A triplet biradical with double bidentate sites based on tert-butyl pyridyl nitroxide as a candidate for strong ferromagnetic couplers

We synthesised a new biradical, 34bpybNO, having two chelating radical sites and demonstrated its crystal structure and ground triplet nature. Frozen-solution magnetic measurement and electron spin resonance results revealed a strong intramolecular ferromagnetic coupling reaching 2J/kB = ∼+170 K, which is supported by density functional theory calculations

ラジカルキレート配位子を用いた遷移金属錯体の構造と磁性

電気通信大学200

Essential Role of Neuron-Enriched Diacylglycerol Kinase (DGK), DGKβ in Neurite Spine Formation, Contributing to Cognitive Function

BACKGROUND: Diacylglycerol (DG) kinase (DGK) phosphorylates DG to produce phosphatidic acid (PA). Of the 10 subtypes of mammalian DGKs, DGKbeta is a membrane-localized subtype and abundantly expressed in the cerebral cortex, hippocampus, and caudate-putamen. However, its physiological roles in neurons and higher brain function have not been elucidated. METHODOLOGY/PRINCIPAL FINDINGS: We, therefore, developed DGKbeta KO mice using the Sleeping Beauty transposon system, and found that its long-term potentiation in the hippocampal CA1 region was reduced, causing impairment of cognitive functions including spatial and long-term memories in Y-maze and Morris water-maze tests. The primary cultured hippocampal neurons from KO mice had less branches and spines compared to the wild type. This morphological impairment was rescued by overexpression of DGKbeta. In addition, overexpression of DGKbeta in SH-SY5Y cells or primary cultured mouse hippocampal neurons resulted in branch- and spine-formation, while a splice variant form of DGKbeta, which has kinase activity but loses membrane localization, did not induce branches and spines. In the cells overexpressing DGKbeta but not the splice variant form, DGK product, PA, was increased and the substrate, DG, was decreased on the plasma membrane. Importantly, lower spine density and abnormality of PA and DG contents in the CA1 region of the KO mice were confirmed. CONCLUSIONS/SIGNIFICANCE: These results demonstrate that membrane-localized DGKbeta regulates spine formation by regulation of lipids, contributing to the maintenance of neural networks in synaptic transmission of cognitive processes including memory

4f-3d, 3d-3d および3d-2p スピンを有する磁性材料における分子構造と交換相互作用の相関についての研究

This thesis describes relationship between the molecular structure and the exchange interaction,which characterizes nature of molecular magnetic materials. Determination of magnetic exchangecoupling is one of the most important issues in the study of magnetic clusters.The contents are mainly divided into the three following subjects.(i) Exchange couplings between lanthanoid ion (4f spin) and transition-metal ion (3d spin)(ii) Exchange couplings between transition-metal ion and organic free radical (2p spin)(iii) Exchange couplings between homo transition-metal ionsThe purpose of Subject (i) is as follows. The exchange couplings between a lanthanide ion anda transition-metal ion have been only roughly determined by means of pulsed-field magnetizationmeasurements. We applied a high-frequency (HF)-EPR technique to the 4f－3d hetelometallic SMMs,which has never been utilized for such purpose before our work.The determination of exchange couplings between 4f- and 3d-spins in [Dy2Cu] and [Dy2Ni]SMMs is demonstrated. The one-dimensional compound [Dy2Cu2]n showed SMM behavior and twoDy－Cu exchange parameters were precisely evaluated. The study on isomorphous [Ln2Cu2]n (Ln =Gd, Tb, Dy, Ho, and Er) revealed that the J4f－3d value monotonically decreased in the order ofincreasing the number of the 4f-electrons.The purpose of Subject (ii) is to establish strongly ferromagnetic couplings in the metal－radialhybrid systems. 3d- and 2p-spins seem to be promising for development of strongly correlatedmagnetic materials, in comparison with 4f-spins.A simple magneto-structure relationship in copper(II) and nickel(II) complexes chelated withtert-butyl 2-pyridyl nitroxide radicals was proposed. tert-Butyl 2-pyridyl nitroxide, known to beunisolable under ambient conditions, was successfully utilized in this work. Furthermore, synthesis,crystal structures, and magnetic properties of the two novel stable nitroxide and its coordinationcompounds are presented.The purpose of Subject (iii) is to construct homometallic spin systems showing ferromagneticcouplings. Heterometallic approaches have a disadvantage of potential difficulty in preparation,because of possible metal-scrambling and low positional selectivity. Facile preparation is desired.Magnetic interactions between 3d－3d spins connected with a spiro-bridge were investigated.Intramolecular 3d－3d couplings are ferro- and antiferromagnetic for the dinuclear nickel(II) andmanganese(II) complexes, respectively. This finding can be explained in terms of the orthogonalarrangement of SOMO－SOMO orbitals.電気通信大学200

Kinetically controlled self-assembly of Rh(II)-based squares assisted by monotopic ligand

