No abstract

A series of metal ion-containing ionic liquids [Bmim]2[MCl4] (M = Sn, Cu, Ni, Mn, Fe, Co, Zn, and Pt; [Bmim] = 1-butyl-3-methylimidazolium) and [Bmim]2[ZrCl6] were synthesized and their single-crystal structures were determined by X-ray crystallographic analysis. The crystal structures showed the existence of an interaction between chlorometalate anions and imidazolium cations via C–H···Cl hydrogen bonding as well as an interaction between the cations through C–H···π hydrogen bonding and/or π···π stack interaction. The melting points of the metal salts were found to correlate with the number of halide ions coordinated to each metal ion and the overall symmetry of the chlorometalate anions. Ionic conductivity measured in super-cooled states of the synthesized salts unambiguously confirmed that these salts behaved as ionic liquids. The synthesized salts have a high thermal stability as evaluated by TGA and negligible vapor pressure before decomposition.

Propylene oxide (PO) is a versatile chemical intermediate, and by volume it is among the top 50 chemicals produced in the world. The catalytic conversion of propylene to PO by molecular oxygen with minimum waste production is of high significance from an academic as well as an industrial point of view. We have developed a new synthesis strategy to prepare 2–5 nm metallic silver nanoparticles (AgNPs) supported on tungsten oxide (WO3) nanorods with diameters between 30 and 40 nm, in the presence of cationic surfactant (cetyltrimethylammonium bromide: CTAB), capping agent (polyvinylpyrrolidone: PVP), and hydrazine. The synergy between the surface AgNPs and WO3 nanorods facilitates the dissociation of molecular oxygen on the metallic Ag surface to produce silver oxide, which then transfers its oxygen to the propylene to form PO selectively. The catalyst exhibits a PO production rate of 6.1 × 10–2 mol gcat –1 h–1, which is almost comparable with the industrial ethylene-to-ethylene oxide production rate.

Five anhydrous polymorphs (forms I−V) and one hydrate of furosemide−nicotinamide 1:1 cocrystal were discovered, and their solid-state properties were characterized using X-ray powder diffraction and differential scanning calorimetry. The crystal structures of forms I−IV were determined from the X-ray powder diffraction data and showed the structural differences between forms, which are mainly attributable to molecular conformations and supramolecular synthons. The slurry conversion experiments revealed that the order of thermodynamic stability of the polymorphs at 25 °C is I > III > II > V > IV. Dynamic vapor sorption analysis and X-ray single-crystal structure determination of the hydrate were conducted to study the dehydration mechanism. We observed structural similarities between the hydrate and its dehydrate, form IV, such as lattice parameters (except the a-axis length), synthons between furosemide and nicotinamide molecules, and the molecular conformation of furosemide; after dehydration, however, the a-axis contracted and nicotinamide molecules were displaced, along with the pyridine ring twisting.