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.     

Synthesis of Sialyl-α-(2→3)-Neolactotetraose Derivatives Containing Different Sialic Acids: Molecular Probes for Elucidation of Substrate Specificity of Human α1,3-Fucosyltransferases

ABSTRACT

A series of sialyl-α-(2→3)-neolactotetraose derivatives containing N-acetyl-(NeuAc), N-glycolyl- (NeuGc) and N-butanoylneuraminic acid, and 3-deoxy-D-glycero-D-galacto-2-nonulosonic acid (KDN) have systematically been synthesized as molecular probes for elucidation of substrate specificity of human α1,3-fucosyltransferases (Fuc-TVII and Fuc-TVI). 2-Methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-D-glucopyrano)-[2',1':4,5]-2-oxazoline (1) was coupled with 2-(trimethylsilyl)ethyl (2,4,6-tri-O-benzyl-β-D-galactopyranosyl)-(1 → 4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside (2) to give a trisaccharide 3 which, upon successive O-deacetylation, benzylidenation and reductive opening of the benzylidene group, afforded a common glycosyl acceptor 5. Glycosylation of 5 with sialyl-α-(2→3)-galactose donors 6-8, 19 and 21 gave the corresponding pentasaccharides 22-25, which were converted to a series of sialyl-α-(2→3)-neolactotetraose derivatives 30-33. In the competitive enzyme assay, the NeuGc derivative 32 showed the most potent activity for Fuc-TVII, while the KDN derivative 31 was less active than the standard NeuAc derivative 30. In contrast, the N-butanoylation of neuraminic acid enhanced the activity for Fuc-TVI.     

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.     

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.     

Inclusive Λ, Λ and Σ±(1385) production in 405 GeV/c pp interactions

We have investigated inclusive Λ, $\text{Λ}$ and Σ^±(1385) productions in 405 GeV/c pp interactions. The observed cross sections are σ(Λ)=4.05±0.39 mb, $\text{σ(}\text{Λ}\text{=0.63±0.17}$ mb, σ(Σ⁺(1385))=0.74±0.17 mb and σ(Λ^?(1385))=0.56±0.17 mb. $\text{Λ}$ production is dominant in a central region of ∣x∣≤0.4. The $\text{Λ/}\text{Λ}$ production ratio at ∣x∣≈0 is found to be 1.2±0.5. The excess, about 0.2 mb, of σ(Λ⁺(1385)) over σ(Λ^?(1385)) is most likely attributed to proton fragmentations (∣x∣≥0.4), and gives an evidence for scaling.     

Construction of the multidecker anthracene-silver(I) system by intramolecular pi-pi interactions

As a continuation of the study on the construction of the multidecker aromatic compounds with pi-pi interactions, the anthracene derivatives 9,10-dimethylanthracene (dman), 9,10-diphenylanthracene (dpan), and 7,12-dimethylbenz[a]anthracene (dmban) have been studied toward complexation with the silver(I) ion. The crystal structures of [Ag(dman)(0.5)(p-xylene)(ClO(4))], [Ag(2)(dpan)(0.5)(C(6)H(6))(0.5)(CF(3)SO(3))(2)], and [Ag(2)(dmban)(2)(ClO(4))(2)](p-xylene), together with the metal-free ligand dpan, have been determined by single-crystal X-ray diffraction. These pi-electron-rich aromatic compounds are found to have great promise as an approach to the effective self-assembly of high nuclearity in a multilayer fashion.     

Syntheses and structures of photochromic silver(I) coordination polymers with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene

Five novel silver(I) coordination polymers with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3- thienyl)ethene (cis-dbe) were synthesized and are characterized in this paper. Treatment of AgCF(3)SO(3) or AgCF(3)CO(2) with cis-dbe afforded [Ag(2)(cis-dbe)(CF(3)SO(3))(2)] (1) and [Ag(2)(cis-dbe)(CF(3)CO(2))(2)] (2), and both complexes exhibit a 1-D infinite chain structure with two cyano groups and two thienyl groups of the ligand bridging four metal ions. Reaction of AgC(n)()F(2)(n)(+1)CO(2) with cis-dbe gave rise to an unprecedented cocrystallization of a 2-D sheet structure, [Ag(2)(cis-dbe)(C(n)F(2)(n)(+1)CO(2))(2)], where n = 2 (3), 3 (4), and 4 (5). Upon irradiation with 450 nm light, these five silver(I) complexes turned orange or red from yellow, and the color reverted to yellow on exposure to 560 nm light, indicative of the reversible cyclization/ring-opening reaction occurring in the crystalline phase. Furthermore, different anions gave not only the different structural dimensions but also the different photoresponsive patterns. The correlation between the crystal structures and the photochromic reactivity is discussed.     

Partial Oxidation of Methane into Syngas with Oxygen Permeating Ceramic Membrane Reactors

Partial oxidation of methane (CH₄ +1/2O₂ CO + 2H₂) is considered as an alternative reforming reaction to steam reforming for production of syngas. This reaction is a slightly exothermic reaction and produces syngas of H₂/CO = 2, which is suitable for the synthesis of hydrocarbon or methanol. In this paper, the catalytic partial oxidation of CH₄ with a membrane reactor using oxygen permeating ceramic, in particular, LaGaO₃-based oxide, is reported. Supported Ni or Rh catalysts are active and selective for this reaction. On the other hand, a mixed ionic and electronic conducting (MIEC) ceramic membrane is useful for obtaining pure oxygen from air when the gradient in oxygen partial pressure is obtained. As for a MIEC membrane, mixed electronic–oxide ionic conductors of Fe- or Co-based perovskite oxides are widely investigated. However, the improvement in stability in a reducing atmosphere is critically required for the MIEC membrane for the application to the membrane reactor for CH₄ partial oxidation. Perovskite oxides of LaGaO₃ doped with Sr for a La site and a Fe, Co, or Ni for a Ga site, respectively, are promising as the oxygen-separating membrane for CH₄ partial oxidation because of high stability in a reducing atmosphere as well as high permeability of oxygen. The partial oxidation of CH₄ with solid oxide fuel cells (SOFCs) is also described. Simultaneous generation of electrical power and syngas is demonstrated by the fabricated fuel cell type reactor using a LaGaO₃-based oxide electrolyte.