Sample records for macrocyclic polyether compounds

  1. Experimental and theoretical study for corrosion inhibition of mild steel in normal hydrochloric acid solution by some new macrocyclic polyether compounds

    Lebrini, M. [Unite de Catalyse et de Chimie du Solide, CNRS UMR 8181, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Lagrenee, M. [Unite de Catalyse et de Chimie du Solide, CNRS UMR 8181, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Vezin, H. [Laboratoire de Chimie Organique et Macromoleculaire, CNRS UMR 8009, USTL Bat C4, F-59655 Villeneuve d' Ascq Cedex (France); Traisnel, M. [Laboratoire des Procedes d' Elaboration des Revetements Fonctionnels, PERF UMR 8008, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Bentiss, F. [Laboratoire de Chimie de Coordination et d' Analytique, Faculte des Sciences, Universite Chouaib Doukkali, BP 20, M-24000 El Jadida (Morocco)]. E-mail:


    New macrocyclic polyether compounds containing a 1,3,4-thiadiazole moiety have been prepared to study the corrosion inhibitive effect of mild steel in normal hydrochloric acid solutions. The salient features obtained from weight loss and electrochemical impedance spectroscopy (EIS) have been discussed. The results of these investigations have shown enhancement in inhibition efficiencies with the extent of the polyethylene glycol unit that forms a cavity. Data obtained from EIS show a frequency distribution and therefore a modelling element with frequency dispersion behaviour, a constant phase element (CPE) has been used. Display Omitted Adsorption of n-MCTH was found to follow the Langmuir's adsorption isotherm. The thermodynamic functions of adsorption process were calculated from experimental ac impedance data and the interpretation of the results are given. Molecular modelling has been conducted in an attempt to correlate the corrosion inhibition properties with the calculated quantum chemical parameters.

  2. Enhanced corrosion resistance of carbon steel in normal sulfuric acid medium by some macrocyclic polyether compounds containing a 1,3,4-thiadiazole moiety: AC impedance and computational studies

    Bentiss, F. [Laboratoire de Chimie de Coordination et d' Analytique, Faculte des Sciences, Universite Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco)], E-mail:; Lebrini, M. [Unite de Catalyse et de Chimie du Solide, UMR-CNRS 8181, ENSCL, BP. 90108, F-59652 Villeneuve d' Ascq Cedex (France); Vezin, H. [Laboratoire de Chimie Organique et Macromoleculaire, UMR-CNRS 8009, USTL Bat C4, F-59655 Villeneuve d' Ascq Cedex (France); Chai, F. [Groupe de Recherche sur les biomateriaux, Laboratoire de Biophysique, UPRES EA 1049, Faculte de Medecine, F-59045 Lille Cedex (France); Traisnel, M.; Lagrene, M. [Laboratoire des Procedes d' Elaboration des Revetements Fonctionnels, PERF UMR-CNRS 8008, ENSCL, B.P. 90108, F-59652 Villeneuve d' Ascq Cedex (France)


    We report here the use of macrocyclic polyether compounds containing a 1,3,4-thiadiazole moiety (n-MCTH) in the corrosion inhibition of C38 carbon steel in 0.5 M H{sub 2}SO{sub 4} acid medium. The aim of this work is devoted to study the inhibition characteristics of these compounds for acid corrosion of C38 steel using electrochemical impedance spectroscopy (EIS). Data obtained from EIS show a frequency distribution and therefore a modeling element with frequency dispersion behaviour, a constant phase element (CPE) has been used. The experimental results obtained revealed that these compounds inhibited the steel corrosion in acid solution and the protection efficiency increased with increasing inhibitors concentration. The difference in their inhibitive action can be explained on the basis of the number of oxygen atoms present in the polyether ring which contribute to the chemisorption strength through the donor acceptor bond between the non bonding electron pair and the vacant orbital of metal surface. Adsorption of n-MCTH was found to follow the Langmuir's adsorption isotherm. The thermodynamic functions of adsorption process were calculated and the interpretation of the results is given. These results are complemented with quantum chemical study in order to provide an explanation of the differences between the probed inhibitors. Correlation between the inhibition efficiency and the structure of these compounds are presented.

  3. Fourth symposium on macrocyclic compounds

    Christensen, J. J.; Izatt, R. M.


    Both theoretical and experimental aspects of the properties and behavior of synthetic and naturally occurring macrocyclic compounds are covered in this symposium. This document contains abstracts of the papers. (DLC)

  4. Macrocyclic trichothecenes as antifungal and anticancer compounds.

    de Carvalho, Maira Peres; Weich, Herbert; Abraham, Wolf-Rainer


    Trichothecenes are sesquiterpenoid metabolites produced by fungi and species of the plant genus Baccharis, family Asteraceae. They comprise a tricyclic core with an epoxide at C-12 and C-13 and can be grouped into non-macrocyclic and macrocyclic compounds. While many of these compounds are of concern in agriculture, the macrocyclic metabolites have been evaluated as antiviral, anti-cancer, antimalarial and antifungal compounds. Some known cytotoxic responses on eukaryotic cells include inhibition of protein, DNA and RNA syntheses, interference with mitochondrial function, effects on cell division and membranes. These targets however have been elucidated essentially employing non-macrocyclic trichothecenes and only one or two closely related macrocyclic compounds. For several macrocyclic trichothecenes high selectivity against fungal species and against cancer cell lines have been reported suggesting that the macrocycle and its stereochemistry are of crucial importance regarding biological activity and selectivity. This review is focused on compounds belonging to the macrocyclic type, where a cyclic diester or triester ring binds to the trichothecane moiety at C-4 and C- 15 leading to natural products belonging to the groups of satratoxins, verrucarins, roridins, myrotoxins and baccharinoids. Their biological activities, cytotoxic mechanisms and structure-activity relationships (SAR) are discussed. From the reported data it becomes evident that even small changes in the molecules can lead to pronounced effects on biological activity or selectivity against cancer cells lines. Understanding the underlying mechanisms may help to design highly specific drugs for cancer therapy.

  5. Macrocycles

    Raymond, Kenneth N.; Xu, Jide; Pham, Tiffany A.


    The invention provides macrocycles useful in chelating metal ions, particularly radionuclides, to provide metal ion complexes. The invention also provides methods of using the compounds and complexes of the invention, such as in therapeutic and diagnostic applications.

  6. Synthesis and Characterization of Macrocyclic Polyether N,N′-Diallyl-7,16-diaza-1,4,10,13-tetraoxa-dibenzo-18-crown-6

    Julius Toeri


    Full Text Available In this study an efficient and direct production procedure for a macrocyclic polyether N,N′-diallyl-7,16-diaza-1,4,10,13-tetraoxa-dibenzo-18-crown-6 from the reaction of catechol and N,N-bis(2-chloroethylprop-2-en-1-amine in n-butanol in the presence of a strong base is reported. The synthesis involves a two-step addition of sodium hydroxide to enhance the cyclization process, and at the end of the reaction, the reaction mixture is neutralized and the solvent replaced with water in-situ through distillation to afford a relatively pure precipitate that is easily recrystallized from acetone. The yield of the macrocycle was 36%–45% and could be scaled-up to one-mole quantities. The structure and purity of this compound was verified on the basis of elemental analysis, IR, UV-Vis, 1H-, 13C-NMR, 2D-NMR, mass spectroscopy, and thermal analysis. The white crystalline compound has a sharp melting point of 124 °C and a crystallization temperature of 81.4 °C determined by differential scanning calorimetry. Our motivation behind the synthesis of the bibracchial lariat azacrown polyether ligand was to examine its possible applications in ion-selective polymer-supported materials.

  7. Biologically Active Macrocyclic Compounds – from Natural Products to Diversity‐Oriented Synthesis

    Madsen, Charlotte Marie; Clausen, Mads Hartvig


    Macrocyclic compounds are attractive targets when searching for molecules with biological activity. The interest in this compound class is increasing, which has led to a variety of methods for tackling the difficult macrocyclization step in their synthesis. This microreview highlights some recent...

  8. Organic Electrofluorescent Materials Using Pyridine-Containing Macrocyclic Compounds

    Tingxi LI; Long FU; Wenwen YU; Renhe HUANG


    Novel pyridine-containing macrocyclic compounds, such as 6,12,19,25-tetramethyl-7,11,20,24-dinitrilo-dibenzo[b,m]l,4,12,15-tetra-azacyclodoc osine (TMCD), were synthesized and used as electron transport layer in organic electroluminescent devices. Devices with a structure of glass/indium-tin oxide/arylamine derivative/tris(quinolinolato)aluminum(Ⅲ) (AIq)/TMCD/LiF/AI exhibited green emission from the Alq layer with external quantum efficiency of 0.84% and luminous efficiency of 1.3 lm/W. The derivatives of TMCD were synthesized and characterized as well. These compounds were also found to be useful as the electron-transporting materials in organic electroluminescent devices.

  9. Electron transfer reactions of macrocyclic compounds of cobalt

    Heckman, R.A.


    The kinetics and mechanisms of reduction of H/sub 2/O/sub 2/, Br/sub 2/, and I/sub 2/ by various macrocyclic tetraaza complexes of cobalt(II), including Vitamin B/sub 12r/, were studied. The synthetic macrocycles studied were all 14-membered rings which varied in the degree of unsaturation,substitution of methyl groups on the periphery of the ring, and substitution within the ring itself. Scavenging experiments demonstrated that the reductions of H/sub 2/O/sub 2/ produce free hydroxyl radicals only in the case of Co((14)ane)/sup 2 +/ but with none of the others. In the latter instances apparently H/sub 2/O/sub 2/ simultaneously oxidizes the metal center and the ligand. The reductions of Br/sub 2/ and I/sub 2/ produce an aquohalocobalt(III) product for all reductants (except B/sub 12r/ + Br/sub 2/, which was complicated by bromination of the corrin ring). The mechanism of halogen reduction was found to involve rate-limiting inner-sphere electron transfer from cobalt to halogen to produce a dihalide anion coordinated to the cobalt center. This intermediate subsequently decomposes in rapid reactions to halocobalt(III) and halogen atom species or reacts with another cobalt(II) center to give two molecules of halocobalt(III). The reductions of halomethylcobaloximes and related compounds and diamminecobaloxime by Cr/sup 2 +/ were also studied. The reaction was found to be biphasic in all cases with the reaction products being halomethane (for the halomethylcobaloximes), Co/sup 2 +/ (in less than 100 percent yield), a Cr(III)-dimethylglyoxime species, a small amount of free dmgH/sub 2/, and a highly-charged species containing both cobalt and chromium. The first-stage reaction occurs with a stoichiometry of 1:1 producing an intermediate with an absorption maximum at 460 nm for all starting reagents. The results were interpreted in terms of inner-sphere coordination of the cobaloxime to the Cr(II) and electron transfer through the oxime N-O bond.

  10. Synthesis of Tetra-Schiff Base Macrocyclic Compound Containing Benzo-12-crown-4


    Tetra-Schiff base macrocyclic compound containing benzo-12-crown-4 was synthesized via condensation of 2, 6-diformyl-4-methyl-phenol with 4(, 5(- diaminobenzo-12-C- 4 promoted by proton. The compound was characterized by MS, IR 1HNMR spectroscopy and elemental analysis.

  11. New macrocyclic compounds using organotin complexes as intermediates: synthesis and characterization

    Harminder Kaur


    Full Text Available Background & Aim:A new series of macrocyclic compounds 1-4 have been synthesized using tin as templates.Method:Tin templates are formed by refluxing the solution of dibutyltin (IV oxide with orthophenylenediamine (L1H,4-chlorocatechol (L2H, butane dithiol (L3H and 3-carboxypropyldisulphide (L4H. Results:The reaction is visualizedby cleavage X-Sn-X (X= oxygen/ nitrogen/ sulphur atom bond of tin template when treated withadipoyldichloride. Conclusion:The compounds 1-4 are characterized with the aid of elemental analyses, IR and NMR(1H, 13C studies which confirmed their proposed framework.

  12. Macrocyclic fragrance materials

    Salvito, Daniel; Lapczynski, Aurelia; Sachse-Vasquez, Christen


    A screening-level aquatic environmental risk assessment for macrocyclic fragrance materials using a “group approach” is presented using data for 30 macrocyclic fragrance ingredients. In this group approach, conservative estimates of environmental exposure and ecotoxicological effects thresholds...... for compounds within two subgroups (15 macrocyclic ketones and 15 macrocyclic lactones/lactides) were used to estimate the aquatic ecological risk potential for these subgroups. It is reasonable to separate these fragrance materials into the two subgroups based on the likely metabolic pathway required...... for both regions is materials, and minimal in stream dilution (3:1), the conservatively predicted exposure concentrations for macrocyclic ketones would range from

  13. Macrocyclic compound as ionophores in lead(Ⅱ)ion-selective electrodes with excellent response characteristics

    HUANG MeiRong; MA XiaoLi; LI XinGui


    Macrocyclic compounds, such as crown ethers, azacrown ethers, thiacrown ethers, calixarenes and porphyrins, which act as ionophores in lead(Ⅱ) ion-selective electrodes, are systematically summarized based on the latest literatures. The molecular structure characteristics of the ionophores are general-ized. The modification regulations for the substituted ionophores are elaborated with the purpose ofimproving the response features of the lead(Ⅱ) ion-selective electrodes assembled by them. It is pointed out that the introduction of pendant moieties which contain soft base coordination centers like N, S and P atoms is in favor of adjusting the cavity size and conformation of the macrocyclic com-pounds. Furthermore, there is synergic effect between the cavity and the donor sites of the ligand and thus the selective complexation of lead ions is easily realized, resulting in significant avoidance of the interference from other metal ions. The macrocyclic ionophore having the best response characteris-tics thus far was found to be N,N'-dimethylcyanodiaza-18-crown-6 with the detection limit of 7.0×10-8 (14.5 μg/L), which is one of the uncommon ionophores that can really eliminate the interference from silver and mercury ions. The selectivity coefficients of the ionophore for lead ions over other metal ions, such as alkali, alkaline earth and transition metal ions are in the order of 10-4 or smaller, where the se-lectivity coefficient of lead(Ⅱ) over mercury(Ⅱ) ions is much lower, down to 8.9×10-4. The structure de-sign idea for high-performance ionophore is proposed according to present results. The incorporation of nitrogen atom, especially cyano group or thiocyano group or amino/imino groups, rather than thio atom alone could result in new excellent lead ionophores. The aborative design for metacyclophanes containing aromatic nitrogen atoms with the aim of creating excellent ionophores would also become a potential research trend. The lead(Ⅱ) ion

  14. Push-pull macrocycles: donor-acceptor compounds with paired linearly conjugated or cross-conjugated pathways.

    Leu, Wade C W; Fritz, Amanda E; Digianantonio, Katherine M; Hartley, C Scott


    Two-dimensional π-systems are of current interest in the design of functional organic molecules, exhibiting unique behavior for applications in organic electronics, single-molecule devices, and sensing. Here we describe the synthesis and characterization of "push-pull macrocycles": electron-rich and electron-poor moieties linked by a pair of (matched) conjugated bridges. We have developed a two-component macrocyclization strategy that allows these structures to be synthesized with efficiencies comparable to acyclic donor-bridge-acceptor systems. Compounds with both cross-conjugated (m-phenylene) and linearly conjugated (2,5-thiophene) bridges have been prepared. As expected, the compounds undergo excitation to locally excited states followed by fluorescence from charge-transfer states. The m-phenylene-based systems exhibit slower charge-recombination rates presumably due to reduced electronic coupling through the cross-conjugated bridges. Interestingly, pairing the linearly conjugated 2,5-thiophene bridges also slows charge recombination. DFT calculations of frontier molecular orbitals show that the direct HOMO-LUMO transition is polarized orthogonal to the axis of charge transfer for these symmetrical macrocyclic architectures, reducing the electronic coupling. We believe the push-pull macrocycle design may be useful in engineering functional frontier molecular orbital symmetries.

  15. Smart macrocyclic molecules: induced fit and ultrafast self-sorting inclusion behavior through dynamic covalent chemistry.

    Han, Ji-Min; Pan, Jin-Long; Lei, Ting; Liu, Chenjiang; Pei, Jian


    A family of macrocycles with oligo(ethylene glycol) chains, 4O, 5O, and 6O, was developed to construct a series of new incorporated macrocycles through dynamic covalent chemistry. These flexible macrocycles exhibited excellent "self-sorting" abilities with diamine compounds, which depended on the "induced-fit" rule. For instance, the host macrocycles underwent conformational modulation to accommodate the diamine guests, affording [1+1] intramolecular addition compounds regardless of the flexibility of the diamine. These macrocycles folded themselves to fit various diamines with different chain length through modulation of the flexible polyether chain, and afforded intramolecular condensation products. However, if the chain of the diamine was too long and rigid, oligomers or polymers were obtained from the mixture of the macromolecule and the diamine. All results demonstrated that inclusion compounds involving conformationally suitable aromatic diamines were thermodynamically favorable candidates in the mixture due to the restriction of the macrocycle size. Furthermore, kinetic and thermodynamic studies of self-sorting behaviors of both mixed 4O-5O and 4O-6O systems were investigated in detail. Finally, theoretical calculations were also employed to further understand such self-sorting behavior, and indicated that the large enthalpy change of H(2)NArArNH(2)@4O is the driving force for the sorting behavior. Our system may provide a model to further understand the principle of biomolecules with high specificity due only to their conformational self-adjusting ability.

  16. Tools for Chemical Biology: New Macrocyclic Compounds from Diversity-Oriented Synthesis and Toward Materials from Silver(I) Acetylides

    Madsen, Charlotte Marie

    Part I The formation of a library of diverse macrocyclic compounds with different functionalities and ring sizes in a few steps from two easily accessible α,ω-diol building blocks is presented. The building blocks are combined by esteriffcations in four different ways leading to the formation of ...... of uoro-iodoadamantanes. However, overall the results provide a good starting point for the synthesis of new triptycene and adamantane-containing molecules that can interact with carbon nanotubes....

  17. The role of macrocyclic compounds in the extraction and possible separation of platinum and rhodium from chloride solutions

    Jyothi, Rajesh Kumar; Lee, Jin-Young


    Macrocyclic compounds (crown ethers), specifically 18-crown-6 (18-C-6), benzo-15-crown-5 (B-15-C-5), di-benzo-18-crown-6 (DB-18-C-6) and di-cyclohexano-18-crown-6 (DC-18C-6), are used as extractants as well as synergists with amine-group extractants. Platinum and rhodium belong to platinum-group metals (PGMs) and have very similar ionic radii and similar properties. The separation of PGMs is most useful for the preparation of functional materials. Macrocyclic compounds are tested for platinum and rhodium separation and are found to achieve marginal separation. Amines (used as extractants) are paired with macrocyclic compounds (used as synergists), and the separation factor between platinum and rhodium is increased with synergistic enhancement from a chloride solution. The present study discusses extraction chemistry, separation factors and the synergy between platinum and rhodium from chloride solutions. To ensure accurate data, the aqueous samples in this study are analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES).

  18. Role of Modular Polyketide Synthases in the Production of Polyether Ladder Compounds in Ciguatoxin-producing Gambierdiscus polynesiensis and G.excentricus (Dinophyceae).

    Kohli, Gurjeet S; Campbell, Katrina; John, Uwe; Smith, Kirsty F; Fraga, Santiago; Rhodes, Lesley L; Murray, Shauna A


    Gambierdiscus, a benthic dinoflagellate, produces ciguatoxins that cause the human illness Ciguatera. Ciguatoxins are polyether ladder compounds that have a polyketide origin, indicating that polyketide synthases (PKS) are involved in their production. We sequenced transcriptomes of G. excentricus and G. polynesiensis and found 264 contigs encoding single domain ketoacyl synthases (KS; G. excentricus: 106, G. polynesiensis: 143) and ketoreductases (KR; G. excentricus: 7, G. polynesiensis: 8) with sequence similarity to type I PKSs, as reported in other dinoflagellates. Additionally, 24 contigs (G. excentricus: 3, G. polynesiensis: 21) encoding multiple PKS domains (forming typical type I PKSs modules) were found. The proposed structure produced by one of these megasynthases resembles a partial carbon backbone of a polyether ladder compound. Seventeen contigs encoding single domain KS, KR, s-malonyltransacylase, dehydratase and enoyl-reductase with sequence similarity to type II fatty acid synthases (FAS) in plants were found. Type I PKS and type II FAS genes were distinguished based on the arrangement of domains on the contigs and their sequence similarity and phylogenetic clustering with known PKS/FAS genes in other organisms. This differentiation of PKS and FAS pathways in Gambierdiscus is important, as it will facilitate approaches to investigating toxin biosynthesis pathways in dinoflagellates. This article is protected by copyright. All rights reserved.

  19. Luminescent macrocyclic lanthanide complexes

    Raymond, Kenneth N [Berkeley, CA; Corneillie, Todd M [Campbell, CA; Xu, Jide [Berkeley, CA


    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  20. Synthesis of azomethine macrocycles by condensation of dicarbonyl compounds with diamines without using metal ions as template agents

    Borisova, Natalia E; Reshetova, Marina D; Ustynyuk, Yuri A [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)


    Different strategies for the synthesis of symmetrical and unsymmetrical macrocyclic Schiff bases in the absence of metal ions are considered. General methods for performing macrocyclisation under thermodynamic or kinetic control are analysed. The key factors influencing the structure of macrocyclic azomethines are discussed.

  1. Synthesis of New Polyether Ether Ketone Derivatives with Silver Binding Site and Coordination Compounds of Their Monomers with Different Silver Salts

    Jérôme Girard


    Full Text Available Polyether ether ketone (PEEK is a well-known polymer used for implants and devices, especially spinal ones. To overcome the biomaterial related infection risks, 4-4′-difluorobenzophenone, the famous PEEK monomer, was modified in order to introduce binding sites for silver ions, which are well known for their antimicrobial activity. The complexation of these new monomers with different silver salts was studied. Crystal structures of different intermediates were obtained with a linear coordination between two pyridine groups and the silver ions in all cases. The mechanical and thermal properties of different new polymers were characterized. The synthesized PEEKN5 polymers showed similar properties than the PEEK ones whereas the PEEKN7 polymers showed similar thermal properties but the mechanical properties are not as good as the ones of PEEK. To improve these properties, these polymers were complexed with silver nitrate in order to “cross-link” with silver ions. The presence of ionic silver in the polymer was then confirmed by thermogravimetric analysis (TGA and X-ray powder diffraction (XRPD. Finally, a silver-based antimicrobial compound was successfully coated on the surface of PEEKN5.

  2. Efficient removal of uranium from mice by a novel compound of fullerence multi-macrocyclic polyamine derivatives

    刘晓青; 杨吉军; 唐军; 刘宁; 杨远友; 廖家莉; 欧巍; 孔芳; 兰静波; 罗顺忠; 刘国平; 何佳恒


    Uranium removal efficacy of fullerence multi-macrocyclic polyamine derivatives (C60-MMP), a novel chelat-ing agent, was evaluated in mice. C60-MMP was administrated intravenously into mice at 30 min after the uranium contamination. The molar ratio of chelating ligand/uranium was about 1:1. The results indicate that C60-MMP can effectively prevent accumulation of uranium in liver at 8 h after C60-MMP injection. At 48 h af-ter the last injection, uranium deposition in liver of C60-MMP treated mice is approximately 65%less than that of the control group. C60-MMP reacted positively in promoting the removal of uranium from kidney, and the urinary uranium excretion increased significantly, compared with the control and DTPA-treated mice. However, repeated administration of C60-MMP, and combined injection of DTPA and C60-MMP, did not show desirable effects on uranium removal from mice. It implies that more investigations are needed for the treatment protocols and clinical applications of C60-MMP.

  3. Structures and Properties of Naturally Occurring Polyether Antibiotics

    Jacek Rutkowski


    Full Text Available Polyether ionophores represent a large group of natural, biologically active substances produced by Streptomyces spp. They are lipid soluble and able to transport metal cations across cell membranes. Several of polyether ionophores are widely used as growth promoters in veterinary. Polyether antibiotics show a broad spectrum of bioactivity ranging from antibacterial, antifungal, antiparasitic, antiviral, and tumour cell cytotoxicity. Recently, it has been shown that some of these compounds are able to selectively kill cancer stem cells and multidrug-resistant cancer cells. Thus, they are recognized as new potential anticancer drugs. The biological activity of polyether ionophores is strictly connected with their molecular structure; therefore, the purpose of this paper is to present an overview of their formula, molecular structure, and properties.

  4. Hydrolysis of p-Nitrophenyl Picolinate Catalyzed by Mono-and Binuclear Transition Metal Complexes with Polyether Bridged Dihydroxamic Acid

    李建章; 李鸿波; 冯发美; 谢家庆; 李慎新; 周波; 秦圣英


    Two polyether bridged dihydroxamic acids and their mono-and binuclear manganese(Ⅱ), zinc(Ⅱ) complexes have been synthesized and employed as models to mimic hydrolase in catalytic hydrolysis of p-nitrophenyl picolinate (PNPP). The reaction kinetics and the mechanism of hydrolysis of PNPP have been investigated. The kinetic mathematical model for PNPP cleaved by the complexes has been proposed. The effects of the different central metal ion, mono-and binuclear metal, the pseudo-macrocyclic polyether constructed by polyethoxy group of the complexes, and reactive temperature on the rate for catalytic hydrolysis of PNPP have been examined. The results showed that the transition metal dthydroxamates exhibited high catalytic activity to the hydrolysis of PNPP, the catalytic activity of binuclear complexes was higher than that of mononuclear ones, and the pseudo-macrocyclic polyether might synergetically activate H20 coordinated to metal ion with central metal ion together and promote the catalytic hydrolysis of PNPP.

  5. Engineering macrocyclic figure-eight motif

    V Haridas; Harinder Singh; Yogesh K Sharma; Kashmiri Lal


    The design and synthesis of figure-eight macrocycles are very scarce owing to the intricacies and lack of predictability from first principles. This review emphasizes on discrete macrocyclic systems both synthetic and natural with a defined figure eight knotted topology. In almost all the helical macrocycles, the helical arrangement is held by intramolecular hydrogen bonding or as a backbone requirement, but in all cases, a planar graph can be drawn and so these compounds are trivial from the topological stand point. Nature presents great deal of complexity in terms of structures in macromolecules like DNA and proteins and also displays intriguing topology in simple natural products. Patellamide, tawicyclamides, nosiheptide and thiostrepton are natural products with figure eight topology which shows interesting biological activity. Expanded porphyrins, Cu(II) complexes of thiomacrocycles, cyclic peptides and oligoesters are synthetic macrocycles showing intriguing topology. Analysis of structure and folding behaviour will enable chemists to design molecules with intriguing topology.

  6. Organotin Polyethers as Biomaterials

    Michael R. Roner


    Full Text Available Organotin polyethers are easily synthesized employing interfacial polymerization systems involving the reaction of hydroxyl-containing Lewis bases and organotin halides. A wide variety of organotin-containing polymeric products have been synthesized including those derived from natural and synthetic polymers such as lignin, xylan, cellulose, dextran, and poly(vinyl alcohol. Others have been synthesized employing known drug diols such as dicumarol, DES, and dienestrol and a wide variety of synthetic diols. Included in these materials are the first water soluble organotin polymers. The organotin polyethers exhibit a wide range of biological activities. Some selectively inhibit a number of unwanted bacteria, including Staph. MRSA, and unwanted yeasts such as Candida albicans. Some also inhibit a variety of viruses including those responsible for herpes infections and smallpox. Others show good inhibition of a wide variety of cancer cell lines including cell lines associated with ovarian, colon, lung, prostrate, pancreatic and breast cancer. The synthesis, structural characterization, and biological characterization of these materials is described in this review.

  7. Synthesis of macrocyclic polyazomethines

    Elizbarashvili,Elizbar; Matitaishvili,Tea; Topuria,Khatuna


    The synthesis of 20-membered macrocyclic polyazomethine dyes 3a and 3b from 4,4'-dihydroxybiphenyl-3,3'-dicarbaldehyde (2a) and 5,5'-diamino-4,4'-dihydroxybiphenyl-3,3'-dicarbaldehyde (2b) and macrocyclic polyazomethine pigments 4 and 5 from 3a is described.

  8. Synthesis of New Macrocyclic Polyamides as Antimicrobial Agent Candidates

    Osama I. Abd El-Salam


    Full Text Available A series of macrocyclic imides and Schiff-bases have been prepared via the cyclocondensation of pyridine-2,6-dicarbonyl dichloride (1 with L-ornithine methyl ester to give the corresponding macrocyclic bisester 2. Treatment of 2 with hydrazine hydrate gave macrocyclic bisacid hydrazide 3, which was used as starting material. Condensation of bishydrazide 3 with diacid anhydrides or aromatic aldehydes in refluxing acetic acid or ethanol gave the corresponding macrocyclic bisimides 4, 5a,b and macrocyclic bis- hydrazones 6a–j, respectively. The structure assignments of the new compounds were based on chemical and spectroscopic evidence. The antimicrobial screening showed that many of these newly synthesized compounds have good antimicrobial activities, comparable to ampicillin and ketaconazole used as reference drugs.

  9. Polyether-polyester graft copolymer

    Bell, Vernon L. (Inventor)


    Described is a polyether graft polymer having improved solvent resistance and crystalline thermally reversible crosslinks. The copolymer is prepared by a novel process of anionic copolymerization. These polymers exhibit good solvent resistance and are well suited for aircraft parts. Previous aromatic polyethers, also known as polyphenylene oxides, have certain deficiencies which detract from their usefulness. These commercial polymers are often soluble in common solvents including the halocarbon and aromatic hydrocarbon types of paint thinners and removers. This limitation prevents the use of these polyethers in structural articles requiring frequent painting. In addition, the most popular commercially available polyether is a very high melting plastic. This makes it considerably more difficult to fabricate finished parts from this material. These problems are solved by providing an aromatic polyether graft copolymer with improved solvent resistance and crystalline thermally reversible crosslinks. The graft copolymer is formed by converting the carboxyl groups of a carboxylated polyphenylene oxide polymer to ionic carbonyl groups in a suitable solvent, reacting pivalolactone with the dissolved polymer, and adding acid to the solution to produce the graft copolymer.

  10. Synthesis of novel symmetrical macrocycle via oxidative homocoupling of bisalkyne

    Kamalulazmy, Nurulain; Hassan, Nurul Izzaty [School of Chemical Sciences and Food Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan (Malaysia)


    A novel symmetrical macrocycle has been synthesised via oxidative homocoupling of bisalkyne, diprop-2-ynyl pyridine-2,6-dicarboxylate mediated by copper (I) iodide (CuI) and 4-dimethylaminopyridine (DMAP). The precursor compound was synthesised from 2,6-pyridine dicarbonyl dichloride and propargyl alcohol in the presence of triethylamine. The reaction mixture was stirred overnight and further purified via column chromatograpy with 76% yield. Single crystal for X-ray study was obtained by recrystallization from acetone. Subsequently, a symmetrical macrocycle was synthesised from oxidative homocoupling of precursor compound in open atmosphere. The crude product was purified by column chromatography to furnish macrocycle compound with 5% yield. Both compounds were characterised by IR, {sup 1}H and {sup 13}C NMR and mass spectral techniques. The unusual conformation of the bisalkyne and twisted conformation of designed macrocycle has influence the percentage yield. This has been studied thoroughly by X-ray crystallography and electronic structure calculations.

  11. Predicting bioactive conformations and binding modes of macrocycles

    Anighoro, Andrew; de la Vega de León, Antonio; Bajorath, Jürgen


    Macrocyclic compounds experience increasing interest in drug discovery. It is often thought that these large and chemically complex molecules provide promising candidates to address difficult targets and interfere with protein-protein interactions. From a computational viewpoint, these molecules are difficult to treat. For example, flexible docking of macrocyclic compounds is hindered by the limited ability of current docking approaches to optimize conformations of extended ring systems for pose prediction. Herein, we report predictions of bioactive conformations of macrocycles using conformational search and binding modes using docking. Conformational ensembles generated using specialized search technique of about 70 % of the tested macrocycles contained accurate bioactive conformations. However, these conformations were difficult to identify on the basis of conformational energies. Moreover, docking calculations with limited ligand flexibility starting from individual low energy conformations rarely yielded highly accurate binding modes. In about 40 % of the test cases, binding modes were approximated with reasonable accuracy. However, when conformational ensembles were subjected to rigid body docking, an increase in meaningful binding mode predictions to more than 50 % of the test cases was observed. Electrostatic effects did not contribute to these predictions in a positive or negative manner. Rather, achieving shape complementarity at macrocycle-target interfaces was a decisive factor. In summary, a combined computational protocol using pre-computed conformational ensembles of macrocycles as a starting point for docking shows promise in modeling binding modes of macrocyclic compounds.

  12. Tunable, antibacterial activity of silicone polyether surfactants.

    Khan, Madiha F; Zepeda-Velazquez, Laura; Brook, Michael A


    Silicone surfactants are used in a variety of applications, however, limited data is available on the relationship between surfactant structure and biological activity. A series of seven nonionic, silicone polyether surfactants with known structures was tested for in vitro antibacterial activity against Escherichia coli BL21. The compounds varied in their hydrophobic head, comprised of branched silicone structures with 3-10 siloxane linkages and, in two cases, phenyl substitution, and hydrophilic tail of 8-44 poly(ethylene glycol) units. The surfactants were tested at three concentrations: below, at, and above their Critical Micelle Concentrations (CMC) against 5 concentrations of E. coli BL21 in a three-step assay comprised of a 14-24h turbidometric screen, a live-dead stain and viable colony counts. The bacterial concentration had little effect on antibacterial activity. For most of the surfactants, antibacterial activity was higher at concentrations above the CMC. Surfactants with smaller silicone head groups had as much as 4 times the bioactivity of surfactants with larger groups, with the smallest hydrophobe exhibiting potency equivalent to sodium dodecyl sulfate (SDS). Smaller PEG chains were similarly associated with higher potency. These data link lower micelle stability and enhanced permeability of smaller silicone head groups to antibacterial activity. The results demonstrate that simple manipulation of nonionic silicone polyether structure leads to significant changes in antibacterial activity.

  13. Ion-polyether coordination complexes: crystalline ionic conductors for clean energy storage.

    Bruce, Peter G


    Ion-polyether complexes are the solid state analogues of crown ether and cryptand complexes. They represent a fascinating class of coordination compounds in their own right, with the ability to support ionic conductivity and the potential to be used as electrolytes in all-solid-state rechargeable lithium batteries. Here the recent discovery of ionic conductivity in crystalline ion-polyether complexes, when for 30 years such materials were considered to be insulators, is described, along with their closely related structural chemistry.

  14. Observations on the Influence of Precursor Conformations on Macrocyclization Reactions

    Hammershøj, Peter; Beldring, Klavs; Nielsen, Anders R.;


    Macrocycles hold great promise in drug discovery as an underutilized class of lead compounds. The low abundance of these molecules can, in part, be explained by the inherent difficulties in the synthesis of macrocycles and the lack of general methods for their rapid assembly. We have undertaken...... a research program aimed at developing methods for facile synthesis of macrocycles from simple precursors. The synthesis of two new cyclization precursors is described and the results of their reaction with thionyl chloride are presented and discussed. Whereas one acyclic diol smoothly underwent...

  15. Polyether ionophores: broad-spectrum and promising biologically active molecules for the control of drug-resistant bacteria and parasites

    Kevin, Dion A; Meujo, Damaris AF; Hamann, Mark T


    Background As multidrug-resistant (MDR) pathogens continue to emerge, there is a substantial amount of pressure to identify new drug candidates. Carboxyl polyethers, also referred to as polyether antibiotics, are a unique class of compounds with outstanding potency against a variety of critical infectious disease targets including protozoa, bacteria and viruses. The characteristics of these molecules that are of key interest are their selectivity and high potency against several MDR etiological agents. Objective Although many studies have been published about carboxyl polyether antibiotics, there are no recent reviews of this class of drugs. The purpose of this review is to provide the reader with an overview of the spectrum of activity of polyether antibiotics, their mechanism of action, toxicity and potential as drug candidates to combat drug-resistant infectious diseases. Conclusion Polyether ionophores show a high degree of promise for the potential control of drug-resistant bacterial and parasitic infections. Despite the long history of use of this class of drugs, very limited medicinal chemistry and drug optimization studies have been reported, thus leaving the door open to these opportunities in the future. Scifinder and PubMed were the main search engines used to locate articles relevant to the topic presented in the present review. Keywords used in our search were specific names of each of the 88 compounds presented in the review as well as more general terms such as polyethers, ionophores, carboxylic polyethers and polyether antibiotics. PMID:23480512

  16. Polyethism in a colony of artificial ants

    Marriott, Chris


    We explore self-organizing strategies for role assignment in a foraging task carried out by a colony of artificial agents. Our strategies are inspired by various mechanisms of division of labor (polyethism) observed in eusocial insects like ants, termites, or bees. Specifically we instantiate models of caste polyethism and age or temporal polyethism to evaluated the benefits to foraging in a dynamic environment. Our experiment is directly related to the exploration/exploitation trade of in machine learning.

