Modular Design of Highly Stable Semiconducting Porous Coordination Polymer for Efficient Electrosynthesis of Ammonia.

Developing highly stable porous coordination polymers (PCPs) with integrated electrical conductivity is crucial for advancing our understanding of electrocatalytic mechanisms and the structure-activity relationship of electrocatalysts. However, achieving this goal remains a formidable challenge because of the electrochemical instability observed in most PCPs. Herein, we develop a "modular design" strategy to construct electrochemically stable semiconducting PCP, namely, Fe-pyNDI, which incorporates a chain-type Fe-pyrazole metal cluster and π-stacking column with effective synergistic effects. The three-dimensional electron diffraction (3D ED) technique resolves the precise structure. Both theoretical and experimental investigation confirms that the π-stacking column in Fe-pyNDI can provide an efficient electron transport path and enhance the structural stability of the material. As a result, Fe-pyNDI can serve as an efficient model electrocatalyst for nitrate reduction reaction (NO3RR) to ammonia with a superior ammonia yield of 339.2 µmol h-1 cm-2 (14677 µg h-1 mgcat. -1) and a faradaic efficiency of 87 % at neutral electrolyte, which is comparable to state-of-the-art electrocatalysts. The in-situ X-ray absorption spectroscopy (XAS) reveals that during the reaction, the structure of Fe-pyNDI can be kept, while part of the Fe3+ in Fe-pyNDI was reduced in situ to Fe2+, which serves as the potential active species for NO3RR.

Fine Pore-Structure Engineering by Ligand Conformational Control of Naphthalene Diimide-Based Semiconducting Porous Coordination Polymers for Efficient Chemiresistive Gas Sensing.

Exploring new porous coordination polymers (PCPs) that have tunable structure and conductivity is attractive but remains challenging. Herein, fine pore structure engineering by ligand conformation control of naphthalene diimide (NDI)-based semiconducting PCPs with π stacking-dependent conductivity tunability is achieved. The π stacking distances and ligand conformation in these isoreticular PCPs were modulated by employing metal centers with different coordination geometries. As a result, three conjugated PCPs (Co-pyNDI, Ni-pyNDI, and Zn-pyNDI) with varying pore structure and conductivity were obtained. Their crystal structures were determined by three-dimensional electron diffraction. The through-space charge transfer and tunable pore structure in these PCPs result in modulated selectivity and sensitivity in gas sensing. Zn-pyNDI can serve as a room-temperature operable chemiresistive sensor selective to acetone.

Ultrasmall Copper Nanoclusters in Zirconium Metal-Organic Frameworks for the Photoreduction of CO2.

Encapsulating ultrasmall Cu nanoparticles inside Zr-MOFs to form core-shell architecture is very challenging but of interest for CO2 reduction. We report for the first time the incorporation of ultrasmall Cu NCs into a series of benchmark Zr-MOFs, without Cu NCs aggregation, via a scalable room temperature fabrication approach. The Cu NCs@MOFs core-shell composites show much enhanced reactivity in comparison to the Cu NCs confined in the pore of MOFs, regardless of their very similar intrinsic properties at the atomic level. Moreover, introducing polar groups on the MOF structure can further improve both the catalytic reactivity and selectivity. Mechanistic investigation reveals that the CuI sites located at the interface between Cu NCs and support serve as the active sites and efficiently catalyze CO2 photoreduction. This synergetic effect may pave the way for the design of low-cost and efficient catalysts for CO2 photoreduction into high-value chemical feedstock.

Coexistence of Two Types of Spin Splitting Originating from Different Symmetries.

