Macrocyclic Oligomers Research Articles

Recent work on entropically‐driven ring‐opening polymerizations: some potential applications

AbstractThe entropically‐driven ring‐opening polymerization of macrocyclic monomers (>ca. 14 ring atoms per repeat unit) and/or macrocyclic oligomers is a relatively new method of polymer synthesis that exploits the well‐known phenomenon of ring‐chain equilibria. It attracts interest because of its novel features. For example, these ring‐opening polymerizations emit no volatiles and little or no heat. This review considers the principles of entropically‐driven ring‐opening polymerizations, gives selected examples and discusses potential applications. The latter include micromolding, high throughput syntheses and the synthesis of supramolecular polymers. Copyright © 2005 John Wiley & Sons, Ltd.

Antimycobacterial Calixarenes Enhance Innate Defense Mechanisms in Murine Macrophages and Induce Control ofMycobacterium tuberculosisInfection in Mice

Tuberculosis remains the leading cause of death among infectious diseases, accounting for more than two million deaths annually. The incidence of the disease is increasing globally, partially because of the resurgence of drug-resistant strains of Mycobacterium tuberculosis. Calixarenes are macrocyclic oligomers, some of which are able to modify the growth of M. tuberculosis in infected cells. Most experimental work has been carried out with Macrocyclon, also known as HOC 12.5EO. In this study, we demonstrate that Macrocyclon is effective in controlling M. tuberculosis infections, and we provide evidence that its effect is partially mediated by an l-arginine-dependent mechanism of macrophage activation that involves the activity of the inducible nitric oxide synthase. We also show that Macrocyclon is effective in athymic and major histocompatibility complex class II-/- mice and synthesized a number of structurally related calixarenes expressing significant antimycobacterial activity.

Synthesis of macrocyclic aliphatic disulfide oligomers from dithiols by oxidative coupling with oxygen using a copper‐amine catalyst

AbstractA new effective method is provided for the synthesis of macrocyclic aliphatic disulfide oligomers by catalytic oxidation of aliphatic dithiols with oxygen in the presence of a copper‐amine catalyst. Copyright © 2004 John Wiley & Sons, Ltd.

Synthesis and properties of poly(4,4′-oxybis(benzene)disulfide)/graphite nanocomposites via in situ ring-opening polymerization of macrocyclic oligomers

An effective method for the preparation of poly(4,4′-oxybis(benzene)disulfide)/graphite nanosheet composites via in situ ring-opening polymerization of macrocyclic oligomers were reported. Completely exfoliated graphite nanosheets were prepared under the microwave irradiation followed by sonication in solution. The nanocomposites were fabricated via in situ melt ring-opening polymerization of macrocyclic oligomers in the presence of graphite nanosheets. The graphite nanosheets and resulted poly(arylene disulfide)/graphite nanocomposites were characterized with field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), tensile tester and electrical conductivity measurements. Compared with pure polymer, the electrical conductivity of the poly(arylene disulfide)/graphite nanocomposites were dramatically increased and had a value of about 10 −3 S/cm for the nanocomposite containing 5 wt% graphite. The nanocomposites exhibit as both high performance polymeric material and electrically conductive material. Therefore, they show potential applications as high temperature conducting materials.

Synthesis and ring‐opening polymerization of macrocyclic aromatic sulfide oligomers

AbstractA series of macrocyclic(arylene sulfide) oligomers were synthesized by reaction of 4,4′‐oxybis(benzenethiol) with a number of difluoro compounds in dimethylformamide (DMF) in the presence of anhydrous K2CO3 under high dilution conditions. The difluoro compound can be 4,4′‐difluorobenzophenone, bis(4‐fluorophenyl)sulfone or 1,3‐bis(4‐fluorobenzoyl)benzene. Detailed structural characterization of these oligomers by matrix‐assisted laser desorption and ionization‐time of flight‐mass spectroscopy (MALDI‐TOF‐MS) demonstrated their cyclic nature. The MALDI‐TOF‐MS technique has proved to be a powerful tool to analyze these cyclics. These cyclic oligomers are amorphous and highly soluble in DMF and N,N′‐dimethyl acetamide. Moreover, these cyclic(arylene sulfide) oligomers readily underwent ring‐opening polymerization in the melt at 285 °C in the presence of 2,2′‐dibenzothiazole disulfide, affording linear, high molecular weigh poly(aromatic sulfide)s. These polymers are insoluble in most common solvents. Copyright © 2004 Society of Chemical Industry

Cyclo-depolymerisations of polyurethanes to give macrocyclic oligomers: entropically driven ring-opening polymerisations of the macrocyclic oligomers produced

