Synthesis of Pyrene‐based Planar Conjugated Polymers and the Regioisomers by Intramolecular Cyclization

Several planar conjugated polymers and model compounds containing pyrene units are synthesized. The precursor polymers and model compounds are obtained through the Pd(0)‐catalyzed Suzuki reaction, then the planar structure is formed through intramolecular cyclization in the presence of acid. We investigate the regioisomers in intramolecular cyclization reaction by using model compounds, suggesting that the syn‐ and anti‐structures are formed in ladder‐type polymer LP1 , and the syn‐structure is more easily formed in LP3 . The planar conjugated polymers and model compounds show untypical features of ladder‐type polymers, they display broad absorption and blue or blue‐green emission in solution, and interchain π‐π stacking in film still occurs. Moreover, the new polymers and model compounds are characterized by nuclear magnetic resonance (NMR) spectroscopy, gel‐permeation chromatography (GPC) and cyclic voltammetry (CV).     

Ferrocenyl Quinone Methide–Thiol Adducts as New Antiproliferative Agents: Synthesis,Metabolic Formation from Ferrociphenols,and Oxidative Transformation

Ferrociphenols ( FCs ) and their oxidized, electrophilic quinone methide metabolites ( FC‐QMs ) are organometallic compounds related to tamoxifen that exhibit strong antiproliferative properties. To evaluate the reactivity of FC‐QMs toward cellular nucleophiles, we studied their reaction with selected thiols. A series of new compounds resulting from the addition of these nucleophiles, the FC‐SR adducts, were thus synthesized and completely characterized. Such conjugates are formed upon metabolism of FCs by liver microsomes in the presence of NADPH and thiols. Some of the FC‐SR adducts exhibit antiproliferative properties comparable to those of their FC precursors. Under oxidizing conditions they either revert to their FC‐QM precursors or transform into new quinone methides (QMs) containing the SR moiety, FC‐SR‐QM . These results provide interesting data about the reactivity and mechanism of antiproliferative effects of FCs , and also open the way to a new series of organometallic antitumor compounds.     

Ferrocenyl Quinone Methide–Thiol Adducts as New Antiproliferative Agents: Synthesis,Metabolic Formation from Ferrociphenols,and Oxidative Transformation

Ferrociphenols ( FCs ) and their oxidized, electrophilic quinone methide metabolites ( FC‐QMs ) are organometallic compounds related to tamoxifen that exhibit strong antiproliferative properties. To evaluate the reactivity of FC‐QMs toward cellular nucleophiles, we studied their reaction with selected thiols. A series of new compounds resulting from the addition of these nucleophiles, the FC‐SR adducts, were thus synthesized and completely characterized. Such conjugates are formed upon metabolism of FCs by liver microsomes in the presence of NADPH and thiols. Some of the FC‐SR adducts exhibit antiproliferative properties comparable to those of their FC precursors. Under oxidizing conditions they either revert to their FC‐QM precursors or transform into new quinone methides (QMs) containing the SR moiety, FC‐SR‐QM . These results provide interesting data about the reactivity and mechanism of antiproliferative effects of FCs , and also open the way to a new series of organometallic antitumor compounds.     

Michael addition polymerizations of difunctional amines (AA′) and triacrylamides (B3)

Novel hyperbranched poly(amido amine)s containing tertiary amines on the backbones and acryl or secondary amines as the surface groups were successfully synthesized via the Michael addition polymerizations of a triacrylamide [1,3,5‐triacryloylhexahydro‐1,3,5‐triazine (TT)] and a difunctional amine [n‐butylamine (BA)] NMR techniques were used to clarify the structures of hyperbranched polymers and polymerization mechanism. The reactivity of the secondary amine formed in situ was much lower than that of the primary amines in BA. When the feed molar ratio was 1:1 TT/BA, the secondary amine formed in situ was almost kept out of the reaction before the BA (AA′) and TT (B₃) monomers were consumed, and this led to the formation of A′B₂ intermediates containing one secondary amine group and two acryl groups. The self‐polymerization of the A′B₂ intermediates produced hyperbranched polymers bearing acryl as surface groups. For the polymerization with the feed molar ratio of 1:2 TT/BA, A′₂B intermediates containing one acryl group and two secondary amine groups were accumulated until self‐polymerization started; the self‐polymerization of the intermediates formed hyperbranched polymers with secondary amines as their surface groups. Modifications of surface functional groups were studied to form new hyperbranched polymers. The hyperbranched poly(amido amine)s were amorphous. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6226–6242, 2006     

