Ring-opening Metathesis Copolymerization Research Articles

Hydrophobic, pellicular, monolithic capillary columns based on cross-linked polynorbornene for biopolymer separations.

Monolithic capillary columns were prepared by transition metal-catalyzed ring-opening metathesis copolymerization of norborn-2-ene and 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene inside a silanized 200-microm-i.d. fused-silica capillary using a mixture of toluene and 2-propanol as porogen and Cl2(PCy3)2Ru(=CHPh) as initiator. The synthesized columns allowed the rapid and highly efficient separation of single- and double-stranded nucleic acids by ion-pair reversed-phase high-performance liquid chromatography and of proteins by reversed-phase high-performance liquid chromatography. Compared to 3-mm-i.d. analytical columns synthesized from an identical polymerization mixture, a considerable improvement in the peak widths at half-height of oligonucleotides in the order of 60-80% was obtained. Significant differences in morphology between the capillary column, where the surface of the monolith was rather soft and rugulose, and the analytical column, where the surface was very sharp and smooth, were observed, most probably due to differences in polymerization kinetics. The synthesized monoliths were successfully applied to the separation of the diastereomers of phosphorothioate oligodeoxynucleotides. To confirm the identity of the eluting compounds on the basis of their intact molecular masses, the chromatographic separation system was on-line hyphenated to electrospray ionization mass spectrometry.

Block and Random Living, Ring-Opening Metathesis Copolymerization of Functionally Differentiated Carbazole-Containing Norbornene Monomers

The synthesis of novel diblock polymers containing both a potential charge transport and a non-linear optic block has been accomplished. The synthesis exploits the living, ring-opening metathesis block copolymerization of two norbornene type monomers, one of which contains an unsubstituted N-carbazolyl ring while the other has a bromo substituent at the 3-position of the carbazole ring. Conversion of the bromo functionality to a 2,2-dicyanovinyl group introduces the non-linear optic property. The first monomer was prepared by the previously reported efficient cation radical Diels–Alder cycloaddition of N-trans-1-propenylcarbazole to 1,3-cyclopentadiene, while the second was obtained by N-bromosuccinimide bromination of the first monomer. For purposes of comparison, the corresponding random copolymer was also synthesized.

Bis(pyrimidine)-based palladium catalysts: synthesis, X-ray structure and applications in Heck–, Suzuki–, Sonogashira–Hagihara couplings and amination reactions

The synthesis of N, N-bis(pyrimid-2-yl)amine ( 1), N-acetyl- N, N-bis(pyrimid-2-yl)amide ( 2), N-norborn-2-ene-5-ylbis(pyrimid-2-yl)carbamide ( 4) is described. The Pd-complex N-acetyl- N, N-bis(pyrimid-2-yl)amine palladium dichloride ( 3) has been prepared from compound 2 and its X-ray structure has been determined. A polymer supported catalytic system ( 6) was prepared via ring-opening metathesis copolymerization of 4 with 1,4,4a,5,8,8a-hexahydro-1,4,5,8- exo- endo-dimethanonaphthalene (HDMN-6) and subsequent loading with PdCl 2. Both the homogeneous and heterogeneous catalysts 3 and 6 were active in Heck–, Suzuki–, Sonogashira–Hagihara-type couplings and amination reactions using aryl iodides, bromides and chlorides.

Metathesis-based monoliths: influence of polymerization conditions on the separation of biomolecules.