  17. Structural basis for precursor protein-directed ribosomal peptide macrocyclization

    Li, Kunhua; Condurso, Heather L.; Li, Gengnan; Ding, Yousong; Bruner, Steven D. (Florida)


    Macrocyclization is a common feature of natural product biosynthetic pathways including the diverse family of ribosomal peptides. Microviridins are architecturally complex cyanobacterial ribosomal peptides that target proteases with potent reversible inhibition. The product structure is constructed via three macrocyclizations catalyzed sequentially by two members of the ATP-grasp family, a unique strategy for ribosomal peptide macrocyclization. Here we describe in detail the structural basis for the enzyme-catalyzed macrocyclizations in the microviridin J pathway of Microcystis aeruginosa. The macrocyclases MdnC and MdnB interact with a conserved α-helix of the precursor peptide using a novel precursor-peptide recognition mechanism. The results provide insight into the unique protein–protein interactions that are key to the chemistry, suggest an origin for the natural combinatorial synthesis of microviridin peptides, and provide a framework for future engineering efforts to generate designed compounds.

  18. Macrocyclic 2,7-Anthrylene Oligomers.

    Yamamoto, Yuta; Wakamatsu, Kan; Iwanaga, Tetsuo; Sato, Hiroyasu; Toyota, Shinji


    A macrocyclic compound consisting of six 2,7-anthrylene units was successfully synthesized by Ni-mediated coupling of the corresponding dibromo precursor as a novel π-conjugated compound. This compound was sufficiently stable and soluble in organic solvents due to the presence of mesityl groups. X-ray analysis showed that the molecule had a nonplanar and hexagonal wheel-shaped framework of approximately S6 symmetry. The dynamic process between two S6 structures was observed by using the dynamic NMR technique, the barrier being 58 kJ mol(-1) . The spectroscopic properties of the hexamer were compared with those of analogous linear oligomers.

  19. A diversity-oriented synthesis strategy enabling the combinatorial-type variation of macrocyclic peptidomimetic scaffolds.

    Isidro-Llobet, Albert; Hadje Georgiou, Kathy; Galloway, Warren R J D; Giacomini, Elisa; Hansen, Mette R; Méndez-Abt, Gabriela; Tan, Yaw Sing; Carro, Laura; Sore, Hannah F; Spring, David R


    Macrocyclic peptidomimetics are associated with a broad range of biological activities. However, despite such potentially valuable properties, the macrocyclic peptidomimetic structural class is generally considered as being poorly explored within drug discovery. This has been attributed to the lack of general methods for producing collections of macrocyclic peptidomimetics with high levels of structural, and thus shape, diversity. In particular, there is a lack of scaffold diversity in current macrocyclic peptidomimetic libraries; indeed, the efficient construction of diverse molecular scaffolds presents a formidable general challenge to the synthetic chemist. Herein we describe a new, advanced strategy for the diversity-oriented synthesis (DOS) of macrocyclic peptidomimetics that enables the combinatorial variation of molecular scaffolds (core macrocyclic ring architectures). The generality and robustness of this DOS strategy is demonstrated by the step-efficient synthesis of a structurally diverse library of over 200 macrocyclic peptidomimetic compounds, each based around a distinct molecular scaffold and isolated in milligram quantities, from readily available building-blocks. To the best of our knowledge this represents an unprecedented level of scaffold diversity in a synthetically derived library of macrocyclic peptidomimetics. Cheminformatic analysis indicated that the library compounds access regions of chemical space that are distinct from those addressed by top-selling brand-name drugs and macrocyclic natural products, illustrating the value of our DOS approach to sample regions of chemical space underexploited in current drug discovery efforts. An analysis of three-dimensional molecular shapes illustrated that the DOS library has a relatively high level of shape diversity.

  20. Fixation of carbon dioxide by macrocyclic lanthanide(III) complexes under neutral conditions producing self-assembled trimeric carbonato-bridged compounds with μ3-η2:η2:η2 bonding.

    Bag, Pradip; Dutta, Supriya; Biswas, Papu; Maji, Swarup Kumar; Flörke, Ulrich; Nag, Kamalaksha


    A series of mononuclear lanthanide(III) complexes [Ln(LH(2))(H(2)O)(3)Cl](ClO(4))(2) (Ln = La, Nd, Sm, Eu, Gd, Tb, Lu) of the tetraiminodiphenolate macrocyclic ligand (LH(2)) in 95 : 5 (v/v) methanol-water solution fix atmospheric carbon dioxide to produce the carbonato-bridged trinuclear complexes [{Ln(LH(2))(H(2)O)Cl}(3)(μ(3)-CO(3))](ClO(4))(4)·nH(2)O. Under similar conditions, the mononuclear Y(III) complex forms the dimeric compound [{Y(LH(2))(H(2)O)Cl}(μ(2)-CO(3)){Y(LH(2))(H(2)O)(2)}](ClO(4))(3)·4H(2)O. These complexes have been characterized by their IR and NMR ((1)H, (13)C) spectra. The X-ray crystal structures have been determined for the trinuclear carbonato-bridged compounds of Nd(III), Gd(III) and Tb(III) and the dinuclear compound of Y(III). In all cases, each of the metal centers are 8-coordinate involving two imine nitrogens and two phenolate oxygens of the macrocyclic ligand (LH(2)) whose two other imines are protonated and intramolecularly hydrogen-bonded with the phenolate oxygens. The oxygen atoms of the carbonate anion in the trinuclear complexes are bonded to the metal ions in tris-bidentate μ(3)-η(2):η(2):η(2) fashion, while they are in bis-bidentate μ(2)-η(2):η(2) mode in the Y(III) complex. The magnetic properties of the Gd(III) complex have been studied over the temperature range 2 to 300 K and the magnetic susceptibility data indicate a very weak antiferromagnetic exchange interaction (J = -0.042 cm(-1)) between the Gd(III) centers (S = 7/2) in the metal triangle through the carbonate bridge. The luminescence spectral behaviors of the complexes of Sm(III), Eu(III), and Tb(III) have been studied. The ligand LH(2) acts as a sensitizer for the metal ions in an acetonitrile-toluene glassy matrix (at 77 K) and luminescence intensities of the complexes decrease in the order Eu(3+) > Sm(3+) > Tb(3+).

  1. Rules of Macrocycle Topology: A [13]-Macrodilactone Case Study.

    Magpusao, Anniefer N; Rutledge, Kelli; Hamlin, Trevor A; Lawrence, Jean-Marc; Mercado, Brandon Q; Leadbeater, Nicholas E; Peczuh, Mark W


    Shape is an inherent trait of a molecule that dictates how it interacts with other molecules, either in binding events or intermolecular reactions. Large-ring macrocyclic compounds in particular leverage their shape when they are selectively bound by biomolecules and also when they exhibit macrocyclic diastereoselectivity. Nonetheless, rules that link structural parameters to the conformation of a macrocycle are still rudimentary. Here we use a structural investigation of a family of [13]-macrodilactones as a case study to develop rules that can be applied generally to macrocycles of different sizes and with a variety of functionality. A characteristic "ribbon" shape is adopted by the [13]-macrodilactones in the absence of stereogenic centres, which exhibits planar chirality. When one stereogenic centre at key positions on the backbone is incorporated into the structure, the planar chirality is dictated by the configuration of the centre. In cases where two stereogenic centres are present, their relationships can either reinforce the characteristic ribbon shape or induce alternative shapes to be adopted. The rules established in the case study are then applied to the analysis of a structure of the natural product migrastatin. They lay the groundwork for the development of models to understand macrocycle-biomolecule interactions and for the preparation of macrocycles with designed properties and activities.

  2. Anticancer Activity of Polyether Ionophore-Salinomycin.

    Antoszczak, Michał; Huczyński, Adam


    Since the discovery of unusual anti-tumor activity of natural polyether antibiotic - Salinomycin, this compound, along with its derivatives, has been intensively studied against different human cancer cells, both in vivo and in vitro. Salinomycin has shown strong inhibition activity against the proliferation process of many different cancer cells, including multi-drug resistance (MDR) cancer cells, as well as cancer stem cells (CSCs), i.e. leukemic stem cells, colon carcinoma stem cells, prostate cancer stem cells and many others. Additionally, the application of Salinomycin has been proved to enhance the anti-cancer effect of radio- and chemotherapy. Preliminary clinical studies have shown tumor regression and only transient acute side effects after application of Salinomycin. Up to now, major efforts have been devoted to elucidate the biological mechanisms of anti-tumor activity of Salinomycin and it is expected that the results may provide new therapeutic strategies based on biological modulation of Salinomycin activity. This review is focused on and describes the possible role of Salinomycin in cancer therapy and gives an overview of its properties.

  3. Organic spin clusters: macrocyclic-macrocyclic polyarylmethyl polyradicals with very high spin S = 5-13.

    Rajca, Andrzej; Wongsriratanakul, Jirawat; Rajca, Suchada


    Synthesis and magnetic studies of a new class of organic spin clusters, possessing alternating connectivity of unequal spins, are described. Polyarylmethyl polyether precursors to the spin clusters, with linear and branched connectivity between calix[4]arene-based macrocycles, are prepared via modular, multistep syntheses. Their molecular connectivity and stereoisomerism are analyzed using NMR spectroscopy. The absolute masses (4-10 kDa) are determined by FABMS and GPC/MALS. Small angle neutron scattering (SANS) provides the radii of gyration of 1.2-1.8 nm. The corresponding polyradicals with 15, 22, and 36 triarylmethyls, which are prepared and studied as solutions in tetrahydrofuran-d(8), may be described as S' = 7/2, 1/2, 7/2 spin trimer (average S = 5-6), S' = 7/2, 1/2, 6/2, 1/2, 7/2 spin pentamer (average S = 7-9), and spin nonamer (average S = 11-13), respectively, as determined by SQUID magnetometry and numerical fits to linear combinations of the Brillouin functions. For spin trimer and pentamer, the quantitative magnetization data are fit to new percolation models, based upon random distributions of chemical defects and ferromagnetic vs antiferromagnetic couplings. The value of S = 13 is the highest for an organic molecule.

  4. The mechanism of patellamide macrocyclization revealed by the characterization of the PatG macrocyclase domain.

    Koehnke, Jesko; Bent, Andrew; Houssen, Wael E; Zollman, David; Morawitz, Falk; Shirran, Sally; Vendome, Jeremie; Nneoyiegbe, Ada F; Trembleau, Laurent; Botting, Catherine H; Smith, Margaret C M; Jaspars, Marcel; Naismith, James H


    Peptide macrocycles are found in many biologically active natural products. Their versatility, resistance to proteolysis and ability to traverse membranes has made them desirable molecules. Although technologies exist to synthesize such compounds, the full extent of diversity found among natural macrocycles has yet to be achieved synthetically. Cyanobactins are ribosomal peptide macrocycles encompassing an extraordinarily diverse range of ring sizes, amino acids and chemical modifications. We report the structure, biochemical characterization and initial engineering of the PatG macrocyclase domain of Prochloron sp. from the patellamide pathway that catalyzes the macrocyclization of linear peptides. The enzyme contains insertions in the subtilisin fold to allow it to recognize a three-residue signature, bind substrate in a preorganized and unusual conformation, shield an acyl-enzyme intermediate from water and catalyze peptide bond formation. The ability to macrocyclize a broad range of nonactivated substrates has wide biotechnology applications.

  5. The mechanism of patellamide macrocyclization revealed by the characterization of the PatG macrocyclase domain

    Koehnke, Jesko; Bent, Andrew; Houssen, Wael E; Zollman, David; Morawitz, Falk; Shirran, Sally; Vendome, Jeremie; Nneoyiegbe, Ada F; Trembleau, Laurent; Botting, Catherine H; Smith, Margaret C M; Jaspars, Marcel; Naismith, James H


    Peptide macrocycles are found in many biologically active natural products. Their versatility, resistance to proteolysis and ability to traverse membranes has made them desirable molecules. Although technologies exist to synthesize such compounds, the full extent of diversity found among natural macrocycles has yet to be achieved synthetically. Cyanobactins are ribosomal peptide macrocycles encompassing an extraordinarily diverse range of ring sizes, amino acids and chemical modifications. We report the structure, biochemical characterization and initial engineering of the PatG macrocyclase domain of Prochloron sp. from the patellamide pathway that catalyzes the macrocyclization of linear peptides. The enzyme contains insertions in the subtilisin fold to allow it to recognize a three-residue signature, bind substrate in a preorganized and unusual conformation, shield an acyl-enzyme intermediate from water and catalyze peptide bond formation. The ability to macrocyclize a broad range of nonactivated substrates has wide biotechnology applications. PMID:22796963

  6. The posttranslational modification cascade to the thiopeptide berninamycin generates linear forms and altered macrocyclic scaffolds.

    Malcolmson, Steven J; Young, Travis S; Ruby, J Graham; Skewes-Cox, Peter; Walsh, Christopher T


    Berninamycin is a member of the pyridine-containing thiopeptide class of antibiotics that undergoes massive posttranslational modifications from ribosomally generated preproteins. Berninamycin has a 2-oxazolyl-3-thiazolyl-pyridine core embedded in a 35-atom macrocycle rather than typical trithiazolylpyridine cores embedded in 26-atom and 29-atom peptide macrocycles. We describe the cloning of an 11-gene berninamycin cluster from Streptomyces bernensis UC 5144, its heterologous expression in Streptomyces lividans TK24 and Streptomyces venezuelae ATCC 10712, and detection of variant and incompletely processed scaffolds. Posttranslational maturation in S. lividans of both the wild-type berninamycin prepeptide (BerA) and also a T3A mutant generates macrocyclic compounds as well as linear variants, which have failed to form the pyridine and the macrocycle. Expression of the gene cluster in S. venezuelae generates a variant of the 35-atom skeleton of berninamycin, containing a methyloxazoline in the place of a methyloxazole within the macrocyclic framework.

  7. Supramolecular networking of macrocycles based on exo-coordination: from discrete to continuous frameworks.

    Park, Sunhong; Lee, So Young; Park, Ki-Min; Lee, Shim Sung


    Macrocyclic ligands typically show high selectivity for specific metal ions and small molecules, and these features make such molecules attractive candidates for nanoscale chemical sensing applications. Crown ethers are macrocyclic structures with polyether linkages where the oxygen donors are often separated by an ethylene unit (-O-CH(2)-CH(2)-O-). Because the oxygen lone pairs in crown-type macrocycles are directed inward, the preorganized macrocyclic cavity tends to form complexes where metals coordinate inside the cavity (endo-coordination). However, sulfur-containing macrocycles often demonstrate metal coordination outside of the cavity (exo-coordination). This coordination behavior results from the different torsion arrangements adopted by the X-CH(2)-CH(2)-X atom sequence (X = O, gauche; X = S, anti) in these molecules. Exo-coordination is synthetically attractive because it would provide a means of connecting macrocyclic building blocks in diverse arrangements. In fact, exo-coordination could allow the construction of more elaborate network assemblies than are possible using conventional endocyclic coordination (which gives metal-in-cavity products). Exo-coordination can also serve as a tool for crystal engineering through the use of diverse controlling factors. Although challenges remain in the development of exo-coordination-based synthetic approaches and, in particular, for the architectural control of supramolecular coordination platforms, we have established several strategies for the rational synthesis of new metallosupramolecules. In this Account, we describe our recent studies of the assembly of metallosupramolecules and coordination polymers based on sulfur-containing macrocycles that employ simple and versatile exo-coordination procedures. Initially, we focus on the unusual topological products such as sandwich (1:2, metal-to-ligand), club sandwich (2:3), and cyclic oligomeric complexes as discrete network systems. The primary structures we

  8. 40 CFR 721.7500 - Nitrate polyether polyol (generic name).


    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Nitrate polyether polyol (generic name... Substances § 721.7500 Nitrate polyether polyol (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance nitrate polyether polyol (PMN P88-2540)...

  9. Late First-Row Transition-Metal Complexes Containing a 2-Pyridylmethyl Pendant-Armed 15-Membered Macrocyclic Ligand. Field-Induced Slow Magnetic Relaxation in a Seven-Coordinate Cobalt(II) Compound.

    Antal, Peter; Drahoš, Bohuslav; Herchel, Radovan; Trávníček, Zdeněk


    The 2-pyridylmethyl N-pendant-armed heptadentate macrocyclic ligand {3,12-bis(2-methylpyridine)-3,12,18-triaza-6,9-dioxabicyclo[12.3.1]octadeca-1,14,16-triene = L} and [M(L)](ClO4)2 complexes, where M = Mn(II) (1), Fe(II) (2), Co(II) (3), Ni(II) (4), and Cu(II) (5), were prepared and thoroughly characterized, including elucidation of X-ray structures of all the compounds studied. The complexes 1-5 crystallize in non-centrosymmetric Sohncke space groups as racemic compounds. The coordination numbers of 7, 6 + 1, and 5 were found in complexes 1-3, 4, and 5, respectively, with a distorted pentagonal bipyramidal (1-4) or square pyramidal (5) geometry. On the basis of the magnetic susceptibility experiments, a large axial zero-field splitting (ZFS) was found for 2, 3, and 4 (D(Fe) = -7.4(2) cm(-1), D(Co) = 34(1) cm(-1), and D(Ni) = -12.8(1) cm(-1), respectively) together with a rhombic ZFS (E/D = 0.136(3)) for 4. Despite the easy plane anisotropy (D > 0, E/D = 0) in 3, the slow relaxation of the magnetization below 8 K was observed and analyzed either with Orbach relaxation mechanism (the relaxation time τ0 = 9.90 × 10(-10) s and spin reversal barrier Ueff = 24.3 K (16.9 cm(-1))) or with Raman relaxation mechanism (C = 2.12 × 10(-5) and n = 2.84). Therefore, compound 3 enlarges the small family of field-induced single-molecule magnets with pentagonal-bipyramidal chromophore. The cyclic voltammetry in acetonitrile revealed reversible redox processes in 1-3 and 5, except for the Ni(II) complex 4, where a quasi-reversible process was dominantly observed. Presence of the two 2-pyridylmethyl pendant arms in L with a stronger σ-donor/π-acceptor ability had a great impact on the properties of all the complexes (1-5), concretely: (i) strong pyridine-metal bonds provided slight axial compression of the coordination sphere, (ii) substantial changes in magnetic anisotropy, and (iii) stabilization of lower oxidation states.


    YU Yunchao; LI Yiming


    Carboxyl terminated polyethers, the adducts of hydroxyl terminated polytetrahydrofuran and maleic anhydride, were used as toughener for epoxy resins. The morphology of the toughened resins was investigated by means of turbidity measurement, dynamic mechanical testing and scanning electron microscope observation. It turned out that the molecular weight and the carboxyl content of the polyether and the cure conditions are important factors, which affect the particle size of the polyether-rich domains and, in turn, the mechanical properties of the cured resin. Carboxyl terminated polytetrahydrofurans have a low glass transition temperature, and in appropriate amount they do not affect the thermal resistance of the resin. These advantages make them preferable as toughener for epoxy resins.

  11. Synthesis of arylenealkyne conjugated macrocycles containing a long alkylene bridge

    Xiaohong CHENG; Sigurd HOEGER


    The synthesis of the first two arylenealkyne conjugated macrocycles containing a long alkylene bridge via Glaser coupling of template-directed tetra-acetylenes was reported. Tetraacetylene intermediates with complex structures were constructed rapidly via quadruple Hagihara coupling of monoprotected bisace-tylenes to appropriate tetraiodides and subsequent desilylation. The characterization of such compounds was carried out by NMR, GPC and UV-Vis spectra. Unfortunately, the two compounds were not liquid crystals and had no biaxial nematic mesophase character as expected,

  12. Polyether matrices for lithium generators; Matrices polyethers pour generateurs au lithium

    Alloin, F.; Sanchez, J.Y. [Laboratoire d`Electrochimie et de Physicochimie des Materiaux et des Interfaces, 38 - Saint-Martin-d`Heres (France)


    The use of solvating polymers of polyether type is an interesting solution for the manufacturing of high capacity lithium batteries with lithium metal anodes and which can operate at T > 50 deg. C. These operating conditions are perfectly compatible with electric-powered vehicle and stationary battery applications. In order to improve the ionic conductivity of polymer electrolytes, new aprotic and amorphous polyether lattices have been synthesized having a good conductivity but also good thermal, mechanical and electrochemical stabilities. Two type of 3-D polyether lattices obtained by reticulation of linear pre-polymers have been selected as host polymers: unsaturated poly-condensate and unsaturated co-polyethers. (J.S.) 18 refs.

  13. Assembly of macrocycles by zirconocene-mediated, reversible carbon-carbon bond formation.

    Gessner, Viktoria H; Tannaci, John F; Miller, Adam D; Tilley, T Don


    Macrocyclic compounds have attracted considerable attention in numerous applications, including host-guest chemistry, chemical sensing, catalysis, and materials science. A major obstacle, however, is the limited number of convenient, versatile, and high-yielding synthetic routes to functionalized macrocycles. Macrocyclic compounds have been typically synthesized by ring-closing or condensation reactions, but many of these procedures produce mixtures of oligomers and cyclic compounds. As a result, macrocycle syntheses are often associated with difficult separations and low yields. Some successful approaches that circumvent these problems are based on "self-assembly" processes utilizing reversible bond-forming reactions, but for many applications, it is essential that the resulting macrocycle be built with a strong covalent bond network. In this Account, we describe how zirconocene-mediated reductive couplings of alkynes can provide reversible carbon-carbon bond-forming reactions well-suited for this purpose. Zirconocene coupling of alkenes and alkynes has been used extensively as a source of novel, versatile pathways to functionalized organic compounds. Here, we describe the development of zirconocene-mediated reductive couplings as a highly efficient method for the preparation of macrocycles and cages with diverse compositions, sizes, and shapes. This methodology is based on the reversible, regioselective coupling of alkynes with bulky substituents. In particular, silyl substituents provide regioselective, reversible couplings that place them into the α-positions of the resulting zirconacyclopentadiene rings. According to density functional theory (DFT) calculations and kinetic studies, the mechanism of this coupling involves a stepwise process, whereby an insertion of the second alkyne influences regiochemistry through both steric and electronic factors. Zirconocene coupling of diynes that incorporate silyl substituents generates predictable macrocyclic products

  14. Effects of poly-ether B on proteome and phosphoproteome expression in biofouling Balanus amphitrite cyprids

    Dash, Swagatika


    Biofouling is ubiquitous in marine environments, and the barnacle Balanus amphitrite is one of the most recalcitrant and aggressive biofoulers in tropical waters. Several natural antifoulants that were claimed to be non-toxic have been isolated in recent years, although the mechanism by which they inhibit fouling is yet to be investigated. Poly-ether B has shown promise in the non-toxic inhibition of larval barnacle attachment. Hence, in this study, multiplex two-dimensional electrophoresis (2-DE) was applied in conjunction with mass spectrometry to investigate the effects of poly-ether B on barnacle larvae at the molecular level. The cyprid proteome response to poly-ether B treatment was analyzed at the total proteome and phosphoproteome levels, with 65 protein and 19 phosphoprotein spots found to be up- or down-regulated. The proteins were found to be related to energy-metabolism, oxidative stress, and molecular chaperones, thus indicating that poly-ether B may interfere with the redox-regulatory mechanisms governing the settlement of barnacle larvae. The results of this study demonstrate the usefulness of the proteomic technique in revealing the working mechanisms of antifouling compounds. © 2012 Copyright Taylor and Francis Group, LLC.

  15. Selective Synthesis of [2+2] Macrocyclic Schiff Bases from Chiral 1,4-Diamines

    ZHU Hai-Bin; HU Da-Hua; DONG Hua-Ze; LI Gen-Xi; GOU Shao-Hua


    [2+2] macrocyclic Schiff bases of three kinds have been synthesized from chiral 1,4-diamines by use of different methods. Macrocyclic Schiff bases 1a-1c have been selectively obtained based on a non-templated dilution method from chiral 1,4-diamines a-c and dialdehyde DA1, whereas macrocycles 2a-2c have been selectively produced from reaction of diamines a-c and dialdehyde DA2 in the presence of boric acid as templates. Macrocyclic Schiff bases 3a-3c have been afforded in high selectivity from diamines a-c and dialdehyde DA3 by means of sodium-template. All the titled compounds have been confirmed by 1H NMR and ESI-MS analyses.

  16. Poly-ethers from Winogradskyella poriferorum: Antifouling potential, time-course study of production and natural abundance

    Dash, Swagatika


    A sponge-associated bacterium, Winogradskyella poriferorum strain UST030701-295T was cultured up to 100l for extraction of antifouling bioactive compounds. Five poly-ethers were isolated and partially characterized based on nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS); two of them showed inhibitory effects on biofilm formation of marine bacteria and larval settlement of macro-foulers but did not produce any adverse effects on the phenotypes of zebra fish embryos at a concentration of 5μgml -1. The effect of culture duration on the production of the poly-ethers and the bioactivity of the relevant extracts was monitored over a period of 12days. The total crude poly-ether production increased from day 2 to day 5 and the highest bioactivity was observed on day 3. The poly-ethers were found to be localized in the cellular fraction of the extracts, implying their natural occurrence. The potent bioactivity of these poly-ethers together with their high natural abundance in bacteria makes them promising candidates as ingredients in antifouling applications. © 2011 Elsevier Ltd.

  17. From 2 + 2 to 8 + 8 Condensation Products of Diamine and Dialdehyde: Giant Container-Shaped Macrocycles for Multiple Anion Binding.

    Gregoliński, Janusz; Ślepokura, Katarzyna; Paćkowski, Tomasz; Panek, Jarosław; Stefanowicz, Piotr; Lisowski, Jerzy


    The combination of 2,6-diformylpyridine and trans-1,2-diaminocyclopentane fragments results in 2 + 2, 3 + 3, 4 + 4, 6 + 6, and 8 + 8 macrocyclic imine condensation products. These imines can be reduced to the corresponding 2 + 2, 3 + 3, 4 + 4, 6 + 6, and 8 + 8 macrocyclic amines. The X-ray crystal structures of their protonated derivatives show a rich variety of macrocycle conformations ranging from a stepped 2 + 2 macrocycle to a multiply folded 8 + 8 macrocycle of globular shape. These compounds bind anions via hydrogen bonds: two chloride anions are bound above and below the macrocyclic ring of the 2 + 2 amine, one chloride anion is bound approximately in the center of the 3 + 3 macrocycle, and two chloride anions are deeply buried inside a folded container-shaped 4 + 4 macrocycle, while in the case of the previously reported 6 + 6 amine four chloride anions and two solvent molecules are buried inside a container-shaped macrocycle. Yet another situation was observed for a multiply folded protonated 8 + 8 macrocycle which binds six sulfate anions; two of them are deeply buried inside the container structure while four anions interact with the clefts at the surface of the container.

  18. Alternating 2,6-/3,5-substituted pyridine-acetylene macrocycles: π-stacking self-assemblies enhanced by intermolecular dipole-dipole interaction.

    Abe, Hajime; Ohtani, Kohei; Suzuki, Daiki; Chida, Yusuke; Shimada, Yuta; Matsumoto, Shinya; Inouye, Masahiko


    Macrocyclic compounds consisting of three 2,6-pyridylene and three 3,5-pyridylene units linked by acetylene bonds were synthesized by a Sonogashira reaction. The X-ray structures showed π-stacked pairs of two macrocycles, in which a 2,6-pyridylene unit of the one molecule overlaps a 3,5-pyridylene of the other molecule because of dipole-dipole interaction. Atomic force microscope (AFM) measurements revealed fibril structures indicating the stacking of the rigid planar macrocycles. Hydrogen-bonding ability of the macrocyclic inside was demonstrated by the addition of octyl β-D-glucopyranoside.

  19. Polyether precursors of molecular recognition systems based on the 9,10-anthraquinone moiety

    Wcisło, Anna; Cirocka, Anna; Zarzeczańska, Dorota; Niedziałkowski, Paweł; Nakonieczna, Sandra; Ossowski, Tadeusz


    A series of novel polyether derivatives of 9,10-anthraquinone (AQ) was synthesized and characterized by means of UV-Vis spectroscopy, acid-base titration and complexometric titration. The results were compared with 1-NEt2AQ and 1-NHEtAQ - model compounds of alkylaminoanthraquinones. Acetonitrile and methanol were used as solvents for determination of spectroscopic and acid-base properties. Complexometric titrations were carried out exclusively in acetonitrile. Spectral characteristic of these compounds strongly depends on pH. Addition of acid causes the decrease of absorption intensity and in some cases also a shift of the visible range band. The weakest base is the compound (2), and the strongest - compound (1), both in methanol and acetonitrile solution. The introduction of an additional substituent in the position 8 of the anthraquinone compound increases its basicity. The presence of metal ions causes changes in intensity of absorption (decrease for compounds (2) and (3) and increase with bathochromic shift for (1) and (4)). For the determination of the coordination properties aluminum (III) ions were chosen. The highest complex stability constant with Al (III) ions is observed for compound (1), and the weakest for compound (3). The elongation of the polyether chain decreases the stability of the complex formed.

  20. Synthesis and Application of the Polyether Modified Organic Silicone

    TONG Dong-feng; LIU Jie; ZHAO Chuan-jun


    Polyether modified organic silicone was successfully prepared from Eight methyl siloxane, tetramethyl dihydro two siloxane and UPEO. The chemical structure of the Polyether modified organic silicone was characterized by FT-IR. The wettability of treated cotton fabrics was increased. And the softness was improved significantly.

  1. Crossed and Linked Histories of Tetrapyrrolic Macrocycles and Their Use for Engineering Pores within Sol-Gel Matrices

    Miguel A. García-Sánchez


    Full Text Available The crossed and linked histories of tetrapyrrolic macrocycles, interwoven with new research discoveries, suggest that Nature has found in these structures a way to ensure the continuity of life. For diverse applications porphyrins or phthalocyanines must be trapped inside solid networks, but due to their nature, these compounds cannot be introduced by thermal diffusion; the sol-gel method makes possible this insertion through a soft chemical process. The methodologies for trapping or bonding macrocycles inside pristine or organo-modified silica or inside ZrO2 xerogels were developed by using phthalocyanines and porphyrins as molecular probes. The sizes of the pores formed depend on the structure, the cation nature, and the identities and positions of peripheral substituents of the macrocycle. The interactions of the macrocyclic molecule and surface Si-OH groups inhibit the efficient displaying of the macrocycle properties and to avoid this undesirable event, strategies such as situating the macrocycle far from the pore walls or to exchange the Si-OH species by alkyl or aryl groups have been proposed. Spectroscopic properties are better preserved when long unions are established between the macrocycle and the pore walls, or when oligomeric macrocyclic species are trapped inside each pore. When macrocycles are trapped inside organo-modified silica, their properties result similar to those displayed in solution and their intensities depend on the length of the alkyl chain attached to the matrix. These results support the prospect of tuning up the pore size, surface area, and polarity inside the pore cavities in order to prepare efficient catalytic, optical, sensoring, and medical systems. The most important feature is that research would confirm again that tetrapyrrolic macrocycles can help in the development of the authentic pore engineering in materials science.

  2. Natural and Synthetic Macrocyclic Inhibitors of the Histone Deacetylase Enzymes

    Maolanon, Alex; Kristensen, Helle; Leman, Luke


    Inhibition of histone deacetylase (HDAC) enzymes has emerged as a target for development of cancer chemotherapy. Four compounds have gained approval for clinical use by the Food and Drug Administration (FDA) in the US, and several are currently in clinical trials. However, none of these compounds...... HDAC enzymes may hold an advantage over traditional hydroxamic acid-containing inhibitors, which rely on chelation to the conserved active site zinc ion. Here, we review the literature on macrocyclic HDAC inhibitors obtained from natural sources and structure-activity relationship studies inspired...

  3. Macrocyclic prolinyl acyl guanidines as inhibitors of β-secretase (BACE).

    Boy, Kenneth M; Guernon, Jason M; Wu, Yong-Jin; Zhang, Yunhui; Shi, Joe; Zhai, Weixu; Zhu, Shirong; Gerritz, Samuel W; Toyn, Jeremy H; Meredith, Jere E; Barten, Donna M; Burton, Catherine R; Albright, Charles F; Good, Andrew C; Grace, James E; Lentz, Kimberley A; Olson, Richard E; Macor, John E; Thompson, Lorin A


    The synthesis, evaluation, and structure-activity relationships of a class of acyl guanidines which inhibit the BACE-1 enzyme are presented. The prolinyl acyl guanidine chemotype (7c), unlike compounds of the parent isothiazole chemotype (1), yielded compounds with good agreement between their enzymatic and cellular potency as well as a reduced susceptibility to P-gp efflux. Further improvements in potency and P-gp ratio were realized via a macrocyclization strategy. The in vivo profile in wild-type mice and P-gp effects for the macrocyclic analog 21c is presented.

  4. Novel antibiotics: C-2 symmetrical macrocycles inhibiting Holliday junction DNA binding by E. coli RuvC.

    Pan, Po-Shen; Curtis, Fiona A; Carroll, Chris L; Medina, Irene; Liotta, Lisa A; Sharples, Gary J; McAlpine, Shelli R


    Holliday junctions (HJs) are formed as transient DNA intermediates during site-specific and homologous recombination. Both of these genetic exchange pathways are critical for normal DNA metabolism and repair. Trapping HJs leads to bacterial cell death by preventing proper segregation of the resulting interlinked chromosomes. Macrocyclic peptides designed to target this intermediate were synthesized with the goal of identifying compounds with specificity for this unique molecular target. We discovered ten macrocycles, both hexameric and octameric peptides, capable of trapping HJs in vitro. Those macrocycles containing tyrosine residues proved most effective. These data demonstrate that C-2 symmetrical macrocycles offer excellent synthetic targets for the development of novel antibiotic agents. Furthermore, the active compounds identified provide valuable tools for probing different pathways of recombinational exchange.

  5. Kinetically E-selective macrocyclic ring-closing metathesis

    Shen, Xiao; Nguyen, Thach T.; Koh, Ming Joo; Xu, Dongmin; Speed, Alexander W. H.; Schrock, Richard R.; Hoveyda, Amir H.


    Macrocyclic compounds are central to the development of new drugs, but preparing them can be challenging because of the energy barrier that must be surmounted in order to bring together and fuse the two ends of an acyclic precursor such as an alkene (also known as an olefin). To this end, the catalytic process known as ring-closing metathesis (RCM) has allowed access to countless biologically active macrocyclic organic molecules, even for large-scale production. Stereoselectivity is often critical in such cases: the potency of a macrocyclic compound can depend on the stereochemistry of its alkene; alternatively, one isomer of the compound can be subjected to stereoselective modification (such as dihydroxylation). Kinetically controlled Z-selective RCM reactions have been reported, but the only available metathesis approach for accessing macrocyclic E-olefins entails selective removal of the Z-component of a stereoisomeric mixture by ethenolysis, sacrificing substantial quantities of material if E/Z ratios are near unity. Use of ethylene can also cause adventitious olefin isomerization—a particularly serious problem when the E-alkene is energetically less favoured. Here, we show that dienes containing an E-alkenyl–B(pinacolato) group, widely used in catalytic cross-coupling, possess the requisite electronic and steric attributes to allow them to be converted stereoselectively to E-macrocyclic alkenes. The reaction is promoted by a molybdenum monoaryloxide pyrrolide complex and affords products at a yield of up to 73 per cent and an E/Z ratio greater than 98/2. We highlight the utility of the approach by preparing recifeiolide (a 12-membered-ring antibiotic) and pacritinib (an 18-membered-ring enzyme inhibitor), the Z-isomer of which is less potent than the E-isomer. Notably, the 18-membered-ring moiety of pacritinib—a potent anti-cancer agent that is in advanced clinical trials for treating lymphoma and myelofibrosis—was prepared by RCM carried out at a

  6. Ring-closing metathesis for the synthesis of a highly G-quadruplex selective macrocyclic hexaoxazole having enhanced cytotoxic potency.

