Synthesis of boradiazaindacene-imidazopyrazinone conjugate as lipophilic and yellow-chemiluminescent chemosensor for superoxide radical anion

As a chemiluminescent chemosensor that emits yellow light on reacting with a superoxide radical anion (O₂⁻) and has a lipophilic character, a 6-phenylimidazo[1,2-a]pyrazin-3(7H)-one derivative possessing a boradiazaindacene (BODIPY) at the para position of 6-phenyl (1) was synthesized. The lipophilicity of 1 was investigated by reversed-phase liquid chromatography, and its log P_ow value was found to be 3.57. This value was much higher than that of 2-methyl-6-(4-methoxypheyl)imidazo[1,2-a]pyrazin-3(7H)-one (MCLA, log P_ow=1.19) and 6-[4-[2-{N′-(5-fluoresceinyl)thioureido}ethoxy]phenyl]-2-methylimidazo[1,2-a]pyrazin-3(7H)-one (FCLA, log P_ow=−0.08), and it was comparable to that of benzenoid hydrocarbons. The O₂⁻-induced chemiluminescence of 1 was investigated using the hypoxanthine/xanthine oxidase system as the source of O₂⁻, and as a result, yellow emission was observed. The maximum wavelength was observed at 542 nm, and it was longer than that of FCLA.     

Synthesis, crystal structures and photochromic properties of novel chiral Schiff base macrocycles

Enantiomerically pure and racemic forms of calixsalen-type macrocycles 1 and 2 were synthesized and their crystal structures were determined. The enantiomerically pure crystals of (S,S,S,S,S,S)-1 exhibited thermally reversible photochromism from yellow to orange-red upon photoirradiation in the solid state, while rac-crystals of 2 with the guest CH₃CN did not show any photocolouration.     

Remarkable switch of regioselectivity in epoxide ring opening of 3-benzyl-7-oxa-3-azabicyclo[4.1.0]heptane with amines: practical synthesis of trans-4-amino-3-hydroxypiperidines and trans-3-amino-4-hydroxypiperidines

A simple and highly C3 selective ring-opening method for 3,4-epoxypiperidines has been developed. We also describe a practical improvement of the C4 selective ring-opening method using the same N-alkyl substituted 3,4-epoxypiperidines. This method provides access to pharmaceutically relevant trans-3-amino-4-hydroxypiperidines and trans-4-amino-3-hydroxypiperidines with simple procedures.     

High heat generation ability in AC magnetic field for nano-sized magnetic Y3Fe5O12 powder prepared by bead milling

Nano-sized magnetic Y₃Fe₅O₁₂ ferrite having a high heat generation ability in an AC magnetic field was prepared by bead milling. A commercial powder sample (non-milled sample) of ca. 2.9 μm in particle size did not show any temperature enhancement in the AC magnetic field. The heat generation ability in the AC magnetic field improved with a decrease in the average crystallite size for the bead-milled Y₃Fe₅O₁₂ ferrites. The highest heat ability in the AC magnetic field was for the fine Y₃Fe₅O₁₂ powder with a 15-nm crystallite size (the samples were milled for 4 h using 0.1 mm? beads). The heat generation ability of the excessively milled Y₃Fe₅O₁₂ samples decreased. The main reason for the high heat generation property of the milled samples was ascribed to an increase in the Néel relaxation of the superparamagnetic material. The heat generation ability was not influenced by the concentration of the ferrite powder. For the samples milled for 4 h using 0.1 mm? beads, the heat generation ability (W g⁻¹) was estimated using a 3.58×10⁻⁴ fH² frequency (f/kHz) and the magnetic field (H/kA m⁻¹), which is the highest reported value of superparamagnetic materials.     

9,9′‐spirobifluorene‐containing polycarbonates: Transparent polymers with high refractive index and low birefringence

Syntheses of 2,2′‐bisalcoholic group‐substituted 9,9′‐spirobifluorene monomers 2 were performed by the reaction of 2,2′‐dihydroxy‐9,9′‐spirobifluorene 2a with haloalcohols. Polycarbonates consisting of 9,9′‐spirobifluorene skeleton in the main chain (PC 4 ) were synthesized by the polycondensation of 2,2′‐bisalcoholic monomers 2 and triphosgene or diphenyl carbonate. PC 4 showed good thermal stability: the 5% weight loss temperature was over 330 °C under both nitrogen and air atmospheres. The glass transition temperature was in a range of 16–269 °C estimated by differential scanning calorimetry, depending on the flexibility of the alkylene or oxyethylene chains of 2 . PC 4 showed high solubility toward ordinary organic solvents such as CHCl₃, benzene, and THF, making possible the preparation of the flexible thin films. Very high refractive index in a range of 1.62–1.66 at 589 nm was observed although PC 4 consists only of C, H, and O atoms, whereas very low degree of birefringence was confirmed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3658–3667, 2010     

57Fe Mössbauer study under high pressure; ε-Fe and Fe2O3

Using diamond anvil cell, the⁵⁷Fe Mössbauer spectra of pure iron foil and α-Fe₂O₃ powder under high pressure have been measured at room temperature.⁵⁷Fe Mössbauer spectra of α-Fe were measured from 15 GPa to 45 GPa. Isomer shift value decreased and the quadrupole splitting slightly increased as the pressure increased.⁵⁷Fe Mössbauer spectra of Fe₂O₃ under high pressure up to 72 GPa were observed. Above 52 GPa, the new lines appeared at the center portion of the spectrum corresponding to the new high pressure phase. The spectrum of new high pressure phase consisted of 6-line splitting and doublet, suggesting the existence of the two different kinds of iron states in it.