We report the cyclo-depolymerisations of two polyurethanes by heating suspensions in 1,2-dichlorobenzene at ≈180 °C in the presence of 2 mol% of either tetrabutylammonium tetraphenylborate, titanium tetraisopropoxide, a dioxastannane, sodium hydride or boron trifluoride ethererate as the catalyst. Each reaction gave an homologous series of macrocyclic oligomers: one with 20 ring atoms per repeat unit and one with 26 ring atoms per repeat unit. The mixtures of cyclics were characterized by matrix assisted laser desorption ionisation time of flight mass spectrometry and by gel permeation chromatography. In each case the cyclic monomer was isolated and characterized by infrared and 1H NMR spectroscopy, matrix assisted laser desorption ionisation time of flight mass spectrometry and elemental analysis. Some entropically driven ring-opening polymerisations of the pure macrocyclic monomers and of the series of macrocyclic oligomers were investigated.

Porphyrin supramolecules by complementary coordination for units constructing photosynthetic systems

Among unique structural arrangements provided by nature, special pair and macroring antenna complexes in bacterial photosynthetic systems have been mimicked by simple organization of choromophores. The special pair was mimicked by imidazolyl-substituted porphyrinatozinc which gave a complementary coordination dimer of slipped cofacial orientation with an extremely large stability constant of 1010 M-1 in CHCl 3. When two imidazolylporphyrinatozinc units were linked directly at the meso positions, linear and continuous growth of the complementary coordination lead to porphyrin arrays of a few hundreds nanometer scale, corresponding to molecular weights of a few 105. At the same time, the porphyrin array could be dissociated into the monomeric unit by competitive coordination of solvents. This provided a way of terminating or initiating the oligomeric porphyrin array with appropriate chain terminals/initiators. Two imidazolylporphyrinatozinc complexes were then linked by a m-phenylene unit with an angle of 120°. The linear and macrocyclic oligomer mixtures initially obtained were converged smoothly by reorganization equilibrium into a mixture of hexameric and pentameric macrocycles under high-dilution conditions. The ring mimicked the structure and function of the light harvesting complexes of bacterial photosynthetic systems. The covalent linking of coordination organized porphyrins was also developed to maintain the structure even in highly coordinating solvents such as pyridine. The linear array formation and the facile introduction of specific terminal/initiator groups by complementary coordination were then applied to introduce antenna function onto solar cell. Through thiolate attachment on a gold surface, imidazolylporphyrinatozinc initiated the growth of meso-meso linked porphyrin arrays by successive complementary coordination. This methodology improved the efficiency of absorption of incident photon and increased significantly the total photocurrent generation efficiency.

Ring-opening polymerization of macrocyclic(aromatic disulfide) oligomer derived from 4,4′-oxybis(benzenethiol)

Ring-opening polymerization of macrocyclic(aromatic disulfide) oligomer derived from 4,4′-oxybis(benzenethiol) was studied. Ring-opening reactions were carried out in nitrogen and oxygen atmosphere, respectively. Oxidation reaction and cross-linking reaction took place in oxygen atmosphere. The melt copolymerization between cyclic 1 and elemental sulfur was studied using DSC, and TGA techniques. With increasing the contents of sulfur in the polymer, the T g values, and 5% weight loss temperatures decreased. When the ratio of sulfur to cyclic reached 5, the polymer appeared as a rubber with a T g of 23.0 °C and a 5% weight loss temperature of 269.4 °C. A series of poly(thiol aromatic)s were prepared from cyclic 1 and dibromo aromatic compounds in diphenyl ether at 260 °C. The dibromo aromatic compounds can be bis(4-bromophenyl) ether, 4,4′-dibromobiphenyl, and 1,4-dibromobenzene. 4,4′-Dibromobiphenyl gave poly(thiol aromatic) with a T g of 122.2 °C and a T m of 221.3 °C by reacting with the cyclic 1.

The influence of multiple ortho-substituted phenylenes on the nature of poly(ether imide)s

The new ortho-aminophenyl diamine 1,2-bis(2′-aminophenoxy)benzene has been synthesized and polymerized with 1,2-bis(3′,4′dicarboxyphenoxy)benzene dianhydride to yield a poly(ether imide) with four ortho-catenated phenylenes per structural repeat unit. The polymer has been characterized by gel permeation chromatography and MALDI-TOF mass spectrometry and shown to contain a large proportion of oligomers. The oligomers have been found to be primarily macrocyclic oligomers with two to 10 repeat units. The results are contrasted with the high-molecular-weight polyimides formed from corresponding para-aminophenoxy diamines. It is concluded that either the ortho-aminophenoxy moiety or the large sequence of ortho-catenated phenylene rings gives a high propensity for ring closure and macrocycle formation in competition with propagation.