    Satyanarayana, Mavurapu; Rzuczek, Suzanne G; Lavoie, Edmond J; Pilch, Daniel S; Liu, Angela; Liu, Leroy F; Rice, Joseph E


    The synthesis of a 24-membered macrocyclic hexaoxazole via ring-closing metathesis is described. The target compound selectively stabilizes G-quadruplex DNA with no detectable stabilization of duplex DNA. An MTT cytotoxicity assay indicated that this unsaturated macrocyclic hexaoxazole exhibits significant cytotoxicity toward P388, RPMI 8402, and KB3-1 cell lines with IC50 values of 45, 25, and 38 nM, respectively.

  7. Computational screening of oxetane monomers for novel hydroxy terminated polyethers.

    Sarangapani, Radhakrishnan; Ghule, Vikas D; Sikder, Arun K


    Energetic hydroxy terminated polyether prepolymers find paramount importance in search of energetic binders for propellant applications. In the present study, density functional theory (DFT) has been employed to screen the various novel energetic oxetane derivatives, which usually construct the backbone for these energetic polymers. Molecular structures were investigated at the B3LYP/6-31G* level, and isodesmic reactions were designed for calculating the gas phase heats of formation. The condensed phase heats of formation for designed compounds were calculated by the Politzer approach using heats of sublimation. Among the designed oxetane derivatives, T4 and T5 possess condensed phase heat of formation above 210 kJ mol(-1). The crystal packing density of the designed oxetane derivatives varied from 1.2 to 1.6 g/cm(3). The detonation velocities and pressures were evaluated using the Kamlet-Jacobs equations, utilizing the predicted densities and HOFCond. It was found that most of the designed oxetane derivatives have detonation performance comparable to the monomers of benchmark energetic polymers viz., NIMMO, AMMO, and BAMO. The strain energy (SE) for the oxetane derivatives were calculated using homodesmotic reactions, while intramolecular group interactions were predicted through the disproportionation energies. The concept of chemical hardness is used to analyze the susceptibility of designed compounds to reactivity and chemical transformations. The heats of formation, density, and predicted performance imply that the designed molecules are expected to be candidates for polymer synthesis and potential molecules for energetic binders.

  8. Radical photocyclization route for macrocyclic lactone ring expansion and conversion to macrocyclic lactams and ketones.

    Nishikawa, Keisuke; Yoshimi, Yasuharu; Maeda, Kousuke; Morita, Toshio; Takahashi, Ichiro; Itou, Tatsuya; Inagaki, Sho; Hatanaka, Minoru


    A new method for the synthesis of macrocyclic lactones, lactams, and ketones, which utilizes photoinduced intramolecular radical cyclization reactions of substrates containing tethered carboxylic acids and α,β-unsaturated carbonyl moieties, has been uncovered. Photocyclization of the carboxylic acids tethered acrylate ester, which were prepared starting from the macrocyclic lactones, gave the two-carbon elongated macrocyclic lactones via decarboxylation. Similar photoreactions of carboxylic acid tethered acryl amide or α,β-unsaturated ketone moieties, which were also prepared starting from the macrocyclic lactones, produced macrocyclic lactams or ketones, respectively. The simple approach can be readily applied to the preparation of a variety of macrocyclic lactones, lactams, and ketones with tunable ring sizes.


    Mona IONAŞ


    Full Text Available Polyethers represent imprinting materials largely used on the market due to their precision in reproducing the prosthetic field. The present study aims at evaluating the linear dimensional variations of the models of dental stone following imprinting with polyethers by the technique of monophasic impression. The obtained results show no significant dimensional differences between the models of dental stone gypsum moulded 24 hours or 7 days after imprinting. The conclusion to be drawn is that the imprinting materials containing polyethers, applied by the monophasic technique, permit realization of high-precision models even 7 days after imprinting.

  10. Templating irreversible covalent macrocyclization by using anions.

    Kataev, Evgeny A; Kolesnikov, Grigory V; Arnold, Rene; Lavrov, Herman V; Khrustalev, Victor N


    Inorganic anions were used as templates in the reaction between a diamine and an activated diacid to form macrocyclic amides. The reaction conditions were found to perform the macrocyclization sufficiently slow to observe a template effect. A number of analytical methods were used to clarify the reaction mechanisms and to show that the structure of the intermediate plays a decisive role in determining the product distribution. For the macrocyclization under kinetic control, it was shown that the amount of a template, the conformational rigidity of building blocks, and the anion affinities of reaction components and intermediates are important parameters that one should take into consideration to achieve high yields.

  11. New macrocycles with potent antituberculosis activity accessed by one-pot multicomponent reactions

    Kim, D.; Huang, Y.; Wang, K.; Doemling, A.

    Based on modeling studies, we hypothesized that tylosin derivatives without formyl group should rather adopt an erythromycin-like binding mode to the ribosome. Twenty four 16-membered macrocyclic compounds were accessed by multicomponent reactions (Gewald, Ugi) of tylosin and investigated for their

  12. Short and diverse route toward complex natural product-like macrocycles.

    Beck, Barbara; Larbig, Gregor; Mejat, Beatrice; Magnin-Lachaux, Marina; Picard, Anne; Herdtweck, Eberhardt; Dömling, Alexander


    [reaction: see text] A general strategy toward macrocyclic compounds using multicomponent reaction (MCR) chemistry, e.g., Passerini and Ugi variants, and ring-closing metathesis (RCM) is introduced. The corresponding bifunctional isocyanides carboxylic acids bearing a terminal olefin are easy to pre

  13. New macrocycles with potent antituberculosis activity accessed by one-pot multicomponent reactions

    Kim, D.; Huang, Y.; Wang, K.; Doemling, A.


    Based on modeling studies, we hypothesized that tylosin derivatives without formyl group should rather adopt an erythromycin-like binding mode to the ribosome. Twenty four 16-membered macrocyclic compounds were accessed by multicomponent reactions (Gewald, Ugi) of tylosin and investigated for their

  14. Macrocyclic Peptoid–Peptide Hybrids as Inhibitors of Class I Histone Deacetylases

    Olsen, Christian Adam; Montero, Ana; Leman, Luke J.;


    We report the design, synthesis, and biological evaluation of the first macrocyclic peptoid-containing histone deacetylase (HDAC) inhibitors. The compounds selectively inhibit human class I HDAC isoforms in vitro, with no inhibition of the tubulin deacetylase activity associated with class IIb HD...


    Vasile Lozan


    Full Text Available The steric protection offered by the macrobinucleating hexaazaditiophenolate ligand (L allows for the preparation of the first stable dinuclear nickel(II borohydride bridged complex, which reacts rapidly with elemental sulphur producing a tetranuclear nickel(II complex [{(LNi2}2(μ-S6]2+ bearing a helical μ4-hexa- sulfide ligand. The [(LCoII 2]2+ fragment have been able to trap a monomethyl orthomolybdate in the binding pocket. Unusual coordination modes of substrate in dinuclear macrocyclic compounds was demonstrated.

  16. Synthesis and extended activity of triazole-containing macrocyclic protease inhibitors

    Pehere, A.D.; Pietsch, M.; Gütschow, M.;


    Peptide-derived protease inhibitors are an important class of compounds with the potential to treat a wide range of diseases. Herein, we describe the synthesis of a series of triazole- containing macrocyclic protease inhibitors pre-organized into a b-strand conformation and an evaluation...... of their activity against a panel of proteases. Acyclic azidoalkyne-based aldehydes are also evaluated for comparison. The macrocyclic peptidomimetics showed considerable activity towards calpain II, cathepsin L and S, and the 20S proteasome chymotrypsin-like activity. Some of the first examples of highly potent...

  17. Self-assembled monolayers of shape-persistent macrocycles on graphite: interior design and conformational polymorphism.

    Vollmeyer, Joscha; Eberhagen, Friederike; Höger, Sigurd; Jester, Stefan-S


    Three shape-persistent naphthylene-phenylene-acetylene macrocycles of identical backbone structures and extraannular substitution patterns but different (empty, apolar, polar) nanopore fillings are self-assembled at the solid/liquid interface of highly oriented pyrolytic graphite and 1,2,4-trichlorobenzene. Submolecularly resolved images of the resulting two-dimensional (2D) crystalline monolayer patterns are obtained by in situ scanning tunneling microscopy. A concentration-dependent conformational polymorphism is found, and open and more dense packing motifs are observed. For all three compounds alike lattice parameters are found, therefore the intermolecular macrocycle distances are mainly determined by their size and symmetry. This is an excellent example that the graphite acts as a template for the macrocycle organization independent from their specific interior.

  18. Theoretical prediction of some novel nanotubes composed of macrocyclic structures: A DFT study

    Masoodi, Hamid Reza; Bagheri, Sotoodeh; Ranjbar-Karimi, Reza


    Our interests in this paper are the elucidation of structural and electronic properties of some π-conjugated macrocycles composed of borazine and alumazene rings as well as the investigation of their potential utility for the creation of new nanotubes. Here, the calculations are performed at B3LYP/6-31+G(d) and M06-2X/6-31+G(d)//B3LYP/6-31+G(d) levels of theory. The results suggest that the self-assembly of the macrocyclic compounds can be considered to form new nanotubes through π-π stacking. Also, meaningful correlations are found between the stability and photoconductivity applications of the nanotubes and the number of stacked π-conjugated macrocycles.

  19. Self-assembled monolayers of shape-persistent macrocycles on graphite: interior design and conformational polymorphism

    Joscha Vollmeyer


    Full Text Available Three shape-persistent naphthylene–phenylene–acetylene macrocycles of identical backbone structures and extraannular substitution patterns but different (empty, apolar, polar nanopore fillings are self-assembled at the solid/liquid interface of highly oriented pyrolytic graphite and 1,2,4-trichlorobenzene. Submolecularly resolved images of the resulting two-dimensional (2D crystalline monolayer patterns are obtained by in situ scanning tunneling microscopy. A concentration-dependent conformational polymorphism is found, and open and more dense packing motifs are observed. For all three compounds alike lattice parameters are found, therefore the intermolecular macrocycle distances are mainly determined by their size and symmetry. This is an excellent example that the graphite acts as a template for the macrocycle organization independent from their specific interior.

  20. Thermally curable fluorinated main chain benzoxazine polyethers via Ullmann coupling

    Demirel, A. Levent; Latthe, Sanjay S.; Demir, Kubra Dogan ; Kışkan, Barış; Yağcı, Yusuf


    Fluorinated main chain benzoxazine polyethers were prepared by Ullmann coupling of fluorinated benzoxazines in the presence of a nano-copperoxide catalyst. Various parameters such as the monomer structure, temperature, and the effect of catalyst on the polymerization were studied. The benzoxazine groups present in the polyether structure were shown to readily undergo thermally activated ring-opening polymerization in the absence of an added catalyst forming cross-linked networks. The thermal ...

  1. A rare allergy to a polyether dental impression material.

    Mittermüller, Pauline; Szeimies, Rolf-Markus; Landthaler, Michael; Schmalz, Gottfried


    Polyether impression materials have been used in dentistry for more than 40 years. Allergic reactions to these materials such as reported in the 1970s ceased after replacement of a catalyst. Very recently, however, patients have started to report symptoms that suggest a new allergic reaction from polyether impression materials. Here, we report on the results of allergy testing with polyether impression materials as well as with its components. Eight patients with clinical symptoms of a contact allergy (swelling, redness or blisters) after exposure to a polyether impression material were subjected to patch tests, two of them additionally to a prick test. A further patient with atypical symptoms of an allergy (nausea and vomiting after contact with a polyether impression material in the oral cavity) but with a history of other allergic reaction was also patch tested. The prick tests showed no immediate reactions in the two patients tested. In the patch tests, all eight patients with typical clinical symptoms showed positive reactions to the mixed polyether impression materials, to the base paste or to a base paste component. The patient with the atypical clinical symptoms did not show any positive patch test reactions. Polyether impression materials may evoke type IV allergic reactions. The causative agent was a component of the base paste. In consideration of the widespread use of this impression material (millions of applications per year) and in comparison to the number of adverse reactions from other dental materials, the number of such allergic reactions is very low. In very scarce cases, positive allergic reactions to polyether impression materials are possible.

  2. Bending rigid molecular rods: formation of oligoproline macrocycles.

    Scully, Conor C G; Rai, Vishal; Poda, Gennadiy; Zaretsky, Serge; Burns, Darcy C; Houliston, R Scott; Lou, Tiantong; Yudin, Andrei K


    Bent but not broken: cyclic oligoprolines are accessed in a reaction that effectively bends rigid oligoproline peptides (see scheme; TBDMS=tert-butyldimethylsilyl). The stitching is accomplished during macrocyclization enabled by aziridine aldehydes and isocyanides. Molecular modeling studies suggest that electrostatic attraction between the termini of the linear peptide is pivotal for macrocyclization. The macrocycles were studied by circular dichroism with a polyproline II structure being observed in larger macrocycles.

  3. Salinomycin, a polyether ionophoric antibiotic, inhibits adipogenesis

    Szkudlarek-Mikho, Maria; Saunders, Rudel A. [Department of Medicine, Biochemistry and Cancer Biology, Center for Diabetes and Endocrine Research, College of Medicine, University of Toledo, Toledo, OH 43614 (United States); Yap, Sook Fan [Faculty of Medicine and Health Sciences, Department of Pre-Clinical Sciences, University of Tunku Abdul Rahman (Malaysia); Ngeow, Yun Fong [Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603 (Malaysia); Chin, Khew-Voon, E-mail: [Department of Medicine, Biochemistry and Cancer Biology, Center for Diabetes and Endocrine Research, College of Medicine, University of Toledo, Toledo, OH 43614 (United States)


    Highlights: Black-Right-Pointing-Pointer Salinomycin inhibits preadipocyte differentiation into adipocytes. Black-Right-Pointing-Pointer Salinomycin inhibits transcriptional regulation of adipogenesis. Black-Right-Pointing-Pointer Pharmacological effects of salinomycin suggest toxicity in cancer therapy. -- Abstract: The polyether ionophoric antibiotics including monensin, salinomycin, and narasin, are widely used in veterinary medicine and as food additives and growth promoters in animal husbandry including poultry farming. Their effects on human health, however, are not fully understood. Recent studies showed that salinomycin is a cancer stem cell inhibitor. Since poultry consumption has risen sharply in the last three decades, we asked whether the consumption of meat tainted with growth promoting antibiotics might have effects on adipose cells. We showed in this report that the ionophoric antibiotics inhibit the differentiation of preadipocytes into adipocytes. The block of differentiation is not due to the induction of apoptosis nor the inhibition of cell proliferation. In addition, salinomycin also suppresses the transcriptional activity of the CCAAT/enhancer binding proteins and the peroxisome proliferator-activated receptor {gamma}. These results suggest that the ionophoric antibiotics can be exploited as novel anti-obesity therapeutics and as pharmacological probes for the study of adipose biology. Further, the pharmacological effects of salinomycin could be a harbinger of its toxicity on the adipose tissue and other susceptible target cells in cancer therapy.

  4. Charles J. Pedersen: innovator in macrocyclic chemistry and co-recipient of the 1987 Nobel Prize in chemistry.

    Izatt, Reed M


    Charles J. Pedersen began life in Korea where his father was employed as an engineer at a gold mine in a remote region of that country. He received his primary and secondary school education in Japan and university training in the United States. He was employed as an organic research chemist at DuPont for 42 years. The signal accomplishment of this unusual individual was his serendipitous discovery of macrocyclic polyethers and of their selective complexation of alkali metal cations. This discovery sparked the development of a new field of chemistry and led to his sharing the Nobel Prize in Chemistry in 1987. An attempt is made to understand Pedersen as a person in this article.

  5. Creating molecular macrocycles for anion recognition

    Amar H. Flood


    Full Text Available The creation and functionality of new classes of macrocycles that are shape persistent and can bind anions is described. The genesis of triazolophane macrocycles emerges out of activity surrounding 1,2,3-triazoles made using click chemistry; and the same triazoles are responsible for anion capture. Mistakes made and lessons learnt in anion recognition provide deeper understanding that, together with theory, now provides for computer-aided receptor design. The lessons are acted upon in the creation of two new macrocycles. First, cyanostars are larger and like to capture large anions. Second is tricarb, which also favors large anions but shows a propensity to self-assemble in an orderly and stable manner, laying a foundation for future designs of hierarchical nanostructures.


    SUN Yanhui; QIU Kunyuan; FENG Xinde VOONG Sing-tuh


    Polyethers could form hydroperoxide under air-oxidation or photo-oxidation in the presence of H2O2. The scission of ether linkage induced by moderate oxidation was prevented by controlling the reaction time and hydroperoxide concentration. The oxidation rate was affected by the end groups of polyethers. The decreasing order of oxidation rate for various poly(tetramethylene ether) glycol derivatives having different end groups are as follows: poly(tetramethylene ether) glycol (PTMG)> poly(tetramethylene ether)acetate (PTMGAC) > poly(tetramethylene ether) phenyl carbamate (PTMGPC). The urethane end groups in PTMGPC increase the resistance toward oxidation. Polyether hydroperoxide reacts with ferrous ion or N,N-dimethyl toluidine (DMT) to form polymericoxy radical which then initiates the graft copolymerization of vinyl monomers at low temperature,and was devoid of homopolymerization. The copolymer after separation and purification was proved to be a graft one by IR analysis and elemental analysis.

  7. Chemodiversity of Ladder-Frame Prymnesin Polyethers in Prymnesium parvum.

    Rasmussen, Silas Anselm; Meier, Sebastian; Andersen, Nikolaj Gedsted; Blossom, Hannah Eva; Duus, Jens Øllgaard; Nielsen, Kristian Fog; Hansen, Per Juel; Larsen, Thomas Ostenfeld


    Blooms of the microalga Prymnesium parvum cause devastating fish kills worldwide, which are suspected to be caused by the supersized ladder-frame polyether toxins prymnesin-1 and -2. These toxins have, however, only been detected from P. parvum in rare cases since they were originally described two decades ago. Here, we report the isolation and characterization of a novel B-type prymnesin, based on extensive analysis of 2D- and 3D-NMR data of natural as well as 90% (13)C enriched material. B-type prymnesins lack a complete 1,6-dioxadecalin core unit, which is replaced by a short acyclic C2 linkage compared to the structure of the original prymnesins. Comparison of the bioactivity of prymnesin-2 with prymnesin-B1 in an RTgill-W1 cell line assay identified both compounds as toxic in the low nanomolar range. Chemical investigations by liquid chromatography high-resolution mass spectrometry (LC-HRMS) of 10 strains of P. parvum collected worldwide showed that only one strain produced the original prymnesin-1 and -2, whereas four strains produced the novel B-type prymnesin. In total 13 further prymnesin analogues differing in their core backbone and chlorination and glycosylation patterns could be tentatively detected by LC-MS/HRMS, including a likely C-type prymnesin in five strains. Altogether, our work indicates that evolution of prymnesins has yielded a diverse family of fish-killing toxins that occurs around the globe and has significant ecological and economic impact.

  8. The 'Visualized' macrocycles: Chemistry and application of fluorophore tagged cyclodextrins.

    Benkovics, Gábor; Malanga, Milo; Fenyvesi, Éva


    Cyclodextrins are macrocyclic molecules able to form host-guest complexes due to their hydrophobic cavity. Because of their carbohydrate nature they do not absorb light in the UV-vis region (200-800nm), but they can be converted into spectroscopically active compounds via modification with a chromophore unit. Among the chromophores, the group of fluorophores can provide high sensitivity in analytical applications (chemosensing) and low detection limit in optical imaging methods (fluorescent microscopy). Fluorophore-tagged cyclodextrins therefore combine interesting spectroscopic properties with promising supramolecular features which make these conjugates widely applicable in various pharmaceutical fields. The aim of this work is to review the various types of fluorophores which have been used for cyclodextrin tagging, to discuss the synthetic strategies used for the conjugation and to summarize the pharmaceutical applications of these 'visualized' macrocycles including their use in photodynamic therapy. The recent achievements in studying how the fluorophore-appended cyclodextrin derivatives cross biological barriers are also reviewed. Copyright © 2017 Elsevier B.V. All rights reserved.


    V. Lozan


    Full Text Available A series of novel tri-, tetra- and pentanuclear complexes composed of dinuclear LM units (M=Co, Ni, Zn; L=24-membered macrocyclic hexaaza-dithiophenolate ligand and ferrocenecarboxylate ([CpFeC5H4CO2]ˉ, 1,1’-ferrocenedicarboxy-late ([Fe(C5H4-CO22]2ˉ, acetylene-dicarboxylate, terephthalate, isophthalate, and naphthalene diimide dicarboxylate groups is reported. The complexes, have been synthesized and characterised by UV/Vis-, IR-, NMR-spectroscopy, Cyclovoltammetry, and X-ray crystallography. Each dicarboxylate dianion acts as a quadridentate bridging ligand linking two bioctahedral LM2 units via µ1,3-bridging carboxylate functions to generate discrete dications with a central LM2(O2C-R-CO2M2L core. The magnetic properties of these compounds reveal the presence of weak ferromagnetic exchange interactions between the NiII ions of the dinuclear subunits and negligible coupling across the dicarboxylate bridges.

  10. Enzymatic Macrocyclization of 1,2,3-Triazole Peptide Mimetics.

    Oueis, Emilia; Jaspars, Marcel; Westwood, Nicholas J; Naismith, James H


    The macrocyclization of linear peptides is very often accompanied by significant improvements in their stability and biological activity. Many strategies are available for their chemical macrocyclization, however, enzyme-mediated methods remain of great interest in terms of synthetic utility. To date, known macrocyclization enzymes have been shown to be active on both peptide and protein substrates. Here we show that the macrocyclization enzyme of the cyanobactin family, PatGmac, is capable of macrocyclizing substrates with one, two, or three 1,4-substituted 1,2,3-triazole moieties. The introduction of non-peptidic scaffolds into macrocycles is highly desirable in tuning the activity and physical properties of peptidic macrocycles. We have isolated and fully characterized nine non-natural triazole-containing cyclic peptides, a further ten molecules are also synthesized. PatGmac has now been shown to be an effective and versatile tool for the ring closure by peptide bond formation.

  11. Rapid synthesis of macrocycles from diol precursors

    Wingstrand, Magnus; Madsen, Charlotte Marie; Clausen, Mads Hartvig


    A method for the formation of synthetic macrocycles with different ring sizes from diols is presented. Reacting a simple diol precursor with electrophilic reagents leads to a cyclic carbonate, sulfite or phosphate in a single step in 25-60% yield. Converting the cyclization precursor to a bis-ele...

  12. Assessment of Physical Stability and Antioxidant Activity of Polysiloxane Polyalkyl Polyether Copolymer-Based Creams

    Atif Ali


    Full Text Available The purpose of the present work was to investigate the changes on physical stability (color, creaming, liquefaction, pH, conductivity, centrifugation, viscosity and rheological parameters by non-ionic surfactant polysiloxane polyalkyl polyether copolymer based creams following inclusion of plant extract containing phenolic compounds. The antioxidant activity of the plant extract alone and after addition in the cream was assessed using the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH assay. Physical stability was assessed by submitting the creams to storage at 8°C, 25°C, 40°C, and at 40°C with 70% RH (relative humidity for a period of two months. Physical characteristics of polysiloxane polyalkyl polyether copolymer based creams, that is, color, creaming, liquefaction, centrifugation and pH were noted at various intervals for 2 months. The viscosities and rheological behavior of creams were determined using a rotational rheometer. Data were analyzed by using Brookfield Software Rheocalc version (2.6 with IPC Paste and Power Law (PL math models. Cream with plant extract showed pseudo plastic behaviour with decreasing on viscosity. The Acacia nilotica (AN extract alone and the cream containing this extract showed great antioxidant and free radical scavenging activities. Power Law and IPC analysis were found to fit all the rheograms.

  13. Salinomycin and other polyether ionophores are a new class of antiscarring agent.

    Woeller, Collynn F; O'Loughlin, Charles W; Roztocil, Elisa; Feldon, Steven E; Phipps, Richard P


    Although scarring is a component of wound healing, excessive scar formation is a debilitating condition that results in pain, loss of tissue function, and even death. Many tissues, including the lungs, heart, skin, and eyes, can develop excessive scar tissue as a result of tissue injury, chronic inflammation, or autoimmune disease. Unfortunately, there are few, if any, effective treatments to prevent excess scarring, and new treatment strategies are needed. Using HEK293FT cells stably transfected with a TGFβ-dependent luciferase reporter, we performed a small molecule screen to identify novel compounds with antiscarring activity. We discovered that the polyether ionophore salinomycin potently inhibited the formation of scar-forming myofibroblasts. Salinomycin (250 nm) blocked TGFβ-dependent expression of the cardinal myofibroblast products α smooth muscle actin, calponin, and collagen in primary human fibroblasts without causing cell death. Salinomycin blocked phosphorylation and activation of TAK1 and p38, two proteins fundamentally involved in signaling myofibroblast and scar formation. Expression of constitutively active mitogen activated kinase kinase 6, which activates p38 MAPK, attenuated the ability of salinomycin to block myofibroblast formation, demonstrating that salinomycin targets the p38 kinase pathway to disrupt TGFβ signaling. These data identify salinomycin and other polyether ionophores as novel potential antiscarring therapeutics.

  14. New bromotriterpene polyethers from the Indian alga Chondria armata

    Ciavatta, M.L.; Wahidullah, S.; DeSouza, L.; Scognamiglio, G.; Cimino, G.

    Six new bromotriterpene polyethers, armatol A-F (1-6), with a rearranged carbon skeleton, were isolated from the Indian Ocean red alga Chondria armata. The structures were characterized by spectroscopic techniques, in particular 1D- and 2D-NMR...

  15. 21 CFR 177.2430 - Polyether resins, chlorinated.


    ...) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use Only as... producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyether resins, chlorinated. 177.2430 Section...

  16. Chemodiversity of Ladder-Frame Prymnesin Polyethers in Prymnesium parvum

    Rasmussen, Silas Anselm; Meier, Sebastian; Andersen, Nikolaj Gedsted;


    Blooms of the microalga Prymnesium parvum cause devastating fish kills worldwide, which are suspected to be caused by the supersized ladder-frame polyether toxins prymnesin-1 and -2. These toxins have, however, only been detected from P. parvum in rare cases since they were originally described two...

  17. Photodegradation of poly(ether sulphone). Part 2

    Norrman, K.; Krebs, Frederik C


    The photodegradation of poly(ether sulphone) (PES) was investigated systematically by time-of-flight SIMS (ToF-SIMS) and x-ray photoelectron spectroscopy (XPS). The effect of varying the irradiation dose, wavelength and the atmosphere was studied along with mechanistic photooxidation studies using...

  18. Ipomoeassin F, a new cytotoxic macrocyclic glycoresin from the leaves of Ipomoea squamosa from the Suriname rainforest.

    Cao, Shugeng; Norris, Andrew; Wisse, Jan H; Miller, James S; Evans, Randy; Kingston, David G I


    A new cytotoxic macrocyclic glycoresin, ipomoeassin F (6), has been isolated from the leaves of Ipomoea squamosa. The structure was elucidated by the interpretation of spectral data. Compound 6 was strongly active in the A2780 (human ovarian cancer cell line) assay with an IC(50) value of 0.036 microM.

  19. Azalomycin F4a 2-ethylpentyl ester, a new macrocyclic lactone, from mangrove actinomycete Streptomyces sp.211726

    Gan Jun Yuan; Kui Hong; Hai Peng Lin; Jia Li


    Azalomycin F4a 2-ethylpentyl ester,a new 36-membered macrocyclic lactone antibiotic,was isolated from mangrove actinomycete Streptomyces sp.211726.Its structure was elucidated on the basis of spectroscopic data.The compound showed broad-spectrum antifungal activity and moderate cytotoxicity against human colon tumor cell HCT-116.

  20. Fluorous ionic liquids as solvents for the liquid-liquid extraction of metal ions by macrocyclic polyethers.

    Heitzman, Holly; Young, Blake A; Rausch, David J; Rickert, Paul; Stepinski, Dominique C; Dietz, Mark L


    The predominant mode of strontium ion transfer from aqueous nitrate media into a series of 1-fluoroalkyl-3-methylimidazolium bis[(trifluoromethylsulfonyl)]imides containing dicyclohexano-18-crown-6 (DCH18C6) is shown to shift from cation exchange to strontium nitrato-crown ether complex partitioning as the length of the fluoroalkyl substituent is increased. Fluoroalkyl substituents are shown to be only slightly more effective than their non-fluorous analogs at inducing this shift. At the same time, the fluorinated ionic liquids (ILs) yield strontium distribution ratios as much as an order of magnitude lower than the corresponding 1-alkyl-3-methylimidazolium (C(n)mim(+)) salts. Fluorous ILs thus appear to offer no compelling advantages over C(n)mim(+) ionic liquids as extraction solvents.

  1. Novel Potent Hepatitis C Virus NS3 Serine Protease Inhibitors Derived from Proline-Based Macrocycles

    Chen, Kevin X.; Njoroge, F. George; Arasappan, Ashok; Venkatraman, Srikanth; Vibulbhan, Bancha; Yang, Weiying; Parekh, Tejal N.; Pichardo, John; Prongay, Andrew; Cheng, Kuo-Chi; Butkiewicz, Nancy; Yao, Nanhua; Madison, Vincent; Girijavallabhan, Viyyoor (SPRI)


    The hepatitis C virus (HCV) NS3 protease is essential for viral replication. It has been a target of choice for intensive drug discovery research. On the basis of an active pentapeptide inhibitor, 1, we envisioned that macrocyclization from the P2 proline to P3 capping could enhance binding to the backbone Ala156 residue and the S4 pocket. Thus, a number of P2 proline-based macrocyclic {alpha}-ketoamide inhibitors were prepared and investigated in an HCV NS3 serine protease continuous assay (K*{sub i}). The biological activity varied substantially depending on factors such as the ring size, number of amino acid residues, number of methyl substituents, type of heteroatom in the linker, P3 residue, and configuration at the proline C-4 center. The pentapeptide inhibitors were very potent, with the C-terminal acids and amides being the most active ones (24, K*{sub i} = 8 nM). The tetrapeptides and tripeptides were less potent. Sixteen- and seventeen-membered macrocyclic compounds were equally potent, while fifteen-membered analogues were slightly less active. gem-Dimethyl substituents at the linker improved the potency of all inhibitors (the best compound was 45, K*{sub i} = 6 nM). The combination of tert-leucine at P3 and dimethyl substituents at the linker in compound 47 realized a selectivity of 307 against human neutrophil elastase. Compound 45 had an IC{sub 50} of 130 nM in a cellular replicon assay, while IC{sub 50} for 24 was 400 nM. Several compounds had excellent subcutaneous AUC and bioavailability in rats. Although tripeptide compound 40 was 97% orally bioavailable, larger pentapeptides generally had low oral bioavailability. The X-ray crystal structure of compounds 24 and 45 bound to the protease demonstrated the close interaction of the macrocycle with the Ala156 methyl group and S4 pocket. The strategy of macrocyclization has been proved to be successful in improving potency (>20-fold greater than that of 1) and in structural depeptization.

  2. A Macrocyclic Peptide that Serves as a Cocrystallization Ligand and Inhibits the Function of a MATE Family Transporter

    Hiroaki Suga


    Full Text Available The random non-standard peptide integrated discovery (RaPID system has proven to be a powerful approach to discover de novo natural product-like macrocyclic peptides that inhibit protein functions. We have recently reported three macrocyclic peptides that bind to Pyrococcus furiosus multidrug and toxic compound extrusion (PfMATE transporter and inhibit the transport function. Moreover, these macrocyclic peptides were successfully employed as cocrystallization ligands of selenomethionine-labeled PfMATE. In this report, we disclose the details of the RaPID selection strategy that led to the identification of these three macrocyclic peptides as well as a fourth macrocyclic peptide, MaD8, which is exclusively discussed in this article. MaD8 was found to bind within the cleft of PfMATE’s extracellular side and blocked the path of organic small molecules being extruded. The results of an ethidium bromide efflux assay confirmed the efflux inhibitory activity of MaD8, whose behavior was similar to that of previously reported MaD5.

  3. Theoretical study of stability of metal-N4 macrocyclic compounds in acidic media%密度泛函理论计算研究金属-N4大环化合物在酸性介质中的稳定性

    陈永婷; 华星; 陈胜利


    Fe and Co porphyrins and phthalocyanines are excellent catalysts for the oxygen reduction reaction (ORR) and are promising alternatives to Pt in fuel cells. However, the stability of these molecular catalysts in acidic media is poor. This study explores whether demetalation through proton ex‐change causes these metal macrocyclic catalysts to be unstable in acidic media. We first present a theoretical scheme for investigating exchange reactions of metal ions in metal macrocyclic com‐pounds with protons in acidic media. The equilibrium concentrations of metal ions in solution when various metalloporphyrins (MPs) and metallophthalocyanines (MPcs) are brought into contact with a strongly acidic solution (pH=1) were then estimated using density functional theory calculations;these values were used to evaluate the stability of these metal macrocyclic compounds against demetalation in acidic media. The results show that Fe, Co, Ni, and Cu phthalocyanines and porphy‐rins have considerable resistance to exchange with protons, whereas Cr, Mn, and Zn phthalocya‐nines and porphyrins easily undergo demetalation through ion exchange with protons. This sug‐gests that the degradation in the ORR activity of Fe and Co macrocyclic molecular catalysts and of carbon materials doped with Fe(Co) and nitrogen, which are believed to have metal‐nitrogen coor‐dination structures similar to those of macrocyclic molecules as ORR catalytic centers, is not the result of replacement of metal ions by protons. The calculation results show that electron‐donating substituents could enhance the stability of Fe and Co phthalocyanines.%质子交换膜燃料电池(PEMFCs)是一种能够有效地将化学能转换成电能的装置,其具有较高的效率及功率密度,还兼具环境友好的优点,因而在电动车和分布式电站等领域有广泛应用前景.然而,昂贵的价格及较差的耐久性阻碍了 PEMFCs的广泛应用.阴极氧还原反应(ORR

  4. Synthesis and characterization of new azo containing Schiff base macrocycle

    Saeed Malek-Ahmadi; Amir Abdolmaleki


    Fully conjugated Schiff base macrocycle has been prepared through a simple and mild condition, a one-pot cyclization procedure of four-component without using a template. The condensation reaction of related bis (hydroxybenzaldehyde) with phenylenediamines to prepare a conjugated [2 + 2] Schiff base macrocycle has been investigated and fluorescent [2 + 2] Schiff base macrocycles with N2O2 binding pockets has been prepared and characterized by elemental analysis,' H NMR, IR, fluorescent, UV-visible and MALDI mass spectroscopies.

  5. Macrocyclic G-quadruplex ligands

    Nielsen, M C; Ulven, Trond


    G-quadruplex stabilizing compounds have recently received increased interest due to their potential application as anticancer therapeutics. A significant number of structurally diverse G-quadruplex ligands have been developed. Some of the most potent and selective ligands currently known are macr...

  6. Amide-based Fluorescent Macrocyclic Anion Receptors

    ZENG, Zhen-Ya(曾振亚); XU, Kuo-Xi(徐括喜); HE, Yong-Bing(何永炳); LIU, Shun-Ying(刘顺英); WU, Jin-Long(吴进龙); WEI, Lan-Hua(隗兰华); MENG, Ling-Zhi(孟令芝)


    Two fluorescent anion receptors (1 and 2) based on amide macrocycle were synthesized and corresponding fluorescence quenching induced by anion complexation was observed in different degree. Receptors form 1: 1 complexes with anions by hydrogen bonding interactions. Receptor 1 bound anions in the order of F->Cl->H2PO4->CH3COO->>Br-, I- and receptor 2 showed high selectivity to F- over other anions.

