A series of new a-diimine nickel(II) catalysts bearing bulky chiral sec-phenethyl groups have been synthesized and characterized. The molecular structure of representative chiral ligand, bis[N,N 0 -(4-methyl-2,6-di-sec-phenethylphenyl) imino]-1,2-dimethylethane rac-1c and chiral complexes, {bis[N,N 0 -(4-methyl-2-sec-phenethylphenyl)imino]-2,3-butadiene} dibromidonickel rac-2a and bis{bis[N,N 0 -(4-methyl-2-sec-phenethylphenyl)imino]-2,3-butadiene}dibromidonickel rac-2b, were confirmed by X-ray crystallographic analysis. Complex rac-2c bearing two chiral sec-phenethyl groups in the ortho-aryl position and a methyl group in the para-aryl position, activated by diethylaluminum chloride (DEAC), showed highly catalytic activity for the polymerization of ethylene [4.12 Â 10 6 g PE (mol Ni.h.bar) À1 ], and produced highly branched polyethylenes under low ethylene pressure (branching degree: 104, 118 and 126 branches/1000 C at 20, 40 and 60 C, respectively). Chiral 20-electron bis-a-diimine Ni(II) complex rac-2b also exhibited high activity toward ethylene polymerization [1.71 Â 10 6 g PE (mol Ni Á h Á bar) À1 ]. The type and amount of branches of the polyethylenes obtained were determined by 1 H and 13 C NMR. Experimental General Considerations and MaterialsAll manipulations involving air-and/or water-sensitive compounds were carried out with standard Schlenk techniques under nitrogen. Methylene chloride and o-dichlorobenzene were pre-dried with 4 Å molecular sieves and distilled from CaH 2 under dry nitrogen. Toluene, diethyl ether and 1,2-dimethoxyethane (DME) were distilled from sodium/benzophenone under N 2 atmosphere. Anhydrous NiBr 2 (99%) and diethylaluminum chloride (DEAC, 0.9 M solution in toluene) were obtained from Acros. 2,3-Butanedione (98%), 4-methylaniline (98%), 4-chloroaniline (97%), 2,4-dimethylaniline (98%) and 2,4,6-trimethylaniline (98%) were purchased from Alfa Aesar and used without further purification. [NiBr 2 (DME)] was synthesized according to the literature. [20]

A series of new naphthyl-α-diimine nickel(II) complexes, {bis[N,N′-(1-naphthyl)imino]-1,2-dimethylethane}dibromonickel (2a), {bis[N,N′-(2-methyl-1-naphthyl)imino]-1,2-dimethylethane}dibromonickel (2b), {bis[N,N′-(2-sec-phenethyl-1-naphthyl)imino]-1,2-dimethylethane}dibromonickel (rac-(RR/SS)-2c), {bis[N,N′-(2-methyl-1-naphthyl)imino]acenaphthene}dibromonickel (2d), and {bis[N,N′-(2-naphthyl)imino]-1,2-dimethylethane}dibromonickel (2e), were synthesized and characterized. The crystal structures of ligands 1b, rac-(RR/SS)-1c, 1d, 1e and their representative complexes rac-(RR/SS)-2c and 2d were determined by X-ray crystallography. These complexes, activated by diethylaluminum chloride (DEAC), were tested in the polymerization of ethylene and methyl methacrylate under mild conditions. Complex rac-(RR/SS)-2c, bearing chiral bulky sec-phenethyl groups in the o-naphthyl position, activated by diethylaluminum chloride (DEAC) shows highly catalytic activity for the polymerization of ethylene (2.81 × 106 g PE/((mol of Ni) h bar)) and produced branched polyethylene (75 methyl, 9 ethyl, 5 propyl, and 19 butyl or longer branches/1000 C at 40 °C). Interestingly, rac-(RR/SS)-2c could produce syndiotactic PMMA at low temperature (−30 °C: rr 88.75%, mr 7.26%, mm 3.99%).

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Annexin A2 (ANXA2) is reported to be associated with cancer development. To investigate the roles ANXA2 plays during the development of cancer, the RNAi method was used to inhibit the ANXA2 expression in caco2 (human colorectal cancer cell line) and SMMC7721 (human hepatocarcinoma cell line) cells. The results showed that when the expression of ANXA2 was efficiently inhibited, the growth and motility of both cell lines were significantly decreased, and the development of the motility relevant microstructures, such as pseudopodia, filopodia, and the polymerization of microfilaments and microtubules were obviously inhibited. The cancer cell apoptosis was enhanced without obvious significance. The possible regulating pathway in the process was also predicted and discussed. Our results suggested that ANXA2 plays important roles in maintaining the malignancy of colorectal and hepatic cancer by enhancing the cell proliferation, motility, and development of the motility associated microstructures of cancer cells based on a possible complicated signal pathway.

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