Spin coherence phenomena of an = 1/2 copper(II) system in a polyoxometalate with a less-abundant nuclear spin.

The spin coherence phenomena of a system consisting of a mononuclear 3d transition metal = 1/2 centre embedded in a polyoxometalate with low nuclear-spin abundance, [(-CH)N]H[SiWOCuZn], have been revealed for the first time. Variable-temperature Hahn-echo experiments using the pulsed electron spin resonance technique showed that its coherence lifetime remains at the submicrosecond level even above 100 K.

Modulation of triplet quantum coherence by guest-induced structural changes in a flexible metal-organic framework.

Quantum sensing has the potential to improve the sensitivity of chemical sensing by exploiting the characteristics of qubits, which are sensitive to the external environment. Modulation of quantum coherence by target analytes can be a useful tool for quantum sensing. Using molecular qubits is expected to provide excellent sensitivity due to the proximity of the sensor to the target analyte.

Guest-responsive coherence time of radical qubits in a metal-organic framework.

Metal-organic frameworks (MOFs) integrated with molecular qubits are promising for quantum sensing. In this study, a new UiO-type MOF with a 5,12-diazatetracene (DAT)-containing ligand is synthesized, and the radicals generated in the MOF exhibit high stability and a relatively long coherence time () responsive to the introduction of various guest molecules.

Radical qubits photo-generated in acene-based metal-organic frameworks.

A series of metal-organic frameworks (MOFs) assembled with diazatetracene (DAT)-based linkers were synthesized and characterized. Despite different chromophore orientations and spacings, photoinduced persistent radicals were generated in all the MOFs, and their spin-lattice relaxation time () and spin-spin relaxation time () were found to be relatively long even at room temperature. The generality of long and values of photogenerated radicals in the chromophore-assembled MOFs provides a new platform towards quantum sensing applications.

Spin-Polarized Radicals with Extremely Long Spin-Lattice Relaxation Time at Room Temperature in a Metal-Organic Framework.

The generation of spin polarization is key in quantum information science and dynamic nuclear polarization. Polarized electron spins with long spin-lattice relaxation times () at room temperature are important for these applications but have been difficult to achieve. We report the realization of spin-polarized radicals with extremely long at room temperature in a metal-organic framework (MOF) in which azaacene chromophores are densely integrated.

Clarifying the Electronic Structure of Anion-Templated Silver Nanoclusters by Optical Absorption Spectroscopy and Theoretical Calculation.

Electronic structures of anion-templated silver nanoclusters (Ag NCs) are not well understood compared to conventional, template-free Ag NCs. In this study, we synthesized three new anion-templated Ag NCs, namely [S@Ag(S-4CBM)(PPh)], [S@Ag(S-4CBM)(PPh)], and [Cl@Ag(S-4CBM)(PPh)][PPh], where S-4CBM = 4-chlorobenzene methanethiolate, and single-crystal X-ray crystallography revealed that they have S@Ag, S@Ag, and Cl@Ag cores, respectively. Investigation of their electronic structures by optical spectroscopy and theoretical calculations elucidated the following unique features: (1) their electronic structures are different from those of template-free Ag NCs described by the superatomic concept; (2) optical absorption in the range of 550-400 nm for S-templated Ag NCs is attributed to the charge transitions from S-templated Ag-cage orbitals to the s-shaped orbital in the S moiety; (3) the Cl-templated Ag NCs can be viewed as [Cl@Ag(S-4CBM)(PPh)][PPh] rather than the ion pair [Cl@Ag(S-4CBM)(PPh)][PPh]; and (4) singlet-coupled singly occupied orbitals are involved in the optical absorption of the Cl-templated Ag NC.

Supervalence Bonding in Bi-icosahedral Cores of [MAu(SCHPh)] (M = Pd and Pt): Fusion-Mediated Synthesis and Anion Photoelectron Spectroscopy.

Au(PET) (PET = SCHPh) is known to have a bi-icosahedral Au core consisting of two Au icosahedrons by sharing three Au atoms. Previous theoretical studies based on a supervalence bond (SVB) model have demonstrated that the bonding scheme in the Au core is similar to that in the F molecule. The SVB model predicted that the electron configuration of the Au core with 14 valence electrons is expressed as (1Σ)(1Σ*)(1Π)(2Σ)(1Π*) where each orbital is created by the bonding and antibonding interactions between the 1S and 1P superatomic orbitals of the icosahedral Au units.

Pressure-Induced Superconductivity of the Quasi-One-Dimensional Organic Conductor (TMTTF)TaF.

