Metal hydride clusters show intriguing functionalities based on the cooperativity between the metal atoms and hydrides. However, the exploration of their reactivity has been partially hampered due to the lack of a versatile synthetic strategy, especially for clusters made up of iron-group metals (i.e., Fe, Co, or Ni). Herein, we report the facile synthesis of Fe hydride clusters, [Fe55 H46 (PtBu3 )12 ][Fe6 H8 {N(SiMe3 )2 }6 ] ([Fe55 ][Fe6 ]). The cluster, [Fe55 ][Fe6 ], was synthesized by metal hydride metathesis reactions, where metal(II) amide complexes react with pinacolborane (HBpin) in the presence of PtBu3. Single-crystal X-ray crystallographic analysis was performed to reveal their crystal structures. The metal hydride metathesis reactions are compatible with other types of metals/ligands in principle and thus opens up a new avenue to explore the rich chemistry of iron-group metal hydride clusters at all scales.
Nanoparticles have a multitude of uses in medical imaging and therapy. In particular, they can act as powerful imaging agents for modern imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) while simultaneously providing therapeutic functionality, i.e., drug-loaded drug delivery system (DDS) nanocarriers. This article introduces magnetic particle imaging (MPI) which is an emerging technique that is uniquely specialized for the imaging of magnetic nanoparticles in vivo. This review will first explain the principles underlying MPI and how its imaging performance and functionality are highly dependent on the qualities of the nanoparticle. The middle section then establishes the safety of the nanoparticle and MPI method for clinical use. The last section presents several promising applications of nanoparticles with MPI for multifunctional nanomedicine.
Sub-nano clusters have been reported to have interesting properties not found in bulk materials and nanoparticles, such as dynamic structural changes and amorphous structures. Additionally, alloy sub-nano clusters are expected to form homogeneous mixtures even with various combinations of metallic elements. However, local structural and elemental analyses are challenging because structural analysis methods such as X-ray diffraction cannot be applied at the sub-nanoscale. In this study, we observe the appearance of alloy sub-nano clusters using scanning transmission electron microscopy (STEM) with atomic resolution to investigate their structure. The structural data are statistically analyzed to elucidate the property of miscibility. In this report, we directly observe atomic coordinate structures from STEM images through image processing. Based on these structural data, miscibility was evaluated for each structure, and we developed several miscibility maps categorized by composition and atomicity. We report on the similarities and differences in the elemental miscibility of binary alloy sub-nano clusters by comparing these miscibility maps.