Dibenzo[d,f][1,3] dioxepine derivatives: A review

This review presents a survey of synthetic methods and reaction mechanism of the dibenzo[d,f][1,3] dioxepine derivatives. Furthermore, the influence of the substituent groups in 6,6′‐position of dibenzo[d,f][1,3] dioxepine on their conformation is explored. The functional dibenzo[d,f][1,3] dioxepine synthetically versatiles substrate, as they can be used for synthesis of a large variety of π‐conjugated oligomer and polymer containing heterocyclic compounds, such as dibromination dibenzo[d,f][1,3] dioxepine derivative as a raw material of synthesis for organic semiconductor polymers. The synthetic and fluorescent property of π‐conjugated polymers basic on dibenzo[d,f][1,3] dioxepine also is explored. J. Heterocyclic Chem., (2012).     

Functional aramids: Aromatic polyamides with reactive azido and amino groups in the pendant structure

The structure of the high‐performance aromatic polyamides, also known as aramids, was modified to render functional polymers by the introduction of primary amine and azide functional groups in the main polymer chain. These materials were prepared as parent polymers for future use in the simple and inexpensive preparation of other high‐performance materials by the chemical derivatization of the primary amine and azide groups using their well‐known and broad reactivity. The potential of the parent aramids was exemplified with the preparation of four novel functional aramids containing the fluorescent dansyl group, the anion and cation receptors urea and triazole with free primary alcohol functional groups, and the iminophosphorane ligand for forthcoming synthetic processes. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1469–1477     

Generation of Stoichiometric Ethylene and Isotopic Derivatives and Application in Transition‐Metal‐Catalyzed Vinylation and Enyne Metathesis

Ethylene is one of the most important building blocks in industry for the production of polymers and commodity chemicals. ¹³C‐ and D‐isotope‐labeled ethylenes are also valuable reagents with applications ranging from polymer‐structure determination, reaction‐mechanism elucidation to the preparation of more complex isotopically labeled compounds. However, these isotopic derivatives are expensive, and are flammable gases, which are difficult to handle. We have developed a method for the controlled generation of ethylene and its isotopic variants including, for the first time, fully isotopically labeled ethylene, from simple alkene precursors by using Ru catalysis. Applying a two‐chamber reactor allows both the synthesis of ethylene and its immediate consumption in a chemical transformation permitting reactions to be performed with only stoichiometric amounts of this two carbon olefin. This was demonstrated in the Ni‐catalyzed Heck reaction with aryl triflates and benzyl chlorides, as well as Ru‐mediated enyne metathesis.     

Chromocene catalysts for ethylene polymerization: Scope of the polymerization

Chromocene deposited on silica supports of high surface area forms a highly active catalyst for polymerization of ethylene. Polymerization is believed to occur by a coordinated anionic mechanism previously outlined. The catalyst formation step liberates cyclopentadiene and leads to a new divalent chromium species containing a cyclopentadienyl ligand. The catalyst has a very high chain-transfer response to hydrogen which permits facile preparation of a full range of molecular weights. Catalyst activity increases with an increase in silica dehydration temperature, chromium content on silica, and ethylene reaction pressure. The temperature-activity profile is characterized by a maximum near 60°C, presumably caused by a deactivation mechanism involving silica hydroxyl groups. A value of 72 was estimated for the ethylene–propylene reactivity ratio (r₁). Linear, highly saturated polymers are normally prepared below 100°C. By contrast with other commercial polyethylenes, the chromocene catalyst produces polyethylenes of relatively narrow molecular weight distribution. Above 100°C, unsaturated, branched polymers or oligomers are formed by a simultaneous polymerization–isomerization process.     

Preparation and characterization of novel hyperbranched poly(amido amine)s from Michael addition polymerizations of trifunctional amines with diacrylamides

Novel hyperbranched poly(amido amine)s containing tertiary amines in the backbones and acryl as terminal groups were synthesized via the Michael addition polymerizations of trifunctional amines with twofold molar diacrylamide. The hyperbranched structures of these poly(amido amine)s were verified by ¹³C NMR (INVGATE). The polymerization mechanisms were clarified by following the polymerization process with NMR method, and the results show that the reactivity of secondary amine formed in situ is much lower than that of the secondary amine in 1‐(2‐aminoethyl) piperazine (AEPZ) ring and the primary amine. The secondary amine formed in situ was almost kept out of the reaction before the primary and secondary amines in AEPZ were consumed, leading to the formation of the AB2 intermediate, and the further reaction of the AB2 yielded the hyperbranched polymers. The molecular weights and properties of poly(amindo amine)s obtained were characterized by GPC, DSC, and TGA, respectively. Based on the reaction of active acryl groups in the polymers obtained with glucosamine, hyperbranched polymers containing sugar were formed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5127–5137, 2005     

