Salting-in effect of ionic liquids on poly(N-vinylimidazole) hydrogels

This work attempts to study the interaction of two ionic liquids (1-ethyl-3-methylimidazolium tosylate and 1-hexyl-3-methylimidazolium chloride) with chemically crosslinked poly(N-vinylimidazole) in aqueous media, and to compare it with that of NaCl, a typical salting-out electrolyte. The three salts show a salting-in effect whose intensity was measured on the basis of the decrease of the polymer–solvent interaction parameter and the increase of swelling with increasing ionic strength. It was thus found that the salting-in effect is the same for the two salts with the same anion (chloride), while the intensity of the salting-in effect exerted by the tosylate ionic liquid is larger. The coefficient of selective sorption, which expresses the salt excess inside the swollen gel with respect to the external solution was determined by comparing the initial and equilibrium compositions of the immersion bath. These results are discussed in terms of the hydrophobic character of the ions involved.     

Regioselective Acylation of Benzodioxin Derivatives Employing AlCl3-DMSO or AlCl3-DMF Reagent in the Friedel-Crafts Reaction

A Simple and efficient route to the regioselective acylation of benzodioxin derivatives using AICI₃-DMSO or AICI₃-DMF as reagent with acyl halides and anhydrides is described.     

Synthesis, characterization and anticancer activity of new chiral Pd(II)-complexes derived from unsymmetrical α-diimine ligands

A set of new diastereopure unsymmetrical α-diimine ligands 2a-d derived from methylglyoxal and optically pure primary amines 1a-d afforded the new chiral Pd(II)-complexes (S,S)-3a, (S,S)-3b, (S,S)-3c, and (1S, 2S, 3S, 5R)-3d. All compounds have been characterized by IR, ¹H, and ¹³C NMR spectroscopies along with MS-FAB⁺ spectrometry. The crystal and molecular structure for the complexes 3a, 3b and 3d have been fully confirmed by single-crystal X-ray studies. Likewise, complexes 3a-d have also been screened for their in vitro cytotoxicity against different classes of cancer: leukemia (K-562 CML), colon cancer (HCT-15), human breast adenocarcinoma (MCF-7), central nervous system (U-251 Glio) and prostate cancer (PC-3) cell lines.     

From Iron to Copper: The Effect of Transition Metal Catalysts on the Hydrogen Storage Properties of Nanoconfined LiBH4 in a Graphene-Rich N-Doped Matrix

Incipient wetness impregnation was employed to decorate two N-doped graphene-rich matrixes with iron, nickel, cobalt, and copper nanoparticles. The N-doped matrix was wetted with methanol solutions of the corresponding nitrates. After agitation and solvent evaporation, reduction at 800 °C over the carbon matrix promoted the formation of nanoparticles. The mass of the metal fraction was limited to 5 wt. % to determine if limited quantities of metallic nanoparticles catalyze the hydrogen capture/release of nanoconfined LiBH₄. Isotherms of nitrogen adsorption afforded the textural characterization of the matrixes. Electronic microscopy displayed particles of definite size, evenly distributed on the matrixes, as confirmed by X-ray diffraction. The same techniques assessed the impact of LiBH₄ 50 vol. % impregnation on nanoparticle distribution and size. The hydrogen storage properties of these materials were evaluated by differential scanning calorimetry and two cycles of volumetric studies. X-ray diffraction allowed us to follow the evolution of the material after two cycles of hydrogen capture-release. We discuss if limited quantities of coordination metals can improve the hydrogen storage properties of nanoconfined LiBH₄, and which critical parameters might restrain the synergies between nanoconfinement and the presence of metal catalysts.     

Functionalized polymers I. Poly(dichloroalkyl itaconates), synthesis and solution properties

The synthesis of poly(di-2-chloroethyl itaconate) (PD2CEI) and poly(di-3-chloropropyl itaconate) (PD3CPI) was carried out. The dilute solution behaviour of these polymers in tetrahydrofuran and chloroform at 298 K has been studied, by viscometry, membrane osmometry, and size-exclusion chromatography (SEC) measurements. The Kuhn-Mark-Houwink-Sakurada relationships were established. The flexibility factors σ and C_∞ and the thermodynamic parameters B were calculated using the Stockmayer-Fixman equation. The results obtained are compared with those found for the corresponding poly(methacrylates) and the poly(dialkyl itaconates), and discussed in terms of specific influence of the chlorine incorporated in the side chain.     

Double Hook Perylene Diimide as a New Receptor for PAHs: An Experimental and Theoretical Study

In a one-step reaction, we prepared a dibenzylamine perylene diimide derivative (PDI). Its double hook structure allows for self-association with a constant of K_d ∼10⁸ M⁻¹ determined by fluorescence. We confirmed its ability to bind PAHs using UV/Vis, fluorescence, and ¹H NMR titrations in CHCl₃. The complex formation signature in UV/vis is a new band at 567 nm. The calculated binding constants (K_a∼10⁴ M⁻¹) follow the trend pyrene>perylene>phenanthrene>naphthalene>anthracene. Theoretical modeling of these systems using DFT ωB97X-D/6-311G(d,p) proved helpful in rationalizing the complex formation and the observed association trend. The distinctive signal in UV/vis is due to a charge transfer in the complex from orbitals in the guest to the host. SAPT(DFT) confirmed that the driving forces in the complex formation are exchange and dispersion (π–π interactions). Still, the recognition ability depends on the electrostatic component of the interaction, a minor fraction.     

f-block MOFs: A Pathway to Heterometallic Transuranics

A novel series of heterometallic f-block-frameworks including the first examples of transuranic heterometallic ²³⁸U/²³⁹Pu-metal–organic frameworks (MOFs) and a novel monometallic ²³⁹Pu-analog are reported. In combination with theoretical calculations, we probed the kinetics and thermodynamics of heterometallic actinide(An)-MOF formation and reported the first value of a U-to-Th transmetallation rate. We concluded that formation of uranyl species could be a driving force for solid-state metathesis. Density of states near the Fermi edge, enthalpy of formation, band gap, proton affinity, and thermal/chemical stability were probed as a function of metal ratios. Furthermore, we achieved 97 % of the theoretical maximum capacity for An-integration. These studies shed light on fundamental aspects of actinide chemistry and also foreshadow avenues for the development of emerging classes of An-containing materials, including radioisotope thermoelectric generators or metalloradiopharmaceuticals.     

C−S Cross-Coupling of Aryldiazonium Salts with Thiols Mediated by Gold

In this work, the coupling of aryldiazonium salts with thiols mediated by the readily accessible gold complex Me₂SAuCl is described. In the reported protocol, the addition of 2,2′-bipyridine as a ligand leads to higher yields than phosphines. The reaction proceeds at room temperature under soft mildconditions and has a broad scope in both the aryldiazonium salt and the thiol. Notably, the coupling works with aryldiazonium salts containing two additional substituents.     

Blends of poly(n-vinyl-2-pyrrolidone)/poly(monoitaconates) II. The coefficient of linear expansion

Blends of poly(monoitaconates)^b) containing different side chain structures with poly(N-vinyl-2-pyrrolidone) (PVP) of three different weight-average molecular weights (M̄_w) were studied by thermomechanical analysis. Blends containing PVP of M̄_w =10000 shows a monotonous variation of the coefficient of linear expansion α against composition but PVP samples of higher molecular weights present a minimum which is attributed to polymer-polymer complex due to strong specific interactions.