Monolithic materials were prepared by transition metal-catalyzed ring-opening metathesis copolymerization of norborn-2-ene and 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene within the confines of surface-derivatized borosilicate columns in the presence of the porogenic solvents toluene and 2-propanol using Cl2(PCy3)2Ru(=CHPh) (1) as initiator. Relevant physicochemical data of the porous structure (specific surface area (sigma), pore volume (Vp), volume fraction of pores (epsilon(p)), and intermicroglobule volume (epsilon(z))) of the monolithic columns were determined by inverse size exclusion chromatography in tetrahydrofuran. Mean particle diameters were determined via electron microscopy. The influence of variations in polymerization conditions in terms of stoichiometry of the monomers and porogenic solvents on the chromatographic separation of the oligodeoxynucleotides dT12-dT18 and eight model proteins (ribonuclease A, insulin, cytochrome c, lysocyme, alpha-lactalbumin, alpha-chymotrypsinogen, beta-lactoglobulin B, catalase) were studied. Also, the role of additional phosphine on the entire polymerization setup and the associated chromatographic separations was elucidated. Relevant chromatographic data as well as differences between the separation of oligodeoxynucleotides and proteins may directly be attributed to the above-mentioned physicochemical properties of the metathesis-based monoliths. Finally, DSC-TGA-MS investigations on various monoliths of different composition and age were carried out in order to provide information on stability and oxidation behavior.

N-Acyl- N, N-dipyridyl and N-acyl- N-pyridyl- N-quinoyl amine based palladium complexes. Synthesis, X-ray structures, heterogenization and use in Heck couplings

A series of homogeneous and heterogeneous palladium(II)-catalysts and their use in Heck-couplings is described. Starting from four different amines, N-pyrid-2-yl- N-(3-methylpyrid-2-yl)amine ( 1), N-pyrid-2-yl- N-(6-methylpyrid-2-yl)amine ( 2), N-(6-methylpyrid-2-yl)- N-(4-methylquinolin-2-yl)amine ( 3) and N-bis(6-methylpyrid-2-yl)amine ( 4), the corresponding acetyl- and norbornene derivatives, N-pyrid-2-yl- N-(3-methylpyrid-2-yl) acetamide ( 5), N-pyrid-2-yl- N-(6-methylpyrid-2-yl) acetamide ( 6), N-(6-methylpyrid-2-yl)- N-(4-methylquinolin-2-yl) acetamide ( 7), N-bis(6-methylpyrid-2-yl)acetamide ( 8) and N-pyrid-2-yl- N-(3-methylpyrid-2-yl)- endo-norborn-2-ene-5-carbamide ( 9), N-pyrid-2-yl- N-(6-methylpyrid-2-yl)- endo-norborn-2-ene-5-carbamide ( 10) and N-(6-methylpyrid-2-yl)- N-(4-methylquinolin-2-yl)- endo-norborn-2-ene-5-carbamide ( 11), respectively, have been prepared. The acetyl derivatives 5– 8 have been used for the preparation of the homogeneous Heck catalysts N-acetyl- N-pyrid-2-yl- N-(3-methylpyrid-2-yl)amine palladium dichloride ( 13), N-acetyl- N-pyrid-2-yl- N-(6-methylpyrid-2-yl)amine palladium dichloride ( 14), N-acetyl- N-(6-methylpyrid-2-yl)- N-(4-methylquinolin-2-yl)amine palladium dichloride ( 15) and N-acetyl- N-bis(6-methylpyrid-2-yl)amine palladium dichloride ( 16). X-ray data were obtained for compounds 9, 11, 13 and 14. Polymer supports 17– 19 were prepared via ring-opening metathesis copolymerization of the norbornene derivatives 9– 11 with 1,4,4a,5,8,8a-hexahydro-1,4,5,8- exo- endo-dimethano-naphthalene (HDMN-6) and subsequently loaded with palladium(II) chloride. Both the homogeneous catalysts 13– 16 and the heterogeneous catalysts are active in the vinylation of aryl iodides and aryl bromides with turn-over numbers (TONs) of up to 220 000. Comparably low yields (=34%) and TONs (=2100) are achieved in the tetrabutylammonium bromide- (TBAB-) assisted vinylation of aryl chlorides as well as in the amination of aryl bromides. Structural data of compounds 9, 11, 13 and 14 were compared with those of the parent systems, N-acetyldipyridylamine palladiumdichloride ( 20) and the poly( N, N-dipyrid-2-yl- endo-norborn-2-ene-5-carbamide)based resin ( 21), respectively. Thus, methyl-substitution leads to a significant perturbation of the almost perfect square planar coordination of Pd found in 20 resulting in lowered stabilities of the corresponding Pd-complexes 13– 16 and consequently lowered coupling yields compared to 20 and 21.

