Synthesis and luminescence properties of hybrid organic-inorganic transparent titania thin film activated by in-situ formed lanthanide complexes

Stable transparent titania thin films were fabricated at room temperature by combining thenoyltrifluoroacetone (TTFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, P123) copolymers. The obtained transparent titania thin films were systematically investigated by IR spectroscopy, PL emission and excitation spectroscopy and transmission electron microscopy. IR spectroscopy indicates that TTFA coordinates the titanium center during the process of hydrolysis and condensation. Luminescence spectroscopy confirms the in-situ formation of lanthanide complexes in the transparent titania thin film.

New rare earth metal bis(alkyl)s bearing an iminophosphonamido ligand. Synthesis and catalysis toward highly 3,4-selective polymerization of isoprene

Newrareearth metal bis(alkyl) complexes [(NPNPh)Ln(CH2SiMe3)(2)(THF) (NPNPh:N(Ph)PPh2=NC6H2Me3-2,4,6; Ln = Sc (3a), Ln = Y (3b), Ln = Lu (3c)) and [(NPNPy)Sc(CH2SiMe3)(2)(THF)1 (NPNPY = N(Py)PPh2=NC6H2Me3-2,4,6) (3d)) have been prepared via protonolysis reaction between rare earth metal tris(alkyl)s and the corresponding iminophosphonamines. Complexes 3a-d are analogous monomers of THF solvate. Each metal ion coordinates to a eta(2)-chelated NPN ligand and two cis-located alkyl groups, adopting tetrahedron geometry.

Highly Active Neutral Nickel(II) Catalysts for Ethylene Polymerization Bearing Modified,beta-Ketoiminato Ligands

A series of novel neutral nickel complexes 4a-e bearing modified beta-ketoiminato ligands [(2,6-(Pr2C6H3)-Pr-i)N=C(R-1)CHC(2 '-R2C6H4)O]Ni(Ph)(PPh3) (4a, R-1 R-2 = H; 4b, R-1 = H, R-2 = Ph; 4c, R-1 = H, R-2 = Naphth; 4d, R-1 = CH3, R-2 = Ph; 4e, R-1 = CF3, R-2 Ph) have been synthesized and characterized. Molecular structures of 4b and 4e were further confirmed by X-ray crystallographic analysis. Activated with B(C6F5)(3), all the complexes are active for the polymerization of ethylene to branched polyethylenes. Ligand structure, i.e., substituents R-1 and R-2, greatly influences not only catalytic activity but also the molecular weight and branch content of the polyethylene produced. The phenyl-substituted complex 4b exhibits the highest activity of lip to 145 kg PE/mol(Ni)center dot h center dot atm under optimized conditions, which is about 10 times more than unsubstituted complex 4a (14.0 kg PE/mol(Ni center dot)h center dot atm). Highly branched polyethylene with 103 branches per 1000 carbon atoms has been prepared using catalyst 4e.

Ethylene Polymerization and Ethylene/Hexene Copolymerization with Vanadium(III) Catalysts Bearing Heteroatom-Containing Salicylaldiminato Ligands

A series of novel vanadium(III) complexes hearing heteroatoill-containing group-substituted salicylaldiminato ligands [RN=CH(ArO)]VCl2(THF)(2) (Ar = C6H4, R = C3H2NS, 2a; C7H4NS, 2c; C7H5N2, 2d; Ar = C(6)H(2)tBu(2) (2,4), R = C3H2NS, 2b) have been synthesized and characterized. Structure of complex 2c was further confirmed by X-ray crystallographic analysis. The complexes were investigated as the catalysts for ethylene polymerization in the presence of Et2AlCl. Complexes 2a-d exhibited high catalytic activities (up to 22.8 kg polyethylene/mmolv h bar), and affording polymer with unimodal molecular weight distributions at 25-70 degrees C in the first 5-min polymerization, whereas produced bimodal molecular weight distribution polymers at 70 degrees C when polymerization time prolonged to 30 min. The catalyst structure plays an important role in controlling the molecular weight and molecular weight distribution of the resultant polymers produced in 30 min polymerization. In addition, ethylene/hexene copolymerizations with catalysts 2a-d were also explored in the presence of Et2AlCl, which leads to the high molecular weight and unimodal distributions copolymers with high comonomer incorporation.