The symmetry of a surface or interface plays an important role in determining the spin splitting and texture of a two-dimensional band. Spin-polarized bands of a triangular lattice atomic layer (TLAL) consisting of Sn on a SiC(0001) substrate is investigated by spin- and angle-resolved photoelectron spectroscopy. Surprisingly, both Zeeman- and Rashba-type spin-split bands, without and with spin degeneracy, respectively, coexist at a K point of the Sn TLAL. The K point has a threefold symmetry without inversion symmetry according to the crystal structure including the SiC periodicity, meaning that the Zeeman-type is consistent with the symmetry of the lattice while the Rashba-type is inconsistent. Our density functional calculations reveal that the charge density distribution of the Rashba-type (Zeeman-type) band shows (no) inversion symmetry at the K point. Therefore, the symmetry of the charge density distribution agrees with both types of the spin splitting.

Modulation of Electron-Phonon Coupling in One-Dimensionally Nanorippled Graphene on a Macrofacet of 6H-SiC.

Local electron-phonon coupling of a one-dimensionally nanorippled graphene is studied on a SiC(0001) vicinal substrate. We have characterized local atomic and electronic structures of a periodically nanorippled graphene (3.4 nm period) prepared on a macrofacet of the 6H-SiC crystal using scanning tunneling microscopy/spectroscopy (STM/STS) and angle-resolved photoelectron spectroscopy (ARPES). The rippled graphene on the macrofacets distributes homogeneously over the 6H-SiC substrate in a millimeter scale, and thus replica bands are detected by the macroscopic ARPES. The STM/STS results indicate the strength of electron-phonon coupling to the out-of-plane phonon at the K̅ points of graphene is periodically modified in accordance with the ripple structure. We propose an interface carbon nanostructure with graphene nanoribbons between the surface rippled graphene and the substrate SiC that periodically modifies the electron-phonon coupling in the surface graphene.

Catalytic Hydride Transfer to CO2 Using Ru-NAD-Type Complexes under Electrochemical Conditions.

The catalytic performance of Ru-NAD-type complexes [Ru(tpy)(pbn)(CO)]2+ ([1]2+; tpy = 2,2';6',2″-terpyridine; pbn = 2-(pyridin-2-yl)benzo[b][1,5]naphthyridine) and the Ru-CO-bridged metallacycle [2]+ was investigated in the context of the electrochemical reduction of CO2 in H2O/CH3CN at room temperature. A controlled-potential electrolysis of [1]2+ and [2]+ afforded formate (HCOO-) as the main product, under concomitant formation of minor amounts of CO and H2. Metallacycle [2]+ showed a higher selectivity toward the formation of HCOO- than [1]2+ (HCOO-/CO for [1]2+, 2.7; HCOO-/CO for [2]+, 7). The generation of HCOO- via a catalytic hydride transfer from the NADH-type ligands of [1]2+ and [2]+ to CO2 was supported by the experimental results and a comparison with the reduction of CO2 catalyzed by [Ru(tpy)(bpy)(CO)]2+ under similar conditions. A mechanism for the catalytic reduction of CO2 by [1]2+ and [2]+ was proposed based on the experimental evidence. The thus-obtained results may help to expand the field of NADH-assisted reduction reactions.

Light Lanthanide Complexes with Crown Ether and Its Aza Derivative Which Show Slow Magnetic Relaxation Behaviors.

Two sets of isostructural Ln(III) mononuclear complexes, [Ln(NO3)3(18-crown-6)] (Ln = Ce (1), Pr (2), and Nd (3)) and [Ln(NO3)3(1,10-diaza-18-crown-6)] (Ln = Ce (4), Pr (5), and Nd (6)), were synthesized, and their slow magnetic relaxation behavior was investigated. Since Ln(III) ions are located in an axially stressed ligand field in both sets of complexes, they can exhibit single-molecule magnet (SMM) behavior owing to the oblate-type electronic distributions of the ground sublevels found in Ce(III), Pr(III), and Nd(III). Field-induced slow magnetic relaxation was observed for Ce(III) and Nd(III) complexes 1, 3, 4, and 6 under an applied bias dc field of 1000 Oe, whereas no slow relaxation was observed for Pr(III) complexes 2 and 5. The slow magnetic relaxation behavior of 1, 3, 4, and 6 was correlated with the even-numbered Jz sublevels of Ce(III) and Nd(III) ions, known as the Kramers system.

