Showing papers on "Norbornene published in 2007"

Rh(I)-Catalyzed Carbonylative Cyclization Reactions of Alkynes with 2-Bromophenylboronic Acids Leading to Indenones

Abstract: The Rh-catalyzed reaction of alkynes with 2-bromophenylboronic acids involves carbonylative cyclization to give indenones. The key steps in the reaction involve the addition of an arylrhodium(I) species to an alkyne and the oxidative addition of C−Br bonds on the adjacent phenyl ring to give vinylrhodium(I) species II. The regioselectivity depends on both the electronic and the steric nature of the substituents on the alkynes. A bulky group and an electron-withdrawing group favor the α-position of indenones. In the case of silyl- or ester-substituted alkynes, the regioselectivity is extremely high. The selectivity increases in the order SiMe3 > COOR ≫ aryl ≫ alkyl. The reaction of norbornene with 2-bromophenylboronic acids under 1 atm of CO gives the corresponding indanone derivative. The reaction of alkynes with 2-bromophenylboronic acids under nitrogen gives naphthalene derivatives, in which two molecules of alkynes are incorporated. A vinylrhodium complex similar to II can also be generated by a differ...

Thiol–norbornene materials: Approaches to develop high Tg thiol–ene polymers

Abstract: The ability to prepare high Tg low shrinkage thiol–ene materials is attractive for applications such as coatings and dental restoratives. However, thiol and nonacrylated vinyl materials typically consist of a flexible backbone, limiting the utility of these polymers. Hence, it is of importance to synthesize and investigate thiol and vinyl materials of varying backbone chemistry and stiffness. Here, we investigate the effect of backbone chemistry and functionality of norbornene resins on polymerization kinetics and glass transition temperature (Tg) for several thiol–norbornene materials. Results indicate that Tgs as high as 94 °C are achievable in thiol–norbornene resins of appropriately controlled chemistry. Furthermore, both the backbone chemistry and the norbornene moiety are important factors in the development of high Tg materials. In particular, as much as a 70 °C increase in Tg was observed in a norbornene–thiol specimen when compared with a sample prepared using allyl ether monomer of analogous backbone chemistry. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5686–5696, 2007

Norbornene-based copolymers with iridium complexes and bis(carbazolyl)fluorene groups in their side-chains and their use in light-emitting diodes

Abstract: Solution-processable copolymers with pendant phosphorescent iridium complexes and 2,7-di(carbazol-9-yl)fluorene-type host moieties were synthesized using ruthenium-catalyzed ring-opening metathesis polymerization. Low polydispersity indices and molecular weights around 20 000 Da were obtained for all copolymers. As a result of the living character of the polymerization of the monomer containing the host moiety, a high degree of control over the molecular weights of all copolymers can be obtained. The photo- and electroluminescence properties of the copolymers were investigated. All copolymers retained the photo- and electrophysical properties of the corresponding nonpolymeric iridium complexes. Furthermore, as a proof of principle for the potential use of these materials, organic light-emitting devices were fabricated using the orange-emitting copolymer. A maximum external quantum efficiency of 1.9% at 100 cd/m2 and a turn-on voltage of 3.7 V were obtained with photoluminescence quantum yield of 0.10 demo...

Homobimetallic Ruthenium–N‐Heterocyclic Carbene Complexes: Synthesis, Characterization, and Catalytic Applications

Abstract: Two new homobimetallic ruthenium-arene complexes [(p-cymene)Ru(μ-Cl) 3 RuCl(η 2 -C 2 H 4 )(L)], where L=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (3a) or 1,3-bis(2,4,6-trimethylphenyl)-4,5-di-chloroimidazolin-2-ylidene (3b), were isolated in high yields upon heating a toluene solution of [RuCl 2 (p-cymene)] 2 with 1 equivalent of carbene ligand under an ethylene atmosphere. They were characterized by NMR and TGA. Their catalytic activity was investigated in the atom transfer radical polymerization of vinyl monomers. In the polymerization of methyl methacrylate, complex 3a displayed faster reaction rates than 3b and the related phosphine-based complex 2a (L=tricyclohexylphosphine), although control was more effective with the latter catalyst. When n-butyl acrylate or styrene served as monomer, a major shift of reactivity was observed between complex 2a that promoted controlled radical polymerization, and complexes 3a or 3b that favored metathetical coupling. Further homocoupling experiments with various styrene derivatives confirmed the outstanding aptitude of complex 3a (and to a lesser extent of 3b) to catalyze olefin metathesis reactions. Contrary to monometallic ruthenium-arene complexes of the [RuCl 2 (p-cymene)(L)] type, the new homobimetallic species did not require the addition of a diazo compound or visible light illumination to initiate the ring-opening metathesis of norbornene or cyclooctene. When α,ω-dienes were exposed to 3a or 3b, a mixture of cycloisomerization and ring-closing metathesis products was obtained in a non-selective way. Addition of a terminal alkyne co-catalyst enhanced the metathetical activity while completely repressing the cycloisomerization process. Thus, quantitative conversions of diethyl 2,2-diallylmalonate and N,N-diallyltosylamide were achieved within 2 h at room temperature using 2 mol% of catalyst precursor 3a and 6 mol % of phenylacetylene.