Copolymerizations of ethylene with alpha-olefin-omega-ols by highly active vanadium(III) catalysts bearing [N,O] bidentate chelated ligands

The copolymerizations of ethylene with polar hydroxyl monomers such as 10-undecen-1-ol, 5-hexen-1-ol and 3-buten-1-ol were investigated by the vanadium(III) catalysts bearing bidentate [N,O] ligands (1, [PhN=C(CH3)CHC(Ph)O]VCl2(THF)(2): 2, [PhN=CHC6H4O]VCl2(THF)(2); 3, [PhN=CHC(Ph)CHO]VCl2(THF)(2)). The polar monomers were pretreated by alkylaluminum before the polymerization. High catalytic activities and efficient comonomer incorporations can be easily obtained by changing monomer masking reagents and polymerization conditions in the presence of diethylaluminium chloride as a cocatalyst. The longer the spacer group, the higher the incorporation of the monomer. Under the mild conditions, the incorporation level of 10-undecen-1-ol reached 13.9 mol% in the resultant copolymers was obtained. The reactivity ratios of copolymerization (r(1) = 41.4, r(2) = 0.02, r(1)r(2) = 0.83) were evaluated by Fineman-Ross method. According to C-13 NMR spectra, polar units were located both on the main chain and at the chain end.

Tuning the energy level and photophysical and electroluminescent properties of heavy metal complexes by controlling the ligation of the metal with the carbon of the carbazole unit

Four novel Ir-III and Pt-II complexes with cyclometalated ligands bearing a carbazole framework are prepared and characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. Single-crystal X-ray diffraction studies of complexes 1, 3, and 4 reveal that the 3- or 2-position C atom of the carbazole unit coordinates to the metal center. The difference in the ligation position results in significant shifts in the emission spectra with the changes in wavelength being 84 nm for the Ir complexes and 63 nm for the Pt complexes. The electrochemical behavior and photophysical properties of the complexes are investigated, and correlate well with the results of density functional theory (DFT) calculations. Electroluminescent devices with a configuration of ITO/NPB/CBP:dopant/BCP/AlQ(3)/LiF/Al can attain very high efficiencies.

Synthesis of the first rare earth metal bis(alkyl)s bearing an indenyl functionalized N-heterocyclic carbene

Treatment of indenyl-modified imidazolium bromide [C9H7CH2CH2(NCHCHN(C6H2Me3-2,4,6)CH)Br] ((IndH-NHC-H)Br) with rare earth metal tetra(alkyl) lithium (Ln(CH2SiMe3)(4)Li(THF)(4)) or with (trimethylsilylmethyl)lithium (LiCH2SiMe3) and rare earth metal tris(alkyl)s (Ln(CH2SiMe3)(3)(THF)(2)) sequentially afforded the first NHC-stabilized monomeric rare earth metal bis(alkyl) complexes (Ind-NHC)Ln(CH2SiMe3)(2) (1, Ln = Y; 2, Ln = Lu; 3, Ln = Sc) via double-deprotonation reactions. Complexes 1-3 are THF-free isostructural monomers. The monoanionic Ind-NHC species bond to the central metal ion in a eta(5):kappa(1) constrained geometry configuration (CGC) mode, which combine with the two cis-located alkyl moieties to form a tetrahedron ligand core, leading to the chirality of the complexes. Under the presence of activators AlEt3 and [Ph3C][B(C6F5)(4)], complex 2 showed catalytic activity toward the polymerization of isoprene to afford 3,4-regulated polyisoprene (91%).

