Dialkylaluminum Complexes with Chelating Anilido-Imine Ligands: Synthesis, Structures, and Luminescent Properties

Novel bidentate N-coordinated alkylaluminum complexes: synthesis, characterization, and efficient catalysis for hydrophosphonylation

Five new alkylaluminum complexes with different pyridinyl-substituted imines or cyclohexyl-substituted imines were synthesized and characterized successfully. The aluminum complex [FlCHNCH(CH3)Py]AlMe2(Py = 2-pyridyl) (1) was obtained by reacting 9-[2-pyridyl-CH(CH3)-NCH]Fl (Fl = fluorenyl) (L1) and equimolar AlMe3. The reactions of 9-(2-pyridyl-NCH)Fl (L2) and 9-[2-N(CH3)2-cyclohexyl-NCH]Fl (L3) with equimolar AlMe3 or AlEt3 afforded other alkylaluminum complexes [FlCHNPy]AlMe2(Py = 2-pyridyl) (2), [FlCHNPy]AlEt2 (Py = 2-pyridyl) (3), [FlCHNCyN(CH3)2]AlMe2 (Cy = 2-cyclohexyl) (4) and [FlCHNCyN(CH3)2]AlEt2 (Cy = 2-cyclohexyl) (5). All these complexes (1-5) were characterized using NMR spectroscopy, elemental analysis, and X-ray crystal structure analysis. The catalytic properties of these new alkylaluminum complexes for the hydrophosphonylation of aldimines were examined. Complex 5 showed the best catalytic performance under mild reaction conditions with a low catalyst loading (1 mol%), and 20 different substituents of aldimines were isolated with more than 90% yields.

Anilido-oxazoline-ligated rare-earth metal complexes: synthesis, characterization and highly cis-1,4-selective polymerization of isoprene

Anilido-oxazoline-ligated rare-earth metal dialkyl complexes have been synthesized and structurally characterized. The complexes exhibited strong fluorescence emissions and good catalytic performance on isoprene polymerization with high cis-1,4-selectivity. The treatment of anilido-oxazoline precursors ortho-C6H4[NH(2,6-R12C6H3)][C[double bond, length as m-dash]NC(R2,R3)CH2O] (R1 = R2 = R3 = Me (HL1); R1 = iPr, R2 = R3 = Me (HL2); R1 = R2 = iPr, R3 = H (HL3); and R1 = iPr, R2 = R3 = H (HL4)) with an equimolar amount of Ln(CH2SiMe3)3(THF)2 (Ln = Sc, Y) afforded rare-earth metal complexes L1-4-Ln(CH2SiMe3)2(THF)n (L1-Sc (1), n = 1; L2-Sc (2), n = 0; L1-Y (3), n = 1; L2-Y (4), n = 1; L3-Y (5), n = 1; and L4-Y (6), n = 1) in good yields. The complexes are stable in both the solid state and solution. Single crystal X-ray diffraction study showed that complexes 1, 3 and 4 exhibit a distorted trigonal bipyramidal configuration, while complex 2 is pseudo-tetrahedral without coordinated THF. The luminescence properties of complexes 1-4 were investigated and the emission maxima were found in the range of 465-477 nm. DFT and TD-DFT studies were carried out to explore their characteristic electronic structures and gain insight into their optical properties. Upon activation with organic borates, the reported complexes exhibited high activity and cis-1,4-selectivity for isoprene polymerization. The nature of the central metal and substituent groups in oxazoline have an influence on the cis-1,4-selectivity.

Synthesis of Ti, Zr, and Hf complexes with a new tetra-azane ligand by one-pot HCl-elimination and their properties as catalysts for production of UHMWPE

The first example for the HCl-elimination reaction being applied in the attachment of an amido-containing ligand to Zr and Hf.

