Two crosslinkable poly(p-phenyleneethynylene)s(PPEs): poly[2,5-di(2'-ethyl-hexyloxy)-1,4-phenylenee-thynylene] with end-capped vinyl(PPE1) and poly[2,5-di(allyloxy)-1,4-phenyleneethynylene-2,5-di(2'-ethyl-hexyloxy)-1,4-phenyleneethynylene](PPE2) were synthesized. Via the thermal addition reactions of vinyl end groups of PPE1 and allyloxy side groups of PPE2, crosslinked polymers C-PPE1 and C-PPE2 were obtained, respectively. The two polymers were characterized by wide-angle X-ray diffraction(WXRD), ultraviolet-visible(UV-Vis) absorption, and photoluminescence(PL). The results indicate that in the solid state, the polymer chains of PPE1 were packed with a low degree of crystallinity because of the sterically hindered(2'-ethyl-hexyl)oxy branched side chains, but, because of the introduction of allyloxy side chains, the polymer chains of PPE2 were packed in an order fashion with a high degree of crystallinity. Because of the high crosslinking density in C-PPE2, the formation of aggregates and excimer was hampered by the formed crosslinking network more effectively in C-PPE2 film than in C-PPE1 film.
Photo-isomerization of aromatic α-hydroxy hydrazone was reported. We investigated the structures of salicylaldehyde phenylhydrozone(SP) in the ground state using density functional theory(DFT) with the B3LYP functional and the 6-311+G(d) basis set. All nine possible isomers of SP in the ground state consist of seven phenol forms and two ketone forms. Intrisic reaction coordinate(IRC) analysis discloses the existence of a cycle driven by the two proton transfer processes in the ground and excited states of SP, which suggests that no ketonic form could exist in the ground state. Further theoretical studies of the potential energy surfaces support a trans-cis conversion followed by a relaxation to the stable form of SP in the excited states.
JIN Jing-yiPAN YanLI Xiu-huaHOU JunWU XueSU Zhong-min
Ficin is an important component of plants in Ficus family such as fig latex. It is of special significance in medicine and industry because it exhibits activity throughout a wide range of temperature and pH values. In this work, we purified a component of ficin from the latex homogeneity of Shandong fig trees, and the properties of the purified ficin were studied. The current findings revealed that heavy metal ions were able to inhibit ficin, while DTT, L-cysteine, and β-ME were found to promote ficin activity. It was also observed that the half life of ficin at 65 °C was longer than 1 h and the Michaelis constant(Km) for casein hydrolyzation was determined to be 1.56 mg/mL. Our study shows that this purified ficin is a cysteine protease.
HUANG Lu QU He-zhi ZHANG Lei DU Shan-shan YANG Shuo HAO Dong-yun WANG Xiao-ping
A novel nickel(II) complex Ni[L]Cl2·CH3CN(1) containing the tridentate ligand 2,6-bis[1-(2,4,6- trimethylphenylimino)ethyl]pyridine(L) has been synthesized. The crystal structure of complex 1 was determined by single crystal X-ray diffraction analysis. The catalytic activity of complex 1 for the polymerization of ethylene was studied under activation with methylaluminoxane(MAO).
Eighteen novel triazole compounds containing 1,3,4-oxadiazole groups were synthesized from 2-(1H-1,2,4-triazol-1-yl)acetohydrazide and carbon disulfide by several step reactions. The target compounds were characterized by elemental analysis, 1H NMR, 13C NMR, IR, MS, and X-ray crystallography. The results of preliminary biological tests show that all the compounds exhibit certain fungicidal activities.
XU Liang-zhong BI Wen-zhao SHANG Yu-qing ZHAI Zhi-wei YI Xu
Conductive polyvinylidene fluoride(PVDF)matrix composites filled with graphited fiber(GF)or carbon fiber(CF)were prepared by the melt-mixing method.The breakage and length distribution of the fibers in the polymer matrix were studied by scanning electron microscope(SEM)and optical microscope(OM)observations,respectively. The differences in the positive temperature coefficient(PTC)effects of the composites were mainly attributed to inter-fiber contact ability.The elimination of the negative temperature coefficient(NTC)effect for CF/PVDF composite was because of an increase in the viscosity of the polymer matrix.With the same filler content,CF could be more effective,to eliminate the NTC effect when compared with GF.Addition of 2%CF(mass fraction)in the PVDF composite with 7%GF(mass fraction)could effectively eliminate the NTC phenomenon of the composite.
WANG Xin-lei ZHANG Guo LI Ji-xin LI Zhuo-shi LIU Zhan-fang LIU Xiu-qi