Self-immobilized titanium and zirconium catalysts with phenoxy-imine ligands for ethylene polymerization. X-ray crystal structure of bis(N-(3-tert-butylsalicylidene)-4 '-allyloxyanilinato) zirconium(IV) dichloride

Four self-immobilized FI catalysts with allyl substituted phenoxy-imine ligands [{4-(CH2=CHCH2O)C6H5N=CH-C6H3(3-tert-C4H9)O}(2) MCl2] (1: M = Ti: 2: M = Zr), [{3-(CH2=CHCH2O)C6H5N=CH-C6H3(3-tert-C4H9)O}(2)MCl2] (3: M = Zr), [{4-(CH2=CHCH2-2,6-(iso-C3H7)(2))C6H5N=CH-C6H3(3,5-(NO2)(2))O}(2)MCl2] (4: M = Zr) have been synthesized and characterized. The molecular structure of 2 has been determined by X-ray crystallographic analysis. The results of ethylene polymerization showed that the self-immobilized titanium (IV) and zirconium (IV) catalysts 1-3 kept high activity for ethylene polymerization and 4 showed no activity. SEM showed the immobilization effect could greatly improve the morphology of polymer particles to afford micron-granula polyolefin as supported catalysts.

Micron-granula polyolefin with self-immobilized nickel and iron diimine catalysts bearing one or two allyl groups

Self-immobilized nickel and iron diimine catalysts bearing one or two allyl groups of [ArN=C](2)(C10H6)NiBr2 [Ar = 4-allyl-2,6-(i-Pr)(2)C6H2] (1), [ArN=C(Me)[Ar'N=C(Me)]C5H3NFeCl2 [Ar = Ar' = 4-allyl-2,6-(i-Pr)(2)C6H3, Ar = 2,6-(i-Pr)(2)C6H3, and Ar' = 4-allyl-2,6-(i-Pr)(2)C6H3] were synthesized and characterized. All three catalysts were investigated for olefin polymerization. As a result, these catalysts not only showed high activities as the catalyst free from the allyl group, such as [ArN=C](2)C10H6,NiBr2 (Ar = 2,6-(i-Pr)(2)C6H2)], but also greatly improved the morphology of polymer particles to afford micron-granula polyolefin. The self-immobilization of catalysts, the formation mechanism of microspherical. polymer, and the influence on the size of the particles are discussed. The molecular structure of self-immobilized nickel catalyst 1 was also characterized by crystallographic analysis.

Self-immobilized metallocene catalysts bearing an allyl group for ethylene polymerization, X-ray crystal structure of [(CH2=CHCH2)CH3Si(C13H8)(2)]ZrCl2

A series of ansa-metallocene complexes with an allyl substituted silane bridge [(CH =CHCH2)CH3Si(C5H4)(2)]TiCl2 (1), [(CH2=CHCH2)CH3Si(C9H6)(2)]MCl2 [M = Ti (2), Zr (3), Hf (4)] and [(CH2=CHCH2)CH3Si(C13H8)(2)]ZrCl2 (6) have been synthesized and characterized. The molecular structure of 6 has been determined by X-ray crystallographic analysis. Complexes 1-4, 6 bearing allyl groups have been investigated as self-immobilized catalysts for ethylene polymerization in the presence of MMAO. The results showed that the self-immobilized catalysts 1-4, 6 kept high ethylene polymerization activities of ca. 10(6) g PE mol(-1) M h(-1) and high molecular weight (M-w approximate to 10(5)) of polyethylene.

Syntheses of chromium(III) complexes with Schiff-base ligands and their catalytic behaviors for ethylene polymerization

A series of chromium(III) complexes LCrCl3 (4a-c) bearing chelating 2,2'-iminodiphenyisulfide ligands [L = (2-ArMeC=NAr)(2)S] was synthesized in good yields from the corresponding ligands and CrCl3.(THF). Using modified methylaluminoxane (MMAO) as a cocatalyst, these complexes display moderate activities towards ethylene polymerization, and produce highly linear polyethylenes with broad molecular weight distribution. Polymer yields, catalyst activities and the molecular weights, as well as the molecular weight distributions of the polymers can be controlled over a wide range by the variation of the structures of the chromium(III) complexes and the polymerization parameters, such as Al/Cr molar ratio, reaction temperature and ethylene pressure.