  7. Cd(II and Pb(II complexes of the polyether ionophorous antibiotic salinomycin

    Tanabe Makoto


    Full Text Available Abstract Background The natural polyether ionophorous antibiotics are used for the treatment of coccidiosis in poultry and ruminants. They are effective agents against infections caused by Gram-positive microorganisms. On the other hand, it was found that some of these compounds selectively bind lead(II ions in in vivo experiments, despite so far no Pb(II-containing compounds of defined composition have been isolated and characterized. To assess the potential of polyether ionophores as possible antidotes in the agriculture, a detailed study on their in vitro complexation with toxic metal ions is required. In the present paper we report for the first time the preparation and the structure elucidation of salinomycin complexes with ions of cadmium(II and lead(II. Results New metal(II complexes of the polyether ionophorous antibiotic salinomycin with Cd(II and Pb(II ions were prepared and structurally characterized by IR, FAB-MS and NMR techniques. The spectroscopic information and elemental analysis data reveal that sodium salinomycin (SalNa undergoes a reaction with heavy metal(II ions to form [Cd(Sal2(H2O2] (1 and [Pb(Sal(NO3] (2, respectively. Abstraction of sodium ions from the cavity of the antibiotic is occurring during the complexation reaction. Salinomycin coordinates with cadmium(II ions as a bidentate monoanionic ligand through the deprotonated carboxylic moiety and one of the hydroxyl groups to yield 1. Two salinomycin anions occupy the equatorial plane of the Cd(II center, while two water molecules take the axial positions of the inner coordination sphere of the metal(II cation. Complex 2 consists of monoanionic salinomycin acting in polydentate coordination mode in a molar ratio of 1: 1 to the metal ion with one nitrate ion for charge compensation. Conclusion The formation of the salinomycin heavy metal(II complexes indicates a possible antidote activity of the ligand in case of chronic/acute intoxications likely to occur in the stock

  8. Synthesis of Polyethers Containing Triazole Units in the Backbone by Click Chemistry in a Tricomponent Reaction

    Moslem Mansour Lakouraj


    Full Text Available A series of linear aromatic polyethers containing triazole units were synthesized via the direct click reaction of dibromide and bisethynyl compounds in the presence of sodium azide as one pot reaction. The structures of polymers were approved by using IR and 1H NMR techniques. The solubility experiments showed that polymers have good solubility in polar aprotic solvents such as DMSO, DMF, and NMP at higher temperatures. Thermal stability of the polymers was measured using thermogravimetric analysis (TGA and differential scanning calorimetry (DSC which indicated that they possessed good thermal stability ( up to 558°C and high (191.7–260°C under N2 atmosphere. All the polymers were amorphous according to the DSC and X-ray diffraction. These polymers exhibited strong UV-vis absorption maxima near to 400 nm and up to 500 nm in DMSO solution.

  9. The effect of polyether functional polydimethylsiloxane on surface and thermal properties of waterborne polyurethane

    Zheng, Guikai; Lu, Ming; Rui, Xiaoping


    Waterborne polyurethanes (WPU) modified with polyether functional polydimethylsiloxane (PDMS) were synthesized by pre-polymerization method using isophorone diisocyanate (IPDI) and 1,4-butanediol (BDO) as hard segments and polybutylene adipate glycol (PBA) and polyether functional PDMS as soft segments. The effect of polyether functional PDMS on phase separation, thermal properties, surface properties including surface composition, morphology and wettability were investigated by FTIR, contact angle measurements, ARXPS, SEM-EDS, AFM, TG and DSC. The results showed that the compatibility between urethane hard segment and PDMS modified with polyether was good, and there was no distinct phase separation in both bulk and surface of WPU films. The degradation temperature and low temperature flexibility increased with increasing amounts of polyether functional PDMS. The enrichment of polyether functional PDMS with low surface energy on the surface imparted excellent hydrophobicity to WPU films.

  10. Ring strain and total syntheses of modified macrocycles of the isoplagiochin type

    Andreas Speicher


    Full Text Available Macrocycles of the bisbibenzyl-type are natural products that are found exclusively in bryophytes (liverworts. The molecular framework of the subtype “isoplagiochin” is of substantial structural interest because of the chirality of the entire molecule, which arises from two biaryl axes in combination with two helical two-carbon units in a cyclic arrangement. From a structural as well as a synthetic point of view we report on the total synthesis of compounds which possess more rigid two-carbon biaryl bridges like stilbene (E or Z or even tolane moieties which were introduced starting with a Sonogashira protocol. The McMurry method proved to be a powerful tool for the cyclization to these considerably ring-strained macrocycles.

  11. Aliphatic Polyethers: Classical Polymers for the 21st Century.

    Klein, Rebecca; Wurm, Frederik R


    Polyethers-polymers with the structural element (R'-O-R)n in their backbone--are an old class of polymers which were already used at the time of the ancient Egyptians. However, still today these materials are highly important with applications in all areas of our life, reaching from the automotive and paper industry to cosmetics and biomedical applications. In this Review, different aliphatic polyethers like poly(epoxide)s, poly(oxetane)s, and poly(tetrahydrofuran) are discussed. Special emphasis is placed on the history, the polymerization techniques (industrially and in academia), the properties, the applications as well as recent developments of these materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


    QuanxiaoLiu; HuaiyuZhan; BeihaiHe; ShuhuiYang; JianhuaLiu; JianluLiu(1); ZhenxingPang


    Polyether polyurethane was synthesized from modified wheat straw oxygen-alkaline lignin, polyethylene glycol and two different diisocyanates (diphenylemethane-4, 4'-diisocyanate, tolulene diisocyanate) by solution casting method, its properties were investigated. The results show that modified wheat straw oxygen-alkaline lignin can substitute part of polyethylene glycol to react with diisocyanate to synthesize polyurethane. The molar ratio of NCO to OH and modified wheat straw oxygen-alkaline lignin content affect the properties of lignin-based polyether polyurethane respectively. The addition of plasticizer in the polyurethane synthesis process improves the properties of synthesized polyurethane, especially the elasticity of polyurethane. The synthesized polyurethane from modified wheat straw oxygen-alkali lignin can be used as both engineering plastic and hard foam plastic in future.


    Quanxiao Liu; Huaiyu Zhan; Beihai He; Shuhui Yang; Jianhua Liu; Jianlu Liu; Zhenxing Pang


    Polyether polyurethane was synthesized from modified wheat straw oxygen-alkaline lignin,polyethylene glycol and two different diisocyanates (diphenylemethane-4, 4′-diisocyanate, tolulene diisocyanate) by solution casting method, its properties were investigated. The results show that modified wheat straw oxygen-alkaline lignin can substitute part of polyethylene glycol to react with diisocyanate to synthesize polyurethane. The molar ratio of NCO to OH and modified wheat straw oxygen-alkaline lignin content affect the properties of lignin-based polyether polyurethane respectively. The addition of plasticizer in the polyurethane synthesis process improves the properties of synthesized polyurethane, especially the elasticity of polyurethane. The synthesized polyurethane from modified wheat straw oxygen-alkali lignin can be used as both engineering plastic and hard foam plastic in future.

  14. Solvent-Induced Crystallization of Poly(ether ether ketone)

    McPeak, Jennifer Lynne


    The purpose of this study was learn how the diffusion, swelling, and crystallization processes are coupled during solvent-induced crystallization of poly(ether ether ketone) (PEEK). Unoriented amorphous PEEK films were immersed in aprotic organic liquids at ambient temperature and bulk properties or characteristics were monitored as a function of immersion time. The sorption behavior, Tg and Tm° suppression, crystallinity, and dynamic mechanical response were correlated as a function of sol...

  15. Synthesis of Telechelic Polyisobutylenes and Polyethers and Their Characterization

    Sándor Kéki; Miklós Nagy; Gy(o)rgy Deák; László Orosz; Miklós Zsuga


    @@ 1Introduction Telechelic polymers have attained great consideration as building blocks in the synthesis of block copolymers and networks. Telechelic polymers with various endgroups are also widely used materials for the preparation of polymeric prodrugs. Several methods have been reported to obtain functionalized polymers from the corresponding polyisobutylene (PIB) and polyether derivatives. In this presentation, we will demonstrate very versatile and powerful synthetic methods to obtain telechelic polymers.

  16. Novel Polyethers Doped with Nanoscale Insulating oxides for Lithium Battery Elec Project

    National Aeronautics and Space Administration — Novel polyethers doped with insulating oxides are used to prepare solid polymer electrolytes for high energy density lithium batteries. The electrolytes are...

  17. 40 CFR Table 4 to Subpart Ppp of... - Known Organic HAP From Polyether Polyol Products


    ... CATEGORIES National Emission Standards for Hazardous Air Pollutant Emissions for Polyether Polyols Production...-Hexane (110543) Methanol (67561) Propylene Oxide (75569) Toluene (108883) CAS No. = Chemical Abstracts...

  18. Synthesis of the macrocyclic core of (-)-pladienolide B

    Skaanderup, Philip Robert; Jensen, T.


    An efficient synthesis of the macrocyclic core of (-)-pladienolide B is disclosed. The concise route relies on a chiral auxiliary-mediated asymmetric aldol addition and an osmium-catalyzed asymmetric dihydroxylation to install the three oxygenated stereocenters of the macrocycle. This purely reag...

  19. Observations on the Influence of Precursor Conformations on Macrocyclization Reactions

    Hammershøj, Peter; Beldring, Klavs; Nielsen, Anders R.


    macrocyclization to afford a mixture of diastereomeric sulfites, subjection of the other precursor to identical reaction conditions resulted in the isolation of the linear dichloride. We hypothesize that there is a difference in the ability of the two molecules to adopt a conformation that is germane...... to macrocyclization, a proposition that is supported by conformational analyses using molecular mechanics....

  20. Synthesis of Chiral Macrocyclic or Linear Pyridine Carboxamides from Pyridine-2,6-dicarbonyl Dichloride as Antimicrobial Agents

    Abd El-Galil E Amr


    Full Text Available A series of chiral linear and macrocyclic bridged pyridines has been prepared starting from pyridine-2,6-dicarbonyl dichloride (2. The coupling of 1 with D-alanyl methyl ester gave 2,6-bis-D-alanyl pyridine methyl ester (3. Hydrazinolysis of 3 with hydrazine hydrate afforded bis-hydrazide 4. The latter was reacted with thiophene-2-carbaldehyde, phthalic anhydride or cyclohexanone to afford bis-carboxamide pyridine derivatives 5-7, respectively. Compound 4 was coupled with p-methoxy- or p-nitroaceto-phenone to yield compounds 8 and 9. In addition, 4 was reacted with 1,2,4,5-benzenetetra-carboxylic acid dianhydride or 1,4,5,8-naphthalenetetracarboxylic acid dianhydride to afford the macrocyclic octacarboxaamide pyridines 10 and 11. The detailed synthesis, spectroscopic data and antimicrobial screening for the synthesized compounds are reported.

  1. Mechanical properties and chemical stability of pivalolactone-based poly(ether ester)s

    Tijsma, E.J.; Does, van der L.; Bantjes, A.; Vulic, I.


    The processing, mechanical and chemical properties of poly(ether ester)s, prepared from pivalolactone (PVL), 1,4-butanediol (4G) and dimethyl terephthalate (DMT), were studied. The poly(ether ester)s could easily be processed by injection moulding, owing to their favourable rheological and thermal p

  2. Macrocyclic olefin metathesis at high concentrations by using a phase-separation strategy.

    Raymond, Michaël; Holtz-Mulholland, Michael; Collins, Shawn K


    Macrocyclic olefin metathesis has seen advances in the areas of stereochemistry, chemoselectivity, and catalyst stability, but strategies aimed at controlling dilution effects in macrocyclizations are rare. Herein, a protocol to promote macrocyclic olefin metathesis, one of the most common synthetic tools used to prepare macrocycles, at relatively high concentrations (up to 60 mM) is described by exploitation of a phase-separation strategy. A variety of macrocyclic skeletons could be prepared having either different alkyl, aryl, or amino acids spacers.

  3. Synthesis, cytotoxicity and antibacterial activity of new esters of polyether antibiotic - salinomycin.

    Antoszczak, Michał; Popiel, Katarzyna; Stefańska, Joanna; Wietrzyk, Joanna; Maj, Ewa; Janczak, Jan; Michalska, Greta; Brzezinski, Bogumil; Huczyński, Adam


    A series of 12 novel ester derivatives of naturally occurring polyether antibiotic - salinomycin were synthesized, characterised by spectroscopic method and evaluated for their in vitro antibacterial activity and cytotoxicity. The new esters were demonstrated to form complexes with monovalent and divalent metal cation of 1:1 stoichiometry in contrast to the salinomycin which forms only complexes with monovalent cations. All the obtained compounds show potent antiproliferative activity against human cancer cell lines and a good selectivity index for cancer versus mammalian cells. Additionally, 3 compounds showed higher antiproliferative activity against the drug-resistant cancer cells and lower toxicity towards normal cells than those of unmodified salinomycin and standard anticancer drugs such as cisplatin and doxorubicin. Some of the synthesized compounds showed good inhibitory activity against Staphylococcus strains and clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE). These studies show that salinomycin esters are interesting scaffolds for the development of novel anticancer and Gram-positive antibacterial agents.

  4. ForceGen 3D structure and conformer generation: from small lead-like molecules to macrocyclic drugs

    Cleves, Ann E.; Jain, Ajay N.


    We introduce the ForceGen method for 3D structure generation and conformer elaboration of drug-like small molecules. ForceGen is novel, avoiding use of distance geometry, molecular templates, or simulation-oriented stochastic sampling. The method is primarily driven by the molecular force field, implemented using an extension of MMFF94s and a partial charge estimator based on electronegativity-equalization. The force field is coupled to algorithms for direct sampling of realistic physical movements made by small molecules. Results are presented on a standard benchmark from the Cambridge Crystallographic Database of 480 drug-like small molecules, including full structure generation from SMILES strings. Reproduction of protein-bound crystallographic ligand poses is demonstrated on four carefully curated data sets: the ConfGen Set (667 ligands), the PINC cross-docking benchmark (1062 ligands), a large set of macrocyclic ligands (182 total with typical ring sizes of 12-23 atoms), and a commonly used benchmark for evaluating macrocycle conformer generation (30 ligands total). Results compare favorably to alternative methods, and performance on macrocyclic compounds approaches that observed on non-macrocycles while yielding a roughly 100-fold speed improvement over alternative MD-based methods with comparable performance.

  5. Chemodiversity of Ladder-Frame Prymnesin Polyethers in Prymnesium parvum

    Rasmussen, Silas Anselm; Meier, Sebastian; Andersen, Nikolaj Gedsted;


    Blooms of the microalga Prymnesium parvum cause devastating fish kills worldwide, which are suspected to be caused by the supersized ladder-frame polyether toxins prymnesin-1 and -2. These toxins have, however, only been detected from P. parvum in rare cases since they were originally described two......-HRMS) of 10 strains of P. parvum collected worldwide showed that only one strain produced the original prymnesin-1 and -2, whereas four strains produced the novel B-type prymnesin. In total 13 further prymnesin analogues differing in their core backbone and chlorination and glycosylation patterns could...

  6. New functional polyether binders for low vulnerability propellants; Nouveaux liants polyethers fonctionnels pour propergols a faible vulnerabilite

    Moreau-Friot, C.; Eck, G.; Jacob, G.; Chevalier, S.; Golfier, M.; Guengant, Y. [Groupe SNPE Propulsion/ Centre de Recherches du Boucher, 91 - Vert le Petit (France)


    HTPB propellants are widely used in solid rocket propellants. Their slow cook-off behaviour has to be improved because they lead to reactions type IV or V in the MURAT scale. Some work on propellants with polyether binders has shown that they lead to moderate reactions at slow cook-off tests. Work is based on the synthesis of functional polyethers. The objective consists in preparing a hydroxyl terminated polymer with a molecular weight between 1000 and 4000 g.mol{sup -1}, a low viscosity and a correct functionality. The binder, which is composed of a polymer, a plasticizer and a curing system, will be able to give mechanical properties in the use field (between -40 and +60 deg C). The polymer chosen to answer all those characteristics is composed of tetrahydrofuran and ethylene oxide. It is synthesised by cationic ring opening polymerisation in the presence of a diol and an adapted catalyst (BF{sub 3}OEt{sub 2}, HBF{sub 4}, SnCl{sub 4}/AT-..). First polymerizations were carried out of laboratory scale (from 30 g to 200 g). The study consists in varying the nature of catalysts the temperature, the solvent the purification methods and so on. The selected copolymer is chosen from many analysis results of the structure, particularly the average number molecular weight the hydroxyl rate, and the best alternative between a high molecular weight and a correct functionality. The behaviour of the propellant is also important because it will allow a widely scale synthesis or complementary laboratory work. A transfer has permitted to obtain a 10 kg scale. Its characteristics are the same that those of the product obtained at a laboratory scale. Propellants with polyether binder have been tested. The correct viscosity allows a high charge rate, which means energetic propellants. It also has to be noted that the binder does not crystallize. Those propellants have a good mechanistic behaviour in a large field of temperature. They also have a good behaviour at slow cook-off. The

  7. Synthesis and P1' SAR exploration of potent macrocyclic tissue factor-factor VIIa inhibitors

    Ladziata, Vladimir (Uladzimir); Glunz, Peter W.; Zou†, Yan; Zhang, Xiaojun; Jiang, Wen; Jacutin-Porte, Swanee; Cheney, Daniel L.; Wei, Anzhi; Luettgen, Joseph M.; Harper, Timothy M.; Wong, Pancras C.; Seiffert, Dietmar; Wexler, Ruth R.; Priestley, E. Scott (BMS)


    Selective tissue factor-factor VIIa complex (TF-FVIIa) inhibitors are viewed as promising compounds for treating thrombotic disease. In this contribution, we describe multifaceted exploratory SAR studies of S1'-binding moieties within a macrocyclic chemotype aimed at replacing cyclopropyl sulfone P1' group. Over the course of the optimization efforts, the 1-(1H-tetrazol-5-yl)cyclopropane P1' substituent emerged as an improved alternative, offering increased metabolic stability and lower clearance, while maintaining excellent potency and selectivity.

  8. Synthesis and antituberculosis activity of novel unfolded and macrocyclic derivatives of ent-kaurane steviol.

    Khaybullin, Ravil N; Strobykina, Irina Yu; Dobrynin, Alexey B; Gubaydullin, Aidar T; Chestnova, Regina V; Babaev, Vasiliy M; Kataev, Vladimir E


    New derivatives of steviol 1, the aglycone of the glycosides of Stevia rebaudiana, including a novel class of semisynthetic diterpenoids, namely macrocyclic ent-kauranes were synthesized. These compounds possess antituberculosis activity inhibiting the in vitro growth of Mycobacterium Tuberculosis (H37R(V) strain) with MIC 5-20 μg/ml that is close to MIC 1 μg/ml demonstrated by antituberculosis drug isoniazid in control experiment. For the first time it was found that the change of ent-kaurane geometry (as in steviol 1) of tetracyclic diterpenoid skeleton to ent-beyerane one (as in isosteviol 2) influences on antituberculosis activity.

  9. A New Class of Macrocyclic Chiral Selectors for Stereochemical Analysis



    This report summarizes the work accomplished in the authors laboratories over the previous three years. During the funding period they have had 23 monographs published or in press, 1 book chapter, 1 patent issued and have delivered 28 invited seminars or plenary lectures on DOE sponsored research. This report covers the work that has been published (or accepted). The most notable aspect of this work involves the successful development and understanding of a new class of fused macrocyclic compounds as pseudophases and selectors in high performance separations (including high performance liquid chromatography, HPLC; capillary electrophoresis, CE; and thin layer chromatography, TLC). They have considerably extended their chiral biomarker work from amber to crude oil and coal. In the process of doing this we've developed several novel separation approaches. They finished their work on the new GSC-PLOT column which is now being used by researchers world-wide for the analysis of gases, light hydrocarbons and halocarbons. Finally, we completed basic studies on immobilizing a cyclodextrin/oligosiloxane hybrid on the wall of fused silica, as well as a basic study on the separation behavior of buckminster fullerene and higher fullerenes.

  10. Short communication: Macrocyclic lactone residues in butter from Brazilian markets.

    Macedo, Fabio; Marsico, Eliane Teixeira; Conte-Júnior, Carlos Adam; de Almeida Furtado, Leonardo; Brasil, Taila Figueredo; Pereira Netto, Annibal Duarte


    Macrocyclic lactones (ML) are commonly used in drug formulations for the treatment of parasites in cattle. In Brazil, except for drugs (or formulations) with long-term (half-life) effects, ML are registered for use in bovines. Indiscriminate use of ML may result in the presence of residues in milk and dairy products due to their lipophilic properties and thermal stability. This study applied a method of liquid chromatography with fluorimetric detection, recently developed and validated for the determination of residues of abamectin, doramectin, ivermectin, and moxidectin in butter. The method was applied to 38 samples of commercial butter purchased in the metropolitan area of Rio de Janeiro, Brazil, between June and September 2013, analyzed in triplicate. Ivermectin was detected in 89.5% of the samples, with concentrations between 0.3 and 119.4 µg/kg; 76.3% of the samples contained doramectin (0.6 to 64.7 µg/kg) and 55.2% contained abamectin (0.7 to 4.5 µg/kg). Most butter samples (76.3%) contained residues of more than 1 ML; however, no residues of moxidectin were detected. The results showed a high incidence of the presence of avermectins in butter samples. Butter is not included in the Brazilian National Plan for Control of Residues and Contaminants in Animal Products. As ML residues concentrate in lipophilic compounds, butter and other fatty dairy products should be screened for the presence of ML residues.

  11. Parasite infection accelerates age polyethism in young honey bees.

    Lecocq, Antoine; Jensen, Annette Bruun; Kryger, Per; Nieh, James C


    Honey bees (Apis mellifera) are important pollinators and their health is threatened worldwide by persistent exposure to a wide range of factors including pesticides, poor nutrition, and pathogens. Nosema ceranae is a ubiquitous microsporidian associated with high colony mortality. We used lab micro-colonies of honey bees and video analyses to track the effects of N. ceranae infection and exposure on a range of individual and social behaviours in young adult bees. We provide detailed data showing that N. ceranae infection significantly accelerated the age polyethism of young bees, causing them to exhibit behaviours typical of older bees. Bees with high N. ceranae spore counts had significantly increased walking rates and decreased attraction to queen mandibular pheromone. Infected bees also exhibited higher rates of trophallaxis (food exchange), potentially reflecting parasite manipulation to increase colony infection. However, reduction in queen contacts could help bees limit the spread of infection. Such accelerated age polyethism may provide a form of behavioural immunity, particularly if it is elicited by a wide variety of pathogens.

  12. Enantiocontrol in Macrocycle Formation from Catalytic MetalCarbene Transformations

    DOYLE, Michael P.; DOYLE, Michael P; HU, Wen-Hao(胡文浩); 胡文浩


    The development of catalytic metal carbene transformations for the construction of macrocyclic lactones has dramatically increased their synthetic advantages.This is the first review of this developing methodology.

  13. The effect of polyether on the separation of pentlandite and serpentine

    Xiaowen Zhou


    Full Text Available The effect of polyether on the separation of pentlandite from serpentine has been studied. In addition to flotation and sedimentation tests, electrophoresis and adsorption tests have been conducted. The flotation and sedimentation results show that serpentine impairs flotation performance of pentlandite, by adhering to the pentlandite particles. Addition of the polyether could promote the dispersion of the mixed sample of pentlandite and serpentine in alkaline conditions and significantly reduce adverse effects of serpentine on the pentlandite flotation. The electrophoresis and adsorption tests show that polyether can selectively adsorb onto pentlandite surface through hydrophobic reaction and remove serpentine slime particles from pentlandite surfaces by steric hindrance effect.

  14. Surface Heparinization of Poly(ether ether ketone)

    SUN Hui; CHEN Rui-chao; LIU Shu; XU Guo-zhi


    Photo-grafting of hydrophilic monomer and space arms was used to enhance the hydrophilicity of poly(ether ether ketone)(PEEK) with the aim of extending its application to biological fields.PEEK films were surface modified by UV grafting of acrylic acid(AA) to introduce-COOH on PEEK surface.Adipic amine was used as ann to introduce heparin on PEEK surface based on the condensation reaction between -NH2 and -COOH.The modified PEEK(PEEK-COOH,PEEK-NH2 and PEEK-Hep) was characterized by energy-disperse spectroscopy (EDS),X-ray photoelectron spectroscopy(XPS) and water contact angle measurements,which show that heparin was grafted on PEEK surface.The contact angles of modified PEEK films were lower than those of original films,demonstrating a significant improvement of surface hydrophilicity.

  15. Parasite infection accelerates age polyethism in young honey bees

    Lecocq, Antoine; Jensen, Annette Bruun; Kryger, Per


    Honey bees (Apis mellifera) are important pollinators and their health is threatened worldwide by persistent exposure to a wide range of factors including pesticides, poor nutrition, and pathogens. Nosema ceranae is a ubiquitous microsporidian associated with high colony mortality. We used lab...... micro-colonies of honey bees and video analyses to track the effects of N. ceranae infection and exposure on a range of individual and social behaviours in young adult bees. We provide detailed data showing that N. ceranae infection significantly accelerated the age polyethism of young bees, causing...... them to exhibit behaviours typical of older bees. Bees with high N. ceranae spore counts had significantly increased walking rates and decreased attraction to queen mandibular pheromone. Infected bees also exhibited higher rates of trophallaxis (food exchange), potentially reflecting parasite...

  16. Helical peptide-polyamine and -polyether conjugates as synthetic ionophores.

    Benincasa, Monica; Francescon, Marco; Fregonese, Massimo; Gennaro, Renato; Pengo, Paolo; Rossi, Paola; Scrimin, Paolo; Tecilla, Paolo


    Two new synthetic ionophores in which the hydrophobic portion is represented by a short helical Aib-peptide (Aib=α-amino-isobutyric acid) and the hydrophilic one is a poly-amino (1a) or a polyether (1b) chain have been prepared. The two conjugates show a high ionophoric activity in phospholipid membranes being able to efficiently dissipate a pH gradient and, in the case of 1b, to transport Na(+) across the membrane. Bioactivity evaluation of the two conjugates shows that 1a has a moderate antimicrobial activity against a broad spectrum of microorganisms and it is able to permeabilize the inner and the outer membrane of Escherichia coli cells.

  17. In Situ Preparation of Polyether Amine Functionalized MWCNT Nanofiller as Reinforcing Agents

    Ayber Yıldrım


    Full Text Available In situ preparation of polyether amine functionalized cross-linked multiwalled carbon nanotube (MWCNT nanofillers may improve the thermal and mechanical properties of the composites in which they are used as reinforcing agents. The reduction and functionalization of MWCNT using ethylenediamine in the presence of polyether amine produced stitched MWCNT's due to the presence of two amine (–NH2 functionalities on both sides of the polymer. Polyether amine was chosen to polymerize the carboxylated MWCNT due to its potential to form bonds with the amino groups and carboxyl groups of MWCNT which produces a resin used as polymeric matrix for nanocomposite materials. The attachment of the polyether amine (Jeffamine groups was verified by TGA, FT-IR, XRD, SEM, and Raman spectroscopy. The temperature at which the curing enthalpy is maximum, observed by DSC, was shifted to higher values by adding functionalized MWCNT. SEM images show the polymer formation between MWCNT sheets.

  18. [Chiral separation of drugs based on macrocyclic antibiotics using HPLC, supercritical fluid chromatography (SFC) and capillary electrochromatography (CEC)].

    Dungelová, J; Lehotay, J; Rojkovicová, T; Cizmárik, J


    Separation of enantiomers by means of high-performance liquid chromatography (HPLC), supercritical fluid chromatography (SFC), and capillary electrochromatography (CEC) is of great importance in pharmaceutical analyses. In recent years, separation of various types of racemates employs most frequently chiral stationary phases based on macrocyclic antibiotics. This class of chiral selectors includes vancomycin, teikoplanin, ristocetin A, teikoplanin without saccharide components, avoparcin, etc. The review paper describes the properties of selected antibiotics, the effect of chromatographic conditions on enantioselectivity (effect of the composition of the mobile phase, effect of pH of the mobile phase, effect of temperature), and the study of possible mechanisms of interaction, which play an important role in the separation of enantiomers. Examples of the use of macrocyclic antibiotics in the separation of various compounds by means of the HPLC, SFC, and CEC methods follow.

  19. Characterization of the P. Brevis Polyether Neurotoxin Binding Component in Excitable Membranes


    International Conference on Ciguatera . (T. R. Tosteson and D. Ballantyne, Eds.) in press. Baden, D.G. (1991) The Polyether Brevetoxins and Site Five of the...Confomrations and Potency Correlations. Third Intl. Conf. Ciguatera , Puerto Rico 1990. Tosteson, T.R., and Baden, D.G. Polyether Dinoflagellate Toxins...and Caribbean Ciguatera : Correlation of Fish Toxins with Standard Toxins Third International Conference on Ciguatera , Peurto Rico 1990. Baden, D.G




    A chemically modified field-effect transistor (CHEMFET) with satisfactory Ag+ selectivity is described. The potentiometric Ag+ selectivities of CHEMFETs with plasticized PVC membranes based on macrocyclic thioethers have been determined. All the macrocyclic thioethers tested showed silver response a

  1. Salinomycin Hydroxamic Acids: Synthesis, Structure, and Biological Activity of Polyether Ionophore Hybrids.

    Borgström, Björn; Huang, Xiaoli; Chygorin, Eduard; Oredsson, Stina; Strand, Daniel


    The polyether ionophore salinomycin has recently gained attention due to its exceptional ability to selectively reduce the proportion of cancer stem cells within a number of cancer cell lines. Efficient single step strategies for the preparation of hydroxamic acid hybrids of this compound varying in N- and O-alkylation are presented. The parent hydroxamic acid, salinomycin-NHOH, forms both inclusion complexes and well-defined electroneutral complexes with potassium and sodium cations via 1,3-coordination by the hydroxamic acid moiety to the metal ion. A crystal structure of an cationic sodium complex with a noncoordinating anion corroborates this finding and, moreover, reveals a novel type of hydrogen bond network that stabilizes the head-to-tail conformation that encapsulates the cation analogously to the native structure. The hydroxamic acid derivatives display down to single digit micromolar activity against cancer cells but unlike salinomycin selective reduction of ALDH(+) cells, a phenotype associated with cancer stem cells was not observed. Mechanistic implications are discussed.

  2. Study of distillation and degradation of perfluoro polyether; Estudo da destilacao e degradacao do perfluoropolieter

    Lopergolo, Lilian Cristine


    Perfluoro-polyethers, PFPE, were first synthesised by Sianesi and collaborators giving rise to a new lubricant oils and greases classes with several applications. Perfluoro polyethers have excellent properties, for instance: high chemical stability and thermal stability, high density, high radiation resistance and excellent lubricating properties. FOMBLIN-Y oil is one of the perfluoro polyethers used as a lubricant in vacuum systems applied in the UF{sub 6} enrichment installations. Due to its excellent properties and for its applications in the nuclear field, IPEN-CNEN/S P had the interest to dominate its production technology with the aim to substitute the commercial FOMBLIN-Y oil used in the national consumption. The FOMBLIN-Y oil synthesis method, adopted in IPEN-CNEN/S P, made by the photooxidation of the hexa fluoro propylene. In this work we study the fraction separation of the national available production with restricted an increased molecular weights which was obtained by fraction distillation in a vacuum according to the ASTM D-1160 norm. We also study the catalytic effect of metals on the thermal stability of perfluoro polyethers. The inertness of perfluoro polyethers at temperatures higher than 300 deg C is strongly affected by presence of some metals. Al and Ti alloys cause fluid degradation at 250 deg C. This degradation is very important because it has a yield increase of the perfluoro polyethers production. (author)

  3. Macrocyclic Assembly: A Dive into the Pecking Order and Applied Aspects of Multitalented Metallomacrocycles

    Ashu Chaudhary


    Full Text Available To aid in knowledge of macrocyclic complexes and biomedical scientists, we are presenting here a review article with compilation of work done so far along in relation to macrocyclic ligands and their metal complexes. The metal ion chemistry of macrocyclic ligands has now become a major subdivision of coordination chemistry. This overview focuses on developments in design, synthesis, and self-assembly of metal-based architectures and ligands related to macrocyclic chemistry.

  4. Surface modification of carbon fibers by a polyether sulfone emulsion sizing for increased interfacial adhesion with polyether sulfone

    Yuan, Haojie [National Engineering Laboratory for Carbon Fiber Technology, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Shouchun, E-mail: [National Engineering Laboratory for Carbon Fiber Technology, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China); Lu, Chunxiang [National Engineering Laboratory for Carbon Fiber Technology, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China)


    Highlights: • A polyether sulfone emulsion (PES) sizing was prepared for the first time. • The sizing enhanced the surface activity and wettability of carbon fibers. • Compared to the original sizing, the PES emulsion sizing resulted in an 18.4% increase in the interlaminar shear strength of carbon fiber/PES composites. • Important influences of emulsifier on the fiber surface and composite interface were demonstrated. • The reinforcing mechanisms are the improved fiber surface wettability and interfacial compatibility in composites. - Abstract: Interests on carbon fiber-reinforced thermoplastic composites are growing rapidly, but the challenges with poor interfacial adhesion have slowed their adoption. In this work, a polyether sulfone (PES) emulsion sizing was prepared successfully for increased interfacial adhesion of carbon fiber/PES composites. To obtain a high-quality PES emulsion sizing, the key factor, emulsifier concentration, was studied by dynamic light scattering technique. The results demonstrated that the suitable weight ratio of PES to emulsifier was 8:3, and the resulting PES emulsion sizing had an average particle diameter of 117 nm and Zeta potential of −52.6 mV. After sizing, the surface oxygen-containing functional groups, free energy and wettability of carbon fibers increased significantly, which were advantageous to promote molecular-level contact between carbon fiber and PES. Finally, short beam shear tests were performed to evaluate the interfacial adhesion of carbon fiber/PES composites. The results indicated that PES emulsion sizing played a critical role for the enhanced interfacial adhesion in carbon fiber/PES composites, and a 26% increase of interlaminar shear strength was achieved, because of the improved fiber surface wettability and interfacial compatibility between carbon fiber and PES.

  5. Macrocyclic Hepatitis C Virus NS3/4A Protease Inhibitors: An Overview of Medicinal Chemistry.

    Pillaiyar, Thanigaimalai; Namasivayam, Vigneshwaran; Manickam, Manoj


    Hepatitis C virus (HCV) is a causative agent of hepatitis C infectious disease that primarily affects the liver, ranging in severity from a mild illness lasting a few weeks to a lifelong illness. The 9.6 kb RNA genome of HCV encodes approximately 3000 amino acid polyprotein that must be processed by host and viral proteases into both structural (S) and non-structural (NS) proteins, respectively. Targeting the serine protease NS3 with an activating factor NS4A, i.e., NS3/4A has been considered as one of the most attractive targets for the development of anti-HCV therapy. Although there is no vaccine available, antiviral medicines cure approximately 90% of the persons with hepatitis C infection. On the other hand, efficacy of these medications can be hampered due to the rapid drug and cross resistances. To date, all developed HCV NS3/4A inhibitors are mainly peptide-based compounds derived from the cleavage products of substrate. Specifically macrocyclic peptidomimetics have rapidly emerged as a classical NS3/4A protease inhibitors for treating the HCV infection. This review highlights the development of macrocyclic anti-HCV NS3/4A protease, as well as clinically important inhibitors developed from linear peptides, discovered during the last 12 years (2003-2015) from all sources, including laboratory synthetic methods, virtual screening and structure-based molecular docking studies. We emphasize the rationale behind the design, study of structure-activity relationships, and mechanism of inhibitions and cellular effect of the macrocyclic inhibitors.

  6. Control of olefin geometry in macrocyclic ring-closing metathesis using a removable silyl group.

    Wang, Yikai; Jimenez, Miguel; Hansen, Anders S; Raiber, Eun-Ang; Schreiber, Stuart L; Young, Damian W


    Introducing a silyl group at one of the internal olefin positions in diolefinic substrates results in E-selective olefin formation in macrocyclic ring-forming metathesis. The application of this method to a range of macrocyclic (E)-alkenylsiloxanes is described. Protodesilylation of alkenylsiloxane products yields novel Z-configured macrocycles.

