Publications by authors named "Keita Kuroiwa"

Article Synopsis
  • - The Habu snake's venom contains diverse proteins, particularly phospholipase A (PLA) enzymes, which are valuable for studying molecular evolution but lack understanding in their physical properties and self-assembly.
  • - This research explores the interaction of purified PLA enzymes with anionic metal complexes, revealing that they can form microstructures that grow into fibrous structures in a buffered saline solution.
  • - The results suggest new possibilities for developing flexible and functional hybrid systems using snake venom enzymes, highlighting potential applications in nanotechnology and bioengineering.
View Article and Find Full Text PDF

The self-assembly of discrete cyanometallates has attracted significant interest due to the potential of these materials to undergo soft metallophilic interactions as well as their optical properties. Diblock copolypeptide amphiphiles have also been investigated concerning their capacity for self-assembly into morphologies such as nanostructures. The present work combined these two concepts by examining supramolecular hybrids comprising cyanometallates with diblock copolypeptide amphiphiles in aqueous solutions.

View Article and Find Full Text PDF

A simple strategy for synthesizing supramolecular hybrids was developed for the preparation of bioavailable nanohybrid photosensitizers by assembling visible-light-sensitive Pt(II) meso-tetrakis(4-carboxyphenyl)porphyrinporphyrin (PtTCPP)/tomatine analogues. The hybrids were self-assembled into nanofibrous or nanosheet structures approximately 3-5 nm thick and several micrometers wide. α-Tomatine generated a unique fibrous vesicle nanostructure based on intermolecular interactions, while dehydrotomatine generated nanosheet structures.

View Article and Find Full Text PDF

Bifunctional electrocatalytic properties of freeze-dried Ni/NiOx, freeze-dried NiO, and freeze-dried Ni(OH)2 are reported. Freeze-dried Ni(OH)2 was synthesized by the freeze-drying method. Freeze-dried Ni/NiOx and freeze-dried Ni were obtained from the thermal annealing of the material.

View Article and Find Full Text PDF

A hexagonal cobalt(ii) metallacycle and its "lipid packaged" derivatives, [Co(R-bisterpy)]X (R = H, OCH, OCH; X = BF, C-Glu), have been synthesized and characterized. The compounds incorporating BF anions formed sphere-like aggregates while the compounds with C-Glu lipid anions gave double-layered honeycomb architectures composed of hexagonal stacked tubular structures, which exhibit spin crossover behaviour.

View Article and Find Full Text PDF

Anionic lipid amphiphiles with [Ru(bpy)] complex have been prepared. The metal complexes have been found to form ribbon and tape structures depending on chemical structures of lipid amphiphiles. Especially, the composites showed hypochromic effect and induced circular dichroism in organic media, and flexibly and weakly supramolecular control of morphological and optical properties have been demonstrated.

View Article and Find Full Text PDF

Self-assembled hybrid supramolecular architectures formed between amphiphilic anions and long alkylated cationic cobalt(ii) complexes of type [Co(C-terpy)](C-Glu) (n = 15-20) have been synthesized and characterized by TEM, PXRD and magnetic susceptibility measurements. The hybrids display wire or rolled sheet supramolecular arrangements with odd and even alkyl chain dependence, with the cobalt(ii) centres exhibiting gradual spin-crossover behaviours.

View Article and Find Full Text PDF

Inexpensive solid proton conducting materials with high proton conductivity and thermal stability are necessary for practical solid state electrochemical devices. Here we report that coal oxide (CO) is a promising carbon-based proton conductor with remarkable thermal robustness. The CO produced by simple liquid-phase oxidation of coal demonstrates excellent dispersibility in water owing to the surface carboxyl groups.

View Article and Find Full Text PDF

The integration of discrete metal complexes has been attracting significant interest due to the potential of these materials for soft metal-metal interactions and supramolecular assembly. Additionally, block copolypeptide amphiphiles have been investigated concerning their capacity for self-assembly into structures such as nanoparticles, nanosheets and nanofibers. In this study, we combined these two concepts by investigating the self-assembly of discrete metal complexes in aqueous solution using block copolypeptides.

View Article and Find Full Text PDF

Lipophilic paddlewheel biruthenium complexes [Ru(2)(μ-O(2)CR)(3)X](n) (O(2)CR = 3,4,5-tridodecyloxybenzoate, X = Cl, I) self-assemble in organic media to form halogen-bridged coordination polymers. The polymerization is accompanied by spectral changes in π(RuO,Ru(2)) → π*(Ru(2)) and π(axial ligand) → π*(Ru(2)) absorption bands. These polymeric complexes form lyotropic liquid crystals in n-decane at concentrations above ~100 unit mM.

View Article and Find Full Text PDF

Supramolecular complexes consisting of anionic polyoxometalate (POM) and chiral, cationic lipids are newly developed. They give nanofibers, helical ribbons, and nanotapes in organic media depending on the chemical structure of lipid molecules. Lipid ammonium groups exert significant influence on their photoreduction characteristics.

View Article and Find Full Text PDF

A lipophilic linear Fe(II) complex is dispersed as nanofibers in nematic liquid crystals and displays spin-crossover at temperatures higher than those observed for the bulk crystalline state; thermal bistability is also induced in the liquid crystal environment, reflecting increased ligand field splitting energy and enhanced cooperativity by liquid crystals.

View Article and Find Full Text PDF

A Co(III) biuretato complex, [Co(III){ph(biu)2}]- (ph(biu)2 = o-phenylenebis(biuretato)) can form layer structures by its self-assembling with a multiply hydrogen bonding network. PPh4[Co(III)(ph(biu)2}]. 3CHCl3 (PPh4+ = Tetraphenylphosphonium cation) crystallizes in the triclinic, space group P1, with a = 9.

View Article and Find Full Text PDF

Linear Fe(II) 1,2,4-triazole complexes with lipid counteranions are newly developed. These complexes show sharp and reversible spin conversion in toluene, with temperatures significantly higher (by 20-100 K) than the spin crossover temperatures observed in the crystalline states. This is accounted for in terms of increased metal-ligand interactions in organic media, which is caused by solvophobic compaction of charged coordination chains.

View Article and Find Full Text PDF

A lipophilic linear FeII 1,2,4-triazole complex containing azobenzene chromophores forms molecular wires in organic solvents; photoisomerization of azobenzene units induced morphological changes that lead to reversible, macroscopic gel-to-sol transition phenomena.

View Article and Find Full Text PDF

A novel class of thermally responsive supramolecular assemblies is formed from the lipophilic cobalt(II) complexes of 4-alkylated 1,2,4-triazoles. When an ether linkage is introduced in the alkylchain moiety, a blue gel-like phase is formed in chloroform, even at very low concentration (ca. 0.

View Article and Find Full Text PDF
Article Synopsis
  • - Hydrophobic vitamin B(12) was attached to a platinum electrode, enabling it to serve as a catalyst.
  • - This setup demonstrated a redox couple between Co(ii) and Co(i), meaning it can switch between two states.
  • - Under visible light, the Co(i) reacts with phenethyl bromide, successfully producing styrene with an impressive turnover number over 6000 in just 1 hour.
View Article and Find Full Text PDF