Self-assembled coordination squares consisting of cis-protected dinuclear Rh(II) corner complexes and linear ditopic ligands were selectively produced in solution under kinetic control with the assistance of a weak monotopic carboxylate ligand (2,6-dichlorobenzoate: dcb–) as a leaving ligand. Preventing the cyclization step in the triangular formation by the leaving ligand enabled to produce the molecular square only. It was also found that dcb– can selectively convert the triangular complex into the square complex at room temperature, though heating at 373 K for 2 days is needed for the conversion without dcb– and that DMSO blocked the transformation process with dcb–. These results indicate that the energy landscape of the Rh(II)-based molecular self-assembly can be modulated properly by monotopic carboxylate ligand and solvent so that the self-assembly proceeds under kinetic control. Furthermore, one of the molecular squares assembled into a dimeric structure by the solvophobic effect, whose structure was characterized by NMR spectroscopy and single-crystal X-ray analysis

Halogen Substituent Effect on the Spin-Transition Temperature in Spin-Crossover Fe(III) Compounds Bearing Salicylaldehyde 2-Pyridyl Hydrazone-Type Ligands and Dicarboxylic Acids

Four Fe(III) spin-crossover (SCO) compounds, [Fe(HL1)2](HCl4TPA) (1-Cl), [Fe(HL1)2](HBr4TPA) (1-Br), [Fe(HL2)2](HCl4TPA) (2-Cl), and [Fe(HL2)2](HBr4TPA) (2-Br) (HL1 = 4-chloro-2-nitro-6-(1-(2-(pyridine-2-yl)hydrazono)ethyl)phenolate; HL2 = 4-bromo-2-nitro-6-(1-(2-(pyridine-2-yl)hydrazono)ethyl)phenolate; HCl4TPA = 2,3,5,6-tetrachloro-4-carboxybenzoate; and HBr4TPA = 2,3,5,6-tetrabromo-4-carboxybenzoate), were synthesized to investigate the halogen substituent change effect in salicylaldehyde 2-pyridyl hydrazone-type ligands and dicarboxylic acids in SCO complexes to the spin-transition temperature. Crystal structure analyses showed that these compounds were isostructural. In addition, a one-dimensional hydrogen–bonded column was formed by the dicarboxylic acid anion and weak hydrogen bonds between the Fe(III) complexes. From Mössbauer spectroscopy and magnetic property measurements, these compounds were confirmed to exhibit gradual SCO. The spin-transition temperature can be shifted by changing the halogen substituent in the salicylaldehyde 2-pyridyl hydrazone-type ligands and dicarboxylic acids without changing the molecular arrangement in the crystal packing

Synthesis of Aromatic Carbonyl Thiourea PI-28 Derivatives for the Development of Radicle Elongation Inhibitor of Parasitic Weeds

Aromatic carbonyl thiourea PI-28 has been focused on as a lead compound for the developing radicle elongation inhibitors in germinating Orobanche minor dry seeds. In this study, we have synthesized PI-28 and its derivatives using commercially available phenols, 2-chloroacetamide, and aryl isothiocyanates. In this method, 2-aryloxyacetanilides, which are also attractive as bioactive compounds, were obtained as byproducts. These compounds were formed due to the loss of isothiocyanate moiety from the formed aromatic carbonyl thioureas

Iron-based catholytes for aqueous redox-flow batteries

Redox-flow batteries (RFBs) are promising electrochemical energy storage devices to load-level intermittent power from renewable energy. In particular, aqueous RFBs using aqueous electrolytes possess several advantages over nonaqueous ones, such as low fabrication cost, nontoxicity, safety, and environmental benignity. Therefore, developing high-performance, abundant, less-expensive iron-based catholytes for aqueous RFBs is essential toward their wide deployment in a power grid. In this Perspective, we summarize the recent progress of iron-based catholytes for aqueous RFBs. We emphasize that iron-based catholytes possess widely ranged redox potentials (−1.0 to 1.5 V vs standard hydrogen electrodes) and solubility in water (0.2–4.0 mol L−1), thereby providing a wide range of cell performance. The molecular design, such as ligand functionalization, counter ion mixing, and asymmetrization, allows for rationally improving solubility, redox potential, and energy density. Furthermore, we demonstrate a simple evaluation method of the redox potential of iron-based catholytes using the calculated energy levels of the lowest unoccupied molecular orbital of ligand molecules. Finally, we rationalize the design strategy of iron-based catholytes for advanced aqueous RFBs

Effect of Transition Metal Substitution on the Charge-Transfer Phase Transition and Ferromagnetism of Dithiooxalato-Bridged Hetero Metal Complexes, (<i>n</i>-C₃H₇)₄N[Fe^II_1−<i>x</i>Mn^II<i>_x</i>Fe^III(dto)₃]

The dithiooxalato-bridged iron mixed-valence complex (n-C3H7)4N[FeIIFeIII(dto)3] (dto = dithiooxalato) undergoes a novel charge-transfer phase transition (CTPT) accompanied by electron transfer between adjacent FeII and FeIII sites. The CTPT influences the ferromagnetic transition temperature according to the change of spin configuration on the iron sites. To reveal the mechanism of the CTPT, we have synthesized the series of metal-substituted complexes (n-C3H7)4N[FeII1-xMnIIxFeIII(dto)3] (x = 0&#8315;1) and investigated their physical properties by means of magnetic susceptibility and dielectric constant measurements. With increasing MnII concentration, x, MnII-substituted complexes show the disappearance of CTPT above x = 0.04, while the ferromagnetic phase remains in the whole range of x. These results are quite different from the physical properties of the ZnII-substituted complex, (n-C3H7)4N[FeII1-xZnIIxFeIII(dto)3], which is attributed to the difference of ion radius as well as the spin states of MnII and ZnII