Electrophoretic deposition of phthalocyanine in organic solutions containing trifluoroacetic acid

The absorption spectra of copper phthalocyanine (CuPc) 1,2-dichloroethane (DCE) solutions containing trifluoroacetic acid (TFAA) shows that the number of protons coordinating to the CuPc molecule was 1 and 2 for the first and second proton adducts, respectively, which indicates the formations of CuPcH(+) and CuPcH(2)(2+). This CuPc molecule may act as a catalyst to dissociate TFAA into trifluoroacetate anion (A(-)) and H(+) and form the proton adducts. The electrical conductivity dependence of the solution on CuPc concentration also supports this mechanism. A dense film of CuPc was deposited on an indium tin oxide cathode plate by electrophoresis of the solution. Similar dense films of a wide variety of phthalocyanines (MPc; M = Cu, H(2), Fe, Ni, Zn, Pb, VO) were also deposited using this method. Similar films of CuPc were also formed using dichloromethane (DCM) and 1,1,1-trichloroethane (TCE) in place of DCE. Depositions are ascribed to the migration of positively charged monomers (i.e., protonated MPc). Scanning electron microscopy revealed that these films are composed of fibrous crystallites, size of which was found to increase with the electrophoresis time, the strength of the applied electrical field and the concentration of CuPc in the bath. The influence of the dielectric constant of the organic solvent on the film growth is discussed.     

Mechanism-based molecular design of highly selective fluorescence probes for nitrative stress

Nitrative stress is implicated in various pathogenic processes, including neurodegenerative disorders, but there is no practical fluorescence probe which can monitor the generation of nitrative stress with high selectivity. To design a suitable fluorescence probe, we have first focused on the fluorescence quenching mechanism of the nitro group, which has been believed to be a unique quencher of fluorescent dyes. We found that nitro group-based fluorescence quenching could be explained in terms of an electron transfer process, from the excited fluorophore to the electron-deficient aromatic nitro moiety. By utilizing this result, we succeeded in developing novel fluorogenic probes, NiSPYs, which can selectively monitor the generation of nitrative stress based on aromatic nitration. NiSPYs showed strong fluorescence enhancement upon the reaction with nitrating agents, including peroxynitrite, but showed little or no fluorescence augmentation in the presence of other reactive oxygen species. NiSPYs should be potentially useful as tools to study the role of nitrative stress in various biological applications.     

Creation of superior carboxyfluorescein dyes by blocking donor-excited photoinduced electron transfer

[Structure: see text] Carboxyfluoresceins are widely utilized as fluorescence labeling reagents, but we recently found that their emission intensity is markedly decreased after esterification. On the basis of our hypothesis that the fluorescence decrease is due to a donor-excited photoinduced electron transfer (d-PeT) process, we have developed novel carboxyfluorescein derivatives in which the d-PeT process is hampered, and the emission intensity is not decreased upon esterification. These novel dye derivatives display high quantum yields and are expected to be useful as labeling agents.     

MassBank: a public repository for sharing mass spectral data for life sciences

MassBank is the first public repository of mass spectra of small chemical compounds for life sciences (<3000 Da). The database contains 605 electron‐ionization mass spectrometry(EI‐MS), 137 fast atom bombardment MS and 9276 electrospray ionization (ESI)‐MSⁿ data of 2337 authentic compounds of metabolites, 11 545 EI‐MS and 834 other‐MS data of 10 286 volatile natural and synthetic compounds, and 3045 ESI‐MS² data of 679 synthetic drugs contributed by 16 research groups (January 2010). ESI‐MS² data were analyzed under nonstandardized, independent experimental conditions. MassBank is a distributed database. Each research group provides data from its own MassBank data servers distributed on the Internet. MassBank users can access either all of the MassBank data or a subset of the data by specifying one or more experimental conditions. In a spectral search to retrieve mass spectra similar to a query mass spectrum, the similarity score is calculated by a weighted cosine correlation in which weighting exponents on peak intensity and the mass‐to‐charge ratio are optimized to the ESI‐MS² data. MassBank also provides a merged spectrum for each compound prepared by merging the analyzed ESI‐MS² data on an identical compound under different collision‐induced dissociation conditions. Data merging has significantly improved the precision of the identification of a chemical compound by 21–23% at a similarity score of 0.6. Thus, MassBank is useful for the identification of chemical compounds and the publication of experimental data. Copyright © 2010 John Wiley & Sons, Ltd.     

Isolation and characterization of a new abortifacient protein, karasurin, from root tubers of Trichosanthes kirilowii Max. var. japonicum Kitam

A new abortifacient protein, named karasurin, was isolated from fresh root tubers of Trichosanthes kirilowii MAXIMOWICZ var. japonicum KITAMURA (Cucurbitaceae, Japanese name: kikarasuuri) by the procedure involving acetone fractionation and ion-exchange chromatography on Toyopearlpak SP 650S. Homogeneity of Karasurin was demonstrated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, and high performance liquid chromatography (HPLC). Karasurin was a highly basic protein of pI 10.1 and the molecular weight was estimated as 28000 by SDS-polyacrylamide gel electrophoresis. Karasurin showed a strong abortion effect in pregnant mice.     

Thermal decomposition behavior of mono-aminimides and their application to polymerization of epoxide

Mono-aminimide compounds [N,N-dimethyl-N-(2-hydroxypropyl)-amine-N′-propionimide ( 1 ), trimethylamine valerimide ( 2 ), and trimethylamine benzimide ( 3 )] were found to exhibit different thermal decomposition behaviors and polymerization efficiencies for an epoxide (phenyl glycidyl ether, PGE). The thermal decomposition rate of aminimides at 150°C decreased in the order 1 > 2 > 3 . It seemed that hydrogen bonding enchanced the decomposition rate, and the resonance effect induced by the phenyl group suppressed the decomposition. 1 was thermolyzed to give isocyanate and tertiary aminoalcohol, which subsequently reacted with each other to give isocyanate and tertiary aminoalcohol, which subsequently reacted with each other to give urethane. When 2 was heatted, the isocyanurate generated from 2 remained intact. On heating of 3 , we observed the formation of triphenyl isocyanurate. PGE reacted with those aminimides and gave different products depending on their thermolyzed products. Equimolar mixtures of isocyanate, tertiary amine, PGE were used in the model reactions, and the thermal reaction between the expected decompostion products of aminimides was investigated in the presence and absence of PGE. The rate of PGE consumption was in the order PGE + 2 > PGE + 1 > PGE + 3 . It is clear that the formation of urethanes and oxazolidone derivatives affects the polymerization process.