Precise Synthesis of Poly(macromonomer)s Containing Sugars by Repetitive ROMP and Their Attachments to Poly(ethylene glycol): Synthesis, TEM Analysis and Their Properties as Amphiphilic Block Fragments

Abstract: Various poly(macromonomer)s (PMMs) have been prepared by a repeating ring opening metathesis polymerization (ROMP) technique using the well-defined molybdenum initiators of the type, [Mo(CHCMe(2)Ph)(NAr)(OR)(2)] with OR=OCMe(3), OCMeC(CF(3))(2); Ar=2,6-iPr(2)C(6)H(3), 2,6-Me(2)C(6)H(3). The synthetic strategy is based on the polymerization of norbornene and its derivatives affording di- and triblock side chains bearing sugars (mannose, galactose, glucose etc.), linked via O- (ester), and glycosidase resistant C- (isoxazoline) glycosides. The efficient placement of norbornene units on the side chain termini and their conversion into PMMs, facilitated by the Mo alkylidenes, proceeded in a living manner with the quantitative initiation. The methodology was applied to prepare poly(macromonomer)-graft-PEG [PEG: poly(ethylene glycol)], by the attachment of a pseudo phenol terminus on the PMM main chain to PEG-Ms(2) [MsO(CH(2)CH(2)O)(n)Ms, Ms=MeSO(2)] using a "grafting to" approach. Removal of the acetal protecting groups from the sugar coating of a variety of supramolecular structures including PMMs, linear amphiphilic block copolymers (ABC) and a PMM-graft-PEGby using trifluroacetic acid/water (9:1), and suspension in water, prompted the spontaneous formation of spherical architectures by self-assembly of the amphiphilic PMMs as observed by transmission electron microscopy (TEM). The ability to uptake the hydrophobic dye (Nile Red) into the micellar cores of a variety of amphiphilic polymeric fragments is a significant step towards the production of sugar-coated nanospheres for cell-targeting biomimetic applications.

Steric and electronic factors influencing recognition by a simple, charge neutral norbornene based anion receptor.

Abstract: Based on 1H NMR studies, subtle electronic factors rather than pre-organisation dictate the binding stoichiometry of the new, norbornene based, anion hosts 1 and 2 with acetate, however, the binding of dihydrogenphosphate appears to be based solely on steric constraints.

Ink composition, inkjet recording method, printed material, and process for producing lithographic printing plate

Abstract: An ink composition is provided that includes (A) an N-vinyllactam, (B) a monomer represented by Formula (I), and (C) a radical polymerization initiator, or includes (A) an N-vinyllactam, (B) a monomer represented by Formula (II), (C) a radical polymerization initiator, and phenoxyethyl acrylate. (In Formula (I) and Formula (II), R1 denotes a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbons, X1 denotes a divalent linking group, R2 and R3 independently denote a substituent, k denotes an integer of 1 to 6, q and r independently denote an integer of 0 to 5, n denotes a cyclic hydrocarbon structure, the cyclic hydrocarbon structure may comprise in addition to hydrocarbon bonds a carbonyl bond (-C(O)-) and/or an ester bond (-C(O)O-), and the k R1s, the k X1s, the q R2s, and the r R3s may each be identical to or different from each other; furthermore, one carbon atom in the adamantane framework in Formula (I) may be replaced by a carbonyl bond (-C(O)-) and/or an ester bond (-C(O)O-), and one carbon atom in the norbornene framework in Formula (II) may be replaced by an ether bond (-O-) and/or an ester bond (-C(O)O-).) There are also provided an inkjet recording method, a printed material, and a process for producing a lithographic printing plate that employ the ink composition.