  7. Dereplication of macrocyclic trichothecenes from extracts of filamentous fungi through UV and NMR profiles.

    Sy-Cordero, Arlene A; Graf, Tyler N; Wani, Mansukh C; Kroll, David J; Pearce, Cedric J; Oberlies, Nicholas H


    Macrocyclic trichothecenes (MTs), which have potent cytotoxicity, have been isolated from many different fungal species. These compounds were evaluated clinically by the US National Cancer Institute in the 1970s and 1980s. However, they have yet to be advanced into viable drugs because of severe side effects. Our team is investigating a diverse library of filamentous fungi for new anticancer leads. To avoid reisolating MTs through bioactivity-directed fractionation studies, a protocol for their facile dereplication was developed. The method uses readily available photodiode array detectors to identify one of two types of characteristic UV spectra for these compounds. In addition, diagnostic signals can be observed in the (1)H-NMR spectra, particularly for the epoxide and conjugated diene moieties, even at the level of a crude extract. Using these techniques in a complementary manner, MTs can be dereplicated rapidly.

  8. Macrocycle synthesis by trimerization of boronic acids around a hexaol template, and recognition of polyols by resulting macrocyclic oligoboronic acids.

    Stoltenberg, Dennis; Lüning, Ulrich


    2,6-Bis(alkenyloxy) substituted arylboronic acids can be cyclotrimerized with the help of a hexaol as a template. First, the boronic acids are assembled by boronic ester formation with hexahydroxy-bicyclo[2.2.2]octane. Next, the resulting triboronates are cyclized by ring-closing metathesis to yield trimacrocycles as diastereomeric E/Z mixtures. Catalytic hydrogenation yields a single saturated trimacrocycle. Cleavage of the boronic ester functions liberates the template and generates a macrocycle with three boronic acid functionalities in endo-orientation. Due to this preorganization, macrocycles with boronic acids in endo-positions are good receptors for polyols. The binding of carbohydrates such as fructose was compared with the uptake of the respective templates into macrocycles with two or three boronic acids in endo-orientation.

  9. Discrete and Polymeric, Mono- and Dinuclear Silver Complexes of a Macrocyclic Tetraoxime Ligand with AgI–AgI Interactions

    Mitsuhiko Shionoya


    Full Text Available Macrocyclic compounds that can bind cationic species efficiently and selectively with their cyclic cavities have great potential as excellent chemosensors for metal ions. Recently, we have developed a tetraoxime-type tetraazamacrocyclic ligand 1 formed through a facile one-pot cyclization reaction. Aiming to explore and bring out the potential of the tetraoxime macrocycle 1 as a chelating sensor, we report herein the preparation of several kinds of silver complexes of 1 and their unique coordination structures determined by single-crystal X-ray diffraction analyses. As a result, the formation of two kinds of discrete structures, monomeric complexes [Ag(1X] (X = counter anions and a dimeric complex [Ag2(12]X2, and two kinds of polymeric structures from a mononuclear complex, [Ag(1]nXn, and from a dinuclear complex, [Ag2(1X2]n, was demonstrated. In the resulting complexes, the structurally flexible macrocyclic ligand 1 was found to provide several different coordination modes. Notably, in some silver complexes of 1, AgI–AgI interactions were observed with different AgI–AgI distances which depend on the kind of counter anions and the chemical composition.

  10. Potent macrocyclic inhibitors of insulin-regulated aminopeptidase (IRAP) by olefin ring-closing metathesis.

    Andersson, Hanna; Demaegdt, Heidi; Johnsson, Anders; Vauquelin, Georges; Lindeberg, Gunnar; Hallberg, Mathias; Erdelyi, Mate; Karlen, Anders; Hallberg, Anders


    Macrocyclic analogues of angiotensin IV (Ang IV, Val(1)-Tyr(2)-Ile(3)-His(4)-Pro(5)-Phe(6)) targeting the insulin-regulated aminopeptidase (IRAP) have been designed, synthesized, and evaluated biologically. Replacement of His(4)-Pro(5)-Phe(6) by a 2-(aminomethyl)phenylacetic acid (AMPAA) moiety and of Val(1) and Ile(3) by amino acids bearing olefinic side chains followed by macrocyclization provided potent IRAP inhibitors. The impact of the ring size and the type (saturated versus unsaturated), configuration, and position of the carbon-carbon bridge was assessed. The ring size generally affects the potency more than the carbon-carbon bond characteristics. Replacing Tyr(2) by β(3)hTyr or Phe is accepted, while N-methylation of Tyr(2) is deleterious for activity. Removal of the carboxyl group in the C-terminal slightly reduced the potency. Inhibitors 7 (K(i) = 4.1 nM) and 19 (K(i) = 1.8 nM), both encompassing 14-membered ring systems connected to AMPAA, are 10-fold more potent than Ang IV and are also more selective over aminopeptidase N (AP-N). Both compounds displayed high stability against proteolysis by metallopeptidases.

  11. The ex vivo neurotoxic, myotoxic and cardiotoxic activity of cucurbituril-based macrocyclic drug delivery vehicles.

    Oun, Rabbab; Floriano, Rafael S; Isaacs, Lyle; Rowan, Edward G; Wheate, Nial J


    The cucurbituril family of drug delivery vehicles have been examined for their tissue specific toxicity using ex vivo models. Cucurbit[6]uril (CB[6]), cucurbit[7]uril (CB[7]) and the linear cucurbituril-derivative Motor2 were examined for their neuro-, myo- and cardiotoxic activity and compared with β-cyclodextrin. The protective effect of drug encapsulation by CB[7] was also examined on the platinum-based anticancer drug cisplatin. The results show that none of the cucurbiturils have statistically measurable neurotoxicity as measured using mouse sciatic nerve compound action potential. Cucurbituril myotoxicity was measured by nerve-muscle force of contraction through chemical and electrical stimulation. Motor2 was found to display no myotoxicity, whereas both CB[6] and CB[7] showed myotoxic activity via a presynaptic effect. Finally, cardiotoxicity, which was measured by changes in the rate and force of right and left atria contraction, was observed for all three cucurbiturils. Free cisplatin displays neuro-, myo- and cardiotoxic activity, consistent with the side-effects seen in the clinic. Whilst CB[7] had no effect on the level of cisplatin's neurotoxic activity, drug encapsulation within the macrocycle had a marked reduction in both the drug's myo- and cardiotoxic activity. Overall the results are consistent with the relative lack of toxicity displayed by these macrocycles in whole animal acute systemic toxicity studies and indicate continued potential of cucurbiturils as drug delivery vehicles for the reduction of the side effects associated with platinum-based chemotherapy.

  12. Yessotoxins, a Group of Marine Polyether Toxins: an Overview

    José J. Fernández


    Full Text Available Yessotoxin (YTX is a marine polyether toxin that was first isolated in 1986 from the scallop Patinopecten yessoensis. Subsequently, it was reported that YTX is produced by the dinoflagellates Protoceratium reticulatum, Lingulodinium polyedrum and Gonyaulax spinifera. YTXs have been associated with diarrhetic shellfish poisoning (DSP because they are often simultaneously extracted with DSP toxins, and give positive results when tested in the conventional mouse bioassay for DSP toxins. However, recent evidence suggests that YTXs should be excluded from the DSP toxins group, because unlike okadaic acid (OA and dinophyisistoxin-1 (DTX-1, YTXs do not cause either diarrhea or inhibition of protein phosphatases . In spite of the increasing number of molecular studies focused on the toxicity of YTX, the precise mechanism of action is currently unknown. Since the discovery of YTX, almost forty new analogues isolated from both mussels and dinoflagellates have been characterized by NMR or LC-MS/MS techniques. These studies indicate a wide variability in the profile and the relative abundance of YTXs in both, bivalves and dinoflagellates. This review covers current knowledge on the origin, producer organisms and vectors, chemical structures, metabolism, biosynthetic origin, toxicological properties, potential risks to human health and advances in detection methods of YTXs.

  13. Trace Level Determination of Polyether Ionophores in Feed

    Mervi Rokka


    Full Text Available A liquid chromatography-mass spectrometric method was developed and validated to determine six polyether ionophores (lasalocid sodium, monensin sodium, salinomycin sodium, narasin, maduramicin ammonium alpha, and semduramicin sodium in feed samples. The method developed was very straightforward, involving extraction with 84% acetonitrile of the coccidiostats from the feed samples and filtration of the raw extract prior to chromatographic analysis. Method validation included the determination of selectivity, linearity, specificity, repeatability, the limit of detection, limit of quantification, decision limit (CCα, detection capability (CCβ, and recovery. Feed samples from the Finnish national feed control programme and suspected carry-over samples from a feed manufacturer were analysed in parallel with an existing liquid chromatography method coupled with ultraviolet detection. All feed control samples were negative in LC-UV, but with the developed MS method, monensin, salinomycin, and narasin were detected at concentrations of <0.025–0.73 mg/kg, <0.025–0.027 mg/kg, and <0.025–1.6 mg/kg, respectively. In suspected carry-over samples after an output of 2.0 tonnes of unmedicated feed in the pelletizer line, the concentrations of monensin, salinomycin, and narasin varied from undetected to 16 mg/kg. In the mixer line, after 3.2 tonnes of unmedicated feed output, the concentrations of monensin, salinomycin, and narasin varied from undetected to 2.4 mg/kg.

  14. High Resolution Mass Spectrometry of Polyfluorinated Polyether-Based Formulation

    Dimzon, Ian Ken; Trier, Xenia; Frömel, Tobias; Helmus, Rick; Knepper, Thomas P.; de Voogt, Pim


    High resolution mass spectrometry (HRMS) was successfully applied to elucidate the structure of a polyfluorinated polyether (PFPE)-based formulation. The mass spectrum generated from direct injection into the MS was examined by identifying the different repeating units manually and with the aid of an instrument data processor. Highly accurate mass spectral data enabled the calculation of higher-order mass defects. The different plots of MW and the nth-order mass defects (up to n = 3) could aid in assessing the structure of the different repeating units and estimating their absolute and relative number per molecule. The three major repeating units were -C2H4O-, -C2F4O-, and -CF2O-. Tandem MS was used to identify the end groups that appeared to be phosphates, as well as the possible distribution of the repeating units. Reversed-phase HPLC separated of the polymer molecules on the basis of number of nonpolar repeating units. The elucidated structure resembles the structure in the published manufacturer technical data. This analytical approach to the characterization of a PFPE-based formulation can serve as a guide in analyzing not just other PFPE-based formulations but also other fluorinated and non-fluorinated polymers. The information from MS is essential in studying the physico-chemical properties of PFPEs and can help in assessing the risks they pose to the environment and to human health.

  15. A research on polyether glycol replaced APCP rocket propellant

    Lou, Tianyou; Bao, Chun Jia; Wang, Yiyang


    Ammonium perchlorate composite propellant (APCP) is a modern solid rocket propellant used in rocket vehicles. It differs from many traditional solid rocket propellants by the nature of how it is processed. APCP is cast into shape, as opposed to powder pressing it with black powder. This provides manufacturing regularity and repeatability, which are necessary requirements for use in the aerospace industry. For traditional APCP, ingredients normally used are ammonium peroxide, aluminum, Hydroxyl-terminated polybutadiene(HTPB), curing agency and other additives, the greatest disadvantage is that the fuel is too expensive. According to the price we collected in our country, a single kilogram of this fuel will cost 200 Yuan, which is about 35 dollars, for a fan who may use tons of the fuel in a single year, it definitely is a great deal of money. For this reason, we invented a new kind of APCP fuel. Changing adhesive agency from cross-linked htpb to cross linked polyether glycol gives a similar specific thrust, density and mechanical property while costs a lower price.

  16. Bitemark analysis: Use of polyether in evidence collection, conservation, and comparison

    Gabriel M Fonseca


    Full Text Available Background: While bitemarks are categorical identification evidence, the dynamics of biting, the anatomical location of the bite, and failures in wound records can introduce distorted images and mislead crime investigation. Materials and Methods: In this study, 20 bitemarks were performed on dead pig skin and subsequently photographed, excised, conserved, and analyzed using digital comparison (Adobe Photoshop™ 8.0, following the standard procedures (ABFO; physical comparison was also done using polyether (Impregum™; 3M casts. Study plaster casts of the upper and lower jaws of each subject were taken using type IV yellow densite stone. Polyether was used as impression material to obtain bitemarks, and casts were made from densite stone and polyether. Results: Because of its elasticity, polyether casts can compensate for primary or secondary distortions, so that there is a better degree of match when positioning the subject′s dental cast. Conclusion: Polyether is an alternative impression material and is an excellent option for creating positive casts of the wound for physical dynamic comparison.

  17. Rigid, Conjugated Macrocycles for High Performance Organic Photodetectors.

    Zhang, Boyuan; Trinh, M Tuan; Fowler, Brandon; Ball, Melissa; Xu, Qizhi; Ng, Fay; Steigerwald, Michael L; Zhu, X-Y; Nuckolls, Colin; Zhong, Yu


    Organic photodetectors (OPDs) are attractive for their high optical absorption coefficient, broad wavelength tunability, and compatibility with lightweight and flexible devices. Here we describe a new molecular design that enables high performance organic photodetectors. We use a rigid, conjugated macrocycle as the electron acceptor in devices to obtain high photocurrent and low dark current. We make a direct comparison between the devices made with the macrocyclic acceptor and an acyclic control molecule; we find that the superior performance of the macrocycle originates from its rigid, conjugated, and cyclic structure. The macrocycle's rigid structure reduces the number of charged defects originating from deformed sp(2) carbons and covalent defects from photo/thermoactivation. With this molecular design, we are able to suppress dark current density while retaining high responsivity in an ultrasensitive nonfullerene OPD. Importantly, we achieve a detectivity of ∼10(14) Jones at near zero bias voltage. This is without the need for extra carrier blocking layers commonly employed in fullerene-based devices. Our devices are comparable to the best fullerene-based photodetectors, and the sensitivity at low working voltages (<0.1 V) is a record for nonfullerene OPDs.

  18. Magnetism in (Semi)Conducting Macrocycles of pi conjugated Polymers


    estimation of the chain length or the number of repetitive thiophene units, which were for the four samples 18, 25, 33 and 42. The formyl moieties at...leading to radicals , which can associate together. Scheme 5: Synthetic pathway of fully thiophenic bridged macrocycle by oxidative

  19. Flexible macrocycles as versatile supports for catalytically active metal clusters

    Ryan, JD; Gagnon, KJ; Teat, SJ; McIntosh, RD


    Here we present three structurally diverse clusters stabilised by the same macrocyclic polyphenol; t-butylcalix[8]arene. This work demonstrates the range of conformations the flexible ligand is capable of adopting, highlighting its versatility in metal coordination. In addition, a Ti complex displays activity for the ring-opening polymerisation of lactide

  20. Synthesis of macrocyclic lactones with methoxysulfonyl side chain

    Chuan Jin Hou; Xiao Mei Liang; Jing Ping Wu; Dao Quan Wang


    Two representative macrocyclic lactones with methoxysulfonyl side chain (5a and 5b) were synthesized employing Michael addition with acrolein and ring enlargement as the key steps,starting from potassium a-oxocycloalkylsulfonates (1) in total yields of 45 and 57%,respectively.

  1. Synthesis of new diverse macrocycles from diol precursors

    Madsen, Charlotte Marie; Hansen, Martin; Thrane, Marie V.;


    The formation of a library of diverse macrocycles with different ring sizes from two easily accessible building blocks is presented. Reacting diol precursors with electrophilic reagents lead to 17-membered sulfites and 19-membered malonates in 34–79% yield. Double-reductive amination of dialdehyd...

  2. Schiff base oligopyrrolic macrocycles as ligands for lanthanides and actinides

    Sessler, Jonathan L. [Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, 1 University Station A5300, University of Texas at Austin, Austin, TX 78712-0165 (United States)]. E-mail:; Melfi, Patricia J. [Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, 1 University Station A5300, University of Texas at Austin, Austin, TX 78712-0165 (United States); Tomat, Elisa [Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, 1 University Station A5300, University of Texas at Austin, Austin, TX 78712-0165 (United States); Callaway, Wyeth [Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, 1 University Station A5300, University of Texas at Austin, Austin, TX 78712-0165 (United States); Huggins, Michael T. [Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, 1 University Station A5300, University of Texas at Austin, Austin, TX 78712-0165 (United States); Gordon, Pamela L. [C-Chemistry and NMT-Nuclear Materials Technology Divisions, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Webster Keogh, D. [C-Chemistry and NMT-Nuclear Materials Technology Divisions, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Date, Richard W. [Department of Chemistry, University of Exeter, Stocker Road, Exeter EX4 4QD (United Kingdom); Bruce, Duncan W. [Department of Chemistry, University of Exeter, Stocker Road, Exeter EX4 4QD (United Kingdom); Department of Chemistry, University of York, Heslington, YORK YO10 5DD (United Kingdom); Donnio, Bertrand [Institut de Physique et Chimie des Materiaux de Strasbourg (IPCMS), Groupe des Materiaux Organiques (GMO), CNRS-ULP - UMR 7504, 23 rue du Loess BP 43, F-67034 Strasbourg Cedex 2 (France)


    The coordination of f-block cations with Schiff base oligopyrrolic macrocycles is discussed. Analysis of the mesophase of a uranyl 2,5-diformylpyrrole-derived expanded porphyrin complex through temperature-dependent X-ray diffraction (XRD) methods has provided evidence for liquid-crystalline properties, and for molecular stacking into columns, arranged in a 2D hexagonal lattice. In separate studies, UV-vis spectral analysis has indicated the formation of three new f-block oligopyrrolic complexes. Addition of neptunyl ([NpO{sub 2}]{sup 2+}) or plutonyl ([PuO{sub 2}]{sup 2+}) chloride salts to the free base of a dipyrromethane-derived Schiff base macrocycle induces an immediate spectral change, namely the growth of a Q-like band at 630 nm. Such changes in the absorption spectra cause a dramatic color change from pale yellow to blue. It is postulated that oxidation of this macrocycle, stimulated by reduction of the metal center, leads to the observed spectral changes. An immediate visible and spectral change is also observed with the reaction of lutetium silylamide (Lu[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 3}), with a different, tetrapyrrole-containing Schiff base macrocycle. In this case, the formation of a complex with 1:1 metal-to-ligand binding stoichiometry is further supported by MALDI-TOF mass spectrometry.

  3. Synthesis and Biological Activities of Some New (Nα-Dinicotinoyl- bis-L-Leucyl Linear and Macrocyclic Peptides

    Suzan Khayyat


    Full Text Available A series of linear and macrocyclic peptides 3–12 were synthesized using 3,5-pyridinedicarboxylic acid (1 as starting material and screened for their antimicrobial, anti-inflammatory and anticancer activities. Bis-ester 3 was prepared from 1 and L-leucine methyl ester. Hydrazinolysis and hydrolysis of dipeptide methyl ester 3 with hydrazine hydrate or 1 N sodium hydroxide afforded compounds 4 and 5, respectively. Cyclization of the dipeptide 5 with L-lysine methyl ester afforded cyclic pentapeptide ester 6. Compounds 7–9 were synthesized by reacting hydrazide 4 with phthalic anhydride, 1,8-naphthalene anhydride or acetophenone derivatives. Treatment of acid hydrazide 4 with aromatic aldehydes or tetraacid dianhydrides afforded the corresponding bis-dipeptide hydrazones 10a–e and macrocyclic peptides 11 and 12, respectively. The structures of newly synthesized compounds were confirmed by IR, 1H-NMR, MS spectral data and elemental analysis. The detailed synthesis, spectroscopic data, biological and pharmacological activities of the synthesized compounds was reported.

  4. Preparation and characterization of monovalent ion selective cation exchange membranes based on sulphonated poly(ether ether ketone)

    Balster, J.H.; Krupenko, O.; Krupenko, O.; Punt, Ineke G.M.; Stamatialis, Dimitrios; Wessling, Matthias


    This paper analyses the separation properties of various commercial cation exchange membranes (CEMs) and tailor made membranes based on sulphonated poly(ether ether ketone) and poly(ether sulphone) for binary electrolyte solutions containing protons and calcium ions. All membranes are thoroughly

  5. Preparation and characterisation of monovalent ion selective cation exchange membranes based on sulphonated poly(ether ether ketone)

    Balster, J.; Krupenko, O.; Punt, I.G.M.; Stamatialis, D.; Wessling, M.


    This paper analyses the separation properties of various commercial cation exchange membranes (CEMs) and tailor made membranes based on sulphonated poly(ether ether ketone) and poly(ether sulphone) for binary electrolyte solutions containing protons and calcium ions. All membranes are thoroughly cha

  6. Ammonium Y zeolite applied as a thermochemolysis reagent for identification of polyethers and polyesters.

    Blazsó, Marianne; Bozi, János


    A potential thermochemolysis reagent has been tested for the pyrolysis gas chromatographic identification of polyether, polyester and polyether- or polyester-based thermoplastic polyurethane. The main advantage of ammonium Y zeolite over liquid reagents is that it does not react prior to pyrolysis, and its reactions have no incomplete products. The procedure of the thermochemolysis is as simple as running a pyrolysis-GC/MS analysis sampling a powder mixture of roughly equal mass of polymer and ammonium Y zeolite. The GC/MS chromatograms obtained show that the products of thermochemolysis are specific to the diol and dicarboxylic units of the polymer. It was observed that ethanal or 1,4-dioxane forms from ethylene oxide components of polyethers and polyesters, tetrahydrofuran from butylene oxide units, hexanedinitrile from adipate groups, and benzodinitrile from terephthalate groups.

  7. Compression-induced transformation of aldehydes into polyethers: a first-principles molecular dynamics study.

    Mosey, Nicholas J


    First-principles molecular dynamics simulations are used to investigate the behavior of bulk acetaldehyde (MeCHO) under conditions of increasing pressure. The results demonstrate that increasing pressure causes the aldehydes to polymerize, yielding polyethers through a process involving the rapid formation of C-O bonds between multiple neighboring MeCHO molecules. Attempts to induce polyether formation at different densities through the application of geometric constraints show that polymerization occurs only once a critical density of approximately 1.7 g/cm(3) has been reached. The results of simulations performed at several different temperatures are also consistent with a process that is induced by reaching a critical density. The origins of this effect are rationalized in terms of the structural requirements for the formation of C-O bonds between multiple MeCHO molecules in rapid succession. Specifically, the collective formation of C-O bonds requires the typical distance between the sp(2) carbon atoms and oxygen atoms in neighboring MeCHO molecules to reach a value of approximately 2.5 A. Radial distribution functions calculated at different densities show that this structural requirement is reached when the density is near the observed threshold. The observed reaction may be useful in the context of lubrication, with polyethers being effective lubricants and the extreme conditions experienced in sliding contacts providing the ability to reach the high densities needed to induce the reaction. In this context, the calculations indicate that polyether formation is associated with significant energy dissipation, while energy dissipation is minimal once the polyethers are formed. Furthermore, the polyethers are stable with respect to multiple compression/decompression cycles and pressures of at least 60 GPa.

  8. Synthesis and Mesophase Properties of Intraanular Functionized Shape-persistent Macrocycles Containing Dibenzo [fg,op] naphthacenes


    On the basis of the C-C coupling reactions of dibenzo [ fg, op ] naphthacene bistriflate, which was obtained by the condensation of phenylacetates with 4-aryl-2,6-bis(2-bromo-4-methoxy-phenyl) pyrylium salts followed by palladium-catalyzed dehydrohalogenation, three shape-persistent macrocycles with dibenzonaphthacene corner pieces, a nanometer interior void, and intraanular oligoalkyl side groups were synthesized by the oxidative cyclization of the corresponding bisacetylenes under high-dilution conditions. Their thermotropic liquid crystalline properties were investigated by using polarizing microscopy and differential scanning calorimetry. All the three compounds showed nematic mesophases and belonged to discotic liquid crystals with inverted topology.

  9. Nitrogen macrocyclic molecules for sequestering of heavy metals; Molecules macrocycliques azotees pour la sequestration de metaux lourds

    Chollet, H. [CEA Valduc, 21 - Is-sur-Tille (France); Denat, F.; Guilard, R. [Universite de Bourgogne, LIMSAG, 21 - Dijon (France)


    The tetra-aza-macrocycles and their derivatives have interesting properties in many fields, in particular for heavy metal extraction. Indeed, these ligands are able to complex many metals like uranium, plutonium, americium, cadmium, lead, etc. We describe the evolutions of design of these molecules since a score of years: simplifications of the synthesis leading to the improvement of the outputs, use of intermediate compounds facilitating the transposition at an industrial scale of the production of such molecules. The physicochemical behaviour of these ligands with respect to lanthanides and actinides, and their use within various processes of treatment are evoked. (authors)

  10. Synthesis and properties of new bolaform and macrocyclic galactose-based surfactants obtained by olefin metathesis.

    Satgé, Céline; Granet, Robert; Verneuil, Bernard; Champavier, Yves; Krausz, Pierre


    A series of galactose-based surfactants with various structures likely to display new interesting properties were synthesized. Four monocatenary surfactants were elaborated by microwave-assisted galactosylation of undecanol or 10-undecenol. These compounds were slightly soluble in water. Their tensioactive properties were determined at 45 degrees C. Olefin metathesis was used to synthesize the two single-chain bolaforms from undec-10-enyl galactopyranosides; two pseudomacrocyclic bolaforms were prepared by grafting two carbamates at O-4 and O-4' sugar positions of the single-chain bolaforms. These four surfactants are insoluble in water and undergo monolayer compression. Cyclization of these bolaforms by olefin metathesis led to macrocyclic surfactant analogues of archaeobacterial membrane components.

  11. An investigation of the preparation of high molecular weight perfluorocarbon polyethers

    Watts, R. O.; Tarrant, P.


    High molecular weight perfluorocarbon polyether gums were obtained by photolysis of perfluorodienes and discyl fluorides containing a perfluorocarbon polyether backbond. The materials obtained are represented by chemical formulas. A method was developed whereby reactive acyl fluoride and trifluorovinyl end groups are converted into inert structures. In order to investigate the possible preparation of difunctional molecules which may be useful in polymer synthesis, the reactions of hexafluoropropene oxide (HFPO) with Grignard and organolithium reagents have been studied. Reactions of various nucleophilic reagents with HFPO were also investigated.

  12. Synthesis and Characterization of Poly(ether amide)s Containing Bisphthalazinone and Ether Linkages

    Cheng LIU; Shou Hai ZHANG; Ming Jing WANG; Qi Zhen LIANG; Xi Gao JIAN


    A novel aromatic diacid, 4, 4'-bis[2-(4-carboxyphenyl)phthalazin-1-one-4-yl]-bisphenyl ether Ⅲ, containing bisphthalazinone and ether linkages was prepared from nucleophilic substitution of p-chlorobenzonitrile with the bisphenol-like monomer Ⅰ, followed by alkaline hydrolysis of the intermediate dinitrile Ⅱ. A series of poly(ether amide)s containing bisphthalazinone and ether linkages derived from diacid Ⅲ and aromatic diamines were synthesized by one-step solution condensation polymerization using triphenyl phosphite and pyridine as condensing agents. Moreover, the properties of poly(ether amide)s including thermal stability,solubility and crystallinity were also studied.

  13. A thin film degradation study of a fluorinated polyether liquid lubricant using an HPLC method

    Morales, W.


    A High Pressure Liquid Chromatography (HPLC) separation method was developed to study and analyze a fluorinated polyether fluid which is promising liquid lubricant for future applications. This HPLC separation method was used in a preliminary study investigating the catalytic effect of various metal, metal alloy, and ceramic engineering materials on the degradation of this fluid in a dry air atmosphere at 345 C. Using a 440 C stainless steel as a reference catalytic material it was found that a titanium alloy and a chromium plated material degraded the fluorinated polyether fluid substantially more than the reference material.


    LI Zhenyi; ZHU Jin


    Some physical properties of the polyester-polyether multiblock copolymers with Si-containing hard segment were further examined by a series of physical methods. The hydrophobicity of the copolymers was improved with the incorporation of increasing amount of orgauosilicone, XPS test proved that silicon element was enriched at the surface of the Si-containing polyester-polyether copolymers. It was also found that their heat resistance and gas permeability for O2 and N2 were greatly improved. The study on semipermeability of films made of the Si-containing copolymers was also followed with interest.

  15. Chemical Editing of Macrocyclic Natural Products and Kinetic Profiling Reveal Slow, Tight-Binding Histone Deacetylase Inhibitors with Picomolar Affinities.

    Kitir, Betül; Maolanon, Alex R; Ohm, Ragnhild G; Colaço, Ana R; Fristrup, Peter; Madsen, Andreas S; Olsen, Christian A


    Histone deacetylases (HDACs) are validated targets for treatment of certain cancer types and play numerous regulatory roles in biology, ranging from epigenetics to metabolism. Small molecules are highly important as tool compounds for probing these mechanisms as well as for the development of new medicines. Therefore, detailed mechanistic information and precise characterization of the chemical probes used to investigate the effects of HDAC enzymes are vital. We interrogated Nature's arsenal of macrocyclic nonribosomal peptide HDAC inhibitors by chemical synthesis and evaluation of more than 30 natural products and analogues. This furnished surprising trends in binding affinities for the various macrocycles, which were then exploited for the design of highly potent class I and IIb HDAC inhibitors. Furthermore, thorough kinetic investigation revealed unexpected inhibitory mechanisms of important tool compounds as well as the approved drug Istodax (romidepsin). This work provides novel inhibitors with varying potencies, selectivity profiles, and mechanisms of inhibition and, importantly, affords insight into known tool compounds that will improve the interpretation of their effects in biology and medicine.

  16. Functional materials from self-assembled bis-urea macrocycles.

    Shimizu, Linda S; Salpage, Sahan R; Korous, Arthur A


    CONSPECTUS: This Account highlights the work from our laboratories on bis-urea macrocycles constructed from two C-shaped spacers and two urea groups. These simple molecular units assembled with high fidelity into columnar structures guided by the three-centered urea hydrogen bonding motif and aryl stacking interactions. Individual columns are aligned and closely packed together to afford functional and homogeneous microporous crystals. This approach allows for precise and rational control over the dimensions of the columnar structure simply by changing the small molecular unit. When the macrocyclic unit lacks a cavity, columnar assembly gives strong pillars. Strong pillars with external functional groups such as basic lone pairs can expand like clays to accept guests between the pillars. Macrocycles that contain sizable interior cavities assemble into porous molecular crystals with aligned, well-defined columnar pores that are accessible to gases and guests. Herein, we examine the optimal design of the macrocyclic unit that leads to columnar assembly in high fidelity and probe the feasibility of incorporating a second functional group within the macrocycles. The porous molecular crystals prepared through the self-assembly of bis-urea macrocycles display surface areas similar to zeolites but lower than MOFs. Their simple one-dimensional channels are well-suited for studying binding, investigating transport, diffusion and exchange, and monitoring the effects of encapsulation on reaction mechanism and product distribution. Guests that complement the size, shape, and polarity of the channels can be absorbed into these porous crystals with repeatable stoichiometry to form solid host-guest complexes. Heating or extraction with an organic solvent enables desorption or removal of the guest and subsequent recovery of the solid host. Further, these porous crystals can be used as containers for the selective [2 + 2] cycloadditions of small enones such as 2-cyclohexenone or 3

  17. Comparison of Properties among Dendritic and Hyperbranched Poly(ether ether ketone)s and Linear Poly(ether ketone)s.

    Morikawa, Atsushi


    Poly(ether ether ketone) dendrimers and hyperbranched polymers were prepared from 3,5-dimethoxy-4'-(4-fluorobenzoyl)diphenyl ether and 3,5-dihydroxy-4'-(4-fluorobenzoyl)diphenyl ether through aromatic nucleophilic substitution reactions. 1-(tert-Butyldimethylsiloxy)-3,5-bis(4-fluorobenzoyl)benzene was polycondensed with bisphenols, followed by cleavage of the protective group to form linear poly(ether ketone)s having the same hydroxyl groups in the side chains as the chain ends of the dendrimer and hyperbranched polymers. Their properties, such as solubilities, reduced viscosities, and thermal properties, were compared with one another. Similar comparisons were also carried out among the corresponding methoxy group polymers, and the size of the molecules was shown to affect the properties.

  18. Solar Thermal Energy Storage in a Photochromic Macrocycle.

    Vlasceanu, Alexandru; Broman, Søren L; Hansen, Anne S; Skov, Anders B; Cacciarini, Martina; Kadziola, Anders; Kjaergaard, Henrik G; Mikkelsen, Kurt V; Nielsen, Mogens Brøndsted


    The conversion and efficient storage of solar energy is recognized to hold significant potential with regard to future energy solutions. Molecular solar thermal batteries based on photochromic systems exemplify one possible technology able to harness and apply this potential. Herein is described the synthesis of a macrocycle based on a dimer of the dihydroazulene/vinylheptafulvene (DHA/VHF) photo/thermal couple. By taking advantage of conformational strain, this DHA-DHA macrocycle presents an improved ability to absorb and store incident light energy in chemical bonds (VHF-VHF). A stepwise energy release over two sequential ring-closing reactions (VHF→DHA) combines the advantages of an initially fast discharge, hypothetically addressing immediate energy consumption needs, followed by a slow process for consistent, long-term use. This exemplifies another step forward in the molecular engineering and design of functional organic materials towards solar thermal energy storage and release.

  19. Study on the Application of Microemulsion in Cyclopentane Foaming Blended Polyether Systems%微乳化技术在环戊烷型组合聚醚系统中的应用研究


      本文研究了加入微乳化剂对环戊烷型组合聚醚系统制成的泡沫制品的导热系数等性能的影响,验证了微乳化技术对环戊烷型组合聚醚系统的有效改进。通过添加适量的复合微乳化剂,能够得到泡沫制品的导热系数低于19.0mW/(m·K)的微乳化环戊烷型组合聚醚,实现了环戊烷发泡体系低导热的重要技术突破。%The contents of micro-emulsifler impact on cyclopentane foaming blended polyether systems were investigated by the tests of thermal conductivity from this aticle. The effectively improve of cyclopentane foaming blended polyether systems were identified by microemulsion. Through to added the appropriate amounts of compounding micro-emulsifiers, the rigid polyurethane cellular plastics that thermal conductivity lower than 19. 0mW/ (m· K) were prepared from microemulsifying cyclopentane foaming blended polyether systems, which is a breakthrough in cyclopentane foaming systems with lower thermal conductivity.

  20. Thin sulfonated poly(ether ether ketone) films for the dehydration of compressed carbon dioxide

    Koziara, B.T.


    In this thesis, the properties of thin films from highly sulfonated poly(ether ether ketone) (SPEEK) have been investigated within the context of their application as membranes for the dehydration of compressed carbon dioxide. Spectroscopic ellipsometry has been used as the predominant measurement t

  1. Optical anisotropy, molecular orientations, and internal stresses in thin sulfonated poly(ether ether ketone) films

    Koziara, Beata; Nijmeijer, Dorothea C.; Benes, Nieck Edwin


    The thickness, the refractive index, and the optical anisotropy of thin sulfonated poly(ether ether ketone) films, prepared by spin-coating or solvent deposition, have been investigated with spectroscopic ellipsometry. For not too high polymer concentrations (B5 wt%) and not too low spin speeds

  2. Polyether ether ketone implants achieve increased bone fusion when coated with nano-sized hydroxyapatite

    Johansson, Pär; Jimbo, Ryo; Naito, Yoshihito


    Polyether ether ketone (PEEK) possesses excellent mechanical properties similar to those of human bone and is considered the best alternative material other than titanium for orthopedic spine and trauma implants. However, the deficient osteogenic properties and the bioinertness of PEEK limit its...


    GU Qingchao; XU Weizheng; YE Wenwen; MO Tianlin


    Ionic conductivity values for segmented polyether polyurethaneurea (PEUU) complexes with VTF (Vogel-Tamman-Fulcher) equation and WLF (Williams-Landel-Ferry) type equation. Values have been estimated for the "apparent" activation energies of ion transport from VTF equation and they lie in the range 2.70- 5.53 kJ·mol-1.

  4. Synthesis of Amine-Terminated Polyether%端氨基聚醚的合成



    High pressure catalytic animation of polyether to amine-terminated polyether was studied in the presence of modified Raney Ni catalyst, polyether and liquid ammonia. The reaction factors, including temperature, the amount of catalyst, ratio of ammonia to hydroxyl and ratio of hydrogen to hydroxyl were investigated. The optimized conditions were obtained by experiment. The best process condition was temperature 220 ℃, the ratio of ammonia to hydroxyl 10 ~ 12, the ratio of hydrogen to hydroxyl 0. 6 ~0. 8, the catalyst content 7% ~11% and the reaction time 4 ~ 5 h. The conversion of polyether could be up to 97%.%研究了以改性雷尼镍为催化剂、聚醚和液氨为原料,临氢高压催化氨化制备端氨基聚醚的工艺路线,考察了反应温度、催化剂用量、氨醇比、氢醇比对反应的影响.结果表明,温度220℃、氨醇摩尔比10 ~ 12、氢醇摩尔比0.6~0.8、催化剂质量分数为7%~11%、反应时间4~5h时,聚醚氨化制备端氨基聚醚的转化率大于97%.