Pancreas volume reduction and metabolic effects in Japanese patients with severe obesity following laparoscopic sleeve gastrectomy.

This study aimed to assess the relationship between the metabolic effect after laparoscopic sleeve gastrectomy (LSG) in morbidly obese Japanese patients, with or without type 2 diabetes mellitus (T2DM), and improved pancreatic steatosis (PS). The study enrolled 27 morbidly obese Japanese patients who were undergoing LSG. Their clinical and metabolic effects were evaluated at baseline and six months after LSG. Pancreas volume (PV), pancreatic attenuation (PA), and splenic attenuation (SA) were measured using a 64-row computed tomography (CT). Changes in PV, PA-SA, and PA/SA were evaluated. The mean body-weight loss, body mass index loss, and percentage of excess weight loss (%EWL) were -34.4 kg (p < 0.001), -11.0 kg/m2 (p < 0.001), and 43.7%, respectively. The mean PV was 96.7 mL at baseline, and it decreased six months after LSG (-16.3mL, p < 0.001). The mean PA significantly increased six months after LSG (9.5 HU, p < 0.001). PA-SA (-23.2 HU vs. -13.3 HU, p = 0.003), and PA/SA (0.54 vs. 0.73, p < 0.001) also significantly increased six months after LSG. In T2DM patients, decreased PV correlated with decreased fasting blood sugar, decreased insulin, and reduced liver volume. In conclusion, PV significantly decreased after LSG in morbidly obese Japanese patients, and that decrease correlated with improvements in PS. In addition, PS plays an important role of development and progression of insulin resistance and T2DM.

A Holmium(III)-Based Single-Molecule Magnet with Pentagonal-Bipyramidal Geometry.

The right environment: The remarkable properties of a recently reported holmium(III)-based single-ion magnet have been ascribed to the hyperfine interactions with the half-integer nuclear spin in combination with the pentagonal-bipyramidal coordination environment. These results provide insight into the complicated magnetic properties of nanosized magnetic materials.

Photochemical Reduction of Low Concentrations of CO2 in a Porous Coordination Polymer with a Ruthenium(II)-CO Complex.

Direct use of low pressures of CO2 as a C1 source without concentration from gas mixtures is of great interest from an energy-saving viewpoint. Porous heterogeneous catalysts containing both adsorption and catalytically active sites are promising candidates for such applications. Here, we report a porous coordination polymer (PCP)-based catalyst, PCP-Ru(II) composite, bearing a Ru(II) -CO complex active for CO2 reduction. The PCP-Ru(II) composite showed improved CO2 adsorption behavior at ambient temperature. In the photochemical reduction of CO2 the PCP-Ru(II) composite produced CO, HCOOH, and H2 . Catalytic activity was comparable with the corresponding homogeneous Ru(II) catalyst and ranks among the highest of known PCP-based catalysts. Furthermore, catalytic activity was maintained even under a 5 % CO2 /Ar gas mixture, revealing a synergistic effect between the adsorption and catalytically active sites within the PCP-Ru(II) composite.

A systematic study on the stability of porous coordination polymers against ammonia.

To establish a strategy for designing porous coordination polymers (PCPs) for ammonia capture, the first systematic study on the stability of PCPs against ammonia was conducted. Various types of PCPs were investigated by comparing their powder XRD patterns before and after treatment with ammonia. Among the PCPs tested, ZIF-8, MIL-53(Al), Al-BTB, MOF-76(M) (M=Y or Yb), MIL-101(Cr), and MOF-74(Mg) were stable up to 350 °C under an ammonia atmosphere at ambient pressure. The origin of the stability of PCPs is discussed from the viewpoint of their components, metal cations, and organic linkers. Furthermore, adsorption isotherm measurements show that the adsorptive behavior of PCPs is independent of their stability.

[An adult case of tricuspid valve endocarditis with ventricular septal defect; report of a case].