Organic–inorganic hybrid nanomaterials based on inorganic oxides and a mesomorphic polyazomethine

Organic–inorganic hybrid materials have been obtained by impregnating a mesomorphic polyazomethine into a porous inorganic matrix of zinc oxide (ZnO), tin dioxide (SnO2), or mixed ZnO/SnO2. The porous inorganic matrix has been obtained by magnetron sputtering technique and proved a very high crystallinity degree. The resulting hybrid materials were characterized from morphological and optical points of view by scanning electron microscopy, atomic force microscopy, and ultraviolet-visible and photoluminescence spectroscopy. The inorganic matrix itself exhibited a highly rough surface, which became smoother after polymer impregnation, indicating its complete coverage. The violet emission of the separate inorganic and organic components turned into a blue and green light emission, respectively, of the hybrid materials, suggesting the possibility to modulate the color of emitted light by the simple choice of the inorganic matrix. Considerations with regard of interface phenomena that prompted the photophysical changes of the hybrid materials were done.

Synthesis, structures and electrochemical and photophysical properties of anilido-benzoxazole boron difluoride (ABB) complexes

Four-ring-fused anilido-benzoxazole boron difluoride (ABB) dyes were synthesized, and exhibited very bright luminescence in solution (Φ_f = 0.45–0.96 in CH₂Cl₂) and in the solid-state (Φ_f = 0.07–0.37).

Synthesis of binuclear phenoxyimino organoaluminum complexes and their use as the catalyst precursors for efficient ring-opening polymerisation of ε-caprolactone

A series of novel binuclear phenoxyimino organoaluminum complexes of the type [(RN=CH)C6H3OAlMe2]2 [R = C6H5 (2a), 2,6-(i)Pr2C6H3 (2b), 2,6-Ph2C6H3 (2c), adamantyl (2d), (t)Bu (2e)] have been prepared in high yields, and these complexes were identified by (1)H, (13)C NMR and elemental analysis. Structural analysis for 2a-e revealed that these complexes have a distorted tetrahedral geometry around Al and both the Al-O and the Al-N bond distances were considerably influenced by substituents in the imino groups. The complexes were tested as catalyst precursors for ring-opening polymerisation (ROP) of ε-caprolactone (CL) in the presence of BnOH, and their catalytic activities were strongly affected by the catalyst structures and polymerisation conditions. An efficient living ROP has been achieved using the 2b/BnOH system.

[(E)-10-(2,6-Dimethyl-phenyl-imino)-9-methyl-9,10-dihydro-phenanthren-9-olato]penta-methyl-dialuminum(III)

The two Al atoms in the title compound, [Al₂(CH₃)₅(C₂₃H₂₀NO)], are four-coordinated in a distorted tetra­hedral environment. The coordination of one Al atom includes three methyl-C atoms and the O atom from the ligand, whereas the second Al atom is surrounded by the O atom and one N atom from the ligand as well as by two methyl-C atoms. In the ligand, the dihedral angle between the two phenyl rings in the 9,10-dihydro­phenanthren unit is 20.64 (12)°.

[N-((E)-2-{[2-(Dimethyl-amino)-eth-yl]imino-meth-yl}phen-yl)-N-(2,6-dimethyl-phen-yl)anilinido-κN,N',N'']ethyl-zinc

The title eth­yl–zinc complex, [Zn(C₂H₅)(C₁₉H₂₄N₃)], bears a tridentate anilinide–aldimine ligand and features one long Zn—N(amine) bond length, attributable to the crowded environment of the coordinated metal, arising from the dimethyl­phenyl group. The Zn^II ion adopts a distorted tetra­hedral geometry, the dihedral angle between the two benzene rings being 86.05 (16)°.

Electroluminescent Properties of a Schiff-Base Aluminum Complex in Single Layer Polymer Light-Emitting Diodes

The Schiff-base ligand aluminum complex, [AlLMe2] [L = ortho-C6H4(NC6H3Me2-2,6)(CH=NC6H3Me2-2,6)], has been synthesised and characterised; its electroluminescent properties are reported. Electroluminescent devices were fabricated by doping [AlLMe2] in a polymer host of poly (vinylcarbazole) (PVK) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) using a simple solution spin-coating technique. The single-layer polymer organic light-emitter devices exhibited green emission, showed maximum current efficiency of 1.4 cd/A and maximum luminance of near 1000 cd/m2.