The influence of cross-linking agents on ring-opening metathesis polymerized thermosets

Abstract: The addition of suitable cross-linking agents with norbornene-based monomers has significant effects on the thermal properties of the resulting polymers formed by olefin metathesis. Ethylidene norbornene (ENB) and endo-dicyclopentadiene (endo-DCPD) were mixed separately with various loadings of three different cross-linking agents and then polymerized with the addition of Grubbs’ catalyst. The polymerization kinetics and resulting glass transition temperature (T g) of the systems were evaluated by differential scanning calorimetry (DSC). The addition of the first cross-linking agent, norbornadiene (CL-1), to both endo-DCPD and ENB resulted in decreasing glass transition temperatures with increasing concentrations. In contrast, the addition of the other two cross-linking agents (CL-2 and CL-3), which were both custom synthesized bifunctional norbornyl systems, to both endo-DCPD and ENB resulted in a monotonic increases in T g with cross-linker concentration. By tailoring the loading of these custom cross-linking agents, the properties of these polymer systems can be controlled for various applications, including self-healing composites.

Synthesis and Properties of Polyacetylene and Polynorbornene Derivatives Carrying 2,2,5,5-Tetramethyl-1-pyrrolidinyloxy Moieties

Abstract: PROXYL-containing propargyl ester HC⋮CCH2OCO-3-PROXYL (1), N-propargylamide HC⋮CCH2NHCO-3-PROXYL (2), 1-pentyne-4,4-dimethyl ester HC⋮CCH2C(CH3)(CH2OCO-3-PROXYL)2 (3), and norbornene diester monomers NB-2,3-exo,exo-(CH2OCO-3-PROXYL)2 (4), NB-2,3-endo,endo-(CH2OCO-3-PROXYL)2 (5), and NB-2,2-(CH2OCO-3-PROXYL)2 (6) (NB = norbornene, PROXYL = 2,2,5,5-tetramethyl-1-pyrrolidinyoxy) were polymerized to afford novel polymers containing the PROXYL radical at high densities. While 1 and 2 provided polymers with number-average molecular weights of 3300−29 800 in 60−65% yields in the presence of a Rh catalyst, monomers 4−6 gave polymers with number-average molecular weights up to 209 000−272 000 in 90−94% yields with a Ru catalyst. The formed polymers were thermally stable up to ca. 220 °C according to TGA and soluble in common organic solvents including toluene, CHCl3, and THF. Poly(1), poly(2), and poly(4)−poly(6) hardly exhibited absorption above 400 nm, which corresponds with their very light color. The oxidation...

Investigation into the ROMP copolymerization of peptide‐ and PEG‐functionalized norbornene derivatives

Abstract: The ring-opening metathesis polymerizations (ROMP), using RuCl2 (PCy3)2CHPh, of a series of peptide-functionalized norbornene derivatives have been investigated. Incorporation of a PEG-monomer was found to prevent premature precipitation of polymer strands during the course of polymerization reactions and yield water compatible polymers in high conversions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3178–3190, 2007

Ethylene‐Norbornene Copolymerization by New Titanium Complexes Bearing Tridentate Ligands. Sidearm Effects on Catalytic Activity

Abstract: The Ti complexes containing tridentate [O-NS R ] (R = Me, i Pr) ligands with alkylthio sidearms were prepared. The methylthio ether complex (R=Me shown in the Scheme) exhibits an excellent activity for copolymerization of ethylene with norbornene upon activation with MMAO, which is 10 times more active than the corresponding phenylthio one (R = Ph).

