Ethylene Polymerization of the New Titanium Complexes Bearing a Phosphine Oxide-Bridged Bisphenolato Ligand

A series of novel titanium(IV) complexes combining a phosphine oxide-bridged bisphenolato ligand TiCl2{2,2'-O=P-R-3 (4-R-2-6-R-1-C6H2O)(2)}(THF) (6a: R-1 = tBu, R-2 - H, R-3 Ph; 6b: R-1 - Ph, R-2 = H, R-3 = Ph; 6c: R-1 = R-2 = tBu, R-3 = Ph; 6d: R-1 = R-2 cumyl, R-3 = Ph; 6e: R-1 = tBu, R-2 = H, R-3 = PhF5) were prepared by the reaction of corresponding bisphenolato ligands with TiCl4 in THF. X-ray analysis reveals that complex 6a adopts distorted octahedral geometry around the titanium center. These catalysts were performed for ethylene polymerization in the presence of modified methyaluminoxane (MMAO).

Chiral ligand 2-(2 '-piperidinyl)pyridine: synthesis, resolution and application in asymmetric diethylzinc addition to aldehydes

Chiral ligand 2-(2'-piperidinyl)pyridine 1 has been synthesized in good overall yield by sequential benzylation, hydrogenation and debenzylation of 2,2'-bipyridine. Its enantiomerically pure enantiomers have been obtained by resolution of 2-(1-benzyl-2-piperidinyl)pyridine 2 with D-tartaric acid (or L-tartaric acid) followed by debenzylation. The absolute configuration was determined by X-ray analysis of the (S)-2 D-tartrate. It was demonstrated that I can be used as an effective enantioselective catalyst in the addition of diethylzinc to aldehydes.

The Reasons for Ligand-Dependent Quantum Yields and Absorption Spectrum of Four Polypyridylruthenium(II) Complexes with a Tetrazolate-Based Ligand: TDDFT Study

The quantum yield, lifetime, and absorption spectrum of four [Ru(bpy)(2)L](+) [where bpy is 2,2'-bipyridyl; L is represented by the deprotonated form of 2-(1H-tetrazol-5-yl)pyridine (L1) or 2-(1H-tetrazol-5-yl)pyrazine (L2)], as well as their methylated complexes [Ru(bpy)(2)LMe](2+) (RuL1Me and RuL2Me) are closely ligand dependent. In this paper, density functional theory (DFT) and time-dependent DFT (TDDFT) were performed to compare the above properties among these complexes. The calculated results reveal that the replacement of pyridine by pyrazine or the attachment of a CH3 group to the tetrazolate ring greatly increases the pi-accepting ability of the ancillary ligands.

Novel Near-Infrared Luminescent Hybrid Materials Covalently Linking with Lanthanide [Nd(III), Er(III), Yb(III), and Sm(III)] Complexes via a Primary beta-Diketone Ligand: Synthesis and Photophysical Studies

A series of novel, colorless, and transparent sot-gel derived hybrid materials Ln-DBM-Si covalently grafted with Ln(DBM-OH)(3)center dot 2H(2)O (where DBM-OH = o-hydroxydibenzoylmethane, Ln = Nd, Er, Yb, and Sin) were prepared through the primary beta-diketone ligand DBM-OH. The structures and optical properties of Ln-DBM-Si were studied in detail. The investigation results revealed that the lanthanide complexes were successfully in situ grafted into the corresponding hybrids Ln-DBM-Si. Upon excitation at the maximum absorption of ligands, the resultant materials displayed excellent near-infrared luminescence.

Metal-organic frameworks based on the pyridine-2,3-dicarboxylate and a flexible bispyridyl ligand: syntheses, structures, and photoluminescence

Three new metal-organic coordination polymers, [Cu(2,3-pydc)(bpp)]center dot 2.5H(2)O (1), [Zn(2,3-pydc)(bpp)]center dot 2.5H(2)O (2) and [Cd(2,3-pydc)(bpp)(H2O)]center dot 3H(2)O (3) (2,3-pydcH(2) = pyridine-2,3-dicarboxylic acid, bpp 1,3-bis(4-pyridyl)propane), have been synthesized at room temvperature. All complexes have metal ions serving as 4-connected nodes but represent two quite different structural motifs. Complexes 1 and 2 are isomorphous, both of which feature 2D -> 3D parallel interpenetration. Each two-dimensional (2D) layer with (4, 4) topology is interlocked by two nearest neighbours, one above and one below, thus leading to an unusual 3D motif. Complex 3 has a non-interpenetrating 3D CdSO4 framework with cavities occupied by uncoordinated water molecules.

