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Vibrational circular dichroism (VCD) is effective for analyzing the configuration and conformation of various bio(macro)molecules. In addition to a conventional VCD approach using theoretical calculations, this review explains how the use of an exciton-type VCD couplet can be employed to elucidate the structures of bio(macro)molecules, such as carbohydrates, glycerophospholipids, proteins and polyesters.
Cationic polymerization of p-methylstyrene (pMeSt) was examined using various metal chlorides as Lewis acid catalysts in dichloromethane. Polymerization using SnCl4 and ZnCl2 in conjunction with 2,6-di-tert-butylpyridine (DTBP) proceeded in a controlled manner in contrast to the reactions with metal trichlorides, including AlCl3, FeCl3 and GaCl3. In addition, the combination of SnCl4 and DTBP allowed the controlled polymerization of less reactive styrenes and the synthesis of star-shaped poly(pMeSt)s through the cross-linking reaction using an alkylstyrene-type divinyl compound.
A novel hyperbranched poly(ether nitrile) (HBPEN) and its copolymer were synthesized as supports for palladium nanoparticles (PdNPs). Small PdNPs (3.0±0.8 nm) were obtained by the reduction of HBPEN-Pd2+ complex with NaBH4. A comparison of HBPEN-, HBPEN copolymer- and linear poly(ether nitrile)-supported PdNPs suggested that the branched architecture in HBPEN can help prevent the aggregation of PdNPs generated in the early stages of reduction.
The film stabilities of ω-N-(3-(dimethylamino)propyl)propylamide-terminated polystyrene (PS-N) and conventional polystyrene (PS-H) on SiOx substrates were examined. Whereas a 20-nm-thick PS-H film was dewet at 423 K, a comparable PS-N film was stable because of the interaction between the chain end and the substrate surface. This indicates that end functionalization affects chain mobility with a relatively large scale at the solid interface.
This is the first report on exopeptidase-catalyzed oligopeptide synthesis. Oligo(l-leucine) was synthesized using the exopeptidase carboxypeptidase Y while preventing enzymatic hydrolysis. A high yield of the polypeptide with a narrow polydispersity was successfully obtained by limiting polypeptide cleavage during aminolysis.
In the presence of naphthylbutadiyne (DNB) and dinitronaphthylbutadiyne (DNNB), ESR signals of propagating PMMA radicals with concentration of the order of 1014–1015 radicals per ml were observed from early stage of polymerization, and their concentration increased with conversion. The concentration of the DNNB system was about double of that of the DNB system, indicating that electron accepting groups increase the stabilization of PMMA radicals. No fragment of the butadiynes are found in the PMMA obtained, indicating that the aromatic diacetylenes stabilize free radicals without suffering the addition reaction.
A new 1:1 alternating copolymerization of a five-membered, six-membered, and seven-membered cyclic germylene having a Me3Si-N group with N-phenyl-p-quinoneimine has successfully been demonstrated. The germylenes behaved as a reductant monomer whereas N-phenyl-p-quinoneimine as an oxidant monomer to give copolymers (oxidation-reduction copolymerization). In contrast to the previous observation that the copolymerization of cyclic germylenes with p-benzoquinone led to the formation of 2:1 periodic copolymers, the present copolymerization using a p-quinoneimine derivative produces all 1:1 alternating copolymers.
Hardwood lignin in eucalyptus was first converted to hardwood lignocresol through a phase separation process utilizing wood meal, sulfuric acid, and p-cresol at ambient temperature. A syringyl methyl benzofuran, S2 was selectively obtained via a syringyl-type phenolic dimer with a coumaran ring, S1 by NaOH treatments of hardwood lignocresol at 170 °C. Our process controls the reactivity of Cα linkages, Cβ-aryl-ethers, and Cγ-OH in sequence, successfully resulting in a high yield of specific aromatic chemicals from hardwood lignin based on the successiveness of Cβ-aryl-ethers between syringyl units.
