Chiral weak ferromagnets formed in one-dimensional organic-inorganic hybrid manganese chloride hydrates.

Chiral weak ferromagnets were developed in organic-inorganic hybrid systems of one-dimensional manganese(II) chloride hydrate with chiral organic cations of (S)- and (R)-ß-methylphenethylammonium (= (S)- and (R)-MPA+), [(S)/(R)-MPA]2[MnCl4(H2O)]. The weak ferromagnetic phase found below 3.2 K could be attributed to a spin canting antiferromagnetic state induced by Dzyaloshinskii-Moriya interactions owing to spatial inversion symmetry breaking in chirality introduced systems. This is the first chiral weak ferromagnet found in a spin chain of deformed perovskite derivatives with a corner-sharing structure of transition metal halide hydrates.

Magnetic Phase Switching Performance in an Fe-Tetraoxolene-Layered Metal-Organic Framework via Electrochemical Cycling.

The iron-based tetraoxolene honeycomb-layered compound (NPr4)2[Fe2(Cl2An)3] (1; NPr4+ = tetrapropylammonium cation; Cl2An2- = 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinonate) was used as the cathode material for lithium-ion batteries. We observed a charge-cycling performance (∼16 times) with three electrons/Li+ ion insertion and extraction, corresponding to the stoichiometry redox of Cl2An2- + e- ↔ Cl2An·3- and Fe3+ + e- ↔ Fe2+. The generation/annihilation of radicals, Cl2An·3-, enables the significant improvement/deterioration of the magnetic phase transition temperature with Tc = 100 K.

Magneto-Electric Directional Anisotropy in Polar Soft Ferromagnets of Two-Dimensional Organic-Inorganic Hybrid Perovskites.

Two-dimensional organic-inorganic hybrid perovskites (2D-OIHPs) are attracting interest due to their structural tunability and rich functional characteristics, such as ferroelectricity and ferromagnetism. Here, we report the chiral-polar ferromagnetic 2D-OIHP copper chlorides with discernable electric polarization in the inorganic layers. In these systems, the magneto-electric (ME) correlation has been clearly observed by measuring a magneto-electric directional anisotropy (MEA), in which an optical absorption coefficient changes with reversal of the light propagating direction. We have found that the MEA can be induced by a low magnetic field of about 50 mT, reflecting soft magnetic nature. The present results suggest a new paradigm for designing functional ME multiferroics, which effectively couples magnetic and electric properties.

Chirality-Dependent Circular Photogalvanic Effect in Enantiomorphic 2D Organic-Inorganic Hybrid Perovskites.

The control of the optoelectronic properties of 2D organic-inorganic hybrid perovskite (2D-OIHP) lead halides is an increasingly prevalent topic. Herein, the observation of the circular photogalvanic effect (CPGE) in new enantiomorphic 2D-OIHP lead iodides is reported, which are synthesized as a first OIHP-related system belonging to a chiral space group by incorporating organic chiral cations into the inorganic layers of lead iodides. The CPGE is an optoelectronic phenomenon associated with the spin-orbit coupling of heavy atoms in noncentrosymmetric systems. Owing to the CPGE, light-helicity-dependent steady photocurrents are generated without an external bias voltage under the irradiation of circularly polarized light. Furthermore, the sign reversal of the CPGE photocurrent depending on the chirality of the designed 2D-OIHP lead iodides is observed. This result indicates formation of the theoretically predicted radial spin-polarized texture in k-space of chiral systems owing to spin-momentum locking. Hence, chiral 2D-OIHP lead halides can be a promising platform for engineering opto-spintronic functionalities.

Magnetic Correlation Engineering in Spin-Sandwiched Layered Magnetic Frameworks.

The insertion of "sandwiched spins" between magnetic layers could efficiently affect the interlayer magnetic correlations, but doing so increases the complexity in the interlayer spin alignment because of competition between the inserted spin-layer interaction JNNI and the interlayer through-space interaction JNNNI if the magnitude of JNNI is of the same order as JNNNI with reciprocal signs of the respective interactions. Herein, systematic tuning of the magnetic phase variations by JNNI and JNNNI in two kinds of metal-variable isostructural series of supramolecular pillared layer magnets [MCp*2 ][{Ru2 II,II (2,3,5,6-F4 CO2 )4 }2 (TCNQ)]⋅2 DCE (M=Co, Fe, Cr; 2,3,5,6-F4 PhCO2 - =2,3,5,6-tetrafluorobenzoate; TCNQ=7,7,8,8-tetracyano-p-quinodimethane; DCE=1,2-dichloroethane) and their DCE-free series, in which [MCp*2 ]+ (Cp*=η5 -C5 Me5 ) species with S=0, 1/2, and 3/2 for M=Co, Fe, Cr, respectively, are sandwiched between ferrimagnetic layers of [{Ru2 }2 (TCNQ)]- , is demonstrated. The results showed that the flexible magnetic natures of these magnets are changeable in dependence on JNNI and JNNNI , as well as on interlayer inserted spins M.

Bulk Photovoltaic Effect in a Pair of Chiral-Polar Layered Perovskite-Type Lead Iodides Altered by Chirality of Organic Cations.