We investigated the superconductivity of (TMTTF)TaF (TMTTF: tetramethyl-tetrathiafulvalene) by conducting resistivity measurements under high pressure up to 8 GPa. A cubic anvil cell (CAC) pressure generator, which can produce hydrostatic high-pressure, was used for this study. Since the generalized temperature-pressure (-) diagram of (TMTF) ( = Se, S, : monovalent anion) based on (TMTTF)PF ( = 70 K and spin-Peierls: SP, = 15 K) was proposed by Jérome, exploring superconductivity states using high-pressure measurement beyond 4 GPa has been required to confirm the universality of the electron-correlation variation under pressure in (TMTTF) (TMTTF)TaF, which has the largest octahedral-symmetry counter anion TaF in the (TMTTF) series, possesses the highest charge-ordering (CO) transition temperature ( = 175 K) in (TMTTF) and demonstrates an anti-ferromagnetic transition ( = 9 K) at ambient pressure.

Conformational ensemble of a multidomain protein explored by Gd electron paramagnetic resonance.

Despite their importance in function, the conformational state of proteins and its changes are often poorly understood, mainly because of the lack of an efficient tool. MurD, a 47-kDa protein enzyme responsible for peptidoglycan biosynthesis, is one of those proteins whose conformational states and changes during their catalytic cycle are not well understood. Although it has been considered that MurD takes a single conformational state in solution as shown by a crystal structure, the solution nuclear magnetic resonance (NMR) study suggested the existence of multiple conformational state of apo MurD in solution.

Tetramethyltetrathiafulvalene [(NbOF)]: One-Dimensional Charge Transfer Salt with an Infinite Anion Chain.

An unusual valence one-dimensional (1D) molecular charge transfer salt (TMTTF)(NbOF) [TMTTF = tetramethyltetrathiafulvalene] with infinite anion chains was prepared. To understand the crystal structure and electronic states of the (TMTTF)(NbOF) salt, we performed synchrotron X-ray diffraction, electron spin resonance, and static magnetization measurements. There is only one independent TMTTF molecule in the unit cell of (TMTTF)(NbOF).

Controlled Dimerization and Bonding Scheme of Icosahedral M@Au (M=Pd, Pt) Superatoms.

Targeted syntheses of MM'Au (PET) (M, M'=Pd, Pt; PET=SC H Ph) were achieved by hydride-mediated fusion reactions between [MAu (PPh ) ] and [M'Au (PET) ] . Single-crystal X-ray diffraction analysis indicated that the products have bi-icosahedral MM'Au cores composed of M@Au and M'@Au superatoms. Although the MM'Au superatomic molecules correspond to O in terms of the number of valence electrons (12 e), the distances between the icosahedrons were larger than that in the bi-icosahedral Au core of Au (PET) corresponding to F and the spin state was singlet.

Understanding Doping Effects on Electronic Structures of Gold Superatoms: A Case Study of Diphosphine-Protected M@Au (M = Au, Pt, Ir).

Dopants into ligand-protected Au superatoms have been hitherto limited to group X-XII elements (Pt, Pd, Ag, Cu, Hg, and Cd). To expand the scope of the dopants to the group IX elements, we synthesized unprecedented [IrAu(dppe)Cl] [; dppe = 1,2-bis(diphenylphosphino)ethane] and [PtAu(dppe)Cl] () and compared their electronic structures with that of [Au(dppe)Cl] (). Single-crystal X-ray diffractometry, P{H} NMR, and Ir L-edge extended X-ray absorption fine structure analysis of revealed that the single Ir atom is located at the center of the icosahedral IrAu core.

A Peptoid with Extended Shape in Water.

The term "peptoids" was introduced decades ago to describe peptide analogues that exhibit better physicochemical and pharmacokinetic properties than peptides. Oligo(-substituted glycine) (oligo-NSG) was previously proposed as a peptoid due to its high proteolytic resistance and membrane permeability. However, oligo-NSG is conformationally flexible, and ensuring a defined shape in water is difficult.

Stoichiometric Formation of Open-Shell [PtAu(SCHPh)] via Spontaneous Electron Proportionation between [PtAu(SCHPh)] and [PtAu(SCHPh)].

[PtAu(SCHPh)] () was fully and selectively converted to , having an open electronic structure with seven valence electrons, upon the addition of an equiamount of NaBH. Stoichiometric production of by the reaction between an equal amount of and revealed that the above reaction proceeds via the spontaneous electron transfer (ET) from nascently reduced by H-mediated reduction to remaining in the solution. Theoretical calculation suggested that the driving force of this novel ET reaction was the larger adiabatic electron affinity of compared to that of , partly associated with reduction-induced relief of the Jahn-Teller strain.

