Alternative Route Triggering Multistep Spin Crossover with Hysteresis in an Iron(II) Family Mediated by Flexible Anion Ordering.

Multistep spin crossover (SCO) compounds have attracted much attention, since they can be great candidates for high-density multinary memory devices. The introduction of substituents, such as methyl (Me), chloro (Cl), bromo (Br), and methoxy (MeO) groups, at para positions to the phenyl-substituted tripodal N6 ligand-coordinated SCO FeII material, [FeLPh](NTf2)2 [where LPh = tris(2-{[(1-phenyl-1H-1,2,3-triazol-4-yl)methylidene]amino}ethyl)amine and NTf2 = bis(trifluoromethanesulfonyl)imide], affords a new family of solvent-free FeII complexes: [FeL4-R-Ph](NTf2)2 {where L4-R-Ph = tris[2-({[1-(4-R-phenyl)-1H-1,2,3-triazol-4-yl]methylidene}amino)ethyl]amine, where R = Me (1), Cl (2), Br (3), and MeO (4)}. 1 shows temperature invariant high-spin (HS) state, whereas the others show spin transitions with different characteristics, such as half-SCO (4), two-step SCO (3), and unusual three-step SCO with hysteresis (2). Mössbauer and X-ray absorption fine structure (XAFS) spectroscopic studies of them support the magnetic susceptibilities results. Density functional theory calculations indicate that the electronic effect of different substituents on magnetic properties is negligible in this FeII family. Single-crystal X-ray diffraction studies reveal that 1-4 has a similar packing arrangement with three-dimensional supramolecular network via intermolecular π-π and CH···π interactions between complex cations, and CH···X (X = O, N, and F) hydrogen bonding interactions between cations and inherently frustrated NTf2 anions. Variable-temperature structural studies unveil a variety of stepped SCO behaviors of 2-4 and deactivation of SCO in 1 are governed by the regulation of ordering of NTf2 counteranions through the subtle modification of terminal substituents of complex cations. Quantitative light-induced excited spin-state trapping (LIESST) effect was observed for 2-4 via green light irradiation (532 nm) at 10 K. This study opens up a new way for systematic control of magnetic response from no SCO to half-, two-step, and finally three-step SCO with hysteresis by precise tuning of the ordering of flexible NTf2 anions included in the supramolecular network with potentially SCO-active complex cations.

Preparation of Hierarchically Assembled Silver Nanostructures based on the Morphologies of Crystalline Peptide-Silver(I) Complexes.

The preparation of a hierarchically assembled Ag nanostructures based on a nanocrystalline assembly was demonstrated using an Ag(I) complex of a dipeptide (AspDap). By heating under N2 gas, a spherical assembly of a nanocrystalline dipeptide-Ag(I) complex (diameter 4-5 µm), which has a morphology similar to the assembled structure of the dipeptide, was transformed to an assembly of Ag nanostructures, where the micrometre-order crystalline morphology was maintained. In addition, detailed scanning electron microscopy studies revealed that Ag nanoparticles (diameter ca. 10 nm) were formed on the surface of the Ag nanostructure. When the Ag(I) ions were reduced to Ag(0), this phenomenon exhibited surface dependence due to the anisotropic two-dimensional Ag(I) arrangement in the crystals. Thermogravimetric measurements and X-ray photoelectron spectroscopy revealed that the reduction proceeds in a stepwise manner around 200-250 °C, together with the removal of primary and secondary carboxylic groups in the dipeptide. Comparison with the heating process of the crystalline Ag(I) complex of ß-alanine indicated that stepwise reduction is key for maintaining the original micrometre-order morphology.

[An autopsy case of microscopic polyangiitis complicated with pulmonary aspergilloma and cytomegalovirus pneumonia].

A 71-year-old man was admitted to our hospital because of fever and rapidly progressive renal insufficiency over a month. He had depression and Alzheimer's disease as complications. On admission, his serum creatinine was 5.4 mg/dL, and the serum CRP and MPO-ANCA were 18.2 mg/dL and 285 EU, respectively. A computed tomographic chest scan showed pericardiac effusion and fibrosis in both lower lung fields. Although microscopic polyangiitis(MPA)was inferred from a positive MPO-ANCA, renal biopsy could not be carried out. The initial therapy was started with pulse methylprednisolone therapy, followed by oral administration of prednisolone at the dose of 1 mg/kg(60 mg/day). As a result, his fever and inflammatory findings disappeared, and renal insufficiency was ameliorated with a smooth recovery and the pericardial effusion was markedly diminished. However, on the 18th hospital day, chest radiography revealed a nodular shadow in the right lung. Fungus infection was suspected because his serum beta-D-glucan level was extremely high (above 999 pg/mL). Mikafungin, therefore, was started at a dose of 75 mg/day and then, the dose was increased up to 300 mg/day. Nevertheless, he finally died of respiratory failure on the 26th hospital day. The autopsy findings revealed a cavity of 4.0 x 3.0 x 3.0 centimeters in size in the upper lobe of the right lung. There was a great number of fungal threads with a septal wall branched in a Y-shaped figure around the cavity, thus indicating pulmonary aspergilloma. Intranuclear inclusion bodies staining positive for cytomegalovirus were observed in all the lung fields, suggestive of a cytomegalovirus infection. In the kidney, a cellular crescent formation was noted in the majority of glomeruli showing crescentic glomeluronephritis, compatible with MPA.