁶-CH₃C₆H₅)₂ with 1-benzoyl-6-hydroxy-6-phenyl fulvene, dbcpH, and with pentakis(methoxycarbonyl)cyclopentadiene, pcmcpH, proceeds with evolution of dihydrogen and the formation of the ionic derivatives [Cr(η⁶-CH₃C₆H₅)₂][X] ([X]⁻ = 1,2-dibenzoylcyclopentadienyl, [dbcp]⁻, pentakis(methoxycarbonyl)cyclopentadienyl, [pcmcp]⁻), which have been characterized by IR and EPR spectroscopies, X-ray diffraction and electrochemical techniques. The sterically demanding anions do not affect the structural and electronic properties of the cations in solution but strongly influence crystal packing. In fact, a rare cis-eclipsed conformation of the toluene rings is found for [Cr(η⁶-CH₃C₆H₅)₂][dbcp] · THF, whereas two independent complexes are observed in the unit cell of [Cr(η⁶-CH₃C₆H₅)₂][pcmcp], one with toluene rings in a cis-eclipsed conformation and the other in a staggered conformation (projections of methyl groups form an angle of 151°).     

Malondialdehyde tagging improves the analysis of arginine oligomers and arginine-containing dendrimers by HPLC-MS

The selective modification of arginine residues by malondialdehyde (MDA) was used to improve the mass spectrometric analysis of arginine oligomers (Arg(x), x = 4, 6, 7, 8, 9) and an arginine-containing dendrimeric peptide. MDA tagging significantly increased the hydrophobicity of the arginine side-chain and resulted in improved retention in RP HPLC of the oligoarginines using formic acid as mobile phase additive. This avoided the use of TFA to generate sufficient retention, as TFA was shown to lead to a dramatically reduced sensitivity (up to ten-fold for Arg(8) and Arg(9)) as a result of the strong signal suppression by ion pairing with multiple basic residues. MDA modification of Arg oligomers not only resulted in improved detection sensitivity for most of the peptides studied (e. g., more than six-fold for Arg(7)), but also greatly enhanced the quality of MS/MS spectra, in line with previous results for other peptides. Furthermore, MDA modification helped to identify major side products in a sample of a dendrimeric peptide, a class of peptides that is typically difficult to analyze by MS.     

A highly crystalline microporous hybrid organic-inorganic aluminosilicate resembling the AFI-type zeolite

ECS-14, a crystalline microporous hybrid organic-inorganic aluminosilicate, has been synthesized by using 1,4-bis-(triethoxysilyl)-benzene (BTEB) as a source of silica. Its structure contains a system of linear channels with 12-membered ring openings, running along the [001] direction, resembling the pore architecture of the AFI framework type.