Homo‐ and copolymerization of norbornene derivatives with ethene by ansa‐fluorenylamidodimethyltitanium activated with methylaluminoxane

Abstract: (t-BuNSiMe2Flu)TiMe2 (1) activated with Me3Al-free methylaluminoxane (dried MAO) which conducts vinyl addition polymerization of norbornene (N) with very high activity was applied for homopolymerization of N derivatives (i.e., 5-vinyl-2-norbornene (5V2N), 5-ethylidene-2-norbornene (5E2N), dicyclopentadiene (DCPD)) at 40 °C. The activities for the N derivatives were about two orders of magnitude lower than that for N and decreased in the following order: 5E2N ≫ 5V2N ≫ DCPD. Copolymerization of ethene (E) and 5E2N under an atmospheric pressure of E was then conducted by 1-dried MAO. The copolymerization proceeded with better activity than the homopolymerization of 5E2N and gave poly(E-co-5E2N) with narrow molecular weight distribution. The content of the ethylidene group in poly(E-co-5E2N) was controlled by the feed ratio of 5E2N/E. The Tg value of the copolymer changed from 70 °C to 155 °C according to the 5E2N content from 27 mol % to 68 mol %. The addition of N as a third monomer to the E-5E2N copolymerization improved the activity and raised the Tg values of the terpolymer above 200 °C. The content of 5E2N was controlled by the 5E2N/N ratio with keeping the high Tg values. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4581–4587, 2007

Surface-initiated, ring-opening metathesis polymerization: formation of diblock copolymer brushes and solvent-dependent morphological changes.

Abstract: In this article, we report the formation of diblock copolymer brushes on a gold surface by surface-initiated, ring-opening metathesis polymerization (SI-ROMP) with the newly developed ruthenium catalyst [(H2IMes)(3-Br-py)2(Cl)2RuCHPh]. Taking advantage of the highly improved activity of the ruthenium catalyst and the rapid initiation step of ROMP, we successfully formed thin films of well-defined block copolymers with 5-norbornene-2-endo,3-endo-dimethanol and norbornene carboxylic acid methyl esters (44:56 endo/exo). The catalyst was found to be active enough to polymerize endo isomers of norbonene derivatives from the surface as well as to form diblock copolymer brushes. SI-ROMP of diblock copolymers from the surface was confirmed by ellipsometry, infrared spectroscopy, and X-ray photoelectron spectroscopy. After the formation, the polymer-grafted substrates were immersed in various solvents, and the selective swelling characteristics of polymer brushes were investigated by atomic force microscopy.

Polymerization of carboxylic ester functionalized norbornenes catalyzed by (η3‐allyl)palladium complexes bearing N‐heterocyclic carbene ligands

Abstract: An in situ generated cationic allylpalladium complex bearing N-heterocy- clic carbene (NHC) ligands, derived from the reaction of ((g 3 -C3H5)Pd(NHC)Cl) with AgX (X ¼ BF4 or SbF6), is an active catalyst for the addition polymerization of norbor- nene and norbornene derivatives (5-norbornene-2-carboxylic acid methyl ester (b )a nd 5-norbornene-2-carboxylic acid n-butyl ester (c)) with an ester group containing a large portion of endo-isomers. The catalytic activities, polymer yields, molecular weights, and molecular weight distributions of polynorbornenes were investigated under various reaction conditions: the catalytic activity was highly dependent on the counteranion, the reaction solvent, and the reaction temperature. For b, as the portion of an endo-iso- mer increased, the activity of 13(SbF � ) was much higher than those of 14 and 15 ,a nd for c (exo/endo ¼ 95:5), the maximum turn over number (TON) was observed with 15(SbF � ). V C 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3042-3052, 2007

Chelating Η6-arene -Η1-carbene ligands in ruthenium complexes

Abstract: N-Heterocyclic carbene (NHC) ruthenium complexes containing a chelating NHC-η6-arene ligand have been prepared and evaluated as precursors for ring opening metathesis polymerization (ROMP). The reaction of [RuCl2(p-cymene)]2 with electron-rich olefins of the bis(imidazolinylidene) type containing at least one arylmethyl-N chain (aryl: 2,4,6-trimethylphenyl, 3,4,5-trimethoxyphenyl) selectively leads, upon heating, to ruthenium(II) complexes 2 containing a chelating bridged carbene η6-arene ligand. The reaction of complexes containing an additional ROCH2CH2N group with AgOTf leads to ionic complexes 5 with a tridentate trifunctional carbene/arene/ether ligand. The X-ray structure of[RuCl2{η1-CN(CH2{η6-C6H2Me3-2,4,6})CH2CH2N(CH2{C6H2(OMe)3-3,4,5})}] (2c) and that of the ionic ruthenium complex containing a trifunctional carbene/arene/ether ligand that provides ten electrons, [RuCl{η1-CN(CH2{η6-C6H2Me3-2,4,6})CH2CH2N(CH2CH2OCH3)}][CF3SO3] (5e), have been determined. The precursors 2 in the presence of AgOTf and propargyl alcohol, in order to produce an allenylidene initiator, and complexes 5 in the presence of propargyl alcohol lead to ROMP of norbornene. It is shown that initial chloride abstraction is required and that the catalyst activity is increased by using mesityl–ruthenium precursors and coordinated branched ether complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Main-Chain Calix[4]arene Elastomers by Ring-Opening Metathesis Polymerization

