Substituent Effects on 31P NMR Chemical Shifts and 1JP–Se of triarylselenophosphates

The effect of electron-withdrawing (EW) and electron-releasing (ER) substituents on the ³¹P NMR chemical shifts and the structural parameters of a series of tris-(p-X-aryl)selenophosphates is reported in this article. Similarly to O-aryl phosphates and O-aryl thiophosphates, EW groups attached to aromatic rings induce a shielding effect on the ³¹P NMR signal. After a detailed experimental and theoretical analysis, we confirmed that the selenium atom is the main part responsible for the charge density transfer toward phosphorus through a back-bonding effect. The obtained ¹J_P-Se values for the complete series agree with this observation.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Chiral Synthesis of (S)-(+)-γ-Hydroxymethyl-γ-Butyrolactone

S-(+)-γ-hydroxymethyl-gM-butyrolactone has been synthesized from D-ribonolactone as chiral template.     

Salen and tetrahydrosalen nickel(II) and copper(II) complexes

The synthesis and characterisation of novel bis salen complexes, M(salenH2), N,N-bis-[5(1,1,3,3-tetramethyl- butyl)salicylidene]-1,2-diaminoethane complexes, (M=Ni or Cu), and the corresponding less studied, bis-tetrahydrosalen complexes, M[H2(salenH2)], N,N-bis-[2-hydroxy-5(1,1,3,3-tetramethylbutyl)benzyl]-1,2-diaminoethane complexes, (M=Ni or Cu), with a highly branched substitution pattern at C-5 of the benzene ring is described. The Schiff bases behave as dibasic tetradentate ligands. The tetrahydrosalen complexes show structural properties, chemical and thermal behaviour which is different from those of the corresponding salen complexes. The melting points and decomposition temperatures of these complexes were determined by d.s.c. and t.g.a.     

Natural Eutectic Solvent Mixture of l-Menthol/Malonic acid (4 : 1) and Its Ibuprofen Solution: Thermal and Physical Characterizations and NMR Studies of Molecular Interaction

A eutectic mixture of L-menthol and malonic acid, Me / MA (4 : 1), was characterized by calorimetry and other physical measurements. The new deep eutectic solvent (m.p. 6 °C) solvates 338 mg of ibuprofen per mL, and the solution is stable in a wide temperature range. Strategies of NMR titration used in supramolecular chemistry were employed to explore binding forces between the eutectic constituents as well as solute-solvent interaction in ibuprofen solution. Even in acetonitrile, Me ₄ MA is formed through a hydrogen-bonding network, where the constituents act as hydrogen donors and acceptors at the same time. The estimated association constant is around 30 M⁻¹; the binding forces are enough to build the eutectic mixture at high concentrations. The aggregate Me ₄ MA forms a molecular complex with ibuprofen in acetonitrile as a result of the cooperative effect of the constituents. In addition, van der Waals interactions are operative between ibuprofen and menthol in the saturated IB - Me / MA (4 : 1) solution.