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Reaction of commercial ruthenium complexes M31 and M20 with 2-nitrostyrene gave a new nitroso-chelated cyclic η 1 -acyl ruthenium(II) complexes Ru-4 and Ru-6 respectively instead of expected Hoveyda-Grubbs type (pre)catalyst Ru-3 . New complexes were characterized by means of standard analytical techniques and their crystallographic structure has been confirmed by X-ray structural analysis. It was found that Ru-4 and Ru-6 do not exhibit any activity in standard metathesis reactions. However, a dramatic increase of activity was observed upon treatment with (trimethylsilyl)diazomethane, allowed for the successful application of Ru-4 in ROMP of endo, exo -bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid dimethyl ester. Moreover, such complexes can be effective catalysts of transfer hydrogenation of ketones as well as cycloisomerization reactions. [ABSTRACT FROM AUTHOR]

A series of crosslinked poly(norbornene-dicarboximide)s have been prepared by ring opening metathesis polymerization. Increasing quantities of a bifunctional norbornene-dicarboximide crosslinker was doped into a high T g cyclohexyl-substituted norbornene-dicarboximide monomer before polymerization. The wt% of the crosslinker was increased from 0.00 to 4.40 wt%, after which the polymers became gelated. Polymer molecular weights increased drastically from 23,500 to 2,135,000 g/mol, the polydispersities increased from 1.18 to 73.47 and the viscosities increased from 5.27 to 538.7 mPa·s as the wt% of the crosslinker was increased. The trans : cis vinylene ratio remained constant at 1:0.18 as well as the T g and T d with average values of 210 °C and 392 °C being measured. Five of the crosslinked polymers and the reference homopolymer were utilized as hosts for the high activity tert -butyldiphenylsilyl substituted FTC chromophore guest. The polymer host containing 1.96 wt% crosslinker was found to have a maximum r 33 of 78 pm/V when polled at 150 °C with an electric field strength of 100 V/μm. The r 33 increased linearly from 63 to 78 pm/V as the wt% of the crosslinker was increased from 0.00 to 1.96 wt%. The thermal and temporal stability was found to increase slightly with the 0.00 wt% polymer exhibiting a stability of 77%, while the 1.96 wt% polymer exhibited a stability of 79% when both were heated to 85 °C and aged for 500 h in air. [ABSTRACT FROM AUTHOR]

A latent Ru olefin metathesis catalyst bearing a chelating ligand with an azoxybenzene fragment was obtained and characterized. The complex was inactive in the ring closing metathesis (RCM) reaction of a standard test diene: diethyl diallylmalonate at room temperature but can be subsequently activated by elevated temperature (up to 100 °C). The lack of activity of this azoxy catalyst in RCM of dienes containing terminal C-C double bonds at room temperature and high activity in ring opening metathesis polymerization (ROMP) of bicyclo [2.2.1]hept-2-ene (norbornene, NBE) permitted the ROMP of the challenging monomer: 5-vinyl-2-norbornene yielding soluble polymers with cyclopentenylenevinylene chains with vinyl pendant groups. [ABSTRACT FROM AUTHOR]

A side chain EO copolymer series has been synthesized by ROMP using the Grubbs 3rd generation initiator and quenched with ethyl vinyl ether. The copolymers were prepared by combining two norbornene-dicarboximide monomers, one with a cyclohexyl substituent and another substituted with an FTC chromophore. The mol% of the chromophore-substituted monomer was varied from 0.00 mol% to 22.92 mol%, all polymers were obtained in a yield of between 83 and 92% and a purity of between 97 and 98%. The cis : trans vinylene ratio remained constant at 1:1, confirming the polymers were amorphous. Peak molecular weights increased from 29,541 g/mol to 142,113 g/mol and the PDI increased from 1.36 to 4.01 respectively. Glass transition and thermal decomposition temperatures decreased from 206 °C to 168 °C and 433 °C to 382 °C as the mol% of the chromophore-substituted monomer was increased. UV–vis absorbance spectroscopy was used to quantify the chromophore content. A close correlation (68–95%) between the measured and calculated absorbance was found. The polymer containing 22.92 mol% of the chromophore-substituted monomer had a maximum r 33 of 70 pm/V when polled at an optimum field of 60 V/μm at a polling temperature of 200 °C. This equates to a high polling efficiency of 1.16. High current flow in this polymer film at elevated field strength caused a breakdown of the electrode, preventing access to an elevated electro-optic coefficient. This polymer was found to have an excellent stability of 76% when aged at 85 °C for 1000 h in air. [ABSTRACT FROM AUTHOR]

Highlights: [•] We have reviewed N-donor heterocycles as sensitizers of lanthanide ion emission. [•] Terpyridine-based sensitizers are among the most studied and the published work deals increasingly with applications in bioimaging and sensing. [•] Work published with other N-donor ligands still involves mostly exploratory structure-property research. [Copyright &y& Elsevier]

Abstract: Porous polymers with well-defined porosities and high specific surface areas in the form of monoliths, films, and beads are being used in a wide range of applications (reaction supports, separation membranes, tissue engineering scaffolds, controlled release matrices, responsive and smart materials) and are being used as templates for porous ceramics and porous carbons. The surge in the research and development of porous polymer systems is a rather recent phenomenon. PolyHIPEs are porous emulsion-templated polymers synthesized within high internal phase emulsions (HIPEs). HIPEs are highly viscous, paste-like emulsions in which the major, “internal” phase, usually defined as constituting more than 74% of the volume, is dispersed within the continuous, minor, “external” phase. This review focuses upon the recent advances in polyHIPEs involving innovations in polymer chemistry, macromolecular structure, multiphase architecture, surface functionalization, and nanoparticle stabilization. The effects of these innovations upon the natures of the resulting polyHIPE-based materials (including bicontinuous polymers, nanocomposites, hybrids, porous ceramics, and porous carbons) and upon the applications involving polyHIPEs are discussed. The advances in polyHIPEs described in this review are now being used to generate new families of porous materials with novel porous architectures and unique properties. [Copyright &y& Elsevier]