One-pot method of preparing novel macrocyclic(thio arylene) oligomers

A series of macrocyclic(thio arylene) oligomers were synthesized under high dilution conditions by reacting diphenyl ether, diphenyl, diphenyl disulfide or diphenyl methane with dichloro disulfide in the presence of trace amount of iron powder by a one-step method. The composition of these macrocyclic oligomers was analyzed by MALDI-TOF technology, and the experimental results showed that the cyclics were a mixture with repeating units separated by one to seven sulfur atoms. These macrocyclics can undergo ring-opening polymerization to form linear polymers under mild conditions. The glass transition temperatures of produced polymers varied with the sulfur content.

One‐step synthesis and ring‐opening polymerization of novel macrocyclic(arylene multisulfide) oligomers

AbstractA series of macrocyclic(arylene multisulfide) oligomers were synthesized under high dilution conditions by reacting diphenyl ether/diphenyl/diphenyl disulfide/diphenyl methane with dichloro disulfide in the presence of a trace amount of iron powder by a one‐step reaction. From MALDI‐TOF mass spectra, it was established that the repeating units of the cyclization ranged from two to seven and the unit of macrocyclic(arylene multisulfide) oligomers had one to seven sulfur atoms. The macrocyclic oligomers readily underwent ring‐opening polymerization in the melt, resulting in linear, high molecular weight polymultisulfides. DSC thermograms demonstrated that the four polymultisulfides, derived from the macrocyclic(arylene multisulfide) oligomers, are amorphous in nature. The macrocyclic(arylene multisulfide) oligomers and polymers were analyzed by MALDI‐TOF‐MS, IR, HPLC, NMR, DSC, and TGA methods. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 735–741, 2004

Ring−Chain Interconversion in High-Performance Polymer Systems. 1. [Poly(oxy-4,4‘-biphenyleneoxy-1,4-phenylenesulfonyl-1,4-phenylene)] (Radel-R)

At a polymer concentration of 1 wt % in dimethylacetamide, fluoride-promoted cleavage of ether linkages in Radel-R (an industrially important aromatic poly(ether sulfone) derived from 4,4‘-biphenol) leads to ring-closing depolymerization. A high molar mass poly(ether sulfone) is thus converted in good yield to a family of macrocycles containing from eight up to at least sixty aromatic rings. Detailed analyses of the reaction products indicate a linear oligomer content of less than 4 wt %. Individual macrocycles containing eight, twelve, sixteen, and twenty aromatic rings have been isolated and characterized as pure, monodisperse oligomers (the first two by single-crystal X-ray analysis). The cyclic dimer and trimer both adopt open, flattened conformations with substantial free pathways through the ring centers, and the cyclic dimer packs to give a continuous-channel structure in the solid state. These macrocyclic oligomers undergo efficient ring-opening polymerization in the presence of phenoxide and espe...

Synthesis of mayolene-16 and mayolene-18: larval defensive lipids from the European cabbage butterfly.

A tandem Wittig approach has been employed for the synthesis of both (11S,9Z,12Z,15Z)- and (11R,9Z,12Z,15Z)-hydroxyoctadeca-9,12,15-trienoic acid (11-hydroxylinolenic acid, 11-HLA) from (R)-glyceraldehyde acetonide. From (11R)-HLA we have prepared the corresponding palmitic acid and stearic acid esters, mayolene-16 (1) and mayolene-18 (2), insect defensive compounds recently identified from Pieris rapae larvae. In addition, we describe the synthesis of three macrocyclic oligomers (24-26) derived from (11R)-HLA.

LB Film Structure of Nanometer-Scale PEEKK Macrocyclic Oligomers

A rigid macrocyclic oligomer (RCO), cyclic poly(aryl ether ketone), was synthesized and used to produce Langmuir-Blodgett (LB) films. The isotherm of surface pressure versus surface area showed that the RCO molecules form a stable monolayer on the water subphase with an area per molecule of about 1.7 nm 2 . The structure of the LB film was confirmed by means of atomic force microscope, and two-dimensionally ordered cavities of nanometer scale were observed in the LB film.

Synthesis of Cyclic Poly(Methacrylic Acid) by Template Polymerization of β-Cyclodextrin Monomer

Atom transfer radical polymerization of template monomer synthesized by introduction of methacryloyl groups into secondary hydroxyl groups of β-cyclodextrin [β-CD] was carried out with 1,3-dibromobutane as an initiator. Then, closing of polymerized methacryloyl groups was carried out by reaction of bromine groups at both ends with 1,3-diamino propane [DAP] or 1,4-diamino butane [DAB]. The macrocyclic poly(methacrylic acid) [PMAA] obtained by hydrolysis of products was analyzed by GPC, MALDI-TOF-mass. It was found that template monomer of β-CD was effective for synthesisof macrocyclic oligomers and that DAP was the preferred closing reagent for the methacryloyl groups polymerized in the template monomer.

