The effects of simultaneous Sb doping on the superconductivity of 112-type Ca 1¹x RE x FeAs 2 (RE = La, Ce, Pr, and Nd) were studied through measurements of the magnetization and electrical resistivity. In Sb-free materials, the superconducting transition temperature T c of the La-doped sample was 35 K, while those of the Pr-and Nd-doped samples were ³10 K; no superconductivity was observed in the Ce-doped sample. Sb doping increased the T c of all REdoped samples: T c increased to 47, 43, 43, and 43 K for RE = La, Ce, Pr, and Nd, respectively. We also found that the enhanced superconductivity results from the increase in the lattice parameter b, which increases the As-Fe-As bond angle to be closer to the ideal tetrahedron value. These observations provide insight for further increasing the T c of the 112 phase.

Mechanochromic organic molecules (MOMs) that exhibit a large difference of fluorescence wavelength between two states have important potential applications, but few such compounds are known. Here, we report a new MOM, cis-ABPX01(0), which shows switchable near-IR and blue fluorescence responses. Detailed spectrophotometric and single-crystal X-ray analyses revealed that the near-IR fluorescence is attributable to fluorescence from slip-stacked dimeric structures in crystals, while the blue fluorescence is attributable to fluorescence from the monomer. Switching between the two is achieved by dynamic structural interconversion between the two molecular packing arrangements in response to mechanical grinding and solvent vapor-fuming.

Facile synthesis of single crystal of two-dimensional mixed-halide copper-based perovskites with tunable band gaps and their capability of exfoliation and reversible thermochromism.

Azulene-fused polycyclic aromatic hydrocarbons (PAHs) were synthesized from commercially available azulene in four steps. The resulting azulene conjugates exhibited significantly narrow HOMO-LUMO bandgaps with high air stability, confirmed by photophysical study. Introduction of azulene also enabled the unique reversible stimuli-responsiveness even with the weak acid and base, which can potentially control the degree of conjugation and optoelectronic properties by simple acid-base and redox processes.

Among chiral macrocycles 1 synthesized, 1m with the 3,5-bis(trifluoromethyl)phenylethynyl group was the best organocatalyst for the enantioselective synthesis of cyclic carbonates from disubstituted or monosubstituted epoxides and CO. The X-ray crystal structure of 1m revealed a well-defined chiral cavity with multiple hydrogen-bonding sites that is suitable for the enantioselective activation of epoxides. A catalytic cycle proposed was supported by DFT calculations.

A ternary compound, MgPtSi, was synthesized by solid-state reaction. An examination of the compound by powder X-ray diffraction revealed that it crystallizes in the orthorhombic TiNiSi-type structure with the P nma space group. The structure comprises alternately stacked layers of Mg and PtSi honeycomb network, which is reminiscent of MgB2, and the buckling of the honeycomb network causes orthorhombic distortion. Electrical and magnetic studies revealed that MgPtSi exhibited superconductivity with a transition temperature of 2.5 K. However, its isostructural compounds, namely, MgRhSi and MgIrSi, were not found to exhibit superconductivity.

We investigated the pressure-dependence of electric transport and crystal structure of Ag-doped Bi 2 Se 3 . In the sample prepared by Ag-doping of Bi 2 Se 3 , the Bi atom was partially replaced by Ag, i.e., Ag 0.05 Bi 1.95 Se 3 . X-ray diffraction (XRD) patterns of Ag 0.05 Bi 1.95 Se 3 measured at 0 -30 GPa showed three different structural phases, with rhombohedral, monoclinic and tetragonal structures forming in turn as pressure increased, and structural phase transitions at 8.8 and 24 GPa. Ag 0.05 Bi 1.95 Se 3 showed no superconductivity down to 2.0 K at 0 GPa, but under pressure, superconductivity suddenly appeared at 11 GPa. The magnetic field (H) dependence of the superconducting transition temperature, T c , was measured at 11 and 20.5 GPa, in order to investigate whether the pressure-induced superconducting phase is explained by either p-wave polar model or s-wave model.

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