A 50-year-old man was admitted to hospital because of an elevated fever. He had been diagnosed with ventricular septal defect in his childhood, but surgery had not been recommended. An echocardiogram showed vegetations on the tricuspid valve, severe tricuspid regurgitation and perimembranous ventricular septal defect. He was diagnosed with infective endocarditis( IE) and treated with antibiotics and diuretics. Five serious dental caries, which had probably caused IE, were found and extracted before surgery. After 4 weeks of medical treatment, we performed tricuspid valve repair and closed the ventricular septal defect. The postoperative course was uneventful. He has been free from any complication for over 3 years.

Molecular elastic crystals exhibiting slow magnetic relaxations.

We report an elastic crystal of a copper(II) porphyrinato complex that exhibits slow magnetic relaxations and is a promising candidate for an external-force-responsive spin qubit.

Width-dependent band gap of arm-chair graphene nanoribbons formed on vicinal SiC substrates by MBE.

Formation and electronic states of graphene nanoribbons with arm-chair edges (AGNR) are studied on the SiC(0001) vicinal surfaces toward the [11-00] direction. The surface step and terrace structures of both 4H and 6H-SiC substrates are used as the growth templates of one-dimensional arrays of AGNRs, which are prepared using the carbon molecular beam epitaxy followed by hydrogen intercalation. A band gap is observed above theπ-band maximum by angle-resolved photoelectron spectroscopy (ARPES) for the both samples. The average widths of the AGNRs are 6 and 10 nm, and the estimated average band gaps are 0.40 and 0.28 eV for the 4H- and 6H- substrates, respectively. A simple and phenomenological inverse relation between the energy gap and AGNR width works in the analyses of the ARPES data.

Photoinduced Catalytic Organic-Hydride Transfer to CO2 Mediated with Ruthenium Complexes as NAD+ /NADH Redox Couple Models.

The catalytic organic-hydride transfer to CO2 was first achieved through the photoinduced two-electron reduction of the [Ru(bpy)2 (pbn)]2+ /[Ru(bpy)2 (pbnHH)]2+ (bpy=2,2'-bipyridine, pbn=2-(pyridin-2-yl)benzo[b]-1,5-naphthyridine, and pbnHH=2-(pyridin-2-yl)-5,10-dihydrobenzo[b]-1,5-naphthyridine) redox couple in the presence of 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH). The active species for the catalytic hydride transfer to carbon dioxide giving formate is [Ru(bpy)(bpy⋅- )(pbnHH)]+ formed by one-electron reduction of [Ru(bpy)2 (pbnHH)]2+ with BI⋅.

Wheel-shaped icosanuclear homo- and heterometallic complexes of Ni(II), Co(II), and Cu(II) ions supported by unsymmetrical aminoalcohol ligands.