A New Class of Continuous Polymer Supports Prepared by Ring-Opening Metathesis Polymerization: A Straightforward Route to Functionalized Monoliths

Functionalized monolithic materials have been prepared by ring-opening metathesis copolymerization of norborn-2-ene (NBE) and 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene (DMN-H6) within borosilicate columns in the presence of porogenic solvents such as toluene, methylene chloride, methanol, and 2-propanol. Grubbs-type initiators of the general formula Cl2(PR3)2Ru(CHPh) (R = phenyl, cyclohexyl) were used throughout. The resulting separation media possess microstructures consisting of microporous, spherical microglobules with a narrow microglobule size distribution. By variation of the polymerization conditions in terms of stoichiometry of the monomers, porogenic solvents, and temperature, microglobule diameters may be varied within a range of 2 ± 1 μm up to 30 ± 10 μm. Specific surface areas (σ) and inter-microglobule pore volumes (ez) may be altered within 60−210 m2/g and 2−50%, respectively. Nonfunctionalized separation media were successfully used for the separation of 10 different mod...

Hybrid Inorganic/Organic Diblock Copolymers. Nanostructure in Polyhedral Oligomeric Silsesquioxane Polynorbornenes.

ABSTRACTOur main approach to the synthesis and study of hybrid organic/inorganic materials involves incorporating nano-size inorganic polyhedral oligomeric silsesquioxane (POSS) clusters into various polymeric resins. A typical POSS cluster is a discrete silicon and oxygen framework solubilized with organic groups and contains a single reactive site. This lone site of reactivity is used to covalently attach the inorganic macromers pendent to a polymer backbone without causing any crosslinking. This strategy permits the synthesis of melt processable, linear hybrid polymers containing pendent inorganic clusters, and allows us to study the effect these clusters have on chain motion, polymer properties and morphology. The synthesis of norbornenyl-based (POSS) macromers, their ring opening metathesis copolymerizations with varying amounts of norbornene, and analysis of the effect of the pendent POSS group is presented. Ring opening metathesis polymerization permits the easy synthesis of both random and diblock copolymers. Transmission electron microscopy (TEM) clearly images POSS-rich domains against the POSS-free regions. Major differences in polymer morphology are observed as the amount of inorganic POSS is varied, between random and diblock copolymers, as well as between polymers that differ only in the solubilizing cycloalkyl groups on the POSS cluster.

Access to Well-Defined Heterogeneous Catalytic Systems via Ring-Opening Metathesis Polymerization (ROMP): Applications in Palladium(II)-Mediated Coupling Reactions

The preparation of a new heterogeneous palladium(II)-based catalyst and its homogeneous analogue and their use for Heck-type, alkyne and amine couplings are described. The heterogeneous catalytic system is based on a polymer-bound dichloropalladium di(pyrid-2-yl)amide and was prepared via ring-opening metathesis copolymerization of norborn-2-ene-5-(N,N-di(pyrid-2-yl))carbamide with 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphthalene and subsequent loading of the resulting resin with palladium(II) chloride. The heterogeneous catalyst is air, moisture, and temperature stable up to 150 °C and highly active (94−99% yields) in the vinylation of aryl iodides and aryl bromides (Heck-type couplings) with turn-over numbers (TONs) of up to 210000. Even higher TON's (up to 350000) may be achieved in the arylation of alkynes. High yields (≤95%) and TONs (≤24000) may additionally be achieved in the tetrabutylammonium bromide (TBAB) assisted vinylation of aryl chlorides. Moderate yields (<65%) and TONs (<4000...