Phosphorescence Color Tuning by Ligand, and Substituent Effects of Multifunctional Iridium(III) Cyclometalates with 9-Arylcarbazole Moieties

The synthesis, isomeric studies, and photophysical characterization of a series of multifunctional cyclometalated iridium(III) complexes containing a fluoro- or methyl-substituted 2[3-(N-plienylcarbazolyl)]pyridine molecular framework are presented. All of the complexes are thermally stable solids and highly efficient electrophosphors. The optical, electrochemical, photo-, and electrophosphorescence traits of these iridium phosphors have been studied in terms of the electronic nature and coordinating site of the aryl or pyridyl ring substituents. The correlation between the functional properties of these phosphors and the results of density functional theory calculations was made. Arising from the propensity of the electron-rich carbazolyl group to facilitate hole injection/transport, the presence of such a moiety can increase the highest-occupied molecular orbital levels and improve the charge balance in the resulting complexes relative to the parent phosphor with 2-phenylpyridine ligands. Remarkably, the excited-state properties can be manipulated through ligand and substituent effects that allow the tuning of phosphorescence energies from bluish green to deep red.

Highly 3,4-Selective Polymerization of Isoprene with NPN Ligand Stabilized Rare-Earth Metal Bis(alkyl)s. Structures and Performances

Deprotonation of (ArNHPPh2NAr2)-N-1 (H[NPN](n), n = 1 - 10) by Ln(CH2SiMe3)(3)(THF)(2) (Ln = Lu, Y, Sc, Er) generated a series of rare-earth metal bis(alkyl) complexes [NPN](n)Ln(CH2SiMe3)(2)(THF)(2) (1-10), which under activation with [Ph3C][B(C6F5)(4)] and AliBu(3) were tested for isoprene polymerization. The correlation between catalytic performances and molecular structures of the complexes has been investigated. Complexes 1-5 and 8, where Ar-1 is nonsubstituted or ortho-alkyl-substituted phenyl, adopt trigonal-bipyramidal geometry. The Ar-1 and Ar-2 rings are perpendicular in 1-4 and 8 but parallel in 5. When Ar-1 is pyridyl, the resultant lutetium and yttrium complexes 9a and 9b adopt tetragonal geometry with the ligand coordinating to the metal ions in a N,N,N-tridentate mode, whereas in the scandium analogue 9c, the ligand coordinates to the Sc3+ ion in a N,N-bidentate mode. These structural characteristics endow the complexes with versatile catalytic performances, With increase of the steric bulkiness of the ortho-substituents Ar-1 and Ar-2, the 3,4-selectivity increased stepwise from 81.6% for lutetium complex 1 to 96.8% for lutetium complex 6 and to 97.8% for lutetium complex 7a. However, further increase of the steric bulk of the ligand led to a slight drop of 3,4-selectivity for the attached complex 5 (95.1%).

Sensitive, selective and label-free protein detection using a smart polymeric transducer and aptamer/ligand system

We have demonstrated a smart polymeric transducer and aptamer/intercalating dye system that allows the label-free detection of protein with high sensitivity and selectivity.

Ligand effect on the performance of organic light-emitting diodes based on europium complexes

A series of europium complexes were synthesized and their electroluminescent (EL) characteristics were studied. It was found by comparison that the different substituted groups, such as methyl, chlorine, and nitryl, on ligand 1,10-phenanthroline affect significantly the EL performance of devices based on these complexes. The more methyl-substituted groups on ligand 1,10-phenanthroline led to higher device efficiency. A chlorine-substituted group showed the approximate EL performance as two methyl-substituted groups, whereas a nitryl substituent reduced significantly the EL luminous efficiency. However, beta-diketonate ligand TTA and DBM exhibited similar EL performance. The improved EL luminous efficiency by proper substituted groups on the 1, 10-phenanthroline was attributed to the reduction of the energy loss caused by light hydrogen atom vibration, as well as concentration quenching caused by intermolecular interaction, and the match of energy level between the ligand and Eu3+.

