Unpredictable cycloisomerization of 1,11-dien-6-ynes by a common cobalt catalyst

1,11-Dien-6-ynes undergo cycloisomerization in the presence of the cobalt catalytic system CoBr2/phosphine ligand/Zn/ZnI2 giving cyclohexene, diene or cyclopropane structures depending on the type of the phosphine ligand. This unpredictable behaviour suggests that, although the availability of the cobalt catalytic system is appealing, the development of well-defined catalysts is desirable for further progress

3D-Printed Porous Magnetic Carbon Materials Derived from Metal–Organic Frameworks

Here we report new porous carbon materials obtained by 3D printing from photopolymer compositions with zinc- and nickel-based metal–organic frameworks, ZIF-8 and Ni-BTC, followed by high-temperature pyrolysis. The pyrolyzed materials that retain the shapes of complex objects contain pores, which were produced by boiling zinc and magnetic nickel particles. The two thus provided functionalities—large specific surface area and ferromagnetism—that pave the way towards creating heterogenous catalysts that can be easily removed from reaction mixtures in industrial catalytic processes

Probing Spin Crossover in a Solution by Paramagnetic NMR Spectroscopy

Spin transitions in spin-crossover compounds are now routinely studied in the solid state by magnetometry; however, only a few methods exist for studies in solution. The currently used Evans method, which relies on NMR spectroscopy to measure the magnetic susceptibility, requires the availability of a very pure sample of the paramagnetic compound and its exact concentration. To overcome these limitations, we propose an alternative NMR-based technique for evaluating spin-state populations by only using the chemical shifts of a spin-crossover compound; those can be routinely obtained for a solution that contains unknown impurities and paramagnetic admixtures or is contaminated otherwise

Universal Character of Breaking of Wormlike Surfactant Micelles by Additives of Different Hydrophobicity

Wormlike surfactant micelles are widely used in various applications including fracturing technology in oil industry, template synthesis of different nanoobjects, micellar copolymerization of hydrophilic and hydrophobic monomers, and so forth. Most of those applications suggest the solubilization of different additives in the micelles. The present paper is aimed at the comparative study of the effect of the solubilization of hydrophobic (n-decane and 1-phenylhexane) and hydrophilic (N-isopropylacrylamide and acrylamide) substances on the rheological properties and structure of the micelles using several complementary techniques including rheometry, small angle neutron scattering, dynamic light scattering, and diffusion ordered NMR spectroscopy. For these studies, mixed micelles of potassium oleate and n-octyltrimethylammonium bromide containing the excess of either anionic or cationic surfactants were used. It was shown that hydrophobic additives are completely solubilized inside the micelles being localized deep in the core (n-decane, 1-phenylhexane) or near the core/corona interface (1-phenylhexane). At the same time, only a small fraction of hydrophilic additives (14% of N-isopropylacrylamide and 4% of acrylamide) penetrate the micelles being localized at the corona area. Despite different localization of the additives inside the micelles, all of them induce the breaking of wormlike micelles with the formation of either ellipsoidal microemulsion droplets (in the case of hydrophobic additives) or ellipsoidal surfactant micelles (in the case of hydrophilic additives). The breaking of micelles results in the drop of viscosity of the solution up to water value. The main result of this paper consists in the observation of the fact that for all the additives under study, the dependences of the viscosity on the volume fraction of additive lie on the same master curve being shifted along the volume fraction axis by a certain factor depending on the hydrophobicity of the added species. Those data are quite useful for various applications of wormlike surfactant micelles suggesting the solubilization of different additives inside them

Binuclear Nickel Complexes of a New Di(hydroxyphenyl)imidazolate

Here, we report a new di(hydroxyphenyl)imidazolate ligand with an N2O2 donor set synthesized by a modified Debus–Radziszewski procedure. Its binuclear nickel(II) complexes feature a weak antiferromagnetic interaction with J12 = −3.16 cm−1 between the two nickel(II) ions identified by magnetometry measurements. As follows from cyclic voltammetry experiments and DFT calculations, they undergo ligand-centered oxidation via the formation of cation radicals with short lifetimes that can be potentially stabilized by bulkier t-butyl groups in the ortho-positions of the ligand. The reported ligand widens the range of the building blocks available to molecular magnetism community and thus provides new ways to the design of magnetic materials with switchable properties

Binuclear Nickel Complexes of a New Di(hydroxyphenyl)imidazolate

Here, we report a new di(hydroxyphenyl)imidazolate ligand with an N2O2 donor set synthesized by a modified Debus–Radziszewski procedure. Its binuclear nickel(II) complexes feature a weak antiferromagnetic interaction with J12 = −3.16 cm−1 between the two nickel(II) ions identified by magnetometry measurements. As follows from cyclic voltammetry experiments and DFT calculations, they undergo ligand-centered oxidation via the formation of cation radicals with short lifetimes that can be potentially stabilized by bulkier t-butyl groups in the ortho-positions of the ligand. The reported ligand widens the range of the building blocks available to molecular magnetism community and thus provides new ways to the design of magnetic materials with switchable properties

CCDC 1016989: Experimental Crystal Structure Determination

Related Article: Valentin V. Novikov, Alexander A. Pavlov, Yulia V. Nelyubina, Marie-Emmanuelle Boulon, Oleg A. Varzatskii, Yan Z. Voloshin, Richard E.P. Winpenny|2015|J.Am.Chem.Soc.|137|9792|doi:10.1021/jacs.5b0573

CCDC 1016990: Experimental Crystal Structure Determination

Related Article: Valentin V. Novikov, Alexander A. Pavlov, Yulia V. Nelyubina, Marie-Emmanuelle Boulon, Oleg A. Varzatskii, Yan Z. Voloshin, Richard E.P. Winpenny|2015|J.Am.Chem.Soc.|137|9792|doi:10.1021/jacs.5b0573

Parahydrogen-Induced Hyperpolarization of Unsaturated Phosphoric Acid Derivatives

Parahydrogen-induced nuclear polarization offers a significant increase in the sensitivity of NMR spectroscopy to create new probes for medical diagnostics by magnetic resonance imaging. As precursors of the biocompatible hyperpolarized probes, unsaturated derivatives of phosphoric acid, propargyl and allyl phosphates, are proposed. The polarization transfer to 1H and 31P nuclei of the products of their hydrogenation by parahydrogen under the ALTADENA and PASADENA conditions, and by the PH-ECHO-INEPT+ pulse sequence of NMR spectroscopy, resulted in a very high signal amplification, which is among the largest for parahydrogen-induced nuclear polarization transfer to the 31P nucleus