Graphene nanoparticles as pseudostationary phase for the electrokinetic separation of nonsteroidal anti‐inflammatory drugs

The exceptional properties of graphene (G) were exploited here to facilitate capillary electrokinetic separations. Two types of commercially available G consisting of nanoparticles containing—one to three and—four to six G sheets, respectively, were compared for this purpose. Both proved effective in separating the arylpropyl derivatives of nonsteroidal anti‐inflammatory drugs. The highest resolution and shortest migration times were obtained with G containing high amount of single and double G nanosheets. G affords higher resolution than other types of nanoparticles; stable suspensions can be easily prepared and used as BGE without the need of adding an additional surfactant. This results in a high reproducibility in migration times and stability in background noise. The LOD and LOQ obtained by using G nanoparticles as pseudostationary phases spanned the range 0.29–1.18 mg/L and 0.95–3.95 mg/L, respectively, and the RSD was less than 4.7% in all instances.     

Magnetic properties of the seven-coordinated nanoporous framework material Co(bpy)(1.5)(NO(3))(2) (bpy = 4,4'-bipyridine)

The magnetic properties of the porous metal-organic complex Co(bpy)(1.5)(NO(3))(2) (bpy = 4,4'-bipyridine), investigated by SQUID magnetometry, EPR and heat capacity measurements, are reported. The tongue-and-groove structure of this complex is formed by the assembly of T-shaped building blocks, where each Co is bound to three bpy ligands. Co(ii) is hepta-coordinated by three N atoms from the bpy units, and four O atoms from two nitrate groups. Experimental results showed a large crystal field effect induced anisotropy with a zero field splitting of Δ = 198 K between the ground and excited Kramers doublets, a factor of two larger than previously reported values in Co(ii) hepta-coordinated complexes. EPR revealed orthorhombic crystal field anisotropy, with gyromagnetic principal values of g(1)(*) = 6.1, g(2)(*) = 4.2 and g(3)(*) = 2.2, in an S(*) = 1/2 effective spin on the ground state Kramers doublet. Ab initio simulations allowed us to assign the anisotropy easy axis of magnetization to the binary symmetry axis of the molecule, aligned with the Co-N apical direction of the T-block.     

Asymmetric synthesis of fluorinated cyclic beta-amino acid derivatives through cross metathesis

The asymmetric synthesis of several fluorinated cis-2-aminocycloalkane carboxylic acids (cis-2-ACACs) with a cross metathesis (CM) reaction as the key step has been carried out, constituting the first time a metathesis protocol has been undertaken with fluorinated imidoyl chlorides. Subsequent chemoselective hydrogenation of the olefin moiety, Dieckmann condensation, and stereoselective reduction of the iminic double bond afforded the corresponding beta-amino esters with several ring sizes. The asymmetric version of the process was achieved by using (-)-8-phenylmenthol as a chiral auxiliary.