Pyrrolide-supported lanthanide alkyl complexes. Influence of ligands on molecular structure and catalytic activity toward isoprene polymerization

The N,N- bidentate ligands 2- {( N- 2,6- R) iminomethyl)} pyrrole ( HL1, R) dimethylphenyl; HL2, R) diisopropylphenyl) have been prepared. HL1 reacted readily with 1 equiv of lanthanide tris( alkyl)s, Ln(CH2SiMe3)(3)(THF)(2), affording lanthanide bis(alkyl) complexes L(1)Ln(CH2SiMe3)(2)(THF)(n) (1a, Ln= Lu, n = 2; 1b, Ln = Sc, n = 1) via alkane elimination. Reaction of the bulky ligand HL2 with 1 equiv of Ln(CH2SiMe3)(3)( THF)(2) gave the bis(pyrrolylaldiminato) lanthanide mono(alkyl) complexes L(2)(2)Ln- (CH2SiMe3)(THF) (2a, Ln) Lu; 2b, Ln = Sc), selectively. The N,N- bidentate ligand HL3, 2- dimethylaminomethylpyrrole, reacted with Ln( CH2SiMe3) 3( THF) 2, generating bimetallic bis( alkyl) complexes of central symmetry ( 3a, Ln = Y; 3b, Ln = Lu; 3c, Ln = Sc). Treatment of the N,N,N,N- tetradentate ligand H2L4, 2,2'-bis(2,2-dimethylpropyldiimino) methylpyrrole, with equimolar Lu(CH2SiMe3)(3)(THF)(2) afforded a C-2- symmetric binuclear complex ( 4). Complexes 3a, 3b, 3c, and 4 represent rare examples of THF- free binuclear lanthanide bis( alkyl) complexes supported by non- cyclopentadienyl ligands. All complexes have been tested as initiators for the polymerization of isoprene in the presence of AlEt3 and [ Ph3C][B(C6F5)(4)]. Complexes 1a, 1b, and 3a show activity, and 1b is the most active initiator, whereas 2a, 2b, 3b, 3c, and 4 are inert.

C-H activation motivated by N,N '-diisopropylcarbodiimide within a lutetium complex stabilized by an amino-phosphine ligand

A lutetium bis( alkyl) complex stabilized by a flexible amino phosphine ligand LLu( CH2Si(CH3)(3))(2)(THF) (L = (2,6-C6H3( CH3)(2)) NCH( C6H5) CH2P(C6H5)(2)) was prepared which upon insertion of N, N'-diisopropylcarbodiimide led to C-H activation via metalation of the ligand aryl methyl followed by reduction of the C=N double bond.

Synthesis and reactivity of rare earth metal alkyl complexes stabilized by anilido phosphinimine and amino phosphine ligands

Anilido phosphinimino ancillary ligand H2L1 reacted with one equivalent of rare earth metal trialkyl [Ln{CH2Si(CH3)(3)}(3)(thf)(2)] (Ln = Y, Lu) to afford rare earth metal monoalkyl complexes [L(1)LnCH(2)Si(CH3)(3)(THF)] (1a: Ln = Y; 1b: Ln = Lu). In this process, deprotonation of H2L1 by one metal alkyl species was followed by intramolecular C-H activation of the phenyl group of the phosphine moiety to generate dianionic species L-1 with release of two equivalnts of tetramethylsilane. Ligand L-1 coordinates to Ln(3+) ions in a rare C,N,N tridentate mode. Complex 1a reacted readily with two equivalents of 2,6-diisopropylaniline to give the corresponding bis-amido complex [(HL1)LnY(NHC(6)H(3)iPr(2)-2,6)(2)] (2) selectively, that is, the C-H activation of the phenyl group is reversible. When 1a was exposed to moisture, the hydrolyzed dimeric complex [{(HL1)Y(OH)}(2)](OH)(2) (3) was isolated. Treatment of [Ln{CH2Si(CH3)(3)}(3)-(thf)(2)] with amino phosphine ligands HL2-R gave stable rare earth metal bisalkyl complexes [(L2-R)Ln{CH2Si(CH3)(3)}(2)(thf)] (4a: Ln=Y, R=Me; 4b: Ln=Lu, R=Me; 4c: Ln=Y, R=iPr; 4d: Ln=Y, R=iPr) in high yields. No proton abstraction from the ligand was observed. Amination of 4a and 4c with 2,6-diisopropylaniline afforded the bis-amido counterparts [(L2-R)Y(NHC(6)H(3)iPr(2)-2,6)(2)(thf)] (5a: R=Me; 5b: R=iPr).

