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A solution precursor route has been used to synthesize a series of nanocrystalline rare-earth borates. Amorphous precursor powders are precipitated during an aqueous reaction between RE{sup 3+} and NaBH{sub 4}, and the isolated powders can be annealed in air at 700 deg. C to form YBO{sub 3}, NdBO{sub 3}, SmBO{sub 3}, EuBO{sub 3}, GdBO{sub 3}, and HoBO{sub 3}. YBO{sub 3}:Eu formed using this strategy shows red-orange emission properties that are similar to high-quality nanocrystals prepared by other methods. The materials have been characterized by FTIR spectroscopy, powder XRD, SEM, DSC, UV-Vis fluorimetry, and TEM with EDS and element mapping. - Graphical abstract: Amorphous nanoscopic precursor powders are formed through the aqueous reaction of RE{sup 3+} with NaBH{sub 4}. Once isolated, the powders can be annealed at 700 deg. C in air to form a series of nanocrystalline REBO{sub 3} orthoborates. Nanocrystalline YBO{sub 3}:Eu formed using this strategy shows red-orange emission properties when excited with UV light.

The synthesis of new multidentate nitrogen-containing ligands is of ongoing interest. In this report, the one-step syntheses of a series of (pyridylalkyl)amine derivatives is described. The reported compounds contain both pyridine rings and sp 3 -hybridized nitrogen as potential donor sites. The general synthetic method involves- a room temperature reaction of mono-, bis-, tris-, or tetrakis-(bromomethyl)benzenes with an excess of (pyridylmethyl)amine in tetrahydrofuran. The products can be purified by distillation, chromatography or recrystallization and are obtained in fair to good yields. The advantages of this synthetic method are the procedural simplicity and the ready availability of the starting materials. The applicability of these compounds in supramolecular chemistry is demonstrated by the reaction of two of the described ligands with silver(I) salts.

Metal phosphides can have important properties such as superconductivity, magnetoresistance, magnetocaloric behavior, catalytic activity, and lithium intercalation capacity, which make them useful for a variety of technological applications. Bulk metal phosphides usually require high temperatures and harsh reaction conditions to form, and metal phosphide nanocrystals can also be challenging to synthesize. Here we elaborate on a recently developed alternative approach for synthesizing metal phosphides, which involves the solution-mediated reaction of pre-formed metals with trioctylphosphine (TOP) at temperatures below 370 °C. This chemical conversion strategy is shown to be general and highly versatile, successfully forming a wide range of transition-metal and post-transition-metal phosphides using a range of both bulk and nanoscale metals as precursors. Metal nanocrystals, bulk powders, foils, wires, thin films, lithographically patterned substrates, and supported nanocrystals can all be converted to meta...

Ternary and quaternary transition metal oxides, which offer a wide variety of important physical properties, are traditionally synthesized using high-temperature reactions that often require several days of heating. A new nanoparticle-directed approach for the rapid low-temperature synthesis of nanocrystalline bulk-scale ternary and quaternary transition metal oxides has been developed. Readily available metal oxide nanoparticles can serve as a robust toolkit of highly reactive reagents, which can be mixed in solution in known ratios to form nanomodulated precursors and rapidly transformed, at relatively low temperatures, into more complex oxides. This approach is initially demonstrated for pyrochlore-type Y2Ti2O7 and Eu2Ti2O7 using XRD, DSC, and TEM to monitor the reaction. A nanocomposite of Y2O3 and TiO2 nanoparticles transforms into nanocrystalline Y2Ti2O7 within 2 h of heating to 700 °C, and Eu2Ti2O7 forms within 2 h of heating a nanocomposite of Eu2O3 and TiO2 nanoparticles to 800 °C. NiTiO3, CoTiO3...

The synthesis of new multidentate nitrogen-containing ligands is of ongoing interest. In this report, the one-step syntheses of a series of (pyridylalkyl)amine derivatives is described. The reported compounds contain both pyridine rings and sp 3 -hybridized nitrogen as potential donor sites. The general synthetic method involves- a room temperature reaction of mono-, bis-, tris-, or tetrakis-(bromomethyl)benzenes with an excess of (pyridylmethyl)amine in tetrahydrofuran. The products can be purified by distillation, chromatography or recrystallization and are obtained in fair to good yields. The advantages of this synthetic method are the procedural simplicity and the ready availability of the starting materials. The applicability of these compounds in supramolecular chemistry is demonstrated by the reaction of two of the described ligands with silver(I) salts.

When reacted with trioctylphosphine at approximately 360 degrees C, rhodium nanocrystals convert to rhodium phosphide Rh(2)P nanocrystals. Careful control over synthetic variables, such as temperature, stabilizing ligands, and cosolvents, can result in Rh(2)P nanocrystals with shapes that reflect the Rh nanocrystal templates. Accordingly, Rh nanocrystals with multipod, cube- and triangle-derived shapes convert to Rh(2)P nanocrystals that maintain the shape of their Rh precursors. Both dense and hollow Rh(2)P nanocrystals can be generated using a single unified chemical conversion strategy. These empirical guidelines for generating a morphologically diverse library of Rh(2)P nanocrystals provide important insights into shape conservation using nanocrystal templates and will likely be portable to other multielement systems for which rigorous shape-controlled synthesis remains challenging.

Nanocrystals of metal phosphides, which can have useful catalytic, electronic, and magnetic properties, are known to be accessible by using trioctylphosphine (TOP) as a highly reactive phosphorus source. Here we report a general strategy for synthesizing transition metal phosphides, including those with 4d and 5d transition metals that have not previously been reported as unsupported nanocrystals. Unlike previously reported methods that involve direct decomposition of organometallic precursors, our method utilizes preformed metal nanoparticles as templates for generating metal phosphide nanocrystals. Metal nanoparticles are reacted with TOP in a hot solvent (290−360 °C) to form transition metal phosphides such as Ni2P, PtP2, Rh2P, PdP2, Pd5P2, and Au2P3. Furthermore, nanostructures such as hollow spheres can be easily made using a Kirkendall-type mechanism, which utilizes metal nanoparticles as reactive templates.