  5. Optical anisotropy, molecular orientations, and internal stresses in thin sulfonated poly(ether ether ketone) films

    Koziara, B.T.; Nijmeijer, D.C.; Benes, N.E.


    The thickness, the refractive index, and the optical anisotropy of thin sulfonated poly(ether ether ketone) films, prepared by spin-coating or solvent deposition, have been investigated with spectroscopic ellipsometry. For not too high polymer concentrations (B5 wt%) and not too low spin speeds (C20


    Separation of nonionic octylphenol polyether alcohols (OPA) by supercritical fluid chromatography (SFC) and HPLC is described. Using a density programming and a 50-μm i.d. capillary column, a total of 18 group oligomers was separated. The effects of the operating parameters, such...


    CHEN Chuanfu; LI Xuefen; LI Zhifen


    In this paper the Ce(Ⅳ) salt initiated graft copolymerization of acrylamide onto the film of polyester-polyether block copolymer irradiated by UV-ray was reported. The UV-irradiation of the film and its graft process have been investigated by UV spectrum, ESR and ESCA and the influence of other factors on the graft copolymerization has been discussed.

  8. Poly(ether ester) Ionomers as Water-Soluble Polymers for Material Extrusion Additive Manufacturing Processes.

    Pekkanen, Allison M; Zawaski, Callie; Stevenson, André T; Dickerman, Ross; Whittington, Abby R; Williams, Christopher B; Long, Timothy E


    Water-soluble polymers as sacrificial supports for additive manufacturing (AM) facilitate complex features in printed objects. Few water-soluble polymers beyond poly(vinyl alcohol) enable material extrusion AM. In this work, charged poly(ether ester)s with tailored rheological and mechanical properties serve as novel materials for extrusion-based AM at low temperatures. Melt transesterification of poly(ethylene glycol) (PEG, 8k) and dimethyl 5-sulfoisophthalate afforded poly(ether ester)s of sufficient molecular weight to impart mechanical integrity. Quantitative ion exchange provided a library of poly(ether ester)s with varying counterions, including both monovalent and divalent cations. Dynamic mechanical and tensile analysis revealed an insignificant difference in mechanical properties for these polymers below the melting temperature, suggesting an insignificant change in final part properties. Rheological analysis, however, revealed the advantageous effect of divalent countercations (Ca(2+), Mg(2+), and Zn(2+)) in the melt state and exhibited an increase in viscosity of two orders of magnitude. Furthermore, time-temperature superposition identified an elevation in modulus, melt viscosity, and flow activation energy, suggesting intramolecular interactions between polymer chains and a higher apparent molecular weight. In particular, extrusion of poly(PEG8k-co-CaSIP) revealed vast opportunities for extrusion AM of well-defined parts. The unique melt rheological properties highlighted these poly(ether ester) ionomers as ideal candidates for low-temperature material extrusion additive manufacturing of water-soluble parts.

  9. Synthesis of polyether-based block copolymers based on poly(propylene oxide) and terephthalates

    van der Schuur, J.M.; Feijen, Jan; Gaymans, R.J.


    Poly(propylene oxide) (PPO) is a low reactive telechelic polyether and the synthesis of high molecular weight poly(propylene oxide)-based block copolymers was studied. The poly(propylene oxide) used was end capped with 20 wt % ethylene oxide and had a molecular weight of 2300 g/mol (ultra-low monol

  10. Sustainable metal alkynyl chemistry: 3d metals and polyaza macrocyclic ligands.

    Ren, Tong


    We describe the chemistry of 3d metal alkynyls based on polyaza macrocyclic ligands, an emerging area of alkynyl chemistry that has previously been dominated by 4d and 5d metals with soft ligands. The abundance of 3d metals and low cost of tetraazacyclotetradecane ligands make these compounds more affordable, sustainable alternatives to metal alkynyls based on precious metals. Taking advantage of the rich variety of starting materials available in the literature, trans-[M(cyclam)(C2R)2]X (cyclam = 1,4,8,11-tetraazacyclotetradecane) compounds have been prepared from the reactions between [M(cyclam)X2]X (M = Cr, Fe and Co; X = Cl or OTf) and LiC2R. With [Co(cyclam)Cl2](+), both the {trans-[Co(cyclam)Cl]2(μ-(C≡C)n)}(2+) and trans-[Co(cyclam)(C2R)Cl](+) compounds have been prepared by a dehydrohalogenation reaction. The latter compounds undergo the second alkynylation reaction to afford dissymmetric trans-[Co(cyclam)(C2R)(C2R')](+) compounds. Similar alkynylation chemistry with complexes of the cyclam derivatives TMC (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) and HMC (5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) has been demonstrated in studies of [Ni(TMC)(C2R)](+) and trans-/cis-[Cr(HMC)(C2R)2](+). Me3TACN (1,4,7-N,N',N''-trimethyl-1,4,7-triazacyclononane) is also a supporting ligand that has been observed in transition metal alkynyls. The trans-[M(cyclam)(C2D)(C2A)](+) compounds (D = donor chromophore, A = acceptor chromophore) are excellent candidates for probing photoinduced electron transfer and related photophysical and photochemical processes. 3d Metal ions are often in high-spin ground states, which make these alkynyl compounds promising building blocks for magnetic materials.

  11. Covalent lanthanide(III) macrocyclic complexes: the bonding nature and optical properties of a promising single antenna molecule.

    Rabanal-León, Walter A; Páez-Hernández, Dayán; Arratia-Pérez, Ramiro


    The present work is focused on the elucidation of the electronic structure, bonding nature and optical properties of a series of low symmetry (C2) coordination compounds of type [Ln(III)HAM](3+), where "Ln(III)" are the trivalent lanthanide ions: La(3+), Ce(3+), Eu(3+) and Lu(3+), while "HAM" is the neutral six-nitrogen donor macrocyclic ligand [C22N6H26]. This systematic study has been performed in the framework of the Relativistic Density Functional Theory (R-DFT) and also using a multi-reference approach via the Complete Active Space (CAS) wavefunction treatment with the aim of analyzing their ground state and excited state electronic structures as well as electronic correlation. Furthermore, the use of the energy decomposition scheme proposed by Morokuma-Ziegler and the electron localization function (ELF) allows us to characterize the bonding between the lanthanide ions and the macrocyclic ligand, obtaining as a result a dative-covalent interaction. Due to a great deal of lanthanide optical properties and their technological applications, the absorption spectra of this set of coordination compounds were calculated using the time-dependent density functional theory (TD-DFT), where the presence of the intense Ligand to Metal Charge Transfer (LMCT) bands in the ultraviolet and visible region and the inherent f-f electronic transitions in the Near-Infra Red (NIR) region for some lanthanide ions allow us to propose these systems as "single antenna molecules" with potential applications in NIR technologies.

  12. Hydrogen bond templated 1:1 macrocyclization through an olefin metathesis/hydrogenation sequence.

    Trita, Andrada Stefania; Roisnel, Thierry; Mongin, Florence; Chevallier, Floris


    The construction of pyridine-containing macrocyclic architectures using a nonmetallic template is described. 4,6-Dichlororesorcinol was used as an exotemplate to self-organize two aza-heterocyclic units by OH···N hydrogen bonds. Subsequent sequential double olefin metathesis/hydrogenation reactions employing a single ruthenium-alkylidene precatalyst open access to macrocyclic molecules.

  13. Dielectric Properties of Polyether Sulfone/Bismaleimide Resin Composite Based on Nanolumina Modified by Super-Critical Ethanol

    Chen, Yufei; Li, Zhichao; Teng, Chengjun; Li, Fangliang; Han, Yang


    Nano-alumina was chemically modified with super-critical ethanol enabling a surface active coating. Modified nano-alumina was incorporated in polymer blends based on thermoplastic polyether sulfone and thermosetting bismaleimide resin to produce novel nanocomposites designated as SCE-Al2O3/PES-MBAE. In the SCE-Al2O3/PES-MBAE nano-composites, the matrix was originally formed from 4,4'-diamino diphenyl methane bismaleimide (MBMI) using the diluents of 3,3'-diallyl bisphenol A (BBA) and bisphenol-A diallyl ether (BBE), while polyether sulfone (PES) was used as toughening agent along with super-critically modified nano-alumina (SCE-Al2O3) as filler material. The content of SCE-Al2O3 was varied from 0 wt.% to 6 wt.%. The nano-composites were characterized for their morphological, spectroscopic and dielectric properties. Fourier transform infrared spectroscopy (FT-IR) indicated that ethanol molecules had adhered to the surface of the nano-Al2O3 in super-critical state. A reaction between MBMI and allyl compound occurred and SCE-Al2O3 was doped into the polymer matrix. Volume resistivity of the composite initially increased and then decreased. The modification due to SCE-Al2O3 could overcome the undesirable impact of PES by using a bare minimum level of SCE-Al2O3. The dielectric constant ( ɛ) and dielectric loss (tan δ) as in the case of volume resistivity were initially increased and then decreased with the content of SCE-Al2O3 in the composite. The dielectric constant, dielectric loss and dielectric strength of SCE-Al2O3 (4 wt.%)/PES (5 wt.%)-MBAE nano-composite were 3.53 (100 Hz), 1.52 × 10-3 (100 Hz) and 15.66 kV/mm, respectively, which indicated that the dielectric properties of the composite fulfilled the basic requirements of electrical and insulating material. It was evident from the morphological analysis that the SCE-Al2O3 was evenly dispersed at the nanoscale; for example, the size of SCE-Al2O3 in SCE-Al2O3 (4 wt.%)/PES (5 wt.%)-MBAE measured less than 50 nm.

  14. Influence of different water-ethanol solvent systems on the spectroscopic and physico-chemical properties of the macrocyclic compounds pheophytin and chlorophyll a; Influencia de diferentes sistemas de solvente agua-etanol sobre as propriedades fisico-quimicas e espectroscopicas dos compostos macrociclicos feofitina e clorofila a

    Moreira, Leonardo M.; Rodrigues, Maira R.; Oliveira, Hueder P. M. de [Universidade Camilo Castelo Branco, Sao Jose dos Campos, SP (Brazil); Lima, Adriana [Universidade do Vale do Paraiba, Sao Jose dos Campos, SP (Brazil); Soares, Rafael R. S.; Batistela, Vagner R.; Gerola, Adriana P.; Hioka, Noboru [Universidade Estadual de Maringa (UEM), PR (Brazil). Dept. de Quimica; Severino, Divinomar; Baptista, Mauricio S. [Universidade de Sao Paulo, (USP), SP (Brazil). Inst. de Quimica; Machado, Antonio Eduardo da Hora [Universidade Federal de Uberlandia (UFU), MG (Brazil). Inst. de Quimica


    This work focus on the influence of solvent on the photophysical properties of chlorophyll a and pheophytin. Both compounds are related to the photosynthesis process and are considered prototypes of photosensitizers in Photodynamic Therapy. Fluorescence measurements were developed using water/ethanol mixtures at different compositions, since both solvents could be employed in biological applications. The spectroscopic properties of these compounds undergo profound changes depending on water content in the ethanol due to auto-aggregation processes. The major hydrophobicity and the lower dielectric constant of ethanol when compared with water precluded significantly the auto-aggregation process of these compounds. (author)

  15. Pyrazine motif containing hexagonal macrocycles: synthesis, characterization, and host-guest chemistry with nitro aromatics.

    Bhowmick, Sourav; Chakraborty, Sourav; Das, Atanu; Nallapeta, Sivaramaiah; Das, Neeladri


    The synthesis and characterization of cationic two-dimensional metallamacrocycles having a hexagonal shape and cavity are described. Both macrocycles utilize a pyrazine motif containing an organometallic acceptor tecton with platinum(II) centers along with different donor ligands. While one macrocycle is a relatively larger [6 + 6], the other is a relatively smaller [2 + 2] polygon. A unique feature of the smaller ensemble is that it is an irregular polygon in which all six edges are not of equal length. Molecular modeling of these macrocycles confirmed the presence of hexagonal cavities. The ability of these π-electron rich macrocycles to act as potential hosts for relatively electron deficient nitroaromatics (DNT = 2,4-dinitrotoluene and PA = picric acid) has been studied using isothermal titration calorimetry (ITC) as a tool. Molecular dynamics simulation studies were subsequently performed to gain critical insight into the binding interactions between the nitroaromatic guest molecules (PA/DNT) and the ionic macrocycles reported herein.

  16. Macrocyclic Trichothecenes from Myrothecium roridum Strain M10 with Motility Inhibitory and Zoosporicidal Activities against Phytophthora nicotianae.

    Mondol, Muhammad Abdul Mojid; Surovy, Musrat Zahan; Islam, M Tofazzal; Schüffler, Anja; Laatsch, Hartmut


    The cytotoxicity of the extract obtained from Myrothecium roridum M10 and a characteristic (1)H signal at δH ∼8 led to the assumption that verrucarin/roridin-type compounds were present. Upscaling on rice medium led to the isolation of four new metabolites: verrucarins Y (1) and Z (6) (macrocyclic trichothecenes), bilain D (12) (a diketopiperazine derivative), and hamavellone C (14) (an unusual cyclopropyl diketone). In addition, nine known trichothecenes [verrucarin A (3), 16-hydroxyverrucarin A (5), verrucarin B (7), 16-hydroxyverrucarin B (8), verrucarin J (2), verrucarin X (4), roridin A (9), roridin L-2 (10), and trichoverritone (11)] and a bicyclic lactone [myrotheciumone A (15)] were identified. Their structures and configurations were determined by spectroscopic methods, published data, Mosher's method, and considering biosyntheses. Some trichothecenes showed motility inhibition followed by lysis of the zoospores against devastating Phytophthora nicotianae within 5 min. Compounds 2, 3, 7, and 9 also exhibited potent activities against Candida albicans and Mucor miehei.

  17. Reaction of lanthanide nitrates with macrocyclic amidoacylhydrazones

    Malinka, E.V.; Bondarev, M.L.; Bel' tyukova, S.V.; Poleuktov, N.S.; Nazarenko, N.A.


    This paper deals with a study of the reaction of neodymium and europium nitrates with 3,5,14,16-tetraazasubstituted dibenzo (d,j) (1,2,6,9,13,14) hexaazahexadeca-2,4,10,12-tetraene-7,8,15,16-tetraones. The authors carried out the investigations by means of conductimetry, UV luminescence, IR spectroscopy, and mass spectroscopy. Conductimetric titrations of the neodymium complexes were carried out on an OK-102/1 conductimeter. The luminescence spectra of the europium ion in the region of the /sup 5/D/sub 0/ ..-->.. /sup 7/F/sub 1/ and /sup 5/D/sub 0/ ..-->.. /sup 7/F/sub 2/ transitions (550-620 nm) were recorded on an ISP-51 spectrograph with an FEP-1 photoelectric attachment, using excitation by an SVD-120A mercury quartz lamp. The UV spectra of solutions of the compounds and the IR spectra of the solid substances in KBr disks were recorded on SpecordUViS and UR-20 spectrophotometers, respectively, and the mass spectra on a Varian Mat-112 spectrometer.

  18. 8th International Symposium on Supramolecular and Macrocyclic Chemistry

    Davis, Jeffery T. [Univ. of Maryland, College Park, MD (United States)


    This report summarizes the 8th International Conference on Supramolecular and Macrocyclic Chemistry (ISMSC-8). DOE funds were used to make it more affordable for students, post-docs and junior faculty to attend the conference by covering their registration costs. The conference was held in Crystal City, VA from July 7-11, 2013. See for the conference website. ISMSC-8 encompassed the broad scope and interdisciplinary nature of the field. We met our goal to bring together leading scientists in molecular recognition and supramolecular chemistry. New research directions and collaborations resulted this conference. The DOE funding was crucial for us achieving our primary goal.

  19. Antiferromagnetically Coupled Dimeric Dodecacopper Supramolecular Architectures of Macrocyclic Ligands with a Symmetrical μ6-BO3(3-) Central Moiety.

    Tandon, Santokh S; Bunge, Scott D; Toth, Sara A; Sanchiz, Joaquin; Thompson, Laurence K; Shelley, Jacob T


    Reactions between 2,6-diformyl-4-alkyl(R)-phenol (R = CH3 or C(CH3)3) and 1,3-diamino-2-hydroxypropane (1,3-DAP) in the presence of copper(II) salts (Cu(BF4)2·6H2O, Cu(ClO4)2·6H2O/H3BO3/Ar) and triethylamine (TEA) in a single pot result in self-assembly of dimeric dodecacopper supramolecular architectures of 30-membered hexatopic macrocyclic ligands (H6L4 and H6L5) with unique and fascinating structures having the BO3(3-) anion as the central species bonded to all six copper centers in a symmetrical fashion (μ6-BO3(3-)). A number of closely related macrocyclic hexacopper complexes are reported: {[Cu6(L4)(μ6-BO3)(μ-H2O)(C3H7NO)2(BF4)][BF4]2·3C3H7NO}2 (1) (DMF = C3H7NO), {[Cu6(L4)(μ6-BO3)(μ-C3H7NO)3][ClO4]3·3C3H7NO}2 (2), {[Cu6(L5)(μ6-BO3)(μ-OH)(H2O)3(C3H7NO)][BF4]2·6C3H7NO·4C2H5OH·2H2O}2 (3), {[Cu6(L5)(μ6-BO3)(μ-CH3OH)(CH3OH)2][ClO4]3·10H2O}2 (4), and {[Cu6(L5)(μ6-BO3)(μ-CH3CO2)(μ-CH3O)(CH3OH)][BF4]·13CH3OH·8H2O}2 (5). A polymeric side product {[Cu2(H2L2)(CH3OH)(BF4)][BF4]}n (6), involving a 2 + 2 macrocyclic ligand, was also isolated and structurally characterized. Complex 6 involves dinuclear copper(II) units linked through BF4(-) anions to form a novel 1D single-chain polymeric coordination compound. This appears to be the first report in which a central BO3(3-) species is linked to six copper(II) ions held together by a single macrocyclic ligand through three μ1,1-O(BO3(3-)) and three μ1,3-O(BO3(3-)) bridges. In complexes 1-5 the BO3(3-) is present in the center of the macrocyclic cavity and is bonded to all six metal centers arranged in a benzene-like hexagonal array. In the hexagonal array there are alternate double (μ-alkoxide and μ1,3-O(BO3(3-))) and (μ-phenoxide and μ1,1-O(BO3(3-))) bridges between the Cu(II) centers. The symmetrical hexa-bridging nature of μ6-BO3(3-) is unprecedented in transition metal complex chemistry, and along with alkoxide and phenoxide bridges in the equatorial plane provides effective pathways for an

  20. Proton Conducting Composite Membranes from Sulfonated Polyether Ether Ketone and SiO2

    ZHANG Gaowen; ZHOU Zhentao; LI Chunqing; CHU Heng


    Proton conducting composite membranes from sulfonated polyether ether ketone and SiO2 for direct methanol fuel cell (DMFC) application were prepared with sulfonated polyether ether ketone(SPEEK) and tetracethoxy silane(TEOS) by sol-gel method. The covalent crosslinking structure was formed between -SO3H of SPEEK via SiO2. The SEM images show that the interfacial compatibility of SPEEK and SiO2 is improved obviously and SiO2 disperses uniformly in the polymer matrix and the particle diameter of SiO2 does not exceed 40 nm. The proton conductivity of composite membranes decreases slightly compared with the SPEEK membrane while the methanol permeability and swelling of composite membrane are improved remarkablely owing to covalent cross-linking between -SO3H and SiO2 .

  1. Conductivity enhancement of sulfonated poly(ether ketone ketone) blends using electric field structuring techniques

    Gasa, Jeffrey V.; Shaw, Montgomery T.


    Binary blends composed of an ion-containing polymer and a secondary component were cast under an applied elec. field to produce membranes with anisotropic morphologies. The ion-containing polymer was sulfonated poly(ether ketone ketone) (SPEKK) and the secondary component was either poly(ether imide) (PEI) or styrene-acrylonitrile (SAN) copolymer. A range of compositions and sulfonation levels were studied using this blend system. Optical and SEM micrographs of the resulting membranes showed columnar structures that were oriented along the direction of the field. It was found that electric field alignment only occurs when SPEKK is the dispersed phase but not when it is the matrix. The results show that the conductivities of the membranes that were cast under an electric field were significantly higher than those of the membranes cast without electric field. The conductivity measurements were interpreted in terms of a composite equation with structure-dependent parameters.

  2. Research on Preparation and Properties of Coated Polyether Silicone Microencapsulation Based on Polystyrene

    Ren Shuiyun


    Full Text Available By the method of interfacial polymerization, the novel microcapsules were prepared with polystyrene as wall material and polyether silicone as core material. In order to demonstrate the morphologies, particle size distribution and properties of microcapsules, scanning electron microscopy (SEM, laser particle size analysis and infrared spectroscopy (FTIR are also applied in the experiments, and the thermal stability of microcapsules is obtained by thermal gravimetric (TG and differential scanning calorimetry (DSC. The material ratio (core to wall in weight of microcapsules and stirring rate ratio are discussed. The results show that under the optimum process conditions of a material ratio (core to wall in weight which is 4:10 and agitating rate of 500r·min‒1, the synthesized polyether silicone microcapsules have a higher yield and the coating and densification properties; their average size is 210μm, and the thermal stability temperature can reach up to 390°C.

  3. Novel archaeal macrocyclic diether core membrane lipids in a methane-derived carbonate crust from a mud volcano in the Sorokin Trough, NE Black Sea

    Alina Stadnitskaia


    Full Text Available A methane-derived carbonate crust was collected from the recently discovered NIOZ mud volcano in the Sorokin Trough, NE Black Sea during the 11th Training-through-Research cruise of the R/V Professor Logachev. Among several specific bacterial and archaeal membrane lipids present in this crust, two novel macrocyclic diphytanyl glycerol diethers, containing one or two cyclopentane rings, were detected. Their structures were tentatively identified based on the interpretation of mass spectra, comparison with previously reported mass spectral data, and a hydrogenation experiment. This macrocyclic type of archaeal core membrane diether lipid has so far been identified only in the deep-sea hydrothermal vent methanogen Methanococcus jannaschii. Here, we provide the first evidence that these macrocyclic diethers can also contain internal cyclopentane rings. The molecular structure of the novel diethers resembles that of dibiphytanyl tetraethers in which biphytane chains, containing one and two pentacyclic rings, also occur. Such tetraethers were abundant in the crust. Compound-specific isotope measurements revealed δ13C values of –104 to –111‰ for these new archaeal lipids, indicating that they are derived from methanotrophic archaea acting within anaerobic methane-oxidizing consortia, which subsequently induce authigenic carbonate formation.

  4. Synthesis and Crystal Structure of a Macrocycle [Cu(dadm)(mal)(H2O)]2·2H2O

    林郑忠; 江飞龙; 陈莲; 洪茂椿


    The reaction of 4,4′-diaminodiphenylmethane (dadm), malonic acid (H2mal) and Cu(NO3)2 in aqueous solution results in a discrete binuclear Cu(II) macrocycle: [Cu(dadm)(mal)- (H2O)]2(2H2O. It crystallizes in monoclinic, space group P21/c with a = 15.231(3), b = 11.847(2), c = 9.801(2)A,Z= 106.75(3)o, V = 1693.5(6)A3, Z = 2, C32H40Cu2N4O12, Mr = 799.76, Dc = 1.568 g/cm3, λ(MoK() = 0.71073A, μ = 1.325 mm-1, F(000) = 828, the final R = 0.0531 and Wr = 0.1244 for 3421 observed reflections with I > 2σ(I). Each Cu(II) is coordinated by two oxygen atoms from a mal ligand, two nitrogen atoms from two dadm ligands and a water oxygen atom to form a triangle bipyramidal motif. The title compound possesses a distorted macrocycle enclosed by dadm with approximate dimensions of 8.3A× 5.9A.

  5. XPS investigations on the UV-laser ablation mechanism of poly(ether imide)

    Wambach, J.; Kunz, T.; Schnyder, B.; Koetz, R.; Wokaun, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)


    UV-Laser ablated samples of poly(ether imide) [Kapton{sup TM}] were studied with small-spot XPS. Applying fluences above the threshold level (0.167 J/cm{sup 2}) resulted in the expected behaviour of a decline of both nitrogen and oxygen. Below the threshold level a hint for an altered ablation mechanism was found. (author) 1 fig., 5 refs.

  6. EPR character of gadolinium complexes with noncyclic polyether Schiff bases and its solvent effects

    姚克敏; 陈德余; 王晓南; 邓宁


    EPR characters of three new gadolinium complexes with noncydic polyether Schiff bases in powder or organic solvents, including various oxyethylene chain lengths and different substituting groups in ligands, are investigated respectively. Some regularities are summed up. The difference of EPR character in various solvents, particularly at different temperatures, has been examined. The ’single peak effect’ due to THF solvent at low temperature is observed for the first time. This phenomenon is explicated.

  7. Cloning and Characterization of the Polyether Salinomycin Biosynthesis Gene Cluster of Streptomyces albus XM211

    Jiang, Chunyan; Wang, Hougen; Kang, Qianjin; Jing LIU; Bai, Linquan


    Salinomycin is widely used in animal husbandry as a food additive due to its antibacterial and anticoccidial activities. However, its biosynthesis had only been studied by feeding experiments with isotope-labeled precursors. A strategy with degenerate primers based on the polyether-specific epoxidase sequences was successfully developed to clone the salinomycin gene cluster. Using this strategy, a putative epoxidase gene, slnC, was cloned from the salinomycin producer Streptomyces albus XM211...

  8. UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi

    Gabriela Albara Lando


    Full Text Available Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae, when the films were pre-treated with Ultraviolet (UV irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR, scanning electron microscopy (SEM, and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

  9. Dynamic Viscosity for HFC-134a + Polyether Mixtures up to 373.15 K and 140 MPa at Low Polyether Concentration. Measurements and Modeling

    Comuñas, Maria J P; Boned, Christian; Fernandez, Josefa


    This paper reports viscosity data for mixtures containing a refrigerant (HFC-134a) and a lubricant (triethylene glycol dimethyether, TriEGDME, or tetraethylene glycol dimethyl ether, TEGDME), at 12% of TriEGDME or 14% mass fraction of TEGDME. The measurements (140 data points) were obtained at various pressures (between 10 and 140 MPa) in the monophasic liquid state from 293.15 to 373.15 K. Because HFC-134a and the polyethers are not in the same single phase at normal pressure and temperature (the refrigerant is a gas, whereas the polyethers are liquids), accurate measurements of their mixtures require specific procedures for preparation of the samples and filling of the apparatus. A specially designed isobaric-transfer falling-body viscometer is used in this work. The viscosities of the mixtures are, on average, 40% higher than that of the pure refrigerant, and this increase is more noticeable at low temperatures. The experimental viscosities have been used to check the predictive and correlation ability of ...

  10. Synthesis and Properties of Terminated Polyether%封端聚醚的合成及性能研究

    程亮; 张东恒


    Alkyl terminated polyether was prepared in high yield by using sodium methoxide as alkaline reagent and methyl chloride as alkyl terminated reagent. The structures of the products were characterized by means of infrared spectroscopy ( IR) , nuclear magnetic resonance ( NMR) and gel permeation chromatography ( GPC) . Compared the physical and chemi-cal properties of the alkyl terminated polyether with unsealed polyether, it was found that the alkyl terminated polyether has lower viscosity and higher viscosity index. The anti-oxidation performances of the two kinds of polyether were investigated by rotary oxygen bomb test method ( ROBT) . By the study of the suitability of different antioxidants in two kinds of poly-ether, the antioxidant suitable for alkyl terminated polyether was developed, which can make the ROBT reach to 1950 mi-nutes.%以甲醇钠作为碱性试剂,一氯甲烷为封端试剂,高产率制备了烷基封端聚醚. 并通过红外光谱( IR)、核磁共振( NMR)和凝胶渗透色谱( GPC)对其进行表征. 对比了两种聚醚的指标变化,结果发现,封端聚醚具有更低的黏度、更高的黏度指数. 利用旋转氧弹测试方法考察了封端聚醚与未封端聚醚的抗氧化性能,通过考察不同抗氧剂在两种聚醚中的适应性,开发了适合封端聚醚的抗氧体系,该抗氧体系可以使封端聚醚的旋转氧弹时间达到1950 min.

  11. A review on the toxicity and non-target effects of macrocyclic lactones in terrestrial and aquatic environments.

    Lumaret, Jean-Pierre; Errouissi, Faiek; Floate, Kevin; Römbke, Jörg; Wardhaugh, Keith


    The avermectins, milbemycins and spinosyns are collectively referred to as macrocyclic lactones (MLs) which comprise several classes of chemicals derived from cultures of soil micro-organisms. These compounds are extensively and increasingly used in veterinary medicine and agriculture. Due to their potential effects on non-target organisms, large amounts of information on their impact in the environment has been compiled in recent years, mainly caused by legal requirements related to their marketing authorization or registration. The main objective of this paper is to critically review the present knowledge about the acute and chronic ecotoxicological effects of MLs on organisms, mainly invertebrates, in the terrestrial and aquatic environment. Detailed information is presented on the mode-of-action as well as the ecotoxicity of the most important compounds representing the three groups of MLs. This information, based on more than 360 references, is mainly provided in nine tables, presenting the effects of abamectin, ivermectin, eprinomectin, doramectin, emamectin, moxidectin, and spinosad on individual species of terrestrial and aquatic invertebrates as well as plants and algae. Since dung dwelling organisms are particularly important non-targets, as they are exposed via dung from treated animals over their whole life-cycle, the information on the effects of MLs on dung communities is compiled in an additional table. The results of this review clearly demonstrate that regarding environmental impacts many macrocyclic lactones are substances of high concern particularly with larval instars of invertebrates. Recent studies have also shown that susceptibility varies with life cycle stage and impacts can be mitigated by using MLs when these stages are not present. However information on the environmental impact of the MLs is scattered across a wide range of specialised scientific journals with research focusing mainly on ivermectin and to a lesser extent on abamectin

  12. 聚醚多元醇中醛类组分的HPLC法测定%HPLC Method for Determination of Aldehydes Component in Polyether Polyol

    阎露海; 倪健; 陆巍


    Method of measuring aldehydes component in polyether polyol had been established by precolumn derivatization and high-performance liquid chromatography, using hydrazone by reacting of carbonyl compounds and DNPH. The derivatization conditions were discussed and the calibration curves of formaldehyde-DNPH, acetalde-hyde-DNPH, acrolein-DNPH and propionaldehyde-DNPH were also drawn. Results Indicated that the linear range of the formaldehyde, acetaldehyde and acrolein was 0. 02 ~ 20. 00 μg/mL, the propionaldehyde linea range was 0. 80 ~ 800. 00 μg/mL, the aldehydes detection limit was under 0. 025 μg/mL. The precision determination was measured in this paper, including the formaldehyde, acetaldehyde, acrolein, propionaldehyde in polyether polyol and the method had the advantage of wide measurement range and high recovery, it was an effective methods of determine the content of aldehydes in the polyether polyols.%利用羰基化合物与2,4-二硝基苯肼(DNPH)反应生成腙,建立了柱前衍生、高效液相色谱(HPLC)法测定聚醚多元醇中醛类物质含量的方法,研究了样品衍生化条件,绘制了甲醛-DNPH、乙醛-DNPH、丙烯醛-DNPH及丙醛-DNPH的外标法校准曲线.结果表明,甲醛、乙醛、丙烯醛的线性范围为0.02~20.00 μg/mL,丙醛的线性范围为0.80 ~ 800.00 μg/mL;醛类物质的检测限在0.025 g/mL以下.用于聚醚多元醇样品中甲醛、乙醛、丙烯醛和丙醛的测定取得了满意的结果,该方法具有测定范围广、回收率高等优点,是一种测定聚醚多元醇中多种醛类物质含量的有效方法.

  13. Double template effect in [4 + 4] Schiff base macrocycle formation; an ESI-MS study.

    Barreira-Fontecha, Julia; Kulmaczewski, Rafal; Ma, Xiaomei; McKee, Vickie


    The mechanism of self-assembly of a polynuclear complex of a [4 + 4] Schiff base iminomethylenediphenolate macrocycle [BaCu(4)(4 + 4)](2+) via a non-macrocyclic dialdehyde intermediate has been followed using ESI-MS of the reaction solutions. Both assembly of the intermediate and Schiff-base condensation with diamine give rise to single products; formation of the intermediate metallacycle is fast but Schiff-base condensation is much slower. Both intermediate complex and macrocyclic product have been structurally characterised.

  14. Asymmetric Synthesis of Natural Macrocyclic Diterpene(+)-Methyl Cembra-1,3,7,11-tetraene-16-carboxynate%(+)-Methyl Cembra-1,3,7,11-tetraene-16-carboxynate的不对称合成研究

    孙彬; 梅天胜; 刘佐胜; 李裕林; 李瀛; 彭立增


    The first asymmetric synthesis of (+)-methyl cembra-1,3,7,11-tetraene-16-carboxynate, a naturally occurring cembrane-type macrocyclic diterpene isolated from Sinularia mayi, was achieved via general approach by employing an intramolecular McMurry coupling and Sharpless asymmetric epoxidation as the key steps from readily available starting materials. The synthesis presented here verifies that the absolute configuration of compound 1 was assumed as 15R.

  15. Synthesis of new tren-based tris-macrocycles. Anion cluster assembling inside the cavity generated by a bowl-shaped receptor.

    Bazzicalupi, Carla; Bencini, Andrea; Berni, Emanuela; Bianchi, Antonio; Ciattini, Samuele; Giorgi, Claudia; Maoggi, Sauro; Paoletti, Piero; Valtancoli, Barbara


    The synthesis of three new tris-macrocycles, containing three [12]aneN(4) (L1), [12]aneN(3)O (L2), or [14]aneN(4) (L3) moieties appended to a tren unit, is reported. The crystal structure of the [(Na(ClO(4))(6)) subset L1(2)H(13)]Na(6)Cl(2)(ClO(4))(12) compound shows the anionic cluster [Na(ClO(4))(6)](5)(-) assembled inside the cavity defined by two bowl-shaped polyammonium receptors, held by multiple charge-charge and hydrogen bond interactions.

  16. Nitrate-Bridged One-Dimension Coordination Polymer Self-Assembled from a N4O2-Tetraiminodiphenolate Dicopper(II Macrocyclic Complex

    Julio Cesar da Rocha


    Full Text Available Herein we report on the synthesis and single crystal X-ray structure characterization of [{Cu2(tidf(μ-NO3}∞]ClO4 (tidf = a Robson type macrocyclic ligand obtained upon condensation of 2,6-diformyl-4-methylphenol and 1,3-diaminopropane. The coordination geometry around the copper(II is square-pyramidal and has [Cu2(tidf]2+ units connected to each other through nitrate bridges extending as a one-dimension coordination polymer. The compound exhibits an extensive supramolecular structure supported by nonclassic hydrogen bonding between C-H⋯Operchlorate and C-H⋯Onitrate.

  17. Synthesis and characterization of organometallic macrocyclic rhodium (Ⅲ) complex with pyrazine ligands

    WANG Jianqiang; ZHANG Zheng; WENG Linhong; JIN Guoxin


    The reaction of half-sandwich complex (Cptt Rh)2Cl2(μ-Cl)2 (1) (Cptt = η5-tBu2C5H3) with 1 equiv. Of AgSO3CF3 in CH2Cl2 affords tri-μ-chloro dirhodium (2) cation compound, with 2 equiv. Of AgSO3CF3 providing di-μ-chloro complex 3. The reaction of 3 with pyrazine gives a novel tetra-nuclear 14-member organometallic macrocyclic complex 4. FT-IR, 1H-NMR, and EA were used to characterize these complexes. The structures of complexes 2 and 4 are confirmed by X-ray analysis. In complex 2, the two Cptt ring and tri-chloro atoms faces are approximately parallel to each other. In complex 4, the complex cation has a rectangular cavity with the dimension of 0.3748 nm×0.7027 nm, and the two-pyrazine rings are parallel to each other with a distance of 0.3510 nm.