Reactions of M(OAc)2·4H2O (M = Ni, Co) with 3-[benzyl(2-hydroxyethyl)amino]-1-propanol (H2L) in the presence of pyridine or triethylamine afforded novel homometallic icosanuclear wheel-shaped complexes [M20L4(HL)4(OAc)28] (M = Ni (1), Co (2)), which consist of a central M(II)12 single-stranded, nearly planar loop with four peripheral [M2(HL)(OAc)2] fragments attached in an S4 symmetrical fashion. The complexes can alternatively be recognized as saddle-shaped wheel structures, in which four tetranuclear units of [M4L(HL)(OAc)7](2-) are connected by four M(2+) ions (M5). The tetranuclear unit itself can be derived from an ideal C2 symmetrical [M4(HL)2(µ-η(2)-OAc)4(µ-η(1),η(1)-OAc)2(η(1),η(1)-OAc)](-) structure through deprotonation of the HL(-) ligand, and is composed of two plane-shared M3O4 incomplete cubanes in which the M2 and M3 atoms are involved in the central fused plane and the M1 and M4 atoms are disposed at the apex sites. Mixed-metal icosanuclear complexes [NixM20-xL4(HL)4(OAc)28] (3, M = Co, x = 9.5) and [Ni12M8L4(HL)4(OAc)28] (4, M = Cu) were also synthesized by using equimolar amounts of Ni(II) and M(II) ions, and were shown to have similar structures to 1 and 2. X-ray crystallographic and fluorescent analyses revealed that complex 3 contains nonstoichiometric amounts of Ni(2+) and Co(2+) ions in the ratio of 9.5:10.5 and that these are disordered at every metal site. In striking contrast, complex 4 has a stoichiometric formula of Ni12Cu8, which was confirmed by the Jahn-Teller elongation of Cu(2+) ions, and consequently, the M2 and M5 positions are occupied exclusively by the Cu(2+) ions. The temperature-dependent direct current (dc) magnetic susceptibility data showed the presence of ferromagnetic exchange interactions in the Ni homometallic (1) and NiCu bimetallic (4) complexes, while the Co homometallic (2) and NiCo bimetallic (3) complexes exhibited antiferromagnetic interactions due to spin-orbit coupling effects of the octahedral Co(II) ions. The present results demonstrate that the unsymmetrical aminoalcohol ligand H2L is quite effective in organizing the homo- and heterometallic icosanuclear wheel-shaped metal arrangements.

Different susceptibility to insulin resistance and fatty liver depending on the combination of TNF-α C-857T and adiponectin G+276T gene polymorphisms in Japanese subjects with type 2 diabetes.

The C-857T promoter polymorphism of TNF-α gene is associated with obese type 2 diabetes, while the adiponectin G+276T gene polymorphism in intron 2 may influence the fat accumulation in the liver. In this study, we examined effects of these polymorphisms on clinical markers of insulin resistance and fatty liver (a liver/spleen CT ratio < 0.9). These polymorphisms were determined in 342 Japanese subjects with type 2 diabetes. The liver/spleen CT ratio was lower in the subjects with the adiponectin +276G/G genotype than that in the subjects with the +276T allele (P < 0.05), indicating that fat accumulation in the liver is associated with the +276G/G genotype. Multiple comparisons among the 4 combinations of each polymorphism of the TNF-α and adiponectin genes revealed a significant difference in the liver/spleen CT ratio (P < 0.05) among the 4 groups, indicating that the gene combinations influence the degree of fat accumulation in the liver. The subjects carrying the TNF-α -857T allele (C/T or T/T genotype) and the adiponectin +276G/G genotype had greater risks for fatty liver and insulin resistance that was evaluated by higher levels of fasting insulin and homeostasis model assessment of insulin resistance, as compared with the other groups. Therefore, Japanese subjects with the TNF-α -857T allele and the adiponectin +276G/G genotype may be more susceptible to insulin resistance and fatty liver. The present study provides the evidence for the interaction between TNF-α and adiponectin genes in the insulin resistance and fatty liver in Japanese subjects with type 2 diabetes.

Rotating magnetocaloric effect in highly anisotropic TbIII and DyIII single molecular magnets.

The magnetocaloric effect (MCE) was investigated in highly anisotropic single crystals of two single molecule magnets (SMMs): [LnIII(ZnIIL)2]CF3SO3, where Ln = Tb, Dy and L = tripodal hexadentate Schiff base ligand. The structure of these paramagnetic compounds consists of identically oriented linear trinuclear clusters in a trigonal system with an easy direction c∥Zn-Ln-Zn array and a hard plane ab⊥Zn-Ln-Zn array. The magnitude of MCE measured for c∥H was significantly greater than MCE for ab∥H at a wide temperature range regardless of the studied SMM. Therefore, the rotating magnetocaloric effect (RMCE) was evaluated. The maxima of the magnetic entropy change for RMCE were obtained at 2.0 K and moderate fields: 3.9 J K-1 kg-1 at µ0H = 1.3 T for Ln = Tb and 3.3 J K-1 kg-1 at µ0H = 1.1 T for Ln = Dy. The relative efficiency of RMCE compared to the MCE measured in c∥H was as high as 99% at low magnetic fields.