Modified polysulfones. IV. Synthesis and characterization of polymers with silicon substituents for a comparative study of gas‐transport properties

We previously conducted a detailed study of gas‐transport and other properties of a series of silicon derivatives of Udel polysulfone (PSf) and Radel polyphenylsulfone; we now report the details of their preparation by the reaction of lithiated polymer intermediates with chlorosilylalkylaryl electrophiles. Ortho‐sulfone‐substituted polymers with pendant trimethylsilyl, dimethylphenylsilyl, and diphenylmethylsilyl and other groups were obtained by direct metalation followed by the reaction of the dilithiated intermediate with the appropriate silyl electrophile. In addition, the structural regularity and geometry of the dilithiated site was also exploited to introduce silicon into the main chain by the reaction of dichlorosilyl electrophiles, leading to the formation of a new tricyclic heteroatom ring. Ortho‐ether PSf derivatives were obtained from a dibrominated polymer via the lithiation of brominated polymer and reaction with a silyl electrophile. The degree of substitution of the silyl groups was 2.0 or less from dilithiated polymers and was dependent on the electrophile reactivity and reaction conditions. A detailed structural characterization of the polymers by NMR and IR spectroscopy is reported in addition to glass‐transition temperatures and thermal stabilities. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2103–2124, 2001     

Cationic polyelectrolytes. IV. Kinetic study of the reaction of acrylic polymers containing tertiary amine groups with halogenated compounds in dipolar aprotic solvents

The reaction kinetics of halogenated compounds with tertiary amine groups attached at an acrylic macromolecular chain have ben studied. Three acrylic polymers were used. Two of them have mainly a structural unit of N, N-dimethylaminopropylacrylamide and the third is poly(N,N-dimethylaminoethylmethacrylate). Dimethylformamide, dimethylacetamide, and dimethylsulfoxide (DMSO) were used as dipolar aprotic solvents. Benzyl chloride and allyl chloride were considered as halogenated compounds with increased reactivity. The reaction kinetics depend on the polymer and halogenated-compound structures as well as the nature of the solvent. In the most of the cases the reactions carried out on polymers are accompanied by self-accelerating processes, with the exception of DMSO, which obviously has normal second-order kinetics. The reaction of polymers containing units of N,N-dimethylaminopropylacrylamide are compared with one having a low molecular weight, for instance N,N′-bis(3-dimethylaminopropyl)glutaramide.     

Temporary Intramolecular Generation of Pyridine Carbenes in Metal‐Free Three‐Component C?H Bond Functionalisation/Aryl‐Transfer Reactions

Nucleophilic addition of pyridines to benzyne generates zwitterionic adducts that evolve by a rapid intramolecular proton shift to produce the corresponding pyridine carbenes, N‐phenyl pyrid‐2‐ylidenes. In the presence of electrophilic ketones (isatin derivatives), the pyridylidenes can further react by an original bis‐arylation reaction of the carbonyl compounds involving a formal pyridine C? H bond functionalisation. The overall transformation is an unprecedented three‐component reaction featuring a carbene intermediate. The mechanism of this transformation was examined in detail by using both experimental and theoretical approaches. It was found that the generation of N‐phenyl pyrid‐2‐ylidene from pyridine and benzyne is energetically favoured, and that the corresponding carbene dimer can also form easily. Under the three‐component reaction conditions, the pyridylidene preferentially adds to the ketone group of the isatin derivative to produce a zwitterionic adduct amenable to an intramolecular aryl transfer reaction by a concerted nucleophilic aromatic substitution. This peculiar reactivity for a carbene was compared to possibly competitive known reactions of stable carbenes with carbonyl compounds, and the reaction was found to be under thermodynamic control. The reported method of generation of N‐phenyl pyrid‐2‐ylidenes and their reactivity with carbonyl compounds unlock new perspectives in organic synthesis.     

