Switching of energy transfer reaction by the control of orientation factor between porphyrin derivatives on the clay surface

Photochemical energy transfer was examined on the flat clay surface. By the change of surrounding atmosphere, the molecular adsorption orientation angle of dyes can be modulated. It is turned out that the energy transfer efficiency between dyes can be controlled by the relative orientation change between dyes. The change of orientation factor and spectral overlap factor was the main factor to affect the energy transfer efficiency. This technique would be useful to construct the photo-functional materials such as chromic and light harvesting system.     

Anharmonicity and quantum effects in thermal expansion of an Invar alloy

We have investigated the anharmonicity and quantum effects in the Invar alloy Fe(64.6)Ni(35.4) that shows anomalously small thermal expansion. We have performed Fe and Ni K-edge extended x-ray-absorption fine-structure spectroscopic measurements and the computational simulations based on the path-integral effective-classical-potential theory. The first nearest-neighbor (NN) shells around Fe show almost no thermal expansion, while those around Ni exhibit meaningful but smaller expansion than that of fcc Ni. At low temperature, the quantum effect is found to play an essentially important role, which is confirmed by comparing the quantum-mechanical simulations to the classical ones. The anharmonicity (asymmetric distribution) clearly exists for all the first NN shells as in normal thermal expansion systems, implying the breakdown of the direct correspondence between thermal expansion and anharmonicity.     

[NiFe]Hydrogenase from Citrobacter sp. S‐77 Surpasses Platinum as an Electrode for H2 Oxidation Reaction

Reported herein is an electrode for dihydrogen (H₂) oxidation, and it is based on [NiFe]Hydrogenase from Citrobacter sp. S‐77 ([NiFe]_S77). It has a 637 times higher mass activity than Pt (calculated based on 1 mg of [NiFe]_S77 or Pt) at 50 mV in a hydrogen half‐cell. The [NiFe]_S77 electrode is also stable in air and, unlike Pt, can be recovered 100 % after poisoning by carbon monoxide. Following characterization of the [NiFe]_S77 electrode, a fuel cell comprising a [NiFe]_S77 anode and Pt cathode was constructed and shown to have a a higher power density than that achievable by Pt.     

A natural protecting group strategy to carry an amino acid starter unit in the biosynthesis of macrolactam polyketide antibiotics

Macrolactam antibiotics are an important class of macrocyclic polyketides that contain a unique nitrogen-containing starter unit. In the present study, a set of starter biosynthetic enzymes in the macrolactam antibiotic vicenistatin was characterized. We found that the protection-deprotection strategy of the aminoacyl-ACP intermediate was critical in this system. On the basis of bioinformatics, the described pathway is also proposed as a common method for carrying amino acids in the biosynthesis of other macrolactam antibiotics.     

Radiolanthanide-labeled HA particles in the treatment of rheumatoid arthritis: ready-to-use cold kits for rapid formulation in hospital radiopharmacy

Hydroxyapatite (HA) [Ca₁₀(PO₄)₆(OH)₂] particles radiolabeled with a variety of β^? emitting lanthanide radionuclides and also pseudolanthanide ⁹⁰Y have been proposed for the treatment of arthritis. A ready-to-use cold kit of HA particles (1–10 µm size) was developed for fast and convenient formulation of radiolanthanide-labeled HA particles at hospital radiopharmacy. Six radionuclides namely, ¹⁶⁹Er, ¹⁷⁷Lu, ¹⁵³Sm, ¹⁶⁶Ho, ¹⁴²Pr and ⁹⁰Y, having β^? emissions of a wide range of energy [E_β(max) = 0.34–2.28 MeV] were identified and produced by thermal neutron activation. Clinical doses of HA particles labeled with these radionuclides were prepared in high yield (>97 %) and radiochemical purity (>99 %) using the cold kits. Pre-clinical studies of ¹⁷⁷Lu–HA carried out in Wistar rats bearing arthritis in knee joints revealed no leakage of the activity from the joints. In preliminary clinical investigation using 333 ± 46 MBq doses of the same preparation, significant improvement in the disease conditions was reported in patients with chronic rheumatoid arthritis of knee joints.     

