Temporal evolution of composition and crystal structure of cobalt hexacyanoferrate nano-polymers synthesized in reversed micelles

Nanometer-size metal coordination polymers are fascinating to explore, since their unique properties are controlled by a large ratio of surface atoms, which is an entirely different effect from that in a bulk crystal. In this report, we have demonstrated the reaction time-induced structural conversion of nanometer-sized metal coordination nano-polymers (MCNPs). The MCNP selected here was a Prussian blue analogue, cobalt hexacyanoferrate (Fe-CN-Co) with ca. 3 nm. When Fe-CN-Co MCNPs were synthesized in reverse micelles of cationic surfactants, cetyltrimethylammonium halides [CTAX, X=B (bromide), C (chloride)], their color dramatically changed from red to green with increasing the reaction time. We investigated the mechanism of this characteristic color change using XRD, FT-IR, UV-vis spectra, CHN elemental analyses, ICP, and TGA, which indicated that the coordination geometry of Co(II) ions was changed from a 6-coordinate octahedral (Oh) to a 4-coordinate tetrahedral (Td) with clear crystal distortion. The magnetic behavior of the prepared Fe-CN-Co MCNPs was also reaction-time dependent, as illustrated by SQUID and 57Fe M?ssbauer spectra.     

Manganese(III,IV) and manganese(III) oxide clusters trapped by copper(II) complexes

Reactions of quinquedentate Schiff base ligands with Mn and Cu ions afforded icosa- and hexadecanuclear mixed-metal clusters in which dinuclear CuII complexes trapped oxo-bridged [MnIII8MnIV4O12] and [MnIII6O6] cores, respectively. Maximum entropy method analysis for synchrotron X-ray diffraction data was used to determine the oxidation states of the Mn ions.     

Induction of cell death by photodynamic therapy with water-soluble lipid-membrane-incorporated [60]fullerene

Intracellular uptake of a lipid-membrane-incorporated C(60) with a cationic surface into HeLa cells was found to induce cell death under visible light irradiation in high efficiency.     

Asymmetric 1,3-dipolar cycloadditions of nitrones and methacrolein catalyzed by chiral bis-titanium lewis acid: a dramatic effect of N-substituent on nitrone

Highly stereoselective 1,3-dipolar cycloadditions of methacrolein and nitrones could be realized by the use of bis-titanium chiral Lewis acid catalyst. Key to the success is the introduction of bulky N-substituent on nitrone to attenuate the undesired Lewis acid-nitrone complexation.     

Site-specific oxidative stress induction

In this issue of Chemistry & Biology, Kelly and colleagues describe the development of two novel ROS-generating compounds [1] that specifically localize in the nucleus or mitochondrion. Their application reveals that nuclei and mitochondria respond differently to oxidative stress, in terms of gene expression and survival pathway activation.     

Raman spectroscopic study on the solvation of N,N-dimethyl-p-nitroaniline in room-temperature ionic liquids

Electronic absorption spectra and Raman spectra of N,N-dimethyl-p-nitroaniline (DMPNA) have been measured in various fluids from the gaseous-like conditions in supercritical fluids (SCFs) to highly polar room-temperature ionic liquids (RTILs). We found that the S0-S1 absorption band center of DMPNA in RTILs is mostly determined by the molar concentrations of ions. On the other hand, the bandwidth of the absorption spectrum does not follow the expectation from a simple dielectric continuum model. Especially in SCFs, the bandwidth of the absorption spectrum decreases with increasing solvent density, suggesting that the intramolecular reorganization energy is a decreasing function of the solvent density. The Raman shift of the NO2 stretching mode has been proven to be a good indicator of the solvent polarity; i.e., the vibrational frequency of the NO2 stretching mode changes from 1340 cm-1 in mostly nonpolar solvent such as ethane to 1300 cm-1 in water. The linear relationship between the absorption band center and the vibrational frequency of the NO2 mode, which was observed for conventional liquids in a previous paper (Fujisawa, T.; Terazima, M.; Kimura, Y. J. Chem. Phys. 2006, 124, 184503), holds almost well for all fluids including SCFs and RTILs. On the other hand, the vibrational bandwidth does not show a simple relationship with the absorption band center. The vibrational bandwidths in RTILs are generally larger in comparison with those in conventional liquids with similar polarity scales. Among the RTILs we investigated, the vibrational bandwidth loosely correlates with the molecular size of the anion. A similar dependence on the anion size is also observed for the bandwidth of the absorption spectrum. We have also investigated the excitation wavelength dependence of the Raman shift of the NO2 stretching mode in RTILs. The extent of the dependence on the excitation wavelength in all fluids is well correlated with the vibrational bandwidth.     