Abstract: Alkene-bridged calix[4]arene monomers were synthesized by ring-closing metathesis (RCM). All the three possible conformers (cone, partial cone, and 1,3-alternate) were used as comonomers with cyclooctene and norbornene in ring-opening metathesis polymerization (ROMP). The resultant polymers were high-molecular-weight, transparent and stretchable materials with high calixarene incorporation (up to 25 mol % or 70 wt %) and low glass transition temperatures.

Highly active ethylene polymerization and copolymerization with norbornene using bis(imino-indolide) titanium dichloride-MAO system

Abstract: A catalytic system of new titanium complexes with methylaluminoxane (MAO) was found to effectively polymerize ethylene for high molecular weight polyethylene as well as highly active copolymerization of ethylene and norbornene. The bis (imino-indolide)titanium dichlorides (L2TiCl2, 1–5), were prepared by the reaction of N-((3-chloro-1H-indol-2-yl)methylene)benzenamines with TiCl4, and characterized by elemental analysis, 1H and 13C NMR spectroscopy. The solid-state structures of 1 and 4 were determined by X-ray diffraction analysis to reveal the six-coordinated distorted octahedral geometry around the titanium atom with a pair of chlorides and ligands in cis-forms. Upon activation by MAO, the complexes showed high activity for homopolymerization of ethylene and copolymerization of ethylene and norbornene. A positive “comonomer effect” was observed for copolymerization of ethylene and norbornene. Both experimental observations and paired interaction orbital (PIO) calculations indicated that the titanium complexes with electron-withdrawing groups in ligands performed higher catalytic activities than those possessing electron-donating groups. Relying on different complexes and reaction conditions, the resultant polyethylenes had the molecular weights Mw in the range of 200–2800 kg/mol. The influences on both catalytic activity and polyethylene molecular weights have been carefully checked with the nature of complexes and reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3415–3430, 2007

Growth and Structure of Surface-Initiated Poly(n-alkylnorbornene) Films

Abstract: We report the surface-initiated growth of poly(alkylnorbornene) films via ring-opening metathesis polymerization (ROMP). The films are grown by exposure of a vinyl-terminated self-assembled monolayer (SAM) on gold to Grubbs first-generation catalyst and the subsequent exposure to an alkylnorbornene monomer. We investigate the influence of alkyl side chains on the structure, barrier, surface properties, and the growth kinetics of surface-initiated ROMP-type poly(norbornene) films. Rate constants for film growth are estimated for the comparison of monomer reactivity. The rate constant for film growth decreases by 3 orders of magnitude from norbornene to decylnorbornene, indicating a strong effect of chain length on initiation and/or propagation rates. Reflectance−absorption infrared spectroscopy is used to show the molecular level packing within the poly(alkylnorbornene) films is disrupted by the alkyl side chains. Tapping-mode atomic force microscopy is used to show that norbornene, butylnorbornene, and he...

An Efficient Metal-Catalyzed Hydroalkylation

Abstract: An efficient metal-catalyzed hydroalkylation of various styrenes, norbornene, and cyclohexadiene with 1,3-dicarbonyl compounds has been developed. This new bismuth-catalyzed C-H functionalization provides the corresponding alkylated pentanediones in good to excellent isolated yields after short reaction times.

Isothermal cure characterization of dicyclopentadiene

Abstract: Conversion (α) and the glass transition temperature (T g) were investigated during the isothermal cure of endo-dicyclopentadiene (DCPD) with a Grubbs catalyst for different temperatures using differential scanning calorimetry. Conversion vs. In (time) data at an arbitrary reference temperature were superposed by horizontal shift and the shift factors were used to calculate an Arrhenius activation energy. Glass transition temperature vs. conversion data fell on a single curve independent of cure temperature, implying that reaction of the norbornene and cyclopentene ring of DCPD proceeds in a sequential fashion. Implications of the isothermal reaction kinetics for self-healing composites are discussed.