Highlights: [•] The main backbone is produced using ROMP of various oxanorbornene monomers. [•] The PMMA, PEG and PCL are grafted to the main backbone via quadruple click reactions. [•] The click reactions are thiol-ene, Diels–Alder, CuAAC and NRC. [Copyright &y& Elsevier]

A new ligand, methyl 2,3,5,6-tetrafluoro-4-oxybenzoate (C8H3F4O3), combining an electron withdrawing group (C6F4) to tune the reactivity with an anchor group (CO2Me) for immobilization on supports, was used to prepare four new ruthenium initiators, viz. Ru(C8H3F4O3)2(=CHPh)(3-Br–C5H5N)(H2IMes) and Ru(C8H3F4O3)2XL, where X = C,N-(=CHCH2CH2-2-C5H4N) and L = PiPr3, PCy3 or H2IMes. The new ligand greatly reduced the reactivity of the ruthenium centre at room temperature. The 1H NMR and DSC investigation for the ROMP of norbornene dicarboximide monomers clearly demonstrated that the Ru(C8H3F4O3)2XL initiators were inactive at room temperature and required elevated temperatures for their activation. [ABSTRACT FROM AUTHOR]

Abstract: This article features the current state of research in olefin metathesis polymerization techniques towards the synthesis of functional polymeric materials. Emphasis is laid on work making use of ring opening metathesis polymerization (ROMP) initiated by ruthenium complexes published in the last five years. Other techniques such as alternating diene metathesis polymerization (ALTMET) are only covered when appropriate. A survey on polymer architectures accessible via olefin metathesis is presented and illustrated with manifold examples from research fields like life science, optics and electronics, sensorics or energy storage. Important new developments such as end-group functionalization or stereoselective polymerization are addressed. A chapter on using alternative and green solvents in ROMP is disclosed as well as an overview on the use of olefin metathesis polymerization using sustainable substrates. Applications in material science such as porous, liquid crystal or self-healing materials close the work. [Copyright &y& Elsevier]

Abstract: Two norbornene derivatives bearing phenantroimidazole dyes, namely endo/exo-11-(4-(1H-phenanthro[9,10-d]imidazol-2-yl)phenoxy) undecylbicyclo[2.2.1] hept-5-ene-2-carboxylat (5) and 11-(4-(1-Methyl-1H-phenanthro[9,10-d]imidazol-2-yl)phenoxy) undecylbicyclo[2.2.1]hept-5-ene-2-carboxylate (6) were synthesized. 5 and 6 were used to prepare statistical copolymers with endo,exo-bicyclo[2.2.1.]hept-2-ene-5,6-dicarboxylic acid dimethylester (7) via ring opening metathesis polymerization. The photophysical properties of the monomers and polymers and to what extent polymerization and substitution patterns influence the photophysical properties were investigated. Furthermore, the optical response upon addition of acid was investigated. The emission of monomer 5 shows a small bathochromic shift of 13nm upon protonation while the emission of the resultant polymer poly5/7 exhibits a large red shift of 62nm. In contrast, the according methylated monomer 6 and the resulting polymer poly6/7 gave similar absorption and emission characteristics. The differences were attributed to an increased tendency of the non-methylated dyes to interact when brought in close proximity in the polymer. [Copyright &y& Elsevier]

Abstract: Until now niobium compounds have been very rarely applied for the polymerization of olefins, notwithstanding their moderate cost, limited toxicity and the large availability of stable oxidation states, which makes them versatile precursors. The data reported to date on ethylene and norbornene polymerization catalysts are discussed, with particular reference to the evolution of the approach to the design of these systems, starting from isoelectronic, isolobal or isostructural relationships with Group 4 metallocene catalysts. The catalytic performances in ethylene and norbornene polymerization of the niobium precursors with cyclopentadienyl, diene, amido, amidinate, pyrazolylborate ligands have been compared. The most recent results have been discussed, comparing the reported activities for complexes with phenolate, bis(imino)pyridine and N,N-dialkylcarbamate ligands. Significant improvements in norbornene ROMP have been recently achieved, whilst for ethylene polymerization the process of optimization of the niobium-based catalytic systems still needs hard work. [Copyright &y& Elsevier]

Abstract: A set of poly(norbornenes) was prepared using ring opening metathesis polymerization (ROMP) and used as matrix material for the preparation of optical oxygen sensor layers based on platinum tetrakis(pentafluorophenyl)porphyrin (PtTFPP) as the sensitive dye. Different polymers were prepared and investigated in order to retrieve information on the influence of the anchor group and the side chain attached to the polymer backbone on their performance as matrix material for the dye. Bulky side groups increased the oxygen permeability through ROM polymer layers, especially when the bulky group was directly attached via an anchor group to the polymer backbone without any aliphatic spacer in between. Sensor layers made of poly(endo,exo[2.2.1]bicyclo-5-heptene-2,3-dicarboxyclic acid di-tert-butylester) and PtTFPP exhibited the highest τ 0/τ ratio and responded strongly to small amounts of oxygen. [Copyright &y& Elsevier]

Abstract: The ring opening metathesis polymerization (ROMP) of cycloocta-1,5-diene (COD) is mediated by a series of six well-defined ruthenium-based indenylidene catalysts. The polymerization kinetics are monitored and compared with three generations of Grubbs’ catalyst. Moderate control over the polymerizations was observed for both benzylidene and indenylidene-based catalysts. [Copyright &y& Elsevier]