Photochromism of novel metal coordination polymers with 1,2-Bis(2'-methyl-5'-(carboxylic acid)-3'-thienyl)perfluorocyclopentene in the crystalline phase

Three new metal complexes with 1,2-bis(2'-methyl-5'-(carboxylic acid)-3'-thienyl)perfluorocyclopentene (BM-5-CATP) were synthesized and characterized by X-ray diffraction analysis. BM-5-CATP serves as a bis-monodentate ligand that bridges metal centers to generate three 1D polymers. The two thienyl rings in the three complexes adopt antiparallel fashions, and the distances of 3.39, 3.53, and 3.57 A between the two reactive carbons are short enough to allow photocyclizations to occur in the crystalline phase. [Co(BM-5-CATP)(py)2(MeOH)2] (1) displayed effective photoisomerization in the crystalline phase. Interestingly, solvated 1 underwent a solid-state conversion upon heating to generate, through the release of the coordinated MeOH and rearrangement of the coordination geometry, the desolvated form (1a), while maintaining reversible photochromism. The removal of the solvent led to obvious changes in physical properties such as color and magnetic properties. The ESR spectra of 1 and 1a changed reversibly upon photoexcitation, indicating changes in coordination geometry accompanied by photoreaction. The magnetic susceptibilities of 1 and 1a showed no obvious changes, suggesting that the cobalt-cobalt interaction through the long bridging BM-5-CATP is less effective. Both [Cu(BM-5-CATP)(py)3](EtOH)(py)1.8 (2) and [Zn(BM-5-CATP)(phen)(H2O)] (3) exhibited reversible photoreactions in the crystalline phase. However, 3 did not show remarkable spectral changes because of steric hindrance from the coordinated bulky phenanthroline and the intramolecular H bonds.     

Optimization of double plasma jet torches in a scramjet combustor

Ignition tests by double plasma jet (PJ) torches in a supersonic flow were conducted. Two PJ torches with different feedstocks were arranged in a straight line in the direction of flow. The Mach number of the airflow was 2.3, and the total temperature and total pressure of the main flow were those of room conditions. A C₂H₄ fuel perpendicularly injected with its sonic speed into the main flow was tested. A combination of O₂–O₂ feedstocks for the two torches was more effective than other combinations such as H₂/N₂–O₂. Moreover, the effectiveness of the double PJs was found to be almost the same as that of a single PJ. These results indicate that combustion reactions of the main fuel injected upstream of the PJ were mostly completed in the vicinity of the upstream PJ. The upstream PJ was considered to be dominant for ignition and the combustion process, indicating that the influence of the downstream PJ was small. On the other hand, the advantage of the double PJs over the single PJ in reducing damage to the torch nozzle was confirmed.     

Method for reducing debris and thermal destruction in femtosecond laser processing by applying transparent coating

A cavity processed by a tightly focused femtosecond laser pulse is surrounded by a ring-shaped protrusion, debris, and small droplets. In order to reduce these undesired damages, we propose processing with a coating of transparent material on a target material. PMMA (poly-methyl methacrylate) with the thickness that its surface is not ablated by a single pulse irradiation reduces dissolution and vaporization caused by the interaction between a high-density hot vapor plume and the target material. Furthermore, the material at the target surface does not escape freely due to the coating layer. As a result, a submicrometer-sized cavity is produced with a reduction of debris and a smaller thermal-destruction area. PACS 44.10.+i; 61.80.Ba; 79.20.Ds     

A Bäcklund transformation between two integrable discrete hungry systems

The discrete hungry Toda (dhToda) equation and the discrete hungry Lotka-Volterra (dhLV) system are known as integrable discrete hungry systems. In this Letter, through finding the LR transformations associated with the dhToda equation and the dhLV system, we present a Bäcklund transformation between these integrable systems.     

Aryl ether as a Negishi coupling partner: an approach for constructing C-C bonds under mild conditions

An etheric Negishi coupling: The first cross-coupling reaction between aryl alkyl ethers and dianion-type zincate reagents to afford biaryl compounds through selective cleavage of the etheric C(sp(2))-O bond was developed. Dianion-type zincates showed excellent reactivity toward the aromatic ethers under mild conditions, with good functional group compatibility (see scheme).     

Kobayashi hyperbolic imbeddings into toric varieties

Our main goal of this article is to give a characterization of an algebraic divisor on an algebraic torus whose complement is Kobayashi hyperbolically imbedded into a toric projective variety. As an application of our main theorem, we prove the following: the complement of the union of n + 1 hyperplanes in the n-dimensional projective space ${\mathbb{P}^{n}(\mathbb{C})}$ in general position and a general hypersurface of degree n in ${\mathbb{P}^n(\mathbb{C})}$ is Kobayashi hyperbolically imbedded into ${\mathbb{P}^n(\mathbb{C})}$ .     

Integrable discrete hungry systems and their related matrix eigenvalues

Recently, some of the authors designed an algorithm, named the dhLV algorithm, for computing complex eigenvalues of a certain class of band matrix. The recursion formula of the dhLV algorithm is based on the discrete hungry Lotka–Volterra (dhLV) system, which is an integrable system. One of the authors has proposed an algorithm, named the multiple dqd algorithm, for computing eigenvalues of a totally nonnegative (TN) band matrix. In this paper, by introducing a theorem on matrix eigenvalues, we first show that the eigenvalues of a TN matrix are also computable by the dhLV algorithm. We next clarify the asymptotic behavior of the discrete hungry Toda (dhToda) equation, which is also an integrable system, and show that a similarity transformation for a TN matrix is given through the dhToda equation. Then, by combining these properties of the dhToda equation, we design a new algorithm, named the dhToda algorithm, for computing eigenvalues of a TN matrix. We also describe the close relationship among the above three algorithms and give numerical examples.     

Total synthesis of bleomycin A21)

Bleomycin A2 has been synthesized for the first time.     

Stereoselective synthesis of (2s,3s,4r)-4-amino-3-hydroxy-2-methyl-pentanoic acid,an amino acid constituent of bleomycin,by aldold condensation)

(2S,3S,4R)-4-Amino-3-hydroxy-2-methylpentanoic acid, a novel amino acid constituent of bleomycin, has been synthesized stereoselectively through aldol condensation of (R)-2-aminopropionaldehyde derivatives and E-vinyloxyboranes.     

Magnetophonon resonance recombination of hot carriers with emission of two TA-phonons in LPE-HgTe

Magnetophonon oscillations of longitudinal magnetoresistance of LPE-HgTe were investigated at 4.2 K under hot electron condition by using a second derivative method. Oscillations with 3–5 peaks were observed in 2–9T under electric field of about 1–4V cm^-1. These peaks are interpreted as the first observation of magnetophonon resonance recombination of hot carriers accompanied by two TA-phonon emission. It is deduced for the first time that at low temperatures TA-phonon density of states has two peaks at 2.6 and 3.1 meV respectively.