Half-titanocene 5-t-butyl-2-(1-(arylimino)methyl)quinolin-8-olate chlorides: Synthesis, characterization and ethylene (co-) polymerization behavior

A series of half-titanocene chloride complexes bearing 5-t-butyl-2-(1-(arylimino)methyl)quinolin-8-olate ligands (L), CpTiLCl₂, has been synthesized in acceptable yields by the stoichiometric reaction of CpTiCl₃ with the respective potassium 5-t-butyl-2-(1-(arylimino)methyl)quinolin-8-olate. All half-titanocene complexes were fully characterized by elemental analysis and NMR spectroscopy, and the molecular structures of the representative complexes C1 and C2 were confirmed as pseudo octahedral at titanium by single-crystal X-ray diffraction. When activated with methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all titanium complexes exhibited good activities (up to 4.8 × 10⁵ g mol⁻¹(Ti) h⁻¹) towards ethylene polymerization. The obtained polyethylene exhibited ultra-high molecular weight (up to 11.82 × 10⁵ g mol⁻¹) with narrow polydispersity. Furthermore, effective co-polymerization of ethylene with 1-hexene or 1-octene was achieved with several percentages of co-monomer incorporation in the resultant polyethylenes

Nickel bis{4,6-dibenzhydryl-2-[(arylimino)methyl]phenoxylate} complexes: Synthesis, structures, and catalytic behaviour towards ethylene and norbornene

A series of 4,6-dibenzhydryl-2-[(arylimino)methyl]phenol derivatives (L1-L6) and their nickel complexes (Ni1-Ni6) were synthesized and characterized by spectroscopic and elemental analyses. Molecular structures of Ni3 and Ni6 were further confirmed by single-crystal X-ray crystallographic studies. When activated with ethylaluminium sesquichloride (EASC), all nickel pre-catalysts displayed good catalytic activity (up to 2.89 × 106 g mol -1(Ni) h-1) for ethylene dimerization. Furthermore, these nickel complexes showed high activity for norbornene polymerization in the presence of MAO

Synthesis, structure and photophysical properties of 2-benzhydryl-4-methyl- 6-(aryliminomethyl)phenol ligands and the zinc complexes thereof

The Schiff-base ligands 2-benzhydryl-4-methyl-6-((phenylimino)methyl)phenol (L1-L5), and their corresponding zinc complexes (C1-C5), were prepared and fully characterized. The UV-Vis absorption and fluorescence spectra of the ligands and their Zn(II) complexes were measured in solvents such as methanol, dichloromethane, THF, or toluene, respectively. The results showed that the fluorescence intensity of the ligands was very weak, but upon coordination with Zn2+, the fluorescence intensity was greatly enhanced, and the fluorescent quantum yield ratio of C5 (0.46) to L5 (0.0004) in methanol increased by around 1150 times. The enhanced fluorescence of the zinc complexes is due to the intramolecular charge transfer (ICT) and the stronger geometrical rigidity of the delocalized bonding planes in these molecules. Transient absorption spectrum bands with peaks at about 310 and 460 nm were attributed to triplet state absorptions and absorption dynamic curve fitting showed that lifetimes were of microsecond level scale. There was no time-resolved property observed for the bleaching spectral bands at 350 nm and at ca. 460 nm. This spectral property, like the Stokes shift, can be attributed to the typical behavior of nanosecond transient absorption of the compounds with the excited-state intramolecular proton transfer (ESIPT). © 2012 Elsevier B.V. All rights reserved

6-Benzhydryl-4-methyl-2-(1H-benzoimidazol-2-yl)phenol ligands and their zinc complexes: Syntheses, characterization and photoluminescence behavior

The series of 6-benzhydryl-4-methyl-2-(1H-benzoimidazol-2-yl)phenol derivatives (HL) and their zinc complexes (ZnL2) were synthesized and fully characterized. Single-crystal X-ray diffraction studies were conducted on representative complexes (C1 and C4), which revealed a distorted tetrahedral geometry at zinc. By comparison with these organic compounds (HL), the fluorescent quantum yields of the corresponding zinc complexes were increased. The fluorescence intensities of zinc complexes were affected by the solvents used, and enhanced intensities in methanol were observed compared with those observed in other solvents such as dichloromethane and toluene. The fluorescence decay mainly followed a single exponential in toluene, whereas a double exponential decay was observed in the presence of two active species in methanol and dichloromethane. © 2012 Elsevier B.V. All rights reserved

Synthesis, characterization and ethylene oligomerization behavior of 2-benzoimidazol-8-ethoxyquinolylnickel dihalides

A series of 2-benzoimidazol-8-ethoxyquinolines (L1–L6) and the nickel dihalides thereof (C1–C12) were synthesized and characterized by elemental analysis and infrared spectroscopy. The molecular structures of representative complexes were determined by single crystal X-ray diffraction which revealed a distorted pyramidal geometry at nickel. All complexes, when activated with Et2AlCl, showed high activities towards ethylene oligomerization and enhanced thermodynamic stability

Synthesis and properties of Alkyl <i>α-D-</i>Galactopyranoside

<p>Alkyl <i>α-D-</i>galactopyranosides are sugar-based nonionic surfactants, and it is necessary to research their structure–property relationships since it is not quite clear that the change of the alkyl chain length has effects on a series of physicochemical properties. Here, alkyl <i>α-D-</i>galactopyranosides were prepared by galactose and alcohols through three steps including acetylation, coupling with alcohols in the presence of a catalyst stannic chloride, and deprotection. Furthermore, their water solubility and other properties were investigated. Alkyl <i>α-D-</i>galactopyranosides (4a ∼ 4e, <i>n</i> = 6 ∼ 10) were water soluble, and their dissolution process in water was an endothermic process. Nonyl <i>α-D-</i>galactopyranoside (4d) showed excellent foaming ability and foam stability. Octyl <i>α-D-</i>galactopyranoside (4c) had the strongest emulsifying ability for toluene and nonyl <i>α-D-</i>galactopyranoside (4d) had the strongest emulsifying ability for rapeseed oil. The critical micelle concentration (CMC) values and surface tension at the CMC were decreasing with increasing alkyl chain length. Their standard free energy of adsorption (Δ<i>G</i>_ads) was more negative than their standard free energy of micellization (Δ<i>G</i>_mic). The moisture-absorption abilities were weakening with increasing alkyl chain length. Alkyl <i>α-D-</i>galactopyranosides (4a ∼4f) were thermally stable below 280°C. Alkyl <i>α-D-</i>galactopyranosides (4c ∼4f) had the optical texture of the thermotropic liquid crystal smectic A phase.</p

Synthesis, characterization and ethylene polymerization behavior of nickel dihalide complexes bearing bulky unsymmetrical α-diimine ligands

A series of nickel(II) dihalide complexes (C1–C10) bearing unsymmetrical a-diimine ligands of the type 2,4-dibenzhydryl-N-(2-phenyliminoacenaphthylenylidene)-6-methylbenzenamine (L1–L5) were synthesized and fully characterized. Single-crystal X-ray diffraction revealed a distorted tetrahedral geometry around the nickel center in the complexes C3, C5 and C9. Upon activation with modified methylaluminoxane (MMAO), all nickel pro-catalysts performed with high activities in ethylene polymerization, producing highly branched polyethylene product