Alloyed Tetranuclear Metal Chains of Pd4−nPtn (n=0–3) Scaffolded by a New Linear Tetraphosphine Containing a PNP Bridge

A new linear tetraphosphine containing a PNP phosphazane bridge, rac-bis[(diphenylphosphinomethyl)phenylphosphino]phenylamine (rac-dpmppan), was synthesized and utilized to support a series of Pd/Pt mixed metal tetranuclear chains, [Pd_4−nPt_n(μ-rac-dpmppan)₂(XylNC)₂](PF₆)₂ (XylNC=xylyl isocyanide; n=0: Pd₄ ( 1 ), 1: PtPd₃ ( 2 ), 2: PtPd₂Pt ( 3 ), 2: Pt₂Pd₂ ( 4 ), 3: Pt₂PdPt ( 5 )), in which the number and positions of additional Pt atoms were successfully controlled depending on the respective synthetic procedures using transformations from 1 to 3 through 2 and from 4 to 5 by redox-coupled exchange reactions. The ³¹P{¹H} NMR and ESI mass spectra and X-ray diffraction analyses revealed almost identical tetranuclear structures, with slight contraction of metal-metal bonds according to incorporation of Pt atoms. The electronic absorption spectra of 1 – 5 exhibited characteristic bands at 635–510 nm with an energy propensity depending on the number and positions of Pt centres, which were assigned to HOMO (dσ*σσ*) to LUMO (dσ*σ*σ*) transition by theoretical calculations. The present results demonstrated that the electronic structures of Pd/Pt mixed-metal tetranuclear complexes are finely tuned as orbital-overlapping alloyed metal chains by atomically precise Pt incorporation in the Pd₄ chain.     

Formation of polyketone particle structure by hexafluoroisopropanol solvent evaporation and effects of plasticizer addition

Few solvents are capable of dissolving polyketones (PKs). 1,1,1,3,3,3‐Hexafluoro‐2‐propanol (hexafluoroisopropanol, HFIP) is a better solvent than trifluoroethanol and m‐cresol. When HFIP was evaporated from a PK/HFIP solution, a porous cast‐film with a microparticle structure was formed because the isotactic PKs adopted a helical conformation, and convection during evaporation of the high polarity and low‐boiling‐point HFIP caused aggregation and rolling of the polymer molecules. The addition of plasticizer suppressed particle formation, improving the surface structure and mechanical properties of the film. In particular, the dielectric properties of the film improved significantly. This will enable PKs, which are rigid insulating materials, to be used as dielectric materials, broadening their range of applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 887–892     

Baryogenesis in false vacuum

The null result in the LHC may indicate that the standard model is not drastically modified up to very high scales, such as the GUT/string scale. Having this in the mind, we suggest a novel leptogenesis scenario realized in the false vacuum of the Higgs field. If the Higgs field develops a large vacuum expectation value in the early universe, a lepton number violating process is enhanced, which we use for baryogenesis. To demonstrate the scenario, several models are discussed. For example, we show that the observed baryon asymmetry is successfully generated in the standard model with higher-dimensional operators.     

Decomposition of Insoluble and Hard-to-Degrade Animal Proteins by Enzyme E77 and Its Potential Applications

Insoluble and hard-to-degrade animal proteins are group of troublesome proteins, such as collagen, elastin, keratin, and prion proteins that are largely generated by the meat industry and ultimately converted to industrial wastes. We analyzed the ability of the abnormal prion protein-degrading enzyme E77 to degrade insoluble and hard-to-degrade animal proteins including keratin, collagen, and elastin. The results indicate that E77 has a much higher keratinolytic activity than proteinase K and subtilisin. Maximal E77 keratinolytic activity was observed at pH 12.0 and 65 °C. E77 was also adsorbed by keratin in a pH-independent manner. E77 showed lower collagenolytic and elastinolytic specificities than proteinase K and subtilisin. Moreover, E77 treatment did not damage collagens in ovine small intestines but did almost completely remove the muscles. We consider that E77 has the potential ability for application in the processing of animal feedstuffs and sausages.     