Serum CXCL1 concentrations are elevated in type 1 diabetes mellitus, possibly reflecting activity of anti-islet autoimmune activity.

BACKGROUND: Identification of unique inflammatory markers may facilitate prediction of type 1 diabetes mellitus (T1DM). We previously compared transcript profiles of bone marrow-derived dendritic cells from non-obese diabetic mice with those from non-obese non-diabetic mice and found that bone marrow-derived dendritic cells' expressions of inflammatory mediators, including chemokine (C-X-C motif) ligand 1 (CXCL1), were three to five times higher in 4-week-old female non-obese diabetic mice than in non-obese non-diabetic mice. In humans, microarray analysis results have suggested this chemokine be a biomarker representing active anti-islet autoimmunity. We investigated whether serum CXCL1 levels, reflecting active autoimmune processes, might serve as biomarkers for T1DM. METHODS: The study groups consisted of 26 subjects with acute-onset T1DM, 20 with slowly progressive T1DM, and 20 with type 2 diabetes mellitus as disease controls. All subjects were Japanese. CXCL1 in sera were quantified by solid phase enzyme-linked immunosorbent assays. RESULTS: Serum CXCL1 levels were significantly higher in subjects with acute-onset [median 113.2 ng/mL (41.75-457.2)] or slowly progressive [median 100.8 ng/mL (32.87-225.0)] T1DM than in those with type 2 diabetes mellitus [median 71.58 ng/mL (32.45-152.6), p=0.01 and 0.03, respectively, Mann-Whitney U-test]. Decreases in fasting C-peptide levels per year correlated significantly with CXCL1 levels (n=11, r2=0.524, p=0.012) in a subpopulation of slowly progressive T1DM subjects displaying preserved beta-cell function. CONCLUSIONS: To our knowledge, this is the first study to show elevated serum CXCL1 in T1DM subjects, regardless of diabetes subtype, as compared to control type 2 diabetes mellitus subjects. We propose serum CXCL1 elevation to be a good T1DM marker, possibly indicating a predisposition to autoimmune disease development.

Structural design of easy-axis magnetic anisotropy and determination of anisotropic parameters of Ln(III)-Cu(II) single-molecule magnets.

Four dinuclear Ln(III)-Cu(II) complexes with Ln=Tb (1), Dy (2), Ho (3), and Er (4) were synthesized to investigate the relationship between their respective magnetic anisotropies and ligand-field geometries. These complexes were crystallographically isostructural, and a uni-axial ligand field was achieved by using three phenoxo oxygen groups. Complexes 1 and 2 displayed typical single-molecule magnet (SMM) behaviors, of which the out-of-phase susceptibilities were observed in the temperature range of 1.8-5.0 K (1) and 1.8-20.0 K (2). The Cole-Cole plots exhibited a semicircular shape with α parameters in the range of 0.08-0.18 (2.6-4.0 K) and 0.07-0.24 (3.5-7.0 K). The energy barriers Δ/k(B) were estimated from the Arrhenius plots to be 32.9(4) K for 1 and 26.0(5) K for 2. Complex 3 displayed a slow magnetic relaxation below 3.0 K, whereas complex 4 did not show any frequency-dependent behavior for both in-phase and out-of-phase susceptibilities, which indicates that easy-axis anisotropy was absent. The temperature dependence of the dc susceptibilities for the field-aligned samples of 1-3 revealed that the χ(M) T value continuously increased as the temperature was lowered, which indicates the presence of low-lying Stark sublevels with the highest |J(z) | values. In contrast, complex 4 displayed a smaller and temperature-independent χ(M) T value, which also indicates that easy-axis anisotropy was absent. Simultaneous analyses were carried out for 1-3 to determine the magnetic anisotropy parameters on the basis of the Hamiltonian that considers B(2) (0) , B(4) (0) , and B(6) (0) .