Laser-induced electron impact ionization in a reflectron time-of-flight mass spectrometer

Some details of the generation of electrons by impinging a laser beam on a metal surface are described. It is shown that highly efficient electron generation is observed only during the laser pulse. Therefore, this technique delivers intense pulses of electrons. The process is investigated and different ion source set-ups are discussed. In conjunction with a time-of-flight mass spectrometer this technique can be used to produce mass spectra of different samples ranging from simple organic molecules to peptides.     

Simplified synthesis, H, C, N, Sn NMR spectra and X-ray structures of diorganotin(IV) complexes containing the 4-phenyl-2,4-butanedionebenzoylhydrazone(2−) ligand

Two diorganotin(IV) complexes of the general formula R₂Sn[Ph(O)CCH-C(Me)N-NC(O)Ph] (R=Ph, 1; R=Me, 2) have been synthesised from the corresponding diorganotin(IV) dichloride and the ligand 4-phenyl-2,4-butanedionebenzoylhydrazone(2−) (H₂L), derived from benzoyl acetone and benzoyl hydrazide in methanol at room temperature in presence of triethylamine. The syntheses were performed under very mild conditions, at room temperature and without exclusion of air or moisture from the reaction vessel. Previously, rigorous conditions have been considered necessary for these species. The two compounds have been characterised by elemental analysis, IR and ¹H, ¹³C, ¹⁵N, ¹¹⁹Sn NMR spectra, and their structures have been confirmed single crystal X-ray structure analysis. The central tin atom of both complexes adopts a distorted trigonal bipyramidal coordination with two ligand oxygen atoms in axial positions, the nitrogen atom of the ligand and two organic groups on tin occupying equatorial sites. 2 has crystallised with two crystallographically independent molecules in the asymmetric unit. The δ(¹¹⁹Sn) values for the complexes 1 and 2 are −151.5 and −146.8 ppm, respectively, thus indicating penta-coordinated tin centres.     

Palladium catalyzed atom-efficient cross-coupling reactions of triarylbismuths with aryl bromides

Aryl bromides (3 equiv) were coupled efficiently with triarylbismuths (1 equiv) in an atom-efficient way using the Pd(OAc)₂/PPh₃ catalytic system in the presence of K₃PO₄ as base in DMF at 90 °C, providing excellent yields of the cross-coupled biaryls in short reaction times.     

Sequential [2+2] Photocycloaddition and Rearrangement to Substituted Cyclopentanone. A formal Synthesis of Planococcyl Acetate

An extremely short synthesis of 2,2-dimethyl-3-hydroxymethyl cyclopentanone 2 (R¹ = R² = Me), an advanced intermediate in the synthesis of the pheromone planococcyl acetate 3, is described.     

Identification of Amino Acids with Modified Ninhydrin Reagents on Thin-Layer Chromatography Plates

JPC – Journal of Planar Chromatography – Modern TLC - The four new spray reagents (Benzoic acid and some of its parahaloderivatives) have been introduced. These reagents enable...     

Mixed Polymer‐Coated Magnetic Nanoparticles as Forward Osmosis Draw Agents of Tuned Hydrophilicity

We recently reported a polymer‐coated magnetic nanoparticle (MNP) draw agent for the forward osmosis (FO) water desalination process. The water flux was found to increase when the polymer poly(sodium acrylate) (PSA) was anchored to the MNP surface as compared to the polymer (or polyelectrolyte solution) alone, due to the polymer chains being stretched out and most of the hydrophilic groups on the polymer contributing to water flux. We herein report the use of a secondary polymer poly(N‐isopropylacrylamide) PNIPAM to manipulate the PSA polymer conformation and influence inter‐ and intrachain interactions to enhance the efficiency of the FO draw agent. These PSA–PNIPAM‐coated MNPs generated a much higher water flux of ～11.66 LMH when compared to the 100 % PSA‐coated MNPs featuring a value of ～5.32 LMH under identical FO conditions. The osmotic pressure and water flux driven by the mixed polymer‐coated MNPs were found to be a strong function of the net polymer coverage on MNPs, that is, net available hydrophilic groups. Our new draw agent demonstrates potential for use in the water industry due to its improved efficiency and cost effectiveness as it uses only ～0.062 % (w/v) of the draw agent solution.