  18. Molecular recognition by multiple metal coordination inside wavy-stacked macrocycles.

    Nakamura, Takashi; Kaneko, Yuya; Nishibori, Eiji; Nabeshima, Tatsuya


    Most biological and synthetic receptors for small organic molecules employ a combination of relatively weak intermolecular interactions such as hydrogen bonds. A host compound that utilizes stronger yet reversible bonding in a synergistic manner could realize precise recognition, but the regulation and spatial arrangement of such reactive interaction moieties have been a challenge. Here, we show a multinuclear zinc complex synthesized from a macrocyclic ligand hexapap, which inwardly arranges labile metal coordination sites for external molecules. The metallomacrocycle forms a unique wavy-stacked structure upon binding a suitable length of dicarboxylic acids via multipoint coordination bonding. The saddle-shaped deformation and dimerization realize the differentiation of the interaction moieties, and change of guest-binding modes at specific metal coordination sites among the many present have been achieved utilizing acid/base as external stimuli.Synergistic use of coordination bonds that are strong and reversible realizes unique molecular recognition in artificial systems. Here, the authors show that a zinc-based metallomacrocyle can bind dicarboxylic acids of suitable length at specific metal sites by shape deformation and dimerization.

  19. Macrocyclic cavitands cucurbit[n]urils: prospects for application in biochemistry, medicine and nanotechnology

    Gerasko, O. A.; Kovalenko, E. A.; Fedin, V. P.


    The prospects of using the organic macrocyclic cavitands cucurbit[n]urils (CB[n]) and their derivatives in biochemistry, medicine and nanotechnology are considered. A combination of CB[n] characteristics, such as a rigid highly symmetrical structure, polarized hydrophilic portals, a rather large intramolecular hydrophobic cavity, as well as high resistance to thermolysis and corrosive media and low toxicity, account for a wide range of unique opportunities for the deliberate design of new functional materials, which may find application in various areas of modern chemistry and new technologies. Inclusion compounds of CB[n] with biologically active molecules demonstrate a high potential for the design of a new generation of prolonged action pharmaceuticals. The review presents the prospects for the application of CB[n] to manufacture unique materials, such as CB[n]-containing vesicles, films and surfaces, suitable for immobilization of various molecules and nanoparticles on their surface and for the separation of complex mixtures. Potential applications of CB[n]-modified electrodes and hydrogels are analyzed, and the use of CB[n] in proton-conducting materials and materials for the gas sorption and separation are discussed. The bibliography includes 164 references.

  20. How do the macrocyclic lactones kill filarial nematode larvae?

    Wolstenholme, Adrian J; Maclean, Mary J; Coates, Ruby; McCoy, Ciaran J; Reaves, Barbara J


    The macrocyclic lactones (MLs) are one of the few classes of drug used in the control of the human filarial infections, onchocerciasis and lymphatic filariasis, and the only one used to prevent heartworm disease in dogs and cats. Despite their importance in preventing filarial diseases, the way in which the MLs work against these parasites is unclear. In vitro measurements of nematode motility have revealed a large discrepancy between the maximum plasma concentrations achieved after drug administration and the amounts required to paralyze worms. Recent evidence has shed new light on the likely functions of the ML target, glutamate-gated chloride channels, in filarial nematodes and supports the hypothesis that the rapid clearance of microfilariae that follows treatment involves the host immune system.

  1. Surface enhanced second harmonic generation from macrocycle, catenane, and rotaxane thin films : Experiments and theory

    Arfaoui, [No Value; Bermudez, [No Value; Bottari, G; De Nadai, C; Jalkanen, JP; Kajzar, F; Leigh, DA; Lubomska, M; Mendoza, SM; Niziol, J; Rudolf, P; Zerbetto, F; Arfaoui, Imad; Bermúdez, Verónica; Jalkanen, Jukka-Pekka


    Surface enhanced second harmonic generation (SE SHG) experiments on molecular structures, macrocycles, catenanes, and rotaxanes, deposited as monolayers and multilayers by vacuum sublimation on silver, are reported. The measurements show that the molecules form ordered thin films, where the highest

  2. Radical Polymerization of Vinyl Acetate and Methyl Methacrylate Using Organochromium Initiators Complexed with Macrocyclic Polyamines


    METHYL METHACRYLATE USING ORGANOCHROMIUM REA NTS COMPLEXED WITH MACROCYCLIC A• by Daniela Mardare, Scott Gaynor, Krzysztof Matyjaszewski DTIC Published... Daniela Mardare, Scott Gaynor, Krzysztof Matyjaszewski 7. PERFORMING ORGANIZATION NAME(S) AND ADORESS(ES) a. PERFORMING ORGANIZATION Carnegie Mellon


    Title: Lanthanide Enhance Luminescence (LEL) with one and two photon excitation of Quantum Dyes? Lanthanide(III)-Macrocycles Principal Author:Robert C. Leif, Newport InstrumentsSecondary Authors:Margie C. Becker, Phoenix Flow Systems Al Bromm, Virginia Commonw...

  4. Design, synthesis and biological evaluation of a macrocyclic discodermolide/dictyostatin hybrid.

    Paterson, Ian; Gardner, Nicola M


    A 22-membered macrocyclic discodermolide/dictyostatin hybrid has been designed and synthesised; biological evaluation against a range of human cancer cell lines revealed significant levels of growth inhibition.

  5. Convergent Synthesis of Rigid Macrocycles Containing One and Two Tetrathiafulvalene Units

    Simonsen, Klaus B.; Thorup, Niels; Becher, Jan


    The synthesis of rigid tetrathiafulvalenophanes containing one or two tetrathiafulvalene units is presented, together with a stepwise convergent synthesis of macrocyclic bis-tetrathiafulvalenes via several open dimeric tetrathiafulvalenes. These systems were investigated by cyclic voltammetry...

  6. Heartworms, macrocyclic lactones, and the specter of resistance to prevention in the United States

    Bowman, Dwight D


    In order to provide a background to current concerns relative to the possible resistance of heartworms to macrocyclic lactones, this review summarizes various studies in which lack of efficacies (LOEs...


    Title: Lanthanide Enhance Luminescence (LEL) with one and two photon excitation of Quantum Dyes? Lanthanide(III)-Macrocycles Principal Author:Robert C. Leif, Newport InstrumentsSecondary Authors:Margie C. Becker, Phoenix Flow Systems Al Bromm, Virginia Commonw...

  8. Macrocyclic effects upon isomeric CuIIMII and MIICuII cores. Formation with unsymmetric phenol-based macrocyclic ligands

    Masami Yonemura; Yuuki Nakamura; Naoki Usuki; Hisashi Okawa


    This paper discusses coordination-position isomeric MIICuII and CuIIMII complexes, using unsymmetric dinucleating macrocycles (Lm;n)2- ((L2;2)2-, (L2;3)2- and (L2;4)2- that comprise two 2-(N-methyl)-aminomethyl-6-iminomethyl-4-bromophenonate entities, combined through the ethylene chain ( = 2) between the two amine nitrogens and through the ethylene, trimethylene or tetramethylene chain ( = 2, 3 or 4) between the two imine nitrogens. The macrocycles have dissimilar N(amine)2O2 and N(imine)2O2 metal-binding sites sharing the phenolic oxygens. The reaction of the mononuclear CuII precursors, [Cu(L2;2)], [Cu(L2;2)] and [Cu(L2;2)], with a MII perchlorate and a MII acetate salt formed (acetato)MII CuII complexes:[CoCu(L2;2)(AcO)]ClO4 0 5H2O] (1), [NiCu(L2;2) (AcO)]ClO4 (2), [ZnCu(L2;2((AcO)]ClO4 (3), [CoCu(L2;3)(AcO)]ClO4 0 5H2O (4), [NiCu(L2;3)(AcO)]ClO4 (5), [ZnCu(L2;3)(AcO)]ClO4 0 5H2O (6), [CoCu(L2;4)(AcO)(DMF)]ClO4 (7), [NiCu(L2;4)(AcO)]ClO4 2DMF (8) and [ZnCu(L2;4)(AcO)]ClO4 (9) (the formulation [MM (Lm;n)]2+ means that M resides in the aminic site and M in the iminic site). The site selectivity of the metal ions is demonstrated by X-ray crystallographic studies for 2 MeOH, 3, 5, 7, and 9. An (acetato)CuIIZnII complex, [CuZn(L2;3)(AcO)]ClO4 (10), was obtained by the reaction of [PbCu(L2;3)]-(ClO4)2 with ZnSO4 4H2O, in the presence of sodium acetate. Other complexes of the CuIIMII type were thermodynamically unstable to cause a scrambling of metal ions. The Cu migration from the iminic site to the aminic site in the synthesis of 10 is explained by the `kinetic macrocyclic effect’. The coordination-position isomers, 6 and 10, are differentiated by physicochemical properties.

  9. Shaping the cavity of the macrocyclic ligand in metallocalix[4]arenes: the role of the ligand sphere.

    Radius, U


    The coordination form of calix[4]arene ligands and therefore the cavity of the macrocyclic ligand can be controlled by other ligands in transition metal calix[4]arene complexes, if strong directing coligands such as oxo groups are used. This paper describes the synthesis and characterization of the d(0) transition metal complexes [Cax(OMe)(2)O(2)TiCl(2)] 1 (monoclinic, space group P2(1)/c, lattice constants a = 21.639(4), b = 20.152(3), c = 12.750(3) A, beta = 95.68(3), V = 5532.6(19) A(3)) and [Cax(OMe)(2)O(2)MoO(2)] 2 (monoclinic, space group P2/c, lattice constants a = 12.433(3), b = 16.348(3), c = 24.774(5) A, beta = 99.15(3), V = 4971.6(17) A(3)). Whereas in 1 the calix[4]arene ligand adopts an elliptically distorted cone conformation, the macrocyclic ligand binds in a paco-like conformation to the metal center of 2, in the solid state and in solution. This was predicted by density functional theory calculations on models of different isomers of 1 and 2: cis,cone-1',2', trans,cone-1',2', and cis,paco-1',2'. According to these calculations, the energetic difference of 72.9 kJ/mol between both cis-dioxomolybdenum compounds is quite pronounced in favor of the cis,paco isomer, and 28.0 kJ/mol for the titanium compounds in favor of the cis,cone isomer.

  10. A set of homologous hetarylenediyne macrocycles by oxidative acetylene-acetylene coupling.

    Opris, Dorina M; Ossenbach, Alexander; Lentz, Dieter; Schlüter, A Dieter


    The synthesis of a set of bipyridine-containing macrocycles by oxidative acetylene-acetylene dimerization is described. The cycles are separated by preparative GPC, and the smallest homologue is analyzed by single-crystal X-ray diffraction, which shows a layered structure with channels that are partially filled with parts of the flexible chains of adjacent macrocycles. The cyclic trimer has a D3h symmetry and is a possible candidate for the formation of metal organic supramolecular assemblies on surfaces.

  11. A mesoporous metal–organic framework based on a shape-persistent macrocycle

    Chen, Teng-Hao; Popov, Ilya; Chuang, Yu-Chun; Chen, Yu-Sheng; Miljani; #263; , Ognjen Š. (NSRRC); (UC); (Houston)


    A mesoporous Zn-based metal–organic framework (MOF) was prepared from a shape-persistent phenylene ethynylene macrocycle functionalized with three –COOH groups. The rigid ligand has a ~ 9 Å wide central cavity which serves as a predesigned pore. The macrocycles [ππ] stack into pairs, with their carboxylate groups connected via three Zn₃O₁₄C₆H₂ clusters. The resulting MOF has a void volume of 86%.

  12. Synthesis, structure and ring-opening polymerization of macrocyclic arylates containing phthalic unit

    姜洪焱; 陈天禄; 邢彦; 林永华; 徐纪平


    A series of maerocyclic arylate diraers have been selectively synthesized by an interfacial polyconden-sation of o-phthaloyldichloride with bisphenols A combination of GPC,FAB-MS,1H and 13C NMR unambiguously confirmed the cyclic nature Although single-crystal X-ray analysis of two such macrocycles reveals no severe strain on the cyclic structures,these macrocycles can undergo facile melt polymerization to give high molecular weight polyary-lates.

  13. Pulsed EPR and NMR spectroscopy of paramagnetic iron porphyrinates and related iron macrocycles: how to understand patterns of spin delocalization and recognize macrocycle radicals.

    Walker, F Ann


    Pulsed EPR spectroscopic techniques, including ESEEM (electron spin echo envelope modulation) and pulsed ENDOR (electron-nuclear double resonance), are extremely useful for determining the magnitudes of the hyperfine couplings of macrocycle and axial ligand nuclei to the unpaired electron(s) on the metal as a function of magnetic field orientation relative to the complex. These data can frequently be used to determine the orientation of the g-tensor and the distribution of spin density over the macrocycle, and to determine the metal orbital(s) containing unpaired electrons and the macrocycle orbital(s) involved in spin delocalization. However, these studies cannot be carried out on metal complexes that do not have resolved EPR signals, as in the case of paramagnetic even-electron metal complexes. In addition, the signs of the hyperfine couplings, which are not determined directly in either ESEEM or pulsed ENDOR experiments, are often needed in order to translate hyperfine couplings into spin densities. In these cases, NMR isotropic (hyperfine) shifts are extremely useful in determining the amount and sign of the spin density at each nucleus probed. For metal complexes of aromatic macrocycles such as porphyrins, chlorins, or corroles, simple rules allow prediction of whether spin delocalization occurs through sigma or pi bonds, and whether spin density on the ligands is of the same or opposite sign as that on the metal. In cases where the amount of spin density on the macrocycle and axial ligands is found to be too large for simple metal-ligand spin delocalization, a macrocycle radical may be suspected. Large spin density on the macrocycle that is of the same sign as that on the metal provides clear evidence of either no coupling or weak ferromagnetic coupling of a macrocycle radical to the unpaired electron(s) on the metal, while large spin density on the macrocycle that is of opposite sign to that on the metal provides clear evidence of antiferromagnetic coupling

  14. {sup 60}Co gamma-irradiation effects on electrical properties of a rectifying diode based on a novel macrocyclic Zn octaamide complex

    Ocak, Y.S. [Department of Science, Faculty of Education, University of Dicle, Diyarbakir (Turkey); Kilicoglu, T., E-mail: [Department of Physics, Faculty of Art and Science, University of Batman, Batman (Turkey); Department of Physics, Faculty of Art and Science, University of Dicle, Diyarbakir (Turkey); Topal, G. [Department of Chemistry, Faculty of Education, University of Dicle, Diyarbakir (Turkey); Baskan, M.H. [Department of Physics, Faculty of Education, University of Dicle, Diyarbakir (Turkey)


    C{sub 36}H{sub 28}N{sub 12}O{sub 8}ZnCl{sub 2}.9/2H{sub 2}O, Zn-octaamide (ZnOA) macrocyclic compound was synthesized to be used in the fabrication of electronic and photoelectronic devices. The structure of new compound was identified by using {sup 1}H NMR, {sup 13}C NMR, IR, UV-vis and LC-MS spectroscopic methods. The Sn/ZnOA/n-Si/Au structure was engineered by forming a thin macrocyclic organic compound layer on n-Si inorganic substrate and then by evaporating Sn metal on the organic layer. It was seen that the device had a good rectifying behaviour and showed Schottky diode properties. The diode was irradiated under {sup 60}Co gamma-source at room temperature. Characteristic parameters of the diode were determined from its current-voltage (I-V) and capacitance voltage (C-V) measurements before and after irradiation. It was observed that gamma-irradiation had clear effects on I-V and C-V properties. Also, it was seen that the barrier height, the ideality factor and the series resistance values decreased after the applied radiation, while the saturation current value increased.

  15. Polymerization behaviour of butyl bis(hydroxymethyl)phosphine oxide: Phosphorus containing polyethers for Li-ion conductivity

    Heeralal Vignesh Babu; Billakanti Srinivas; Khevath Praveen Kumar Naik; Krishnamurthi Muralidharan


    Synthesis of phosphorus containing polyethers and their lithium-ion conductivities for the potential use as solid polymer electrolyte (SPE) in high-energy density lithium-ion batteries have been described. Co-polymerization of butyl bis(hydroxymethyl)phosphine oxide with three different dibromo monomers were carried out to produce three novel phosphorous containing polyethers (P1–P3). These polymers were obtained via nucleophilic substitution reactions and were characterized by 1H, 31P NMR spectral data and gel permeation chromatography. SPEs were prepared using polyethers (P1 and P2) with various amounts of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The lithium-ion conductivity of SPE2 containing 40 wt% of LiTFSI was 2.1 × 10−5 S cm−1 at room temperature and 3.7 × 10−4 S cm−1 at 80°C.

  16. Rapid synthesis of cyclic oligomeric depsipeptides with positional, stereochemical, and macrocycle size distribution control.

    Batiste, Suzanne M; Johnston, Jeffrey N


    Macrocyclic small molecules are attractive tools in the development of sensors, new materials, and therapeutics. Within early-stage drug discovery, they are increasingly sought for their potential to interact with broad surfaces of peptidic receptors rather than within their narrow folds and pockets. Cyclization of linear small molecule precursors is a straightforward strategy to constrain conformationally mobile motifs, but forging a macrocycle bond typically becomes more difficult at larger ring sizes. We report the development of a general approach to discrete collections of oligomeric macrocyclic depsipeptides using an oligomerization/macrocyclization process governed by a series of Mitsunobu reactions of hydroxy acid monomers. Ring sizes of 18, 24, 30, and 36 are formed in a single reaction from a didepsipeptide, whereas sizes of 24, 36, and 60 result from a tetradepsipeptide. The ring-size selectivity inherent to the approach can be modulated by salt additives that enhance the formation of specific ring sizes. Use of chemical synthesis to prepare the monomers suggests broad access to functionally and stereochemically diverse collections of natural product-like oligodepsipeptide macrocycles. Two cyclodepsipeptide natural products were prepared along with numerous unnatural oligomeric congeners to provide rapid access to discrete collections of complex macrocyclic small molecules from medium (18) to large (60) ring sizes.

  17. Correlation between oxygen adsorption energy and electronic structure of transition metal macrocyclic complexes.

    Liu, Kexi; Lei, Yinkai; Wang, Guofeng


    Oxygen adsorption energy is directly relevant to the catalytic activity of electrocatalysts for oxygen reduction reaction (ORR). In this study, we established the correlation between the O2 adsorption energy and the electronic structure of transition metal macrocyclic complexes which exhibit activity for ORR. To this end, we have predicted the molecular and electronic structures of a series of transition metal macrocyclic complexes with planar N4 chelation, as well as the molecular and electronic structures for the O2 adsorption on these macrocyclic molecules, using the density functional theory calculation method. We found that the calculated adsorption energy of O2 on the transition metal macrocyclic complexes was linearly related to the average position (relative to the lowest unoccupied molecular orbital of the macrocyclic complexes) of the non-bonding d orbitals (d(z(2)), d(xy), d(xz), and d(yz)) which belong to the central transition metal atom. Importantly, our results suggest that varying the energy level of the non-bonding d orbitals through changing the central transition metal atom and/or peripheral ligand groups could be an effective way to tuning their O2 adsorption energy for enhancing the ORR activity of transition metal macrocyclic complex catalysts.

  18. Template Syntheses, Crystal Structures and Supramolecular Assembly of Hexaaza Macrocyclic Copper(II) Complexes

    Kim, Taehyung; Kim, Ju Chang [Pukyong National Univ., Busan (Korea, Republic of); Lough, Alan J. [Univ. of Toronto, Toronto (Canada)


    Two new hexaaza macrocyclic copper(II) complexes were prepared by a template method and structurally characterized. In the solid state, they were self-assembled by intermolecular interactions to form the corresponding supramolecules 1 and 2, respectively. In the structure of 1, the copper(II) macrocycles are bridged by a tp ligand to form a macrocyclic copper(II) dimer. The dimer extends its structure by intermolecular forces such as hydrogen bonds and C-H···π interactions, resulting in the formation of a double stranded 1D supramolecule. In 2, the basic structure is a monomeric copper(II) macrocycle with deprotonated imidazole pendants. An undulated 1D hydrogen bonded array is achieved through hydrogen bonds between imidazole pendants and secondary amines, where the imidazole pendants act as a hydrogen bond acceptor. The 1D hydrogen bonded supramolecular chain is supported by C-H···π interactions between the methyl groups of acetonitrile ligands and imidazole pendants of the copper(II) macrocycles. In both complexes, the introduction of imidazoles to the macrocycle as a pendant plays an important role for the formation of supramolecules, where they act as intermolecular hydrogen bond donors and/or acceptors, C-H···π and π-π interactions.

  19. Langmuir and Langmuir-Blodgett films of multifunctional, amphiphilic polyethers with cholesterol moieties.

    Reuter, Sascha; Hofmann, Anna M; Busse, Karsten; Frey, Holger; Kressler, Jörg


    Langmuir films of multifunctional, hydrophilic polyethers containing a hydrophobic cholesterol group (Ch) were studied by surface pressure-mean molecular area (π-mmA) measurements and Brewster angle microscopy (BAM). The polyethers were either homopolymers or diblock copolymers of linear poly(glycerol) (lPG), linear poly(glyceryl glycidyl ether) (lPGG), linear poly(ethylene glycol) (lPEG), or hyperbranched poly(glycerol) (hbPG). Surface pressure measurements revealed that the homopolymers lPG and hbPG did not stay at the water surface after spreading and solvent evaporation, in contrast to lPEG. Because of the incorporation of the Ch group in the polymer structure, stable Langmuir films were formed by Ch-lPG(n), Ch-lPGG(n), and Ch-hbPG(n). The Ch-hbPG(n), Ch-lPEG(n), Ch-lPEG(n)-b-lPG(m), Ch-lPEG(n)-b-lPGG(m), and Ch-lPEG(n)-b-hbPG(m) systems showed an extended plateau region assigned to a phase transition involving the Ch groups. Typical hierarchically ordered morphologies of the LB films on hydrophilic substrates were observed for all Ch-initiated polymers. All LB films showed that Ch of the Ch-initiated homopolymers is able to crystallize. This strong tendency of self-aggregation then triggers further dewetting effects of the respective polyether entities. Fingerlike morphologies are observed for Ch-lPEG(69), since the lPEG(69) entity is able to undergo crystallization after transfer onto the silicon substrate.


    ZHANG Shengshui; QIU Weihua; XUE Dacui; LIU Qingguo


    Complexes of comb-shaped polyether and lithium aromatic sulfonates bearing different negative charge number were prepared by in situ thermal polymerization. Their conductivity depends deeply on salt content, ambient temperature and negative charge number of the added salts. Results show that anions can be partly immobilized by increasing their negative charges at lower temperature.Against discharge time the short circuit current of the battery (Li/complex film/Lix V3O8) is stabilized by increasing the anionic charge number of the complex.

  1. Accelerated simulations of aromatic polymers: application to polyether ether ketone (PEEK)

    Broadbent, Richard J.; Spencer, James S.; Mostofi, Arash A.; Sutton, Adrian P.


    For aromatic polymers, the out-of-plane oscillations of aromatic groups limit the maximum accessible time step in a molecular dynamics simulation. We present a systematic approach to removing such high-frequency oscillations from planar groups along aromatic polymer backbones, while preserving the dynamical properties of the system. We consider, as an example, the industrially important polymer, polyether ether ketone (PEEK), and show that this coarse graining technique maintains excellent agreement with the fully flexible all-atom and all-atom rigid bond models whilst allowing the time step to increase fivefold to 5 fs.

  2. An olefin metathesis-iodoetherification-dehydroiodination strategy for spiroketal subunits of the polyether antibiotics

    Tony, Kurissery A.; Dabideen, Darrin; Li, Jialiang; Díaz-Hernández, Maria Dolores; Jiménez-Barbero, Jesús; Mootoo, David R.


    The convergent synthesis of two pentacyclic analogs of the polyether monensin A is described. Although different with respect to the configuration of the alcohol at the 3 position of the six membered ring of the spiroketal subunit, the configuration at the acetal center in both structures is unchanged and is consistent with the anomeric effect. The key synthetic steps are the coupling of two complex segments via an olefin metathesis, and the subsequent conversion of a dihydroxyalkene to the spiroketal through an iodoetherification-dehydroiodination sequence. The compatibility of these transformations with a variety of functional groups makes the overall strategy appropriate for highly substituted frameworks. PMID:19813766

  3. Dispersion of Co-poly Carboxylate Superplasticizer Containing Polyether Side Chain


    Free radical co-polymerization was employed to synthesize co-poly carboxylate (PC) superplasticizers with different amount of carboxyl and methyl polyethylene glycol (MPEG) side chain.Dispersion ability and retention of PC were compared with one another. The results show that increase of side chain is advantageous to dispersion, but it decreases when amount of MPEG is beyond a certain value which is different with the proportion of carboxyl. If the amount of carboxyl increases, the influence of side chain in copolymer on dispersion diminishes. Polyether side chain is advantageous to retention. And the author explained the mechanism of PC using the theory of steric repulsive force.


    LI Zhenyi; ZHU Jin


    A series of Si-containing polyester-polyether multiblock copolymers were synthesized by transesterification and melt copolycondensation of organosilicon monomers [1, 1, 3, 3-tetramethyl-1, 3-bis (p-carbomethoxyphenyl) disiloxane] (I) or dimethyl bis (p-carbomethoxyphenyl) silane] (II) and dimethyl terephthalate (DMT), with 1, 4-butanediol, polytetramethylene glycol (PTMG) respectively. The organosilicon monomers were prepared by Grinard reaction, oxidation and esterification. The structures of the above monomers (Ⅰ), (Ⅱ) and the copolymers were characterized by MS anal. and 1H-NMR.


    DONG Shihua; LIU Shi; XU Yuwu


    Three polystyrene resins containing polyether oligomers as extractants were synthesized and their extraction properties were studied. Gold (Ⅲ) ion could be extracted rapidly by the resins (T1/2<1min.)with high efficiency and capacity (for LS-B resin that were 99.8% and 95.8mg/gR respectively) from aqueous solution but most of the co-existing metal ions such as Pd (Ⅱ),Cu(Ⅱ), Zn (Ⅱ), Pb (Ⅱ) and Cd (Ⅱ) were remained. The extraction capacity and stripping percentage for gold (Ⅲ) remained unchanged in four extraction-stripping cycles. The resins also showed good column extraction-elution properties.

  6. Binding of alkali metal ions by cyclic polyethers: significance in ion transport processes.

    Izatt, R M; Rytting, J H; Nelson, D P; Haymore, B L; Christensen, J J


    Values for the formation constant (log K), the change in enthalpy (triangle upH degrees ), and the change in entropy (triangle upS degrees ) have been determined for the interaction of lithium, sodium, potassium, rubidium, and cesium ions with the two isomers of the cyclic polyether, 2,5,8,15,18,21-hexaoxatricyclo[,14)] hexacosane. The stability order of these metal ions with either isomer is identical to the permeability order for these same metal ions with the structurally related antibiotics, valinomycin and monactin.

  7. Dysprosium complexes with the tetraphenylporphyrin macrocyclic ligand; Complejos de disprosio con el ligante macrociclico tetrafenilporfirina

    Martinez M, V.; Padilla, J.; Ramirez, F.M


    In this report, the results obtained on the synthesis, characterization and study of the chemical behavior of dysprosium complex with the acetylacetone chelating agent (Hacac) and the tetraphenylporphyrin macrocyclic ligand (H{sub 2}TFP) are given. Based on the literature but according to our necessities and interest, the appropriate methodology settled down from the synthesis of prime matters until the obtaining and characterization of the products. The acetyl acetonate complex was obtained of mono hydrated dysprosium [Dy(acac){sub 3}. H{sub 2}0] and trihydrated [Dy(acac){sub 3} .3 H{sub 2}0], the mono tetra phenyl porphyrinate [Dy(TFP)(acac). 2 ac] the double sandwich of the dysprosium porphyrinate [Dy(TFP){sub 2}] and the triple sandwich of the dysprosium porphyrinate [Dy(TFP){sub 3}. 2 TCB] (TCB = trichlorobenzene). Its were characterized by their melting points, solubility, IR, UV, TGA and DTA both first and besides the techniques already mentioned for NMR'H, RPE and Magnetic susceptibility the three last complexes. From the spectroscopic point of view, IR and RPE its suggested the existence of a complex of inverse mixed valence [Dy(TFP){sup 2-} (TFP) {sup 1-}] for the Dy(TFP){sub 2} as a result of the existence of the free radical (TFP' {sup 1-} and that it was not in none of the other porphyrin compounds. In the NMR'H spectra of the compounds were not observed signals in the region from 0 to 10 ppm that which shows that the dysprosium complexes in special those of the porphyrin type are highly paramagnetic and its could be used as displacement reagents, creators of images and contrast agents of great utility in these days in studies of NMR, technique today by today used in medical diagnoses. (Author)

  8. Anti-influenza activity of marchantins, macrocyclic bisbibenzyls contained in liverworts.

    Yuma Iwai

    Full Text Available The H1N1 influenza A virus of swine-origin caused pandemics throughout the world in 2009 and the highly pathogenic H5N1 avian influenza virus has also caused epidemics in Southeast Asia in recent years. The threat of influenza A thus remains a serious global health issue and novel drugs that target these viruses are highly desirable. Influenza A possesses an endonuclease within its RNA polymerase which comprises PA, PB1 and PB2 subunits. To identify potential new anti-influenza compounds in our current study, we screened 33 different types of phytochemicals using a PA endonuclease inhibition assay in vitro and an anti-influenza A virus assay. The marchantins are macrocyclic bisbibenzyls found in liverworts, and plagiochin A and perrottetin F are marchantin-related phytochemicals. We found from our screen that marchantin A, B, E, plagiochin A and perrottetin F inhibit influenza PA endonuclease activity in vitro. These compounds have a 3,4-dihydroxyphenethyl group in common, indicating the importance of this moiety for the inhibition of PA endonuclease. Docking simulations of marchantin E with PA endonuclease suggest a putative "fitting and chelating model" as the mechanism underlying PA endonuclease inhibition. The docking amino acids are well conserved between influenza A and B. In a cultured cell system, marchantin E was further found to inhibit the growth of both H3N2 and H1N1 influenza A viruses, and marchantin A, E and perrotein F showed inhibitory properties towards the growth of influenza B. These marchantins also decreased the viral infectivity titer, with marchantin E showing the strongest activity in this assay. We additionally identified a chemical group that is conserved among different anti-influenza chemicals including marchantins, green tea catechins and dihydroxy phenethylphenylphthalimides. Our present results indicate that marchantins are candidate anti-influenza drugs and demonstrate the utility of the PA endonuclease assay in

  9. Lithiated and sulphonated poly(ether ether ketone) solid state electrolyte films for supercapacitors

    Chiu, K.-F.; Su, S.-H., E-mail:


    Poly(ether ether ketone) (PEEK) films have been synthesised and used as solid-state electrolytes for supercapacitors. In order to increase their ion conductivity, the PEEK films were sulphonated by sulphuric acid, and various amounts of LiClO{sub 4} were added. The solid-state electrolyte films were characterised by Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. The ionic conductivities of the electrolyte films were analysed by performing electrochemical impedance spectroscopy. The obtained electrolyte films can be sandwiched or directly coated on activated carbon electrodes to form solid-state supercapacitors. The electrochemical characteristics of these supercapacitors were investigated by performing cyclic voltammetry and charge–discharge tests. Under an optimal content of LiClO{sub 4}, the supercapacitor can provide a capacitance as high as 190 F/g. After 1000 cycles, the supercapacitors show almost no capacitance fading, indicating high stability of the solid-state electrolyte films. - Highlights: • Poly(ether ether ketone) (PEEK) films have been used as solid-state electrolytes. • LiClO4 addition can efficiently improve the ionic conductivity. • Supercapacitors using PEEK electrolyte films deliver high capacitance.

  10. Isocyanate-terminated Polyethers Toughened Epoxy Resin: Chemical Modification, Thermal Properties, and Mechanical Strength

    CAI Haopeng; WANG Jun; WANG Xiang; XU Renxin


    The toughening of the diglycidyl ether of bisphenol A epoxy resin with isocyanateterminated polyethers (ITPE) was investigated. The progress of the reaction and the structural changes during modification process were studied using FTIR spectroscopy. The studies support the proposition that TDI (tolylene diisocyanate) acts as a coupling agent between the epoxy and polyethers, forming a urethane linkage with the former and the latter, respectively. Me THPA-cured ER/ITPs blends were characterized using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). It is indicated the glass transition temperature (Tg) of systems was lower than the Tg of pure epoxy resin and overfull ITPE separated from the modified epoxy resin and formed another phase at an ITPE-content of more than 10wt%. The thermal stability was decreased by the introduction of ITPE. The impact strength and the flexural strength of the cured modifiedepoxy increased with increasing the ITPE content and a maximum plateau value of about 24.03 kJ/m2 and 130.56 MPa was measured in 10wt% ITPE. From scanning electron microscopy (SEM) studies of the fractrue surfaces of ER/ITPE systems, the nature of the micromechanisms responsible for the increases in toughness of the systems was identified.

  11. Hyperbranched-linear poly(ether sulfone) blend films for proton exchange membranes

    Grunzinger, Stephen J.; Watanabe, Masatoshi; Fukagawa, Kiyotaka; Kikuchi, Ryohei; Tominaga, Yoichi; Hayakawa, Teruaki; Kakimoto, Masa-aki [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)


    Hyperbranched poly(ether sulfone) polymers having sulfonyl chloride end-groups is blended at up to 30 w% with linear poly(ether ether ether sulfone)s and a two-phase system is generated via spinodal decomposition upon drying from a DMAc solution. Conversion of the end-groups from sulfonyl chloride to sulfonic acid is accomplished using 16 M H{sub 2}SO{sub 4} that is also believed to introduce additional sulfonic acid groups at the interface of the linear polymer. The blend films before and after conversion to sulfonic acid have similar tensile strengths as films composed of solely linear polymer (yield stress >40 MPa and Young's modulus >3 GPa m). These films are designed to test the viability of hyperbranched polymers as fuel cell membranes. Proton conductivities of up to 0.03 S cm{sup -1} are observed at 80 C and 90% R.H indicating a good potential for use of hyperbranched polymers as a proton conduction material. (author)

  12. Hydroxyalkylation and polyether polyol grafting of graphene tailored for graphene/polyurethane nanocomposites.

    Appel, Anna-Katharina; Thomann, Ralf; Mülhaupt, Rolf


    Graphene functionalization by hydroxyalkylation and grafting with polyether polyols enables polyurethane (PU) nanocomposites formation by in situ polymerization with isocyanates combined with effective covalent interfacial coupling. Functionalized graphene (FG) hydroxylation is achieved either by alkylation, transesterification, or grafting of thermally reduced graphite oxide. In the presence of K2 CO3 as catalyst the reaction of FG-OH with ethylene carbonate at 180 °C affords hydroxyethylated FG, whereas transesterification with castor oil produces riconoleiate-modified FG polyols. In the "grafting-from" process, FG-alkoholate macro initiators initiate the graft polymerization of propylene oxide to produce hybrid FG polyols containing 38 and 59 wt% oligopropylene oxide. In the "grafting-to" process 3-ethyl-3-hydroxymethyl-oxetane is cationically polymerized onto FG-OH, producing novel hyperbranched FG-based polyether polyols. Whereas hydroxylation and grafting of FG greatly improve FG dispersion in organic solvents, polyols and even PU, as confirmed by transmission electron microscopy, matrix reinforcement of FG/PU is impaired by increasing alkyl chain length and polyol graft copolymer content. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Cloning and characterization of the polyether salinomycin biosynthesis gene cluster of Streptomyces albus XM211.

    Jiang, Chunyan; Wang, Hougen; Kang, Qianjin; Liu, Jing; Bai, Linquan


    Salinomycin is widely used in animal husbandry as a food additive due to its antibacterial and anticoccidial activities. However, its biosynthesis had only been studied by feeding experiments with isotope-labeled precursors. A strategy with degenerate primers based on the polyether-specific epoxidase sequences was successfully developed to clone the salinomycin gene cluster. Using this strategy, a putative epoxidase gene, slnC, was cloned from the salinomycin producer Streptomyces albus XM211. The targeted replacement of slnC and subsequent trans-complementation proved its involvement in salinomycin biosynthesis. A 127-kb DNA region containing slnC was sequenced, including genes for polyketide assembly and release, oxidative cyclization, modification, export, and regulation. In order to gain insight into the salinomycin biosynthesis mechanism, 13 gene replacements and deletions were conducted. Including slnC, 7 genes were identified as essential for salinomycin biosynthesis and putatively responsible for polyketide chain release, oxidative cyclization, modification, and regulation. Moreover, 6 genes were found to be relevant to salinomycin biosynthesis and possibly involved in precursor supply, removal of aberrant extender units, and regulation. Sequence analysis and a series of gene replacements suggest a proposed pathway for the biosynthesis of salinomycin. The information presented here expands the understanding of polyether biosynthesis mechanisms and paves the way for targeted engineering of salinomycin activity and productivity.

