Studies on diacetylenic vinyl compounds. VI. ESR studies on the polymerization of diacetylene containing acrylate and methacrylates

A number of diacetylene containing acrylate and methacrylates have been synthesized and the interaction between their propagating radicals and the diacetylene groups was studied by ESR spectroscopy. In the case of polymerization at 70°C using AIBN as an initiator, the propagating radicals of methacrylates are temporarily trapped with the diacetylenes with rapid exchange of the electron, thus showing strong signals of the propagating radicals. Gamma irradiation of the frozen state produces a blue color in samples, and the ESR signals were found to be those of uninteracted acrylate and methacrylates. From a comparison of spectral widths, there seems to exist an intramolecular interaction between the radicals and the diacetylene group at the frozen state. © 1992 John Wiley & Sons, Inc.     

Synthesis of calix[4]arene library substituted with peptides at the upper rim

A fluorescence-labeled calix[4]arene library substituted with peptides at the upper rim was synthesized. Screening of the library for binding a dye-labeled oligopeptide indicated that some peptidocalix[4]arenes selectively bind the oligopeptide. The chemosensitivity of the library members for a target peptide was also investigated.     

Spatial geometric arrangements of disulfide-crosslinked loops in nonplanar proteins

The method presented earlier [T. Kikuchi, G. Némethy, and H.A. Scheraga, (1986) J. Comput. Chem. 7 , 67] for the classification of patterns of the three-dimensional folding of a covalently crosslinked polypeptide chain has been extended to nonplanar proteins. The procedure described earlier was applicable only to proteins termed planar, i.e., with a connexity of the crosslinks (e.g., disulfide bonds) that can be represented in a planar diagram. The procedure described in the present work is applicable to any (planar or nonplanar) pattern of crosslinking. The classification is based on a systematic and objective method of enumeration of spatial geometric arrangements of loops (SGAL) using no information other than the location of the disulfide bonds in the amino acid sequence. Various SGAL classes correspond to the presence of different ways of mutual penetration of loops, called thrustings and entanglements. Information on SGAL classes can be of use in structural predictions of folding patterns of proteins.     

3-Aroylmethyl derivatives of 2(1H)quinoxalinone and 2H-l,4-benzoxazin-2-ones existing in the enamine form

Seventeen derivatives of 2(1H)quinoxalinone and 2H-l,4-benzoxazin-2-one have been synthesized for structural study. All of the compounds having a substituted phenacyl, isonicotinoylmethyl, or 2-furoylmethyl side chain are shown to exist in the enamine form with an internal chelation both in the crystalline and solution states as evidenced by the ir and pmr spectra, respectively. In the gas phase, however, o-hydroxyphenacyl derivatives can exist in another type of intramolecularly hydrogen-bonded form which is supported by their mass spectra.     

Characterization of tension and normally lignified wood cellulose inPopulus maximowiczii

We have investigated unlignified tension wood and normally lignified wood celluloses inPopulus maximowiczii with particular reference to the composition of two crystalline phases I/I (triclinic/ monoclinic). Four independent techniques, which enable us to detect the two phases, CP/MAS¹³C NMR, Fourier transform infrared microscopy, selected-area electron diffraction, and X-ray diffraction were applied. Because of the low crystallinity of wood celluloses, particularly in the case of celluloses in the lignified cell wall, no single method was decisive enough to be able to determine the composition of the two phases as one can with highly crystalline materials. The I dominant structure (monoclinic crystal type) was, however, preferred for both tension and normal wood celluloses.     

A theorem on the average number of subfaces in arrangements and oriented matroids

It is known that for simple arrangements in thed-dimensional Euclidean spaceR ^d The average number ofj-dimensional subfaces of ak-dimensional face is less than . In this paper, we show that this is also true for all arrangements inR ^d and for all oriented matroids, and we give combinatorial proofs.