Thermoplastics Modified with Nanoscale Inorganic Macromers

AbstractWe have taken a unique approach to the synthesis and study of hybrid organic/inorganic materials. Our method involves synthesizing nano-size inorganic P1R7Si8O12 clusters which contain seven inert “R” groups for solubility and only one functional “P” group for polymerization. This strategy permits the synthesis of melt processable, linear hybrid polymers containing pendent inorganic clusters and allows us to study the effect these clusters have on chain motions and polymer properties. The synthesis of norbomenyl-based polyhedral oligomeric silsesquioxane (POSS) macromers, their ring opening metathesis copolymerizations with varying amounts of norbornene, and analysis of the effect of the pendent POSS group is presented. The mechanical relaxation behavior and microstructure of norbornyl-POSS hybrid copolymers have been examined for their dependencies on the mole fraction of POSS-norbornyl monomer, as well as for potential sensitivity to the seven inert “R” groups present in each POSS macromer. POSS copolymerization is observed to enhance the α-relaxation temperature, Tα, in proportion to the mole fraction of POSS-norbornyl comonomer. Interestingly, however, the magnitude of this dependence is larger for POSS-norbornyl comonomer possessing cyclohexyl groups (CyPOSS) than for cyclopentyl groups (CpPOSS). While POSS copolymerization yields only slight enhancement of the tensile storage modulus measured near room temperature, at temperatures lower than a strong mechanical relaxation (β-relaxation near T = -75 °C), there is a significant POSS-reinforcement of the storage modulus.

Alternating ring-opening metathesis copolymerization of bicyclo[2.2.1]hept-2-ene and cyclopentene

Almost alternating copolymers of bicyclo[2.2.1]hept-2-ene and cyclopentene have been formed by ring-opening metathesis polymerization using a RuCl3–phenol catalyst system; this highly novel result is attributed to differential steric influences exerted by a hydrogen-bonded solvent cage which encloses the catalyst site.

Copolymerization of norbornene containing 3,5-di-tert-butyl-4-hydroxybenzoyl group with norbornene using metathesis catalyst

The ring opening metathesis copolymerization of 5-{[(3,5-di-t-butyl-4-hydroxybenzoyl)oxy]methyl}-2-norbornene (BHBN) with norbornene was carried out using Ru and Os based catalysts. Analysis of the copolymers obtained during the initial stages of copolymerization revealed that both monomers were incorporated randomly and with the same reactivity, indicating that the steric effect of BHBN is not important. The molecular weights of copolymers were found to be in the order of 3×105 with dispersity of around 2. Characterization and some properties of these copolymers are described.

Ring-opening metathesis copolymerization of cyclopentene and [2.2] paracyclophane-1,9-diene: UV-Vis-spectroscopic determination of sequence-length distribution of p-phenylenevinylene units

Ring-opening metathesis copolymerization of cyclopentene (CPE) with [2.2]paracyclophane-1,9-diene (PCPDE) was achieved using the stable tungsten carbene W(CHAr′)(NAr)[OCMe(CF 3) 2] 2(THF) (Ar = 2,6-Me 2C 6H 3, Ar′ = o-MeOC 6H 4) (I).UV-Vis-spectroscopic characterization of the soluble copolymers containing O.1–1% PCPDE proved that PCPDE rings are not only opened to yield [=CH-Phenylene-CHCH-Phenylene-CH=] units, but as the reaction continues these are largely split to give [=CH-Phenylene-CH=] units which are distributed statistically in the polymer chain.

Third-order susceptibilities of soluble polymers derived from the ring opening metathesis copolymerization of cyclooctatetraene and 1,5-cyclooctadiene

We wish to report some preliminary results on the nonlinear optical properties of a new class of polymers synthesized by the ring-opening metathesis polymerization of highly unsaturated monomers. Mixtures of cyclooctatetraene, 1, and 1,5-cyclooctadiene, 2, have been polymerized by using the tungsten carbene complex 3 as the catalyst (see Figure 1). The solution polymerization of monomers 1 and 2 in tetrahydrofuran leads to an essentially random coploymer. The monomers contain exclusively cis double bonds and no attempt has been made to isomerize the double bonds in the resulting polymer. The general constitution of the copolymers is also shown in Figure 1 (an all-trans geometrical configuration is shown for simplicity).