配位子としてピリジンビスニトロキシドを用いた錯体の構造と磁性

ラジカルはSOMO軌道の不対電子が持つスピンによって磁性を持ち、金属へ配位することが知られている。中心金属に磁性原子を用いた場合の金属?ラジカル間の磁気的な相互作用の研究は分子磁性体、ひいては磁性材料の発展という観点から大きな意義がある。PyBNは有機分子でありながらS=1というスピン数を持つ配位子として期待されたが不安定であり単離には至らなかったとの経緯がある。本研究ではPyBN誘導体の4位に置換機を導入し、立体保護による安定化を試みた。3種類のPyBN誘導体の単離に成功し、 X線構造解析により構造を確定した。 MesPyBNを用いて[RE(hfac)3(H2O)2] (RE=Y, Gd, Tb, Dy, Ho, Er, Tm)を合成した。X線構造解析や磁化率測定の結果からMesPyBNは三座の配位子として機能し、配位後もS=1の三重項状態を維持することがわかった。それぞれのラジカルはピリジンの窒素と金属で平面性の高い5員環を形成し、MesPyBNは金属への配位環境とスピンを制御しやすい配位子であることがわかった。この制御された配位環境によりGd-ラジカル間の相互作用は2J/kB = -15.0(1) Kという大きな値となった。磁気異方性を持つTbに配位した錯体ではラジカル-金属間の相互作用により分子1つで磁石として機能する単分子磁石としての性能が観測され、エネルギー障壁はΔ/kB=26.3(6) Kであった。また、安定ラジカルとして知られている2,6-ジ-t-ブチルフェノキシルについてスイッチング可能な有機磁性材料の応用に向けて検討し、非磁性状態の構造を明らかにした。なお本成果の一部はH. Kawakami et al. Dalton Trans. 2016, 45, 1306.で公表し、当該号の表紙を飾った。電気通信大学201

Design of an Architectural Element Generating Hydrogen Energy by Photosynthesis—Model Case of the Roof and Window

As is well known, the realization of a zero-waste society is strongly desired in a sustainable society. In particular, architectural elements that provide an energy-neutral living environment are attractive. This article presents the novel environmentally friendly architectural elements that generate hydrogen energy by the photosystem II (PSII) solution extracted from waste vegetables. In the present work, as an architectural element, the window (PSII window panel) and roof (PSII roof panel) were fabricated by injecting a PSII solution into a transparent double-layer panel, and the aging properties of the power generation and the appearance of these PSII panels are investigated. It was found that the PSII roof can generate energy for 18 days under the sun shining and can actually drive the electronic device. In addition, the PSII window, for which light intensity is weaker than that for the PSII roof, can maintain power generation for 40 days. These results indicate that the PSII roof and PSII window become the architectural elements generating energy, although the lifespan depends on the total light intensity. Furthermore, as an additional advantage, the roof and window panels composed of the semitransparent PSII panel yield an interior space with the natural color of the leaf, which gradually changes over time from green to yellow. Further, it was also found that the thermal fluctuation of the PSII window is smaller than that of the typical glass window. These results indicate that the roof and window panels composed of the PSII solution extracted from waste vegetables can be used as the actual architectural elements to produce not only the electrical energy but also the beautiful, transparent natural green/yellow spaces

Solid-State Hydrogen Fuel by PSII–Chitin Composite and Application to Biofuel Cell

Biomaterials attract a lot of attention as next-generation materials. Especially in the energy field, fuel cells based on biomaterials can further develop clean next-generation energy and are focused on with great interest. In this study, solid-state hydrogen fuel (PSII–chitin composite) composed of the photosystem II (PSII) and hydrated chitin composite was successfully created. Moreover, a biofuel cell consisting of the electrolyte of chitin and the hydrogen fuel using the PSII–chitin composite was fabricated, and its characteristic feature was investigated. We found that proton conductivity in the PSII–chitin composite increases by light irradiation. This result indicates that protons generate in the PSII–chitin composite by light irradiation. It was also found that the biofuel cell using the PSII–chitin composite hydrogen fuel and the chitin electrolyte exhibits the maximum power density of 0.19 mW/cm2. In addition, this biofuel cell can drive an LED lamp. These results indicate that the solid-state biofuel cell based on the bioelectrolyte “chitin” and biofuel “the PSII–chitin composite” can be realized. This novel solid-state fuel cell will be helpful to the fabrication of next-generation energy

Novel Biofuel Cell Using Hydrogen Generation of Photosynthesis

Energies based on biomaterials attract a lot of interest as next-generation energy because biomaterials are environmentally friendly materials and abundant in nature. Fuel cells are also known as the clean and important next-generation source of energy. In the present study, to develop the fuel cell based on biomaterials, a novel biofuel cell, which consists of collagen electrolyte and the hydrogen fuel generated from photochemical system II (PSII) in photosynthesis, has been fabricated, and its property has been investigated. It was found that the PSII solution, in which PSII was extracted from the thylakoid membrane using a surfactant, generates hydrogen by the irradiation of light. The typical hydrogen-generating rate is approximately 7.41 × 1014 molecules/s for the light intensity of 0.5 mW/cm2 for the PSII solution of 5 mL. The biofuel cell using the PSII solution as the fuel exhibited approximately 0.12 mW/cm2. This result indicates that the fuel cell using the collagen electrolyte and the hydrogen fuel generated from PSII solution becomes the new type of biofuel cell and will lead to the development of the next-generation energy