Pyrrolide-ligated organoyttrium complexes. Synthesis, characterization, and lactide polymerization behavior

The N,N-bidentate ligand 2-{(N-2,6-diisopropylphenyl)iminomethyl)}pyrrole (L-1) and the N,N,P-tridentate ligand 2-{(N-2-diphenylphosphinophenyl)iminomethyl)}pyrrole (L-2) have been prepared. Their reactions with homoleptic yttrium tris(alkyl) compound Y(CH2SiMe3)(3)(THF)(2) have been investigated. Treatment of Y(CH2SiMe3)(3)(THF)(2) with 1 equiv of L-1 generated a THF-solvated bimetallic (pyrrolylaldiminato)yttrium mono(alkyl) complex (1) of central symmetry. In this process, L-1 is deprotonated by metal alkyl and its imino CN group is reduced to C-N by intramolecular alkylation, generating dianionic species that bridge two yttrium alkyl units in a unique eta(5)/eta(1):kappa(1) mode. The pyrrolyl ring behaves as a heterocyclopentadienyl ligand. Reaction of Y(CH2SiMe3)(3)(THF)(2) with 2 equiv of L-1 afforded the monomeric bis(pyrrolylaldiminato)yttrium mono(alkyl) complex (2), selectively. Amination of 2 with 2,6-diisopropylaniline gave the corresponding yttrium amido complex (3). In 3 the pyrrolide ligand is monoanionic and bonds to the yttrium atom in a eta(1):kappa(1) mode. The homoleptic tris(eta(1):kappa(1)-pyrrolylaldiminato)yttrium complex (4) was isolated when the molar ratio of L-1 to Y(CH2SiMe3)(3)(THF)(2) increases to 3:1. Reaction of L-2 with equimolar Y(CH2SiMe3)(3)(THF)(2) afforded an asymmetric binuclear complex (5).

Monooxychlorophosphine as a novel and efficient ligand for palladium-catalyzed suzuki-miyaura cross-coupling of aryl chlorides

A new sterically hindered monooxychlorophosphine was synthesized and the complex generated in situ from its reaction with Pd-2(dba)(3) promoted the Suzuki-Miyaura reactions of arylboronic acids with aryl chlorides in good yields.

High-dimensional assembly depending on polyoxoanion templates, metal ion coordination geometries, and a flexible bis(imidazole) ligand

By introducing the flexible 1,1'-(1,4-butanediyl)bis(imidazole) (bbi) ligand into the polyoxovanadate system, five novel polyoxoanion-templated architectures based on [As8V14O42](4-) and [V16O38Cl](6-) building blocks were obtained: [M(bbi)(2)](2)[As8V14O42(H2O)] [M = Co (1), Ni (2), and Zn (3)], [Cu(bbi)](4)[As8V14O42(H2O)] (4), and [Cu(bbi)](6)[V16O38Cl] (5). Compounds 1-3 are isostructural, and they exhibit a binodal (4,6)-connected 2D structure with Schlafli symbol (3(4)center dot 4(2))(3(4)center dot 4(4)center dot 5(4)center dot 6(3))(2), in which the polyoxoanion induces a closed four-membered circuit of M-4(bbi)(4). Compound 4 exhibits an interesting 3D framework constructed from tetradentate [As8V14O42](4-) cluster anions and cationic ladderlike double chains. There exists a bigger M-8(bbi)(6)O-2 circuit in 4. The 3D extended structure of 5 is composed of heptadentate [V16O38Cl](6-) anions and flexural cationic chains; the latter consists of six Cu(bbi) segments arranged alternately. It presents the largest 24-membered circuit of M-24(bbi)(24) so far observed made of bbi molecules and transition-metal cations. Investigation of their structural relations shows the important template role of the polyoxoanions and the synergetic interactions among the polyoxoanions, transition-metal ions, and flexible ligand in the assembly process.