Bacterial Fermentation of Water-Soluble Cellulose Acetate Raises Large-Bowel Acetate and Propionate and Decreases Plasma Cholesterol Concentrations in Rats.

We hypothesized that water-soluble cellulose acetate (WSCA) could be useful tool for the delivery of short-chain fatty acids to the large intestine. Rats were fed a control diet or a diet containing graded levels of WSCA for up to 21 days. Consuming WSCA dose-dependently increased large-bowel acetate and propionate concentrations through the bacterial fermentation.

HGF induces the serine‑phosphorylation and cell surface translocation of ROMK (Kir 1.1) channels in rat kidney cells.

Extracellular potassium homeostasis is dependent on the activity of potassium channels, which are expressed on the apical membrane of epithelial tubular cells. The renal outer medullary potassium channel (ROMK) is considered to be the major route for potassium transport into the tubule lumen. Hepatocyte growth factor (HGF) exerts multiple biological activities and is important for maintaining renal homeostasis.

Successive Dimensional Transition in (TMTTF)_{2}PF_{6} Revealed by Synchrotron X-ray Diffraction.

A quasi-one-dimensional organic charge-transfer salt (TMTTF)_{2}PF_{6} undergoes a multistep phase transition as the temperature decreases. One of these transitions is called a "structureless transition," and these detailed structures were unknown for many years. With synchrotron x-ray diffraction, we observed a slight structural difference owing to the effect of charge-order transition between two TMTTF molecules in a dimer, which corresponds to the charge transfer δ_{CO}=0.

Two-dimensional sp carbon-conjugated covalent organic frameworks.

We synthesized a two-dimensional (2D) crystalline covalent organic framework (spc-COF) that was designed to be fully π-conjugated and constructed from all sp carbons by C=C condensation reactions of tetrakis(4-formylphenyl)pyrene and 1,4-phenylenediacetonitrile. The C=C linkages topologically connect pyrene knots at regular intervals into a 2D lattice with π conjugations extended along both and directions and develop an eclipsed layer framework rather than the more conventionally obtained disordered structures. The spc-COF is a semiconductor with a discrete band gap of 1.

Tryptophan-2,3-Dioxygenase (TDO) deficiency is associated with subclinical neuroprotection in a mouse model of multiple sclerosis.

The catabolism of tryptophan to immunosuppressive and neuroactive kynurenines is a key metabolic pathway regulating immune responses and neurotoxicity. The rate-limiting step is controlled by indoleamine-2,3-dioxygenase (IDO) and tryptophan-2,3-dioxygenase (TDO). IDO is expressed in antigen presenting cells during immune reactions, hepatic TDO regulates blood homeostasis of tryptophan and neuronal TDO influences neurogenesis.

Negative Impact of Hypoxia on Tryptophan 2,3-Dioxygenase Function.

Tryptophan is an essential amino acid for hosts and pathogens. The liver enzyme tryptophan 2,3-dioxygenase (TDO) provokes, by its ability to degrade tryptophan to N-formylkynurenine, the precursor of the immune-relevant kynurenines, direct and indirect antimicrobial and immunoregulatory states. Up to now these TDO-mediated broad-spectrum effector functions have never been observed under hypoxia in vitro, although physiologic oxygen concentrations in liver tissue are low, especially in case of infection.

Tryptophan 2,3-dioxygenase and indoleamine 2,3-dioxygenase 1 make separate, tissue-specific contributions to basal and inflammation-induced kynurenine pathway metabolism in mice.

Background: In mammals, the majority of the essential amino acid tryptophan is degraded via the kynurenine pathway (KP). Several KP metabolites play distinct physiological roles, often linked to immune system functions, and may also be causally involved in human diseases including neurodegenerative disorders, schizophrenia and cancer. Pharmacological manipulation of the KP has therefore become an active area of drug development.

The hepatocyte growth factor antagonist NK4 inhibits indoleamine-2,3-dioxygenase expression via the c-Met-phosphatidylinositol 3-kinase-AKT signaling pathway.

Indoleamine-2,3-dioxygenase (IDO) is an immunosuppressive enzyme involved in tumor malignancy. However, the regulatory mechanism underlying its involvement remains largely uncharacterized. The present study aimed to investigate the hypothesis that NK4, an antagonist of hepatocyte growth factor (HGF), can regulate IDO and to characterize the signaling mechanism involved.

Identification of Turbid Compounds Generated in Sugarcane Vinegar.

Sugarcane vinegar is produced in various countries of southern Asia. It is also a niche product of the Kagoshima and Okinawa Prefectures in Japan. Turbid compounds are sometimes found in sugarcane vinegar, thereby lowering the market value.