Enzymatic resolution of (+/-)-5-acetoxy-4-aryl-(2E)-pentenoate derivatives

Enzymatic resolution of six (+/-)-5-acetoxy-4-aryl-(2E)-pentenoate derivatives, compounds 9, 11, 13, 15, 17, and 19 bearing a different aromatic substitution pattern, using lipase OF-360 from Candida rugosa was carried out. The absolute configurations of all hydrolyzed products and all unchanged acetates were found to be S and R, respectively. Moreover, the enantiomeric excess of the enzymatic resolution products from 9, 11, and 13 with the ortho-methoxyl group in the aromatic ring was higher than that of the substrates with no methoxyl group at the ortho-position in the aromatic ring.     

Metal-assisted assembly of pyridine-containing arylene ethynylene strands to enantiopure double helicates

Pyridine-containing arylene ethynylene strands were connected to the 2- and 2'-positions of (R)- and (S)-1,1'-binaphthyl templates. The arylene ethynylene moieties underwent intramolecular coordination with Ag(I) or Cu(I) ion to afford enantiopure double helicates. The double-helical structure was elucidated on the basis of circular dichroic (CD) spectra. The importance of intramolecular complexation of the double strands for the helicate formation was confirmed by comparison with a ligand bearing a single strand. Connection of the strands through an ether linkage enabled a sorting out of the Cotton effect induced by double-helical arylene ethynylene moieties. The CD exciton chirality method unambiguously proved that the termini of the strands approach each other upon complexation and that the sense of the induced helicity is the same as predicted by molecular modeling.     

Monte-Carlo-Untersuchung der dielektrischen Verlust-Kurve von Polymeren mit senkrechten Dipolen

Ohne Zusammenfassung     

Investigation of the requirements for plasma-induced polymerization of alcohols

We analyzed the requirements for plasma-induced alcohol polymerization by comparing the reactions of several types of aliphatic alcohols and alkanes. The experiments revealed that alcohol polymerization requires the fixation of atmospheric nitrogen into alcohol. The OH group in alcohol physically contributes to initiate the airborne plasma reactions with its permittivity. However, the group chemically works to inhibit the fixation of nitrogen and successive polymerization of alcohols. Our study demonstrates that the ratio of OH groups per weight percent of each molecule decides the feasibility of the polymerization and the properties of the polymers.     

Poly(2,7-di-n-pentyldibenzofulvene) showing chiroptical properties in the solid state based purely on a chiral conformation

Poly(2,7-di-n-pentyldibenzofulvene)s with no stereocenters, obtained by anionic polymerization using chiral 9-fluorenyllithium ligand complexes, showed intense circular dichroism in film form due purely to the chiral conformation of the main chain, while no chiroptical properties were detectable in solution.     

Isomeric yield ratios of fission products in the system of 24 MeV proton-induced fission of238U

Isomeric yield ratios of 30 fission products in 24 MeV proton-induced fission of²³⁸U were measured by the use of the ion-guide isotope separator on-line. The obtained isomeric yield ratios were converted to the angular momenta of primary fission fragments based on the statistical model. The deduced angular momenta were examined from various aspects. It is found that in general the angular momentum continuously increases with the fragment mass number including the region of symmetric mass division. However, there are some exceptions. For Sn isotopes the deduced angular momenta are quite small due to the spherical shape of the nuclear shell configuration. It is also concluded from the consideration of the charge distribution that the angular momentum of fission product scatters considerably within the narrow range of mass division. The dependence of the angular momentum on the available energy of fragments at scission point indicates that the individual fragment possesses a characteristic deformation at scission and/or the deduced angular momentum is seriously affected by the particle excitation after scission.