Synthesis and ring-expanding oligomerization of an extremely strained macrocyclic aromatic ether-sulfone.

[reaction: see text] An extremely strained, 5-ring, macrocyclic aromatic ether-sulfone, [-1,4-C(6)H(4)SO(2)-1,4-C(6)H(4)O-1,3-C(6)H(4)O-1,4-C(6)H(4)SO(2)-1,4-C(6)H(4)-], synthesized by nickel-catalyzed intramolecular coupling of a bis-chlorophenylene-terminated precursor, undergoes fluoride-promoted ring expansion in dilute solution, giving a series of higher macrocyclic oligomers including cyclic dimer, trimer, and tetramer. The latter contains 20 aromatic residues in a 92-atom ring and is one of the largest synthetic organic macrocycles to be crystallographically characterized. The synthesis, structure, and ring expansion of a related macrocyclic ether-ketone are also reported.

High Molecular Weight Aromatic Polyformals Free of Macrocyclic Oligomers. A Condensative Chain Polymerization Reaction

ADVERTISEMENT RETURN TO ISSUEPREVNoteHigh Molecular Weight Aromatic Polyformals Free of Macrocyclic Oligomers. A Condensative Chain Polymerization ReactionKenji Miyatake, Antisar R. Hlil, and Allan S. HayView Author Information Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal, Quebec H3A 2K6, Canada Cite this: Macromolecules 2001, 34, 12, 4288–4290Publication Date (Web):May 5, 2001Publication History Received28 November 2000Revised2 March 2001Published online5 May 2001Published inissue 1 June 2001https://doi.org/10.1021/ma002020rCopyright © 2001 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views580Altmetric-Citations40LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (44 KB) Get e-AlertsSUBJECTS:Mixtures,Oligomers,Polymerization,Polymers,Salts Get e-Alerts

Some applications of reactions which interconvert monomers, polymers and/or macrocycles

Various reactions which interconvert monomers, polymers and/or macrocycles are considered and, in most cases, recent examples presented. The reactions include step-growth polymerisations, high dilution syntheses of macrocyclic oligomers, entropically-driven ring-opening polymerisations of macrocyclic oligomers, cyclo-depolymerisations to afford cyclic oligomers, and equilibrations between cyclic oligomers to give soluble combinatorial libraries of macrocycles. The latter may be screened using a soluble functionalised polymer and high resolution diffusion ordered NMR spectroscopy.

Synthesis, structure and ring-opening polymerization of phenolphthalein macrocyclic polyarylates

Phenolphthalein based polyarylate macrocyclic oligomers were selectively synthesized by an interfacial polycondensation reaction of o-phthaloyl dichloride with phenolphthalein. The high selectivity benefits from the role of phenolphthalein as a color indicator, an efficient phase transfer catalyst, and a preferred conformation of the starting materials as indicated by analyzing a single-crystal X-ray structure of an analogous macrocycle. The melt ROP of phenolphthalein polyarylate cyclic dimer was studied using nucleophilic initiators. The molecular weight of the resulting polymers builds up very rapidly at the very early stage of polymerization but decreases with time. During the ROP of cyclic dimer, analogous macrocycles with higher degree of polymerization (n ≥ 3) and linear oligomers were produced by backbiting reaction especially at later stage of polymerization. Conversion of cyclic dimer is very fast at the earlier stage of polymerization and then increases slowly with time as analyzed by gel permeation chromatography. However, the total amount of cyclic oligomers in the ROP system increases with time at the later stage of polymerization because of the formation of larger macrocycles. The resulting polymers are amorphous. Glass transition temperatures (Tgs) of these polymers are influenced by the polymerization time, type of initiator, and initiator concentration.

Novel macrocyclic precursors of poly{aryl ether ketone (sulfone)} containing hexafluoroisopropylidene units: Synthesis, characterization, and polymerization

Cyclic oligomers containing hexafluoroiso-propylidene(HFIP) units were prepared in excellent yields by a nucleophilic aromatic substitution reaction of 4,4(7)- (hexafluoroisopropylidene) diphenol with difluoro-monomers in the presence of anhydrous potassium carbonate under pseudo high dilution conditions. A combination of GPC, MALDI-TOF MS and NMR analysis confirmed the structure of the cyclic oligomers. All macrocyclic oligomers are crystalline and undergo facile melt polymerization to give high molecular weight fluorinated polyethers.