Novel fluorinated polymers by radical polyaddition: Inspiration and progress

The story of the outset and the growth of radical polyaddition of bisperfluoroisopropenyl derivatives [CF₂?C(CF₃)? R? C(CF₃)? CF₂] with several organic compounds possessing carbon–hydrogen bonds is described. The reaction afforded novel fluorinated polymers bearing such organic segments in polymer main chains as 1,4‐dioxane, diethyl ether, dimethoxyethane, 18‐crown‐6, triethylamine, glutaraldehyde, and alkanes which have never been supposed as direct starting compounds for preparation of polymers. The facile method for preparation of fluorinated hybrid polymers bearing alkylsilyl groups was developed with diethoxydimethylsilane and silsesquioxanes. Taking advantage of the high reactivity of the perfluoroisopropenyl group as a radical acceptor, self‐polyaddition and cyclopolymerization were investigated. Triethysilyl perfluoroisopropenyl ether [CF₂? C(CF₃)? O? Si(C₂H₅)₃] was proved to be the most probable candidate for self‐polyaddition. Cyclopolymerization of perfluoroisopropenyl vinylacetate [CF₂?C(CF₃) OCO? CH₂CH? CH₂] was investigated to afford polymers possessing five‐membered‐ring units in main chains. The interconversion of the unstable fluorinated carbon radical and the stable hydrocarbon radical had an important role in the reaction. The radical addition reaction presented herein may be developed for preparation of a wide variety of novel fluorinated polymers and organic compounds possessing functional groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4101–4125, 2004     

Synthesis and properties of vinyl‐terminated and silicon‐containing polysulfones and polyketones

4‐Fluorophenylsulfonylphenyl‐terminated polysulfone and 4‐fluorobenzoylphenyl ketone were prepared with bisphenol A and an excess of bis‐(4‐fluorophenyl)sulfone or 4,4′‐difluorobenzophenone, respectively, at 160 °C using potassium carbonate in N,N‐dimethylacetamide. The resulting polymers were reacted with 4‐hydroxystyrene to synthesize vinyl‐terminated polysulfones and ketones. The silicon‐containing polysulfones and ketones were prepared from the vinyl‐terminated polymer precursor and various H‐functional silanes or siloxanes. The synthesis of silicon‐containing polymers was achieved by hydrosilation with a rhodium catalyst. It was shown that the hydrosilation reaction proceeds with 55:45 chemoselectivity. The resulting polymers were investigated by ¹H NMR spectroscopy, DSC, and thermogravimetric analysis. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2937–2942, 2001     

Synthesis of Functional Bis(pentafluoroethyl)silanes (C2F5)2SiX2, with X=H,F, Cl,Br, OPh,and O2CCF3

As recently shown, the introduction of pentafluoroethyl functionalities into silicon compounds is of general interest due to an enhanced Lewis acidity of the resulting species. By this means, the synthesis of previously inaccessible hypervalent silicon derivatives is enabled. 1 While an easy access to tris(pentafluoroethyl)silanes has already been published, synthetic strategies for the selective preparation of bis derivatives are yet unknown. In this contribution, a convenient protocol for the synthesis of functional bis(pentafluoroethyl)silicon compounds is presented. These compounds represent precursors for the synthesis of pentafluoroethylated polysiloxanes. 2 Furthermore, they prove to be resistant to oxonium cations, which is a key feature for the preparation of stable pentafluoroethylsilic acids. 3 Treatment of dichlorodiphenoxysilane with in situ generated pentafluoroethyl lithium leads to the corresponding bis(pentafluoroethyl)silane in high yields. (C₂F₅)₂Si(OPh)₂ serves as a starting material for further functionalized bis(pentafluoroethyl)silanes. These silanes have been isolated and their reactivity towards N bases studied. The pronounced Lewis acidity of the obtained compounds has been documented by the formation of octahedral adducts with nitrogen donors such as 1,10‐phenanthroline and acetonitrile.     

New photoluminescent conjugated polymers with 1,4‐dioxo‐3,6‐diphenylpyrrolo[3,4‐c]pyrrole (DPP) and 1,4‐phenylene units in the main chain