Novel highly active binuclear neutral nickel and palladium complexes as precatalysts for norbornene polymerization

A series of binuclear neutral nickel and palladium complexes [(XC6H2CH=NC6H3-iPr(2))MRL](2) 4b-f (X=NO2, M=Ni, R=Ph, L=PPh3, 4b; X=H, M=Pd, R=Me, L=PPh3,4c; X=H,M=Pd, R=Me, L=Py, 4d; X=NO2,M=Pd, R=Me, L=PPh3, 4e; X=NO2, M=Pd, R=Me, L=Py, 4f) and [(C10H7CH=NC6H3-iPr(2))MRL](2) 8a-c (M=Ni, R=Ph, L=PPh3, 8a; M=Pd, R=Me, L=PPh3, 8b; M=Pd, R=Me, L=Py, 8c) have been synthesized and characterized. The structures of complexes 4e and 8b have also been confirmed by X-ray crystallographic analysis. With modified methylalummoxane (MMAO) as cocatalysts, these complexes and complex [(C6H3CH=NC6H3-iPr(2))NiPh(PPh3)](2) 4a are capable of catalyzing the addition polymerization of norbomene (NBE) with the high activity up to 2.3 x 10(8) g PNBE/(mol(M) h). The structure of complexes affects considerably catalytic activity towards norbomene polymerization. The polymers obtained with nickel complexes are soluble, while those obtained with palladium complexes are insoluble. Palladium complexes 4c, 4e and 8b bearing PPh3 ligands exhibit much higher activities than the corresponding complexes 4d, M and 8c bearing pyridine ligands under the same conditions.

Ethylene polymerization by self-immobilized neutral nickel catalysts bearing allyl groups

[Ni(Ph)(PPh3)(N,O)] complexes containing phenyliminophenolato ligands (N,O) (1: N,O = A; 2: N,O = B; 3: N,O = Q 4: N,O = D; 5: N,O = E) have been synthesized and characterized. The molecular structure of 4 was determined by single-crystal X-ray analysis. Complexes 2-5 bearing allyl groups have been investigated as self-immobilized catalysts for ethylene polymerization without the use of co-catalysts. The high ethylene polymerization activities of ca. 10(5) g.PE mol(-1) Ni.h(-1) and high molecular weight (M-w approximate to 10(5)) of polyethylene could be accomplished by changing the ligand structures and reaction conditions. The self-immobilization of catalysts brings about a dramatic increase in the catalytic activities of ethylene polymerization.

X-ray crystal structure and molecular mechanics calculations of (2,6-iso-dipropyl-phenylamide) dimethyl (tetra-methylcyclopenta-dienyl) silane titanium dichloride

Crystal and molecular structure of (2.6-dipropylphenylamide) dimethyl (tetra-methyl cyclopentadienyl) silane titanium dichloride (I) was fully characterized by X-ray diffraction. The crystal is obtained from a mixture of ether/hexane as orthorhombic. with a = 12.658 (3) Angstrom. b = 16.62 (3) Angstrom. c = 11.760 (2) Angstrom. V = 2474.2 (9) Angstrom(3). Z = 4, space group Pnma. R = 0.0399; Componud I compose of the pi-bounded ring with its dimethylsilyl-dipropyl phenyl amido group and the two terminal chloride atoms coordinated to central metal to form a so-called constrained geometry catalyst (CGC) structure. The result of molecular mechanics (MM) calculations on compound I shows that bond lengths and bond angles from the MM calculation are comparable to the data obtained from the X-ray diffraction study. The relation of the structure of CGCs and their catalytic activity by MM calculations is also discussed.