Optimisation of the analytical method for octa-, nona- and deca-brominated diphenyl ethers using gas chromatography–quadrupole mass spectrometry and isotope dilution

An analytical method for higher brominated congeners of polybrominated diphenyl ethers (PBDEs) was optimised using a gas chromatograph equipped with an electron impact ionisation-quadrupole mass spectrometer (GC-EI-qMS) and five native PBDEs and three ¹³C₁₂-labelled congeners in biological and environmental samples (mussels, sediment, dust). In the optimised instrumental conditions, abundance and repeatability improved with increase in temperature of the ion source. The instrumental detection limits (IDLs) for BDE-196, BDE-197, BDE-206, BDE-207 and BDE-209 were 0.1, 0.1, 0.2, 0.3 and 0.6?pg, respectively. When compared to the previous reports, the IDLs were the same as for electron capture negative ionisation (ECNI) or EI-double focusing magnetic sector (EI-Sector) mass spectrometer, indicating that sensitive determination could be achieved using a conventional GC-EI-qMS. Validation of the method was carried out by the analysis of reference materials and mussel samples. We confirmed that the concentrations quantified using this method was in the range of reported values for reference materials. Similar concentrations were found in mussels, which were analysed previously by our group. Thus, we conclude that a conventional GC-EI-qMS can be applied for analysis of higher brominated PBDEs in various environmental and biota matrices.     

Effect on carbon lengthening at the side chain terminal of 1 alpha,25-dihydroxyvitamin D3 for calcium regulating activity

A series of analogs of 1 alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3 (1)] with alkyl substitutions in 26- and 27-positions have been tested for their activity 1) in competing with 1,25-(OH)2D3 for binding to chick intestinal cytosol receptor, 2) in ability for formation of multinucleated cells (MNC) with various osteoclastic cell characteristics from blast cells, and 3) in stimulating bone calcium mobilization in vitamin D-deficient rats. The relative potencies of 1,25-(OH)2D3, 1 alpha,25-dihydroxy-26,27-dimethylvitamin D3 (2), 1 alpha,25-dihydroxy-26,27-diethylvitamin D3 (3), and 1 alpha,25-dihydroxy-26,27-dipropylvitamin D3 (4) in competing for intestinal cytosolic binding were 1:1.1:0.25:0.05. The similar order of the abilities on formation of the multinucleated cells in the same series was observed. In a bone calcium mobilization test with vitamin D-deficient rats, 1 alpha,25-dihydroxy-26,27-dimethylvitamin D3 showed slightly less activity than 1,25-(OH)2D3 at 12 h after administration, but long lasting activity was observed during time course experiments. 1 alpha,25-Dihydroxy-26,27-diethylvitamin D3, and 1 alpha,25-dihydroxy-26,27-dipropylvitamin D3 were found to be much less active than 1,25-(OH)2D3 in a bone calcium mobilization test.     

Supramolecular Nanowires from an Acceptor–Donor–Acceptor Conjugated Chromophore

Oligothiophene derivatives have been extensively studied as p-type semiconducting materials in organic electronics applications. This work reports the synthesis, self-assembly and photophysical properties of acceptor–donor–acceptor (A–D–A)-type oligothiophene derivatives by end-group engineering of quaterthiophene (QT) with naphthalene monoimide (NMI) chromophores that are further connected to a trialkoxy benzamide wedge. Conjugation to the NMI units reduces the HOMO–LUMO gap significantly, and consequently the absorption spectrum exhibits a bathochromic shift of about 50 nm compared with QT. Furthermore, extended H-bonding interactions among the amido groups of the peripheral wedges produce entangled fibrillar nanostructures and gelation in hydrocarbon solvents such as methylcyclohexane, wherein the A–D–A chromophore exhibits typical H-aggregation. On the contrary, the fact that the same chromophore, lacking only the amido units, does not produce gels or H-aggregates indicates strong impact of H-bonding on the self-assembly. Computational studies revealed the electronic properties of the chromophore and predicted the geometry of a dimer in the H-aggregate that reasonably matches with the experimental results. Bulk electrical conductivity measurements determined an excellent conductivity of 2.3×10⁻² S cm⁻¹ for the H-aggregated system (OT-1), which is two orders of magnitude higher than that of the same chromophore lacking the amido groups (OT-2).     

Synthesis of sulfonyloxy furoxans via hydroxyfuroxan ammonium salts

Furoxans are distinctive heteroaromatic compounds in that they are potentially capable of releasing nitric oxide under physiological conditions. In order to utilize the furoxan scaffold for the development of functional molecules, synthetically relevant functional groups are required for access to diverse furoxans. In this report, a facile route to furoxans with sulfonyloxy groups, which are halide surrogates, has been developed. The key features of this strategy include the synthesis and utilization of bench-stable hydroxyfuroxan salts, the use of sulfonyl anhydrides in the sulfonylation step instead of sulfonyl chlorides, and the photochemical isomerization of one regioisomer to another in order to gain access to both.