A Peanut‐Shaped Polyaromatic Capsule: Solvent‐Dependent Transformation and Electronic Properties of a Non‐Contacted Fullerene Dimer

Synthesis of molecular containers capable of incorporating multiple fullerenes remains challenging. Reported here is that room‐temperature mixing of metal ions with W‐shaped bispyridine ligands featuring polyaromatic panels results in the quantitative formation of a peanut‐shaped M₂L₄ capsule. The capsule reversibly converts into two molecules of an ML₂ double tube in response to changes in the solvent. Notably, the capsule allows the incorporation of two fullerene molecules into the connected two spherical cavities at room temperature. The close proximity yet non‐contact of the encapsulated C₆₀ molecules, with a separation of 6.4 Å, was revealed by X‐ray crystallographic analysis. The resultant, unusual fullerene dimer undergoes sequential reduction within the capsule to generate (C₆₀^.?)₂, C₆₀^.??C₆₀^2?, and (C₆₀^2?)₂ species. Furthermore, temperature‐controlled stepwise incorporation of two C₆₀ molecules into the capsule is demonstrated.     

Dynamic behavior of temperature field in a buoyancy-driven turbulent fire

We study the dynamic behavior of temperature field in a buoyancy-driven turbulent fire from the viewpoints of symbolic dynamics, complex networks, and statistical complexity. The permutation entropy and the horizontal visibility network entropy allow us to capture the subtle changes in temperature fluctuations. The possible existence of deterministic chaos in temperature fluctuations, as well as in streamwise flow velocity fluctuations [Takagi et al., Phys. Rev. E 96 (2017) 052223], is clearly verified using the multiscale complexity-entropy causality plane.     

Cantilevered actuator using magnetostrictive thin film

This paper describes a cantilevered magnetic actuator driven by magnetostriction in a low magnetic field. The dimensions of the two layers actuator were 1×5 mm and amorphous FeSiB was used as the magnetostrictive material. Since the FeSiB has excellent soft magnetic characteristics, the actuator with FeSiB was able to work in magnetic field strength of less than 10 kA/m. The theoretical formulas for the amount of the displacement and the force of the actuator were obtained. The theoretical results agreed with the experimental one. According to the theoretical formula, the displacement was calculated with the parameter of the mechanical properties of the substrate. To obtain the large displacement, the actuator with Co substrate was designed based on the theoretical formula. The displacement of 153 μm was obtained using Cu substrate of 1.1 μm thickness in the magnetic field of 10 kA/m. © 2008 Elsevier B.V. All rights reserved     

Direct conversion of esters, lactones, and carboxylic acids to oxazolines catalyzed by a tetranuclear zinc cluster

The tetranuclear zinc cluster Zn4(OCOCF3)6O catalyzes the direct conversion of esters, lactones, and carboxylic acids to oxazolines with remarkable chemoselectivity.     

Additive effects of amines on asymmetric hydrogenation of quinoxalines catalyzed by chiral iridium complexes

The additive effects of amines were realized in the asymmetric hydrogenation of 2-phenylquinoxaline, and its derivatives, catalyzed by chiral cationic dinuclear triply halide-bridged iridium complexes [{Ir(H)[diphosphine]}(2) (μ-X)(3) ]X (diphosphine=(S)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl [(S)-BINAP], (S)-5,5'-bis(diphenylphosphino)-4,4'-bi-1,3-benzodioxole [(S)-SEGPHOS], (S)-5,5'-bis(diphenylphosphino)-2,2,2',2'-tetrafluoro-4,4'-bi-1,3-benzodioxole [(S)-DIFLUORPHOS]; X=Cl, Br, I) to produce the corresponding 2-aryl-1,2,3,4-tetrahydroquinoxalines. The additive effects of amines were investigated by solution dynamics studies of iridium complexes in the presence of N-methyl-p-anisidine (MPA), which was determined to be the best amine additive for achievement of a high enantioselectivity of (S)-2-phenyl-1,2,3,4-tetrahydroquinoxaline, and by labeling experiments, which revealed a plausible mechanism comprised of two cycles. One catalytic cycle was less active and less enantioselective; it involved the substrate-coordinated mononuclear complex [IrHCl(2) (2-phenylquinoxaline){(S)-BINAP}], which afforded half-reduced product 3-phenyl-1,2-dihydroquinoxaline. A poorly enantioselective disproportionation of this half-reduced product afforded (S)-2-phenyl-1,2,3,4-tetrahydroquinoxaline. The other cycle involved a more active hydride-amide catalyst, derived from amine-coordinated mononuclear complex [IrCl(2) H(MPA){(S)-BINAP}], which functioned to reduce 2-phenylquinoxaline to (S)-2-phenyl-1,2,3,4-tetrahydroquinoxaline with high enantioselectivity. Based on the proposed mechanism, an Ir(I) -JOSIPHOS (JOSIPHOS=(R)-1-[(S(p) )-2-(dicyclohexylphosphino)ferrocenylethyl]diphenylphosphine) catalyst in the presence of amine additive resulted in the highest enantioselectivity for the asymmetric hydrogenation of 2-phenylquinoxaline. Interestingly, the reaction rate and enantioselectivity were gradually increased during the reaction by a positive-feedback effect from the product amines.     

Zirconocene-Catalyzed Silylation of Alkenes with Chlorosilanes

Vinylsilanes and/or allylsilanes are formed upon silylation of terminal alkenes with R₃^′SiCl in the presence of a Grignard reagent and a catalytic amount of [Cp₂ZrCl₂] [Eq. (a)]. The reaction also proceeds under mild conditions when silylsulfides (X=SPh), silylselenides (X=SePh), and silyltellurides (X=TePh) are used in place of chlorosilanes (X=Cl). R″=alkyl, aryl, alkylsilyl; R′=Me, Et, nPr; R=CH₂R″, aryl, H.     

Trivalent Rare-Earth Metal Amide Complexes as Catalysts for the Hydrosilylation of Benzophenone Derivatives with HN(SiHMe2)2 by Amine-Exchange Reaction

The rare-earth metal complexes Ln( L¹ )[N(SiHMe₂)₂](thf) (Ln=La, Ce, Y; L¹ =N,N′′-bis(pentafluorophenyl)diethylenetriamine dianion) were synthesized by treating Ln[N(SiHMe₂)₂]₃(thf)₂ with L¹ H₂. The lanthanum and cerium derivatives are active catalysts for the hydrosilylation of benzophenone derivatives with HN(SiHMe₂)₂. An amine-exchange reaction was revealed as a key step of the catalytic cycle, in which Ln−Si−H β-agostic interactions are proposed to promote insertion of the carbonyl moiety into the Si−H bond.     

Aromatic Fluorination of Multiblock Amphiphile Enhances Its Incorporation into Lipid Bilayer Membranes

We designed multiblock amphiphiles AmF and AmH , which consist of perfluorinated and non-fluorinated hydrophobic units, respectively. Absorption spectroscopy revealed that both amphiphiles are molecularly dispersed in organic solvent, while they form aggregates under aqueous conditions. Furthermore, we investigated whether AmF and AmH can be incorporated into DOPC lipid bilayer membranes, and found that the maximum concentration of AmF that can be incorporated into DOPC lipid bilayer membranes is 43 times higher than that of AmH .