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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...

A series of {bis[N,N’N′-(2-ethyl-6-methylphenyl)imino]-1,2-dimethylethane}dibromonickels have been synthesized and characterized. The crystal structures of representative chiral ligand, bis[N,N’N′-(2-ethyl-6-methyl-4-s-phenethylphenyl)imino]-1,2-dimethylethane (S,R)–2a and its chiral complex, {bis[N,N’N′-(2-ethyl-6-methyl-4- sec-phenethylphenyl)imino]-1,2-dimethylethane}dibromonickel (S,R)–3a, have been confirmed by X-ray crystallographic analysis. The asymmetric unit of chiral (S,R)–2a contains one half-molecule which exhibits a crystallographically imposed center of symmetry. The single C-–C bond in 1,4-diazabutadiene fragment is trans-configured and situated on an inversion center. However, the trans-configured ligand can be transformed into cis-configured ligand in order to facilitate the formation of chiral complex (S,R)–3a. Complex (S,R)–3a has pseudo-tetrahedral geometry about the nickel center. Complex (S,R)–3a bearing one ethyl and one methyl in the ortho-aryl position and an electron-donating sec-phenethyl groups in the para-aryl position, activated by diethylaluminum chloride (DEAC), shows highly catalytic activity for the polymerization of ethylene [3.22 × 106 106 g g PE/(mol Ni. h. bar)]. Interestingly, complex 3b bearing one ethyl and one methyl groups in the ortho-aryl position and a strong electron-withdrawing Cl substituent group in the para-aryl position produced the more dendritic polyethylenes (branching degree: 92, 114 and 139 branches/1000 C at 20, 40 and 60 60 (°C, respectively) under low ethylene pressure. The dendritic polyethylene particle size can be controlled in the 1–20 nm range, and could be expected to become the nano-targeted drug carrier after modified with water-soluble oligo(ethylene glycol) (OEG).

A series of new α-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′-(4-methyl-2,6-di-sec-phenethylphenyl)imino]-1,2-dimethylethane rac-1c and chiral complexes, {bis[N,N′-(4-methyl-2-sec-phenethylphenyl)imino]-2,3-butadiene}dibromidonickel rac-2a and bis{bis[N,N′-(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 × 106 g PE (mol Ni.h.bar)−1], 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-α-diimine Ni(II) complex rac-2b also exhibited high activity toward ethylene polymerization [1.71 × 106 g PE (mol Ni · h · bar)−1]. The type and amount of branches of the polyethylenes obtained were determined by 1H and 13C NMR. Copyright © 2013 John Wiley & Sons, Ltd.

Three new α-diimine Ni(II) complexes {bis[N,N′-(4-fluoro-2,6-diphenylphenyl)imino]acenaphthene}dibromonickel 4a, {bis[N,N′-(4-chloro-2,6-diphenylphenyl)imino]acenaphthene}dibromonickel 4b, and {bis[N,N′-(4-methyl-2,6-diphenylphenyl)imino]acenaphthene}dibromonickel 4c, were synthesized and characterized. The crystal structure of the complex 4a was determined by X-ray crystallography. Complex 4a has pseudo-tetrahedral geometry about the nickel center, showing C2v molecular symmetry. These complexes, activated by diethylaluminum chloride (DEAC) were tested in the polymerization of ethylene under mild conditions. Complex 4a bearing 2,6-diphenyl and strong electron-withdrawing 4-fluorine groups, activated by diethylaluminum chloride (DEAC) shows highly catalytic activity for the polymerization of ethylene [4.95 × 106 g PE/(mol Ni h bar)] and produced dendritic polyethylene (153.3 branches/1000 C). The dendritic polyethylene particle size obtained by 4a/DEAC can be controlled in the 1–20 nm under 0.2 bar ethylene pressure, and could be expected to become a nano-targeted drug carrier after modified with water-soluble oligo(ethylene glycol) (OEG).

Human hepatocellular carcinoma (HCC) is one of the major causes of death worldwide. To investigate the relative importance of active and passive targeting strategies, the synthesis, characterization, in vitro uptake, and in vivo biodistribution of specific sulfapyridine HPMA (HPMA: N-(2-hydroxypropyl methacrylamide)) copolymer (sulfapyridine: SPD) conjugates, nonspecific HPMA copolymer conjugates, and DTPA are described in this study. The poly(HPMA)-SPD-DTPA (DTPA: diethylenetriaminepentaacetic acid), poly(HPMA)-DTPA, and DTPA conjugates were radiolabeled with the radionuclide (99m)Tc and tested for uptake by cultured H22 cells. The cellular accumulation of poly(HPMA)-SPD-DTPA-(99m)Tc complex was found to be time-dependent. The poly(HPMA)-SPD-DTPA-(99m)Tc tracer exhibited rapid uptake kinetics in cell culture with a t(1/2) of ~5 min. The uptake of poly(HPMA)-SPD-DTPA-(99m)Tc was significantly higher than that of poly(HPMA)-DTPA-(99m)Tc, indicating that the uptake of the poly(HPMA)-SPD-DTPA-(99m)T was active binding. The uptake of poly(HPMA)-DTPA-(99m)Tc was significantly higher than that of DTPA-(99m)Tc, suggesting that the uptake of the poly(HPMA)-DTPA-(99m)T was passive binding. Twenty-four hour necropsy data in the hepatocellular carcinoma tumor model showed significantly higher (p0.001) tumor localization for poly(HPMA)-SPD-DTPA-(99m)Tc (4.98 ± 0.48%ID/g [percentage injected dose per gram tissue]) compared with poly(HPMA)-DTPA-(99m)Tc (2.69 ± 0.15% ID/g) and DTPA-(99m)Tc (0.83 ± 0.03%ID/g). Moreover, higher T/B for poly(HPMA)-SPD-DTPA-(99m)Tc indicated reduced extravazation of the targeted polymeric conjugates in normal tissues. Specific molecular targeting and nonspecific vascular permeability are both significant in the relative tumor localization of poly(HPMA)-SPD-DTPA-(99m)Tc. Extravascular leak in nonspecific organs appears to be a major factor in reducing the T/B for the sulfapyridine molecules. Thus, the poly(HPMA)-SPD-DTPA is expected to be used as the potential macromolecular targeting carrier for hepatoma carcinoma in mice.

Two new α-diimine containing Ni(II) complexes, {bis[N,N′-(2,6-dimethyl-4-naphthylphenyl)imino]-1,2-dimethylethane}dibromonickel 3a and {bis[N,N′-(2-methyl-4-naphthylphenyl)imino]-1,2-dimethylethane}dibromonickel 3b were synthesized and characterized. The crystal structures of representative ligand 2a and its complex 3a were determined by X-ray crystallography. Complex 3a bearing 2,6-dimethyl and 4-naphthyl groups, activated by diethylaluminum chloride (DEAC), shows high catalytic activity for the polymerization of ethylene [4.43 × 106 g PE/(mol Ni h bar)]. Interestingly, complexes 3a and 3b bearing the naphthyl substituent in the para-aryl position produced dendritic polyethylenes (branching degree, 3a: 112, 118, and 147; 3b: 113, 127, and 151 branches/1,000 C at 20, 40, and 60 °C, respectively). The dendritic polyethylene particle size obtained by 3a and 3b/DEAC can be controlled in the 1–20 nm range under low ethylene pressure (diameter, 3a: 18.31, 14.44, and 11.09; 3b: 12.29, 8.98 and 6.27 nm at 20, 40, and 60 °C, respectively) and could be expected to produce a nano-targeted drug carrier after modification with water-soluble oligo(ethylene glycol).