Electrochemical behavior and in situ observation of galvanic couples of copper and silver or zinc wires in acidic copper sulfate solutions

The anodic dissolution reaction of copper in copper electro-refining was studied by considering the reaction of galvanic couples with different metals as impurities. In this study, zinc was chosen as a typical anodic impurity and silver as a cathodic impurity, and electrochemical measurements of galvanic couples with silver or zinc wires winding around a copper wire and in situ observation of the electrode surface using a stereo microscope were carried out. For comparison, copper wire with zinc or silver plating was used. As a result, even the simple method of winding silver or zinc wire around copper wire was able to capture the characteristic behavior of the galvanic reaction of silver and zinc on copper wire. It was also confirmed that zinc dissolution was accelerated by copper and copper dissolution was accelerated by silver, and that the effects were more promoted under anodic polarization. The crystallization and passivation of copper sulfate on the copper electrode surface and the dissolution behavior of silver were also observed. These results indicate that the experimental method presented in this study is an effective way to investigate the effects of impurities on the solubility and passivation of crude copper metal

Solid-State Hydrogen Fuel by PSII–Chitin Composite and Application to Biofuel Cell

Biomaterials attract a lot of attention as next-generation materials. Especially in the energy field, fuel cells based on biomaterials can further develop clean next-generation energy and are focused on with great interest. In this study, solid-state hydrogen fuel (PSII–chitin composite) composed of the photosystem II (PSII) and hydrated chitin composite was successfully created. Moreover, a biofuel cell consisting of the electrolyte of chitin and the hydrogen fuel using the PSII–chitin composite was fabricated, and its characteristic feature was investigated. We found that proton conductivity in the PSII–chitin composite increases by light irradiation. This result indicates that protons generate in the PSII–chitin composite by light irradiation. It was also found that the biofuel cell using the PSII–chitin composite hydrogen fuel and the chitin electrolyte exhibits the maximum power density of 0.19 mW/cm2. In addition, this biofuel cell can drive an LED lamp. These results indicate that the solid-state biofuel cell based on the bioelectrolyte “chitin” and biofuel “the PSII–chitin composite” can be realized. This novel solid-state fuel cell will be helpful to the fabrication of next-generation energy

Flexibility of Hydrogen Bond and Lowering of Symmetry in Proton Conductor

In order to investigate why crystal symmetry lowers with increasing temperature by phase transition of TII–III (=369 K) in Cs3H(SeO4)2, in spite of the fact that crystal symmetry in the high-temperature phase of many ionic conductors becomes higher by the phase transition, we have studied the relation between the change in crystal symmetry and the appearance of proton motion. It was found from the analysis of domains based on crystal structure that the number of possible geometrical arrangement of hydrogen bond in phase II becomes two times larger than that in phase III, derived from the lowering of crystal symmetry with increasing temperature. These results indicate that the lowering of crystal symmetry in phase II appears by the increase of the number of geometrical arrangements and by the enhancement of the flexibility of hydrogen bond. Considering that the enhancement of the flexibility of hydrogen bond yields mobile proton in phase II, it is deduced that mobile proton in phase II appears in exchange for the lowering of crystal symmetry at II–III phase transition

Endogenous Leu332Gln mutation in p53 disrupts the tetramerization ability in a canine mammary gland tumor cell line

Mutations in the p53 gene are associated with more than half of all human cancers. These mutations often cause a disruption of the tumor-suppressor function of p53 and induce genomic instabilities. Wild-type p53 requires tetramerization to function as an initiator of cell cycle arrest and apoptosis. Although alterations in p53 tetramerization caused by mutation have been well studied, there are few cell lines containing an endogenous mutation in the tetramerization domain of p53. Here, we report the discovery of a canine mammary gland tumor cell line CTB-m2, which contains the Leu332Gln (L332Q) mutation corresponding to Leu344 in the tetramerization domain of human p53. Although CTB-m2 cells are genetically heterozygous for the Leu332Gln mutation, the mutant mRNA was almost exclusively expressed. CTB-m2 cells showed enhanced cell proliferation compared to wild-type p53-expressing CTB-m cells of the same lineage. A p53 tetramerization reporter assay showed that the ability of the p53 mutant to form tetramers was significantly lower than that of wild-type p53. An immunoblot analysis of cross-linked p53 oligomerized forms demonstrated that the L332Q mutant lacked the ability to form tetramers but retained the ability to form dimers. These data suggest that the p53 mutant cell line CTB-m2 could be a useful tool for analyzing the precise tetramerization mechanisms of p53 and verifying the effects of therapeutic agents against tumors expressing p53 mutants that lack the ability to tetramerize