C1 Polymerization of Fluorinated Aryl Diazomethanes

A library of fluorinated aryl diazomethanes were polymerized using BF₃·OEt₂ as a catalyst. The polymerization of 2,3,4,5,6-pentafluorophenyl diazomethane was found to be controlled, permitted chain extensions, and facilitated access to a series of block copolymers. Moreover, the polymer chains grew in one carbon increments (so-called "C1 polymerizations") and, as such, afforded highly substituted polymers that featured aryl units pendant to every carbon atom of the backbone. The polymers were characterized using size exclusion chromatography, various spectroscopic techniques, and a series of static and dynamic contact angle measurements. Compared to less-substituted analogues that were prepared using typical C2 polymerization methodologies, the C1 fluorinated polymers were found to be more hydrophobic while maintaining a sufficient solubility to be processed into robust films.

Reactivity of poly(alkoxycarbonylmethylene)s under basic conditions: alkylation of main chain carbon atoms via a ketene silyl acetal-type intermediate and cleavage of the carbon–carbon main chain

We report the alkylation of main chain carbon atoms and cleavage of the carbon–carbon main chain of poly(alkoxycarbonylmethylene)s.

Hybrid Fluorescent Poly(silsesquioxanes) with Amide- and Triazole-Containing Side Groups for Light Harvesting and Cation Sensing

Hybrid polymers containing pyrene (Py) units bound to linear poly(silsesquioxane) (LPSQ) chains through flexible linkers containing heteroatoms (S, N, O) (LPSQ-triazole-Py and LPSQ-amide-Py) exhibit intense fluorescence emission, both in very diluted solutions (c = 10-8 mol/L) and in the solid state. The materials are thermally stable and exhibit good thin film forming abilities. Their optical and physicochemical properties were found to be strongly dependent on the structure of the side chains. Comparative studies with octahedral silsesquioxane (POSS) analogues (POSS-triazole-Py and POSS-amide-Py) emphasized the role of the specific double-strand architecture of the LPSQ backbone and distribution of side Py groups for their photo-luminescent properties. The new hybrid materials were tested as fluorescence energy donors to red-emitting dyes (Nile Red and Coumarine 6). All the silsesquioxanes studied were found to be able to transfer FL emission energy to Coumarin 6, irrespectively of their spatial structure. However, due to the differences in the wavelength range of FL emission, only LPSQ-triazole-Py were able to act as energy donors to Nile Red. The Py-grafted LPSQ may be also applied for development of soluble and highly emissive chemosensors. Their fluorescent nature was explored for the detection of Cu(II), Fe(III), Co(II), Ag(I), Hg(II), Mg(II), Ca(II), Pb(II) and Zn(II). The morphology of the side chains and hydrogen-bonding interactions influenced the sensing capacity of all the studied materials.

Effects of solvents, additives, and π-allyl ligand structures on the polymerization behavior of diazoacetates initiated by π-allylPd complexes

We have revealed that the quality of control of the polymerization was improved by adding some compounds and polymer tacticity was dependent on the structures of π-allyl ligands.

Self-Assembly of Hierarchical Structures Using Cyclotriphosphazene-Containing Poly(substituted methylene) Block Copolymers

The cyclotriphosphazene-substituted diazoacetate homopolymer (polyPNDA') (PNDA' = hexaphenoxy-substituted phosphazene-containing methylene) and a novel poly(substituted methylene) block copolymer, polyPNDA'-block-poly(hexyloxycarbonylmethylene) (polyPNDA'-b-polyHDA'), were synthesized, and the self-assembly behavior of these polymers was studied in detail. A hexagonally packed aggregated structure was observed in the self-assembled structure of polyPNDA', whereas a lamellar structure was observed in the microphase-separated nanoassembly of polyPNDA'-b-polyHDA'. These results indicate that a hierarchical structure composed of highly regular polyPNDA' nanoaggregates and the long-range microphase-separated polyPNDA' and polyHDA' domains had formed.

Migratory Insertion of Carbenes into Au(III)-C Bonds

Migratory insertion of carbon-based species into transition-metal-carbon bonds is a mechanistic manifold of vast significance: it underlies the Fischer-Tropsch process, Mizoroki-Heck reaction, Ziegler-Natta and analogous late-transition-metal-catalyzed olefin polymerizations, and a number of carbonylative methods for the synthesis of ketones and esters, among others. Although this type of reactivity is well-precedented for most transition metals, gold constitutes a notable exception, with virtually no well-characterized examples known to date. Yet, the complementary reactivity of gold to numerous other transition metals would offer new synthetic opportunities for migratory insertion of carbon-based species into gold-carbon bonds. Here we report the discovery of well-defined Au(III) complexes that participate in rapid migratory insertion of carbenes derived from silyl- or carbonyl-stabilized diazoalkanes into Au-C bonds at temperatures ≥ -40 °C. Through a combined theoretical and experimental approach, key kinetic, thermodynamic, and structural details of this reaction manifold were elucidated. This study paves the way for homogeneous gold-catalyzed processes incorporating carbene migratory insertion steps.

Monomer stoichiometry imbalance-promoted formation of multisubstituted polynaphthalenes by palladium-catalyzed polycouplings of aryl iodides and internal diynes

A novel palladium-catalyzed polymerization route toward multisubstituted polynaphthalenes with high thermal stability and advanced functionalities in a monomer stoichiometry imbalance-promoted manner.

Polymerization of alkyl diazoacetates initiated by the amidinate/Pd system: efficient synthesis of high molecular weight poly(alkoxycarbonylmethylene)s with moderate stereoregularity

The initiating ability of a new system, amidinate/Pd, for the polymerization of diazoacetates is described.

Iridium-catalyzed polymerization of benzoic acids and internal diynes: a new route for constructing high molecular weight polynaphthalenes without the constraint of monomer stoichiometry

A green and powerful polymerization tool for constructing functional multisubstituted polynaphthalenes without strict control on monomer stoichiometry.

Pd-initiated controlled polymerization of diazoacetates with a bulky substituent: synthesis of well-defined homopolymers and block copolymers with narrow molecular weight distribution from cyclophosphazene-containing diazoacetates

Pd-initiated polymerization of cyclophosphazene-containing diazoacetates proceeded in a controlled manner.

Synthesis of polymers with densely-grafted oligo(ethylene glycol)s by Pd-initiated polymerization of oxyethylene-containing diazoacetates

The polymers with densely-grafted OEGs showed higher LCSTs and Li-ion conductivities than the corresponding vinyl polymers.