A series of π‐conjugated polymers and copolymers containing 1,4‐dioxo‐3,6‐diphenylpyrrolo[3,4‐c]pyrrole (also known as 2,5‐dihydro‐3,6‐diphenylpyrrolo[3,4‐c]pyrrole‐1,4‐dione) (DPP) and 1,4‐phenylene units in the main chain is described. The polymers are synthesised using the palladium‐catalysed aryl‐aryl coupling reaction (Suzuki coupling) of 2,5‐dihexylbenzene‐1,4‐diboronic acid with 1,4‐dioxo‐2,5‐dihexyl‐3,6‐di(4‐bromophenyl)pyrrolo[3,4‐c]pyrrole and 1,4‐dibromo‐2,5‐dihexylbenzene in different molar ratios. Soluble hairy rod‐type polymers with molecular weights up to 21 000 are obtained. Polymer solutions in common organic solvents such as chloroform or xylene are of orange colour (λ_max = 488 nm) and show strong photoluminescence (λ_max = 544 nm). The photochemical stability is found to be higher than for corresponding saturated polymers containing isolated DPP units in the main chain. Good solubility and processability into thin films render the compounds suitable for electronic applications.     

Synthesis and characterization of conducting poly(aniline‐co‐o‐aminophenethyl alcohol)s

Poly(o‐aminophenethyl alcohol) and its copolymers containing the aniline unit were synthesized in aqueous hydrochloric acid medium by chemical oxidative polymerization. The chemical composition of these novel polymers was determined spectroscopically, and their viscosities were measured. These polymers exhibit good solubility in organic solvents that is attributed mainly to the polar hydroxyethyl side groups. Their structures (chain conformation and morphological structure) and properties (conductivity, electrochemical characteristics, glass transition, and degradation behavior) were characterized and then interpreted on the basis of the chemical composition along with the electronic and steric hindrance effects associated with the hydroxyethyl side group. Overall, the side group has a significant effect on the polymerization and influences the structure, chain conformation, and properties of the resultant polymer. The poly(aniline‐co‐o‐aminophenethyl alcohol)s containing 20–40 mol % o‐aminophenethyl alcohol units are potential conducting materials for microelectronic and electromagnetic shielding applications because they are easier to process than polyaniline but retain its beneficial properties. These polymers can also be used as a functional conducting polymer intermediate owing to the reactivity of the side group. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 983–994, 2002     

Reactivity and Stability of Glucosinolates and Their Breakdown Products in Foods

The chemistry of glucosinolates and their behavior during food processing is very complex. Their instability leads to the formation of a bunch of breakdown and reaction products that are very often reactive themselves. Although excessive consumption of cabbage varieties has been thought for long time to have adverse, especially goitrogenic effects, nowadays, epidemiologic studies provide data that there might be beneficial health effects as well. Especially Brassica vegetables, such as broccoli, radish, or cabbage, are rich in these interesting plant metabolites. However, information on the bioactivity of glucosinolates is only valuable when one knows which compounds are formed during processing and subsequent consumption. This review provides a comprehensive, in‐depth overview on the chemical reactivity of different glucosinolates and breakdown products thereof during food preparation.     

Synthesis of polyamines with pendant cyanoimidazole units and their electrochemical properties

The 2-(1-methyl-4,5-dicyanoimidazolyl) group was attached to poly(diallylamine) and polyethylenimine, affording polymers containing an electron-withdrawing pendant group. The key to their preparation is high reactivity of 1-methyl-2-fluoro-4,5-dicyanoimidazole (1) toward nucleophilic aromatic substitution (NAS) reactions with aliphatic amines. Cyclic voltammograms of these polymers show reduction waves at −2.6 to −2.7 V vs. Ag/Ag⁺ but no reoxidation waves, unlike those of monomeric and oligomeric model compounds, which are quasi-reversible. The cyclic voltammetry studies of oligomeric model compounds with different alkyl spacers show that the degree of quasi-reversibility decreases as dicyanoimidazoles are crowded together in a molecule, suggesting that a certain degree of chemical reaction occurs between reduced dicyanoimidazole groups. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2619–2629, 1998     

Modular In Situ Functionalization Strategy: Multicomponent Polymerization by Palladium/Norbornene Cooperative Catalysis

Herein, we report a cooperatively palladium/norbornene‐catalyzed polymerization, which simplifies the synthesis of functional aromatic polymers, including conjugated polymers. Specifically, an A₂B₂C‐type multicomponent polymerization that is based on an ortho amination/ipso alkynylation reaction was developed for the preparation of various amine‐functionalized arylacetylene‐containing polymers. Within a single catalytic cycle, the amine side chains are site‐selectively installed in situ by C?H activation during the polymerization process, which represents a major difference from conventional cross‐coupling polymerizations. This “in situ functionalization” strategy enables the modular incorporation of functional side chains starting from simple monomers, thereby conveniently affording a diverse range of functional polymers.