Observation of squeezed light at 1.535 microm using a pulsed homodyne detector

Squeezed light was generated at a telecommunication wavelength via single-pass optical parametric amplification in a periodically poled MgO-doped LiNbO(3) waveguide. Classical parametric deamplification of -8.9 dB was achieved. This large magnitude of deamplification indicates that the problem of gain-induced diffraction was avoided by employing the waveguide. Squeezing of 3.2 dB was directly observed using a time-domain pulsed homodyne detector.     

High-energy, high-contrast, multiterawatt laser pulses by optical parametric chirped-pulse amplification

We describe a compact, reliable, high-power, and high-contrast noncollinear optical parametric chirped-pulse amplifier system. With a broadband Ti:sapphire oscillator and grating-based stretching and compression, the chirped pulses are amplified from 0.1 nJ to 122 mJ in type I beta-barium borate optical parametric chirped-pulse amplifiers with a total gain of over 10(9) at 10 Hz repetition rate. Pulse compression down to 19-fs duration achieved after amplification indicates a peak power of 3.2 TW at an average power of 0.62 W. The prepulse contrast is measured to be less than 10(-8) on picosecond time scales.     

Cadinane‐Type Sesquiterpenoids,Strobilols E – K,from the Liquid Culture of Strobilurus ohshimae

New cadinane sequiterpenoids, strobilols E–K ( 5 – 11 , resp.) have been isolated from a liquid culture of Strobilurus ohshimae. Their structures have been established on the basis of spectral analyses.     

Synthesis, stability, and complexation behavior of isolable salen-type N2S2 and N2SO ligands based on thiol and oxime functionalities

The new salen-type N(2)S(2) tetradentate ligands, H(2)L(1) and H(2)L(2), which have a donor set comprising oxime and thiol groups, were synthesized. These ligands are obtained as isolable colorless crystals, whereas the imine analogues are too unstable to be isolated. The unsymmetrical N(2)SO ligands, H(2)L(3) and H(2)L(4), were also obtained as stable compounds. When ligands H(2)L(1)-H(2)L(4) are heated above the melting points, they mainly decompose via cleavage of the N-O bonds of a thiosalicylaldoxime moiety to give 1,2-benzisothiazole derivatives. The complexation of the N(2)S(2) ligands (H(2)L(1) and H(2)L(2)) with nickel(II) acetate afforded square-planar mononuclear complexes [Ni(L(1))] and [Ni(L(2))], respectively. In contrast, the complexation of the N(2)SO ligand H(2)L(3) with nickel(II) acetate resulted in cleavage of the N-O bond, giving a tetranuclear complex having a cubane-type Ni(4)O(4) core. The N-O bonds of H(2)L(1)-H(2)L(4) are more readily cleaved when the ligands are allowed to react with copper(II) acetate. In these cases, the alkoxo-bridged dinuclear complexes having a Cu-O-Cu-O four-membered ring are obtained. On the other hand, mononuclear complexes can be obtained by complexation of the ligands (H(2)L(1) or H(2)L(3)) with palladium(II) acetate without N-O bond cleavage.