The bulk photovoltaic effect (BPVE) is a promising optoelectronic phenomenon for generating a steady-state photocurrent without a bias voltage. Nevertheless, the simple and rational design of materials exhibiting the BPVE remains an important topic in the relevant fields. Here, we report the observation of the BPVE in a simple chiral-polar pair of layered perovskite-type lead iodides in the crystal space group of P1 (#1), which were synthesized by assembling R- and S-chiral organic cations, respectively. The sign of the zero-bias photocurrent is altered by the R/S-chirality of the assembled cations, which define the direction of electric polarization derived from the electric dipole moment of each chiral organic cation aligned in a crystal. The strategy of chirality control in a crystal is expected to be useful when searching for BPVE materials.

Magnetic Switching by the In Situ Electrochemical Control of Quasi-Spin-Peierls Singlet States in a Three-Dimensional Spin Lattice Incorporating TTF-TCNQ Salts.

Magnetic phase switching in a coordination polymer is reported, which is demonstrated by combining two processes: (A) the pre-organization of magnetic/redox-active molecules into a framework, and (B) a post-treatment through electrochemical tuning of the pre-organized molecules. A TTF.+ -TCNQ.- salt (TTF=tetrathiafulvalene; TCNQ=7,7,8,8-tetracyano-p-quinodimethane) was incorporated into a three-dimensional framework with paddlewheel-type dimetal(II, II) units ([M2II,II ]; M=Ru with S=1, 1; and Rh with S=0, 2), where the [M2II,II ] and TCNQ.- units form the coordinating framework, and TTF.+ is located in the pores of framework, forming an irregular π-stacking alternating column with the TCNQ.- in the framework. In 1, the spins of [Ru2II,II ] and TCNQ.- units make a magnetic correlation through the framework upon decreasing the temperature from 300 K, which is, however, suddenly suppressed below 137 K (=Td (1)) by the formation of a spin singlet in the TTF.+ -TCNQ.- columns, as seen in the spin-Peierls transition (Td (2)=200 K). This material was incorporated as a cathode in a Li-ion battery (LIB); a long-range ferrimagnetic correlation was formed through the three-dimensional [{Ru2II,II }2 TCNQ]- framework at Tc =78 K in the discharge process. The reversible magnetic phase switching between the non-volatile ferrimagnetic and paramagnetic states, resulting from the local spin tuning of quasi-spin-Peierls singlet, is demonstrated through the discharge/charge cycling of the LIB.

Construction of an Artificial Ferrimagnetic Lattice by Lithium Ion Insertion into a Neutral Donor/Acceptor Metal-Organic Framework.

Construction of a molecular system in which the magnetic lattice exhibits long-range order is one of the fundamental goals in materials science. In this study, we demonstrate the artificial construction of a ferrimagnetic lattice by doping electrons into acceptor sites of a neutral donor/acceptor metal-organic framework (D/A-MOF). This doping was achieved by the insertion of Li-ions into the D/A-MOF, which was used as the cathode of a Li-ion battery cell. The neutral D/A-MOF is a layered system composed of a carboxylate-bridged paddlewheel-type diruthenium(II,II) complex as the donor and a TCNQ derivative as the acceptor. The ground state of the neutral form was a magnetically disordered paramagnetic state. Upon discharge of the cell, spontaneous magnetization was induced; the transition temperature was variable. The stability of the magnetically ordered lattice depended on the equilibrium electric potential of the D/A-MOF cathode, which reflected the electron-filling level.

Rechargeable magnesium-ion battery based on a TiSe2-cathode with d-p orbital hybridized electronic structure.

Rechargeable ion-batteries, in which ions such as Li(+) carry charges between electrodes, have been contributing to the improvement of power-source performance in a wide variety of mobile electronic devices. Among them, Mg-ion batteries are recently attracting attention due to possible low cost and safety, which are realized by abundant natural resources and stability of Mg in the atmosphere. However, only a few materials have been known to work as rechargeable cathodes for Mg-ion batteries, owing to strong electrostatic interaction between Mg(2+) and the host lattice. Here we demonstrate rechargeable performance of Mg-ion batteries at ambient temperature by selecting TiSe2 as a model cathode by focusing on electronic structure. Charge delocalization of electrons in a metal-ligand unit through d-p orbital hybridization is suggested as a possible key factor to realize reversible intercalation of Mg(2+) into TiSe2. The viewpoint from the electronic structure proposed in this study might pave a new way to design electrode materials for multivalent-ion batteries.

Spred-1 negatively regulates allergen-induced airway eosinophilia and hyperresponsiveness.

T helper 2 cytokines, including interleukin (IL)-4, IL-5, and IL-13, play a critical role in allergic asthma. These cytokines transmit signals through the Janus kinase/signal transducer and activator of transcription (STAT) and the Ras-extracellular signal-regulated kinase (ERK) signaling pathways. Although the suppressor of cytokine signaling (SOCS) family proteins have been shown to regulate the STAT pathway, the mechanism regulating the ERK pathway has not been clarified. The Sprouty-related Ena/VASP homology 1-domain-containing protein (Spred)-1 has recently been identified as a negative regulator of growth factor-mediated, Ras-dependent ERK activation. Here, using Spred-1-deficient mice, we demonstrated that Spred-1 negatively regulates allergen-induced airway eosinophilia and hyperresponsiveness, without affecting helper T cell differentiation. Biochemical assays indicate that Spred-1 suppresses IL-5-dependent cell proliferation and ERK activation. These data indicate that Spred-1 negatively controls eosinophil numbers and functions by modulating IL-5 signaling in allergic asthma.