Preparation of Ring and Chain Condensed Oligophosphates

Preparations of small-ring and short-chain condensed phosphates were made by dry and wet processes, respectively. The crystallization of tetra- hexa-, and octaphosphates from the phosphate solution was not easy, and metal salts of these oligophosphates were amorphous and unstable at normal temperature. Guanidine tetraphosphate and ammonium hexaphosphate were crystalline and stable at normal temperature.     

Synthesis,Redox Properties,and Electronic Spectra of Sterically Crowded Triarylphosphines Conjugated with Electron Acceptors

Abstract

Synthesis, redox properties, and electronic spectra of the sterically crowded triarylphosphines conjugated with π-electron systems, especially electron acceptors such as carbonyl group, are briefly reviewed. The sterically crowded triarylphosphines conjugated with various π-electron systems were synthesized from the common synthetic intermediate, (bromoaryl)phosphine, by conventional manner. The sterically crowded triarylphosphines conjugated with the electron acceptors exhibit visible absorption and fluorescence with large Stokes shift. Large solvent effect, redshift in polar solvent, and good correlation with the difference of the oxidation potential of the phosphine moiety and the reduction potential of the acceptor moiety suggest polar excited state resulting from HOMO-LUMO transition.     

Polymerization of Acrolein by Imidazole

Polymerization of acrolein(AL) in the presence of imidazole(Im) has been investigated in tetrahydrofuran or methanol below room temperature. The polymers obtained, white or pale yellow powders, were found to be composed of vinyl polymer with one Im group attached and having an aldehyde side chain, of which 70–80 mole % of the aldehyde revealed bridge structure. The number-average molecular weight (M _n) of these polymers was determined to be in the range of 317 to 691. The rate of polmerization R_p was expressed by the equation, R + k[Im] [AL]².

The addition of water or dimethyl sulfoxide accelerated the polymerization reaction, while the presence of benzaldehyde or N,N'-dimethylformamide decreased R_p. The structure of addition products in the initial polymerization step was confirmed by IR and NMR spectra, and the observations of polymerization system was carried out by UV and NMR spectra. The polymerization mechanisms were discussed on the basis of these results.     

The synthesis and crystal structure of a new diprotonated Schiff base cryptand

Abstract

The synthesis and crystal structure of the diprotonated cryptand derived from the reaction of tren and 2,6-diacetyl pyridine is reported. The imino nitrogens of the Schiff base linkages are directed so that the dicarbimine functions are in trans, trans geometry relative to the pyridine C-N bond. This configuration has not previously been reported in related pyridine-derived Schiff base macrocycles.     

Fully automated reagent peak‐free liquid chromatography fluorescence analysis of highly polar carboxylic acids using a column‐switching system and fluorous scavenging derivatization

In this study, we combined a column‐switching system with a fluorous scavenging derivatization method to develop a fully automated reagent peak‐free LC fluorescence detection protocol for the analysis of highly polar carboxylic acids. In this method, highly polar carboxylic acids were derivatized with fluorescent 1‐pyrenemethylamine in the presence of 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide and 1‐hydroxy‐1H‐benzotriazole. Residual excess of the unreacted reagent was tagged with 2‐(perfluorooctyl)ethyl isocyanate and then removed selectively using a fluorous column‐switching system placed in front of an analytical reversed‐phase column. The signal of the fluorous‐tagged unreacted reagent was completely absent in the resulting chromatograms; therefore, it did not interfere with the quantification of each acid especially those eluted before 20 min. The detection limits (S/N = 3) for the examined acids were in the range from 4.0 to 22 fmol per injection. We have applied this method to comparative analysis of highly polar carboxylic acids in urine samples obtained from diabetes mellitus type‐II model mice and their control.