Although an infinite number of crystal structures are geometrically possible, formation of experimentally known crystal structures depends on thermodynamics. Because the crystal structure of metal nanomaterials is a crucial factor in determining corresponding physicochemical properties, investigations of unprecedented crystal structures facilitate development of new functions and enhancement of well-known properties. Here, we succeeded in creating ordered alloy nanoparticles with an unprecedented Z3-type structure consisting of an alternate L10-like PdFePd trilayer and PdIn ordered alloy monolayer by an inter-element miscibility of In, which is miscible with Pd but immiscible with Fe. It was confirmed that the use of monodispersed nanoparticles containing three elements like A1-PdInx @FeOy core@shell nanoparticles facilitated the formation of the Z3-type structure. We hope that the crystal structure library will be expanded to contribute to the dramatic modulation of physical and chemical properties.
Recently, the methodology of synthesizing ultrasmall (< 5 nm) metal oxide nanoparticles has been developed by using continuous flow hydrothermal synthesis. Based on this technique, ultrasmall CeO2 nanoparticles (< 5 nm) were successfully synthesized, and the distortion and chemical state of ultrasmall CeO2 nanoparticles were studied intensively. The ultrasmall metal oxides have interesting chemical states, differing from the conventional nanocrystals.
The development of carbon dioxide (CO2 ) capture and utilization technologies has become important for realizing a carbon-recycling society. Among porous materials for efficient gas capture and storage, porous coordination polymers/metal-organic frameworks (PCPs/MOFs) are highly promising as the next generation of CO2 adsorbents due to their versatile designable structures, high specific surface area, and adsorption capacity. This account describes our recent progress in developing porous coordination networks for effective CO2 capture. Through synthetic and mechanistic studies of the design of a coordination network, we have found that the boron-bridging structure in zeolitic imidazolate frameworks is key to controlling the CO2 adsorption ability of their porosity. Following a summary of our studies, we offer a perspective on the possibilities for future development of CO2 capture and storage systems based on metal-organic coordination networks.
One or two phenylacetylide (PA) ligand(s) were successfully removed from the IrAu12 superatomic core of [IrAu12 (dppe)5 (PA)2 ]+ (dppe = 1,2-bis(diphenylphosphino)ethane) by reaction with controlled amounts of tetrafluoroboric acid. Optical and nuclear magnetic resonance spectroscopies and density functional theory calculations revealed the formation of open Au site(s) on the IrAu12 core of [IrAu12 (dppe)5 (PA)1 ]2+ and [IrAu12 (dppe)5 ]3+ with the remaining structure intact. Isocyanide was efficiently trapped at the open electrophilic site on [IrAu12 (dppe)5 (PA)1 ]2+, whereas a dimer or trimer of the IrAu12 superatoms was formed using diisocyanide as a linker. These results open the door to designed assembly of chemically modified metal superatoms.