  14. Isopropyl Myristate-Modified Polyether-Urethane Coatings as Protective Barriers for Implantable Medical Devices

    Pankaj Vadgama


    Full Text Available Polyurethane films have potential applications in medicine, especially for packaging implantable medical devices. Although polyether-urethanes have superior mechanical properties and are biocompatible, achieving water resistance is still a challenge. Polyether based polyurethanes with two different molecular weights (PTMO1000, PTMO2000 were prepared from 4,4’-diphenylmethane diisocyanate and poly(tetra-methylene oxide. Polymer films were introduced using different concentrations (0.5-10 wt % of isopropyl myristate lipid (IPM as a non-toxic modifying agent. The physical and mechanical properties of these polymers were characterised using physical and spectroscopy techniques (FTIR, Raman, DSC, DMA, tensile testing. Water contact angle and water uptake of the membranes as a function of IPM concentration was also determined accordingly. The FTIR and Raman data indicate that IPM is dispersed in polyurethane at ≤ 2wt% and thermal analysis confirmed this miscibility to be dependent on soft segment length. Modified polymers showed increased tensile strength and failure strain as well as reduced water uptake by up to 24% at 1-2 wt% IPM.

  15. Molecular dynamics simulations to calculate glass transition temperature and elastic constants of novel polyethers.

    Sarangapani, Radhakrishnan; Reddy, Sreekantha T; Sikder, Arun K


    Molecular dynamics simulations studies are carried out on hydroxyl terminated polyethers that are useful in energetic polymeric binder applications. Energetic polymers derived from oxetanes with heterocyclic side chains with different energetic substituents are designed and simulated under the ensembles of constant particle number, pressure, temperature (NPT) and constant particle number, volume, temperature (NVT). Specific volume of different amorphous polymeric models is predicted using NPT-MD simulations as a function of temperature. Plots of specific volume versus temperature exhibited a characteristic change in slope when amorphous systems change from glassy to rubbery state. Several material properties such as Young's, shear, and bulk modulus, Poisson's ratio, etc. are predicted from equilibrated structures and established the structure-property relations among designed polymers. Energetic performance parameters of these polymers are calculated and results reveal that the performance of the designed polymers is comparable to the benchmark energetic polymers like polyNIMMO, polyAMMO and polyBAMO. Overall, it is worthy remark that this molecular simulations study on novel energetic polyethers provides a good guidance on mastering the design principles and allows us to design novel polymers of tailored properties.

  16. [Tl(III)(dota)](-): An Extraordinarily Robust Macrocyclic Complex.

    Fodor, Tamás; Bányai, István; Bényei, Attila; Platas-Iglesias, Carlos; Purgel, Mihály; Horváth, Gábor L; Zékány, László; Tircsó, Gyula; Tóth, Imre


    The X-ray structure of {C(NH2)3}[Tl(dota)]·H2O shows that the Tl(3+) ion is deeply buried in the macrocyclic cavity of the dota(4-) ligand (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate) with average Tl-N and Tl-O distances of 2.464 and 2.365 Å, respectively. The metal ion is directly coordinated to the eight donor atoms of the ligand, which results in a twisted square antiprismatic (TSAP') coordination around Tl(3+). A multinuclear (1)H, (13)C, and (205)Tl NMR study combined with DFT calculations confirmed the TSAP' structure of the complex in aqueous solution, which exists as the Λ(λλλλ)/Δ(δδδδ) enantiomeric pair. (205)Tl NMR spectroscopy allowed the protonation constant associated with the protonation of the complex according to [Tl(dota)](-) + H(+) ⇆ [Tl(Hdota)] to be determined, which turned out to be pK(H)Tl(dota) = 1.4 ± 0.1. [Tl(dota)](-) does not react with Br(-), even when using an excess of the anion, but it forms a weak mixed complex with cyanide, [Tl(dota)](-) + CN(-) ⇆ [Tl(dota)(CN)](2-), with an equilibrium constant of Kmix = 6.0 ± 0.8. The dissociation of the [Tl(dota)](-) complex was determined by UV-vis spectrophotometry under acidic conditions using a large excess of Br(-), and it was found to follow proton-assisted kinetics and to take place very slowly (∼10 days), even in 1 M HClO4, with the estimated half-life of the process being in the 10(9) h range at neutral pH. The solution dynamics of [Tl(dota)](-) were investigated using (13)C NMR spectroscopy and DFT calculations. The (13)C NMR spectra recorded at low temperature (272 K) point to C4 symmetry of the complex in solution, which averages to C4v as the temperature increases. This dynamic behavior was attributed to the Λ(λλλλ) ↔ Δ(δδδδ) enantiomerization process, which involves both the inversion of the macrocyclic unit and the rotation of the pendant arms. According to our calculations, the arm-rotation process limits the Λ(λλλλ) ↔

  17. Dynamic covalent chemistry approaches toward macrocycles, molecular cages, and polymers.

    Jin, Yinghua; Wang, Qi; Taynton, Philip; Zhang, Wei


    The current research in the field of dynamic covalent chemistry includes the study of dynamic covalent reactions, catalysts, and their applications. Unlike noncovalent interactions utilized in supramolecular chemistry, the formation/breakage of covalent bonding has slower kinetics and usually requires the aid of a catalyst. Catalytic systems that enable efficient thermodynamic equilibrium are thus essential. In this Account, we describe the development of efficient catalysts for alkyne metathesis, and discuss the application of dynamic covalent reactions (mainly imine, olefin, and alkyne metathesis) in the development of organic functional materials. Alkyne metathesis is an emerging dynamic covalent reaction that offers robust and linear acetylene linkages. By introducing a podand motif into the catalyst ligand design, we have developed a series of highly active and robust alkyne metathesis catalysts, which, for the first time, enabled the one-step covalent assembly of ethynylene-linked functional molecular cages. Imine chemistry and olefin metathesis are among the most well-established reversible reactions, and have also been our main synthetic tools. Various shape-persistent macrocycles and covalent organic polyhedrons have been efficiently constructed in one-step through dynamic imine chemistry and olefin metathesis. The geometrical features and solubilizing groups of the building blocks as well as the reaction kinetics have significant effect on the outcome of a covalent assembly process. More recently, we explored the orthogonality of imine and olefin metatheses, and successfully synthesized heterosequenced macrocycles and molecular cages through one-pot orthogonal dynamic covalent chemistry. In addition to discrete molecular architectures, functional polymeric materials can also be accessed through dynamic covalent reactions. Defect-free solution-processable conjugated polyaryleneethynylenes and polydiacetylenes have been prepared through alkyne metathesis

  18. Influence of disinfection with peracetic acid and hypochlorite in dimensional alterations of casts obtained from addition silicone and polyether impressions.

    Queiroz, Daher Antonio; Peçanha, Marcelo Massaroni; Neves, Ana Christina Claro; Frizzera, Fausto; Tonetto, Mateus Rodrigues; Silva-Concílio, Laís Regiane


    Dental impressions disinfection is important to reduce the risk of cross contamination but this process may produce dimensional distortions. Peracetic acid is a disinfectant agent with several favorable characteristics yet underutilized in Dentistry. The aim of this paper is to compare the dimensional stability of casts obtained from addition silicone and polyether impressions that were immersed for 10 minutes in a solution of 0.2% peracetic acid or 1% sodium hypochlorite. Sixty samples in type IV gypsum were produced after a master cast that simulated a full crown preparation of a maxillary premolar. Samples were divided in 6 groups (n = 10) according to the impression material and disinfection agent: Group AC--addition silicone control (without disinfectant); Group APA--addition silicone + 0.2% peracetic acid; Group AH--addition silicone + 1% sodium hypochlorite; Group PC--polyether control (without disinfectant); Group PPA--polyether + 0.2% peracetic acid; Group PH--polyether + 1% sodium hypochlorite. Cast height, base and top diameter were measured and a mean value was obtained for each sample and group all data was statistically analyzed (ANOVA, p peracetic acid could be considered a reliable material to disinfect dental molds.

  19. Ion conducting solid polymer electrolytes based on polypentafluorostyrene-b-polyether-b-polypentafluorostyrene prepared by atom transfer radical polymerization

    Jankova, Katja; Jannasch, P.; Hvilsted, Søren


    .3. The bromoisobutyrate functionalized polyether macroinitiators with molecular masses (M-n) of approx. 10 000 enabled the addition of between 15 and 39 wt.% flanking PFS as found by H-1 NMR. In a similar fashion monomethoxy PEG ( MPEG, Mn 5 000) was added 50 wt.% PFS. Polymer electrolytes were prepared by complexing...

  20. Dermatobia hominis: Potencial risk of resistance to macrocyclic lactones.

    das Neves, José Henrique; Carvalho, Nadino; Amarante, Alessandro F T


    Dermatobia hominis is an ectoparasite that infests various species of mammals, including cattle, impairing the quality of cowhides and leather. After observing natural infestation with D. hominis larvae in cattle on two farms in the state of São Paulo, Brazil, we evaluated the efficacy of two macrocyclic lactones, ivermectin and moxidectin, against this parasite. The drugs were administered to 10 animals in each group, following the manufacturer's instructions. The groups were: Group 1-treated with ivermectin (0.2mg/kg of body weight (BW)); Group 2-treated with moxidectin (0.2mg/kg BW); and Group 3-control (untreated). On the farm in Pardinho, a total of 12 and 16 live larvae were found in 6 and in 8 animals 10 days after the treatment with ivermectin and moxidectin, respectively, while in the control group 4 bovines had a total of 7 live larvae. On the farm in Anhembi, 2, 4 and 6 live larvae were extracted from ivermectin, moxidectin and control groups, respectively, after the treatment. This is the first report of the presence of live D. hominis larvae after the treatment of cattle with ivermectin and moxidectin in Brazil. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Sequence-defined bioactive macrocycles via an acid-catalysed cascade reaction

    Porel, Mintu; Thornlow, Dana N.; Phan, Ngoc N.; Alabi, Christopher A.


    Synthetic macrocycles derived from sequence-defined oligomers are a unique structural class whose ring size, sequence and structure can be tuned via precise organization of the primary sequence. Similar to peptides and other peptidomimetics, these well-defined synthetic macromolecules become pharmacologically relevant when bioactive side chains are incorporated into their primary sequence. In this article, we report the synthesis of oligothioetheramide (oligoTEA) macrocycles via a one-pot acid-catalysed cascade reaction. The versatility of the cyclization chemistry and modularity of the assembly process was demonstrated via the synthesis of >20 diverse oligoTEA macrocycles. Structural characterization via NMR spectroscopy revealed the presence of conformational isomers, which enabled the determination of local chain dynamics within the macromolecular structure. Finally, we demonstrate the biological activity of oligoTEA macrocycles designed to mimic facially amphiphilic antimicrobial peptides. The preliminary results indicate that macrocyclic oligoTEAs with just two-to-three cationic charge centres can elicit potent antibacterial activity against Gram-positive and Gram-negative bacteria.

  2. Unsaturated 15 and 16 Membered Appended Naphthalene Macrocyclic Molecules for The Development of Fluorometric Chemosensors

    Hasan, S.; Salleh, S.; Hamdan, S.; Yamin, B.


    Unsaturated macrocyclic molecules have got an interest due to their potential in catalysis, ion exchange and electron transfer. Salicaldehyde derivatives macrocyclic molecules have a broad range in synthesis. In this study, two unsaturated macrocyclic molecules (L1 and L2) have been synthesized. The preparation of unsaturated macrocyclic ligands involve two steps; the reaction of salicylaldehyde with 1,2-dibromoethane or 1,4-dibromobutane to produce precursor, then cyclisation were completed using schiff base technique by adding diamines (naphthalene diamine). The ligands were characterized spectroscopically. In FT-IR spectrums, the form of the ligands mainly can be observed on the disappearance of the carbonyl group of aldehyde at approximately 1650cm-1 that was readily assigned to C=O group of salicylaldehyde with the replacement of C=N peak at 1684.13cm-1. The success in producing macrocyclic ligands have been further characterized using fluorescence emission spectroscopy (FES) and revealed the typical emission of naphthalene at ∼430nm. Fluorescence changes of L1 and L2 showed high selectivity for Fe3+ and Cu2+ respectively in the presence of other common metal ions, such as Zn2+, Ni2+ and Co2+. Besides, the ligand was sensitive enough to detect the concentration of ferric ion with the detection limit down to 1.08 x 10-6 M and fluorescence change that was unaffected by the presence of other common coexisting metal ions. Complexation with Co(II) was also attempted.

  3. Characterization of Haemonchus contortus P-glycoprotein-16 and its interaction with the macrocyclic lactone anthelmintics.

    Godoy, P; Che, H; Beech, R N; Prichard, R K


    Anthelmintic resistance in veterinary nematodes, including Haemonchus contortus, has become a limitation to maintaining high standards of animal health. Resistance in this parasite, to all drug families including the macrocyclic lactones (MLs) is a serious issue worldwide. Mechanisms of resistance to the MLs appear to be complex and to include the elimination of these compounds by ABC transporter-like proteins present in nematodes. In order to investigate the potential involvement of ABC transporters in ML resistance in H. contortus, we have characterized the functionality of the ABC transporter H. contortus P-glycoprotein-16 (Hco-PGP-16) expressed in mammalian cells. This has included a study of its interaction with different MLs, including the avermectins, abamectin (ABA) and ivermectin (IVM), and the milbemycin, moxidectin (MOX). Hco-PGP-16 transport activity was studied using the fluorophore Rhodamine 123 (Rho 123). Transfected cells expressing Hco-PGP-16 accumulated less than 50% of Rho 123 than control cells, suggesting an active transport of this tracer dye by Hco-PGP-16. The influence of the MLs on the Rho123 transport by Hco-PGP-16 was then investigated. A marked inhibition of Rho123 transport by ABA and IVM was observed. In contrast, MOX showed less effect on inhibition of Rho123 transport by Hco-PGP-16, and the inhibition was not saturable. The difference in the interaction of the avermectins and MOX with Hco-PGP-16 may help explain the slower rate of development of resistance to MOX compared with the avermectins in H. contortus.

  4. Nitrogen-Phosphorus(III)-Chalcogen Macrocycles for the Synthesis of Polynuclear Silver(I) Sandwich Complexes.

    Yogendra, Sivathmeehan; Hennersdorf, Felix; Weigand, Jan J


    The synthesis of inorganic N-P(III)-Ch-based macrocycles [-PhP-NMe-PPh-Ch-]2 (8Ch; Ch = S, Se) is presented by incorporating two nitrogen, two chalcogen, and four phosphorus atoms. The macrocycles are conveniently obtained via the cyclocondensation reaction of Na2Ch (Ch = S, Se) with the acyclic dichlorodiphosphazane ClPhP-NMe-PClPh (9). Treatment with elemental sulfur (S8) or gray selenium (Segray) results in an oxidative ring contraction to give 1,3,2,4-thiazadiphosphetidine 2,4-disulfide (10S) and 1,3,2,4-selenazadiphosphetidine 2,4-diselenide (10Se), respectively. Macrocycles 8Ch are excellent multidentate ligands for transition metal complexation, as demonstrated by the isolation of mono-, di- tri-, and tetranuclear silver sandwich complexes. The polynuclear silver complexes are comprehensively characterized, including detailed NMR and X-ray analysis.

  5. Reinvestigation on the Reaction of Salicylic Chloride with Salicylic Amide and X-ray Crystal Structure of a New Macrocyclic Polyester

    DU Da-Ming; CHEN Xiao; HUA Wen-Ting; JIN Xiang-Lin


    The reaction of salicylic chloride and salicylic amide at 170 ℃ gave benzoxazine and a new macrocyclic polyester 3, whose crystal structure has been determined by single-crystal X-ray diffraction analysis. Compound 3: C28H16O8, Mr = 480.41, monoclinic, space group P21/n, a = 15.353(3), b = 14.196(3), c = 21.147(4) A, β = 103.32(3)°, V = 4485(2) A3, Z = 8, F(000) = 1984, Dc = 1.423 g/cm3 and μ = 0.106 mm-1. The final R = 0.0535 and Wr = 0.1275 for 7903 observed reflections (I ≥ 2σ(I)). In the asymmetric unit of the compound there exist two independent molecules which are connected by weak aromatic C-H…O hydrogen bonding between C(47)- H(47) and atom O(7) of the carbonyl group.

  6. Design, synthesis and characterization of macrocyclic ligand based transition metal complexes of Ni(II), Cu(II) and Co(II) with their antimicrobial and antioxidant evaluation

    Gull, Parveez; Malik, Manzoor Ahmad; Dar, Ovas Ahmad; Hashmi, Athar Adil


    Three new complexes Ni(II), Cu(II) and Co(II) were synthesized of macrocyclic ligand derived from 1, 4-dicarbonyl-phenyl-dihydrazide and O-phthalaldehyde in the ratio of 2:2. The synthesized compounds were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV-Vis., Mass and 1H NMR spectral studies. The electronic spectra of the metal complexes indicate a six coordinate octahedral geometry of the central metal ion. These metal complexes and the ligand were evaluated for antimicrobial activity against bacteria (E. coli, B. subtilis, S. aureus) and fungi (A. niger, A. flavus, C. albicans) and compared against standard drugs chloramphenicol and nystatin respectively. In addition, the antioxidant activity of the compounds was also investigated through scavenging effect on DPPH radicals.

  7. Thermally stable hyperbranched polyether-based polymer electrolyte for lithium-ion batteries

    Wu, Feng; Feng, Ting; Wu, Chuan; Bai, Ying; Ye, Lin; Chen, Junzheng


    A thermally stable polymer matrix, comprising hyperbranched polyether PHEMO (poly(3-{2-[2-(2-hydroxyethoxy) ethoxy] ethoxy}methyl-3'-methyloxetane)) and PVDF-HFP (poly(vinylidene fluoride-hexafluoropropylene)), has been successfully prepared for applications in lithium-ion batteries. This type of polymer electrolyte has been made by adding different amounts of lithium bis(oxalate)borate (LiBOB) to the polymer matrix. Its thermal and structural properties were measured using differential scanning calorimetry and x-ray diffraction. Experimental results show that the polymer electrolyte system possesses good thermal stability, with a decomposition temperature above 420 °C. The ionic conductivity of the polymer electrolyte system is dependent on the lithium salt content, reaching a maximum of 1.1 × 10-5 S cm-1 at 30 °C and 2.3 × 10-4 S cm-1 at 80 °C when doped with 10 wt% LiBOB.

  8. Influence of technique and pouring time on dimensional stability of polyvinyl siloxane and polyether impressions.

    Gomez-Polo, Miguel; Celemin, Alicia; del Rio, Jaime; Sanchez, Andres


    This study aimed to determine how impression technique and pouring time affect casts obtained using polyvinyl siloxane (PVS) and polyether (PE) impressions. A total of 480 impressions were taken using three techniques: single-step (SS), two-step (TS), and two-step with a spacer (TSS). Impressions were poured after 1 and 24 hours and 7 and 14 days. Significant differences (P < .01) were found between the TS technique and the SS and TSS methods as well as between PE and PVS (P < .01) in terms of the effects of pouring time. SS and TSS yielded similar dimensional results, while greater dimensional change was induced with TS. PE impressions had to be poured no later than 7 days after preparation to ensure dimensional stability.

  9. Ciguatoxins: Cyclic Polyether Modulators of Voltage-gated Iion Channel Function

    Richard J. Lewis


    Full Text Available Ciguatoxins are cyclic polyether toxins, derived from marine dinoflagellates, which are responsible for the symptoms of ciguatera poisoning. Ingestion of tropical and subtropical fin fish contaminated by ciguatoxins results in an illness characterised by neurological, cardiovascular and gastrointestinal disorders. The pharmacology of ciguatoxins is characterised by their ability to cause persistent activation of voltage-gated sodium channels, to increase neuronal excitability and neurotransmitter release, to impair synaptic vesicle recycling, and to cause cell swelling. It is these effects, in combination with an action to block voltage-gated potassium channels at high doses, which are believed to underlie the complex of symptoms associated with ciguatera. This review examines the sources, structures and pharmacology of ciguatoxins. In particular, attention is placed on their cellular modes of actions to modulate voltage-gated ion channels and other Na+-dependent mechanisms in numerous cell types and to current approaches for detection and treatment of ciguatera.

  10. Modification of Poly(ether ether ketone Polymer for Fuel Cell Application

    Devesh Shukla


    Full Text Available Polyelectrolyte membrane (PEM is an important part of PEM fuel cell. Nafion is a commercially known membrane which gives the satisfactory result in PEM fuel cell operating at low temperature. Present research paper includes functionalization of Poly(ether ether ketone (PEEK polymer with phosphonic acid group. The functionalization was done with the help of nickel-based catalyst. Further, the polymer was characterized by the FTIR, EDAX, DSC, TGA, and 1H NMR, and it was found that PEEK polymer was functionalized with phosphonic acid group with good thermal stability in comparison to virgin PEEK. Finally, the thin films of functionalized polymer were prepared by solution casting method, and proton conductivity of film samples was measured by impedance spectra whose value was found satisfactory with good thermal stability in comparison to commercially available Nafion membrane.

  11. Evaluation of Stabilization Performances of Antioxidants in Poly(ether ether ketone)

    ZHOU Zheng; ZHOU Fu-gui; ZHANG Shu-ling; MU Jian-xin; YUE Xi-gui; WANG Gui-bin


    Two types of antioxidants(a primary antioxidant and a secondary antioxidant) were used to improve the stability of poly(ether ether ketone)(PEEK).The effects of the antioxidants on the properties of PEEK and the stabilization mechanism were investigated by some characterization methods,such as rheometer,thermogravinetric analysis(TGA),universal tester and electron spin resonance(ESR).The results indicate that the efficiency of the phosphorous antioxidant(DS) in improving the stability of PEEK was better than that of the phenolic antioxidant(DN) in both melting stability and thermal stability,and the thermal stability of PEEK sample containing 0.07%(mass fraction) DS was the best among all the samples due to the decrease of the free radicals density,as proven by ESR measurement.Additionally,no obvious changes could be observed in mechanical properties of PEEK containing antioxidants compared to those of virgin PEEK.

  12. The Thermoplastic Polyether-imide%热塑性聚醚酰亚胺

    张露; 张雯; 张凯


    Polyether-imide (PEI)is a new amorphous thermoplastic polyimide.It has good processing behavior with typical thermoplastic processing and forming equipment to manufacture a lot of products.It possesses heat resistance,dimensional stability and excellent flame retardancy.In this paper,the properties and application of PEI are briefly introduced.%聚醚酰亚胺(PEI)是一种新型热塑性聚酰亚胺,具有很好的成型加工性能,可用一般热塑性塑料成型加工工艺和设备制造多种制品。产品具有高的长期耐热性、尺寸稳定性及突出的阻燃性。本文介绍了近年来PEI的生产、应用和开发情况。

  13. Study on EPR Spectra of Three Gadolinium Complexes With Noncyclic Polyether Schiff Bases

    陈德余; 姚克敏; 封子先; 蔡乐真; 周佩芬; 薛祺


    The EPR spectra of three new gadolinium complexes with noncyclic polyether Schiff bases in powder and those of these complexes in organic solvents were investigated at different temperatures. It was observed that EPR spectra of nine and four peaks of Gd(Ⅲ) complexes in polycrystalline powder and freezing samples appeared at low temperature respectively for the first time. The interpretations of these results obtained on the basis of spin Hamiltonian of s = 7/2 system are satisfactory. The correlations of EPR feature between crystal-field strength in complexes and local symmetry around Gd3+ ions were revealed. The crystal-field parameters b20 and the asymmetry parameters λ’ of complexes were estimated. A series of interesting regularity and new results were obtained.

  14. Synthesis and antimicrobial activity of amide derivatives of polyether antibiotic-salinomycin.

    Huczyński, Adam; Janczak, Jan; Stefańska, Joanna; Antoszczak, Michał; Brzezinski, Bogumil


    For the first time a direct and practical approach to the synthesis of eight amide derivatives of polyether antibiotic-salinomycin is described. The structure of allyl amide (3a) has been determined using X-ray diffraction. Salinomycin and its amide derivatives have been screened for their in vitro antimicrobial activity against the typical gram-positive cocci, gram-negative rods and yeast-like organisms, as well as against a series of clinical isolates of methicillin-resistant Staphylococcus aureus and methicillin-sensitive S. aureus. Amides of salinomycin have been found to show a wide range of activities, from inactive at 256 μg/mL to active with MIC of 2 μg/mL, comparable with salinomycin. As a result, phenyl amide (3b) was found to be the most active salinomycin derivative against gram-positive bacteria, MRSA and MSSA.

  15. Analysis of Percolation Behavior of Electrical Conductivity of the Systems Based on Polyethers and Carbon Nanotubes

    E.A. Lysenkov


    Full Text Available The basic theoretical models of electrical conductivity of polymer nanocomposites and their accordance to experimental results are analysed for the systems based on polyethers and carbon nanotubes using the methods of mathematical simulation. It is set that models which are based on the effective medium approximation do not take into account existence of percolation threshold and can’t be using for exact definition of experimental data. It is discovered that the Fourier model demonstrats a good accordance with an experiment, however it is applicable only for the systems in which a large increase of conductivity under reaching the percolation threshold is observed, that systems with low own conductivity. It is set that the best accordance to experimental data was shown by the Kirkpatrick model and the generalized McLachlan model, which, except for the percolation threshold, structural descriptions of clusters which are formed from carbon nanotubes take into account.

  16. Macrocyclic ligands for uranium complexation. Final report, August 1, 1986--March 31, 1993

    Potts, K.T.


    Macrocycles, designed for complexation of the uranyl ion by computer modeling studies and utilizing six ligating atoms in the equatorial plane of the uranyl ions, have been prepared and their complexation of the uranyl ions evaluated. The ligating atoms, either oxygen or sulfur, were part of acylurea, biuret or thiobiuret subunits with alkane chains or pyridine units completing the macrocyclic periphery. These macrocycles with only partial preorganization formed uranyl complexes in solution but no crystalline complexes were isolated. Refinement of the cavity diameter by variation of the peripheral functional groups is currently studied to achieve an optimized cavity diameter of 4.7--5.2 {angstrom}. Acyclic ligands containing the same ligating atoms in equivalent functional entities were found to form a crystalline 1:1 uranyl-ligand complex (stability constant log K = 10.7) whose structure was established by X-ray data. This complex underwent a facile, DMSO-induced rearrangement to a 2:1 uranyl-ligand complex whose structure was also established by X-ray data. The intermediates to the macrocycles all behaved as excellent ligands for the complexation of transition metals. Acylthiourea complexes of copper and nickel as well as intermolecular, binuclear copper and nickel complexes of bidentate carbonyl thioureas formed readily and their structures were established in several representative instances by X-ray structural determinations. Tetradentate bis(carbonylthioureas) were found to be very efficient selective reagents for the complexation of copper in the presence of nickel ions. Several preorganized macrocycles were also prepared but in most instances these macrocycles underwent ring-opening under complexation conditions.

  17. The Porphobilinogen Conundrum in Prebiotic Routes to Tetrapyrrole Macrocycles

    Taniguchi, Masahiko; Ptaszek, Marcin; Chandrashaker, Vanampally; Lindsey, Jonathan S.


    Attempts to develop a credible prebiotic route to tetrapyrroles have relied on enzyme-free recapitulation of the extant biosynthesis, but this process has foundered from the inability to form the pyrrole porphobilinogen ( PBG) in good yield by self-condensation of the precursor δ-aminolevulinic acid ( ALA). PBG undergoes robust oligomerization in aqueous solution to give uroporphyrinogen (4 isomers) in good yield. ALA, PBG, and uroporphyrinogen III are universal precursors to all known tetrapyrrole macrocycles. The enzymic formation of PBG entails carbon-carbon bond formation between the less stable enolate/enamine of one ALA molecule (3-position) and the carbonyl/imine (4-position) of the second ALA molecule; without enzymes, the first ALA reacts at the more stable enolate/enamine (5-position) and gives the pyrrole pseudo-PBG. pseudo-PBG cannot self-condense, yet has one open α-pyrrole position and is proposed to be a terminator of oligopyrromethane chain-growth from PBG. Here, 23 analogues of ALA have been subjected to density functional theoretical (DFT) calculations, but no motif has been identified that directs reaction at the 3-position. Deuteriation experiments suggested 5-(phosphonooxy)levulinic acid would react preferentially at the 3- versus 5-position, but a hybrid condensation with ALA gave no observable uroporphyrin. The results suggest efforts toward a biomimetic, enzyme-free route to tetrapyrroles from ALA should turn away from structure-directed reactions and focus on catalysts that orient the two aminoketones to form PBG in a kinetically controlled process, thereby avoiding formation of pseudo-PBG.

  18. Poly(vinylbenzyl sulfonic acid)-grafted poly(ether ether ketone) membranes

    Hwang, Mi-Lim; Choi, Jisun; Woo, Hyun-Su; Kumar, Vinod; Sohn, Joon-Yong; Shin, Junhwa, E-mail:


    Highlights: • PEEK-g-PVBSA, a polymer electrolyte membrane was prepared by a radiation grafting technique. • Poly(ether ether ketone) (PEEK), an aromatic hydrocarbon polymer was used as a grafting backbone film. • The water uptake, proton conductivity, and methanol permeability of the membranes were evaluated. • PEEK-g-PVBSA membranes show considerably lower methanol permeability compared to a Nafion membrane. -- Abstract: In this study, an aromatic hydrocarbon based polymer electrolyte membrane, poly(vinylbenzyl sulfonic acid)-grafted poly(ether ether ketone) (PEEK-g-PVBSA), has been prepared by the simultaneous irradiation grafting of vinylbenzyl chloride (VBC) monomer onto a PEEK film and subsequent sulfonation. Each chemical conversion was monitored by FT-IR and SEM–EDX instruments. The physicochemical properties including IEC, water uptake, proton conductivity, and methanol permeability of the prepared membranes were also investigated and found that the values of these properties increase with the increase of degree of grafting. It was observed that the IEC values of the prepared PEEK-g-PVBSA membranes with 32%, 58%, and 80% DOG values were 0.50, 1.05, and 1.22 meq/g while the water uptakes were 14%, 20%, and 21%, respectively. The proton conductivities (0.0272–0.0721 S/cm at 70 °C) were found to be somewhat lower than Nafion 212 (0.126 S/cm at 70 °C) at a relative humidity of 90%. However, the prepared membranes showed a considerably lower methanol permeability (0.61–1.92 × 10{sup −7} cm{sup 2}/s) compared to a Nafion 212 membrane (5.37 × 10{sup −7} cm{sup 2}/s)

  19. Ion atmosphere relaxation controlled electron transfers in cobaltocenium polyether molten salts.

    Harper, Amanda S; Leone, Anthony M; Lee, Dongil; Wang, Wei; Ranganathan, Srikanth; Williams, Mary Elizabeth; Murray, Royce W


    A room-temperature redox molten salt for the study of electron transfers in semisolid media, based on combining bis(cyclopentadienyl)cobalt with oligomeric polyether counterions, [Cp2Co](MePEG350SO3), is reported. The transport properties of the new molten salt can be varied (plasticized) by varying the polyether content. The charge transport rate during voltammetric reduction of the ionically conductive [Cp2Co](MePEG350SO3) molten salt exceeds the actual physical diffusivity of [Cp2Co]+ because of rapid [Cp2Co](+/0) electron self-exchanges. The measured [Cp2Co](+/0) electron self-exchange rate constants (k(EX)) are proportional to the diffusion coefficients (D(CION)) of the counterions in the melt. The electron-transfer activation barrier energies are also close to those of ionic diffusion but are larger than those derived from optical intervalent charge-transfer results. Additionally, the [Cp2Co](+/0) rate constant results are close to those of dissimilar redox moieties in molten salts where D(CION) values are similar. All of these characteristics are consistent with the rates of electron transfers of [Cp2Co](+/0) (and the other donor-acceptor pairs) being controlled not by the intrinsic electron-transfer rates but by the rate of relaxation of the ion atmosphere around the reacting pair. In the low driving force regime of mixed-valent concentration gradients, the ion atmosphere relaxation is competitive with electron transfer. The results support the generality of the recently proposed model of ionic atmosphere relaxation control of electron transfers in ionically conductive, semisolid materials.

  20. Mass transport of direct methanol fuel cell species in sulfonated poly(ether ether ketone) membranes

    Silva, V.S.; Boaventura, M.; Mendes, A.M.; Madeira, L.M. [LEPAE, Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Ruffmann, B.; Vetter, S.; Nunes, S.P. [GKSS Research Centre, Max-Planck Str., 21502 Geesthacht (Germany)


    Homogeneous membranes based on sulfonated poly(ether ether ketone) (sPEEK) with different sulfonation degrees (SD) were prepared and characterized. In order to perform a critical analysis of the SD effect on the polymer barrier and mass transport properties towards direct methanol fuel cell species, proton conductivity, water/methanol pervaporation and nitrogen/oxygen/carbon dioxide pressure rise method experiments are proposed. This procedure allows the evaluation of the individual permeability coefficients in hydrated sPEEK membranes with different sulfonation degrees. Nafion{sup (R)} 112 was used as reference material. DMFC tests were also performed at 50{sup o}C. It was observed that the proton conductivity and the permeability towards water, methanol, oxygen and carbon dioxide increase with the sPEEK sulfonation degree. In contrast, the SD seems to not affect the nitrogen permeability coefficient. In terms of selectivity, it was observed that the carbon dioxide/oxygen selectivity increases with the sPEEK SD. In contrast, the nitrogen/oxygen selectivity decreases. In terms of barrier properties for preventing the DMFC reactants loss, the polymer electrolyte membrane based on the sulfonated poly(ether ether ketone) with SD lower or equal to 71%, although having slightly lower proton conductivity, presented much better characteristics for fuel cell applications compared with the well known Nafion{sup (R)} 112. In terms of the DMFC tests of the studied membranes at low temperature, the sPEEK membrane with SD=71% showed to have similar performance, or even better, as that of Nafion{sup (R)} 112. However, the highest DMFC overall efficiency was achieved using sPEEK membrane with SD=52%. (author)

  1. Quantitative analysis of oleic acid and three types of polyethers according to the number of hydroxy end groups in Polysorbate 80 by hydrophilic interaction chromatography at critical conditions.

    Zhang, Rui; Wang, Yu; Ji, Yu; Shi, Bei-jia; Zhang, Zai-ping; Zhang, Hai-yan; Yang, Ming; Wang, Yong-mei


    A quantitative characterization of Polysorbate 80 is crucial for its many applications. In this paper we report a quick RP-HPLC method for the quantitative determination of Polysorbate 80. The hydrolysis of Polysorbate 80 to release oleic acid and three types of polyethers was first carried out. A chromatographic method based on liquid chromatography at critical conditions (LCCC) was then developed for an endgroup-based separation of low-molecular-mass polyether. With this method the polyether, irrespective of its molecular-mass, is separated according to endgroups (functionality) due to interactions of the polar endgroups with the hydrophilic stationary phase. The different types of polyethers and oleic acid were identified using on-line electrospray ionization mass spectrometry and quantified by evaporative light scattering detection.

  2. BINOL Macrocycle Derivatives: Synthesis of New Dinaphthyl Sulfide Aza Oxa Thia Crowns (Lariats

    Abbas Shockravi


    Full Text Available In this research work, dinaphthyl sulfide diester was prepared from the reaction of 1,1′-thiobis (2-hydroxy naphthalene and methylchloroacetate. Its aza-macrocyclic derivative was synthesized from the reaction of dinaphthyl sulfide diester and diethylenetriamine. Lariats were prepared from the reaction of chloroamides (four derivatives and initial macrocycle. Chloroamides were synthesized from the reaction of amines (aniline, benzylamine, 8-amino quinoline and 4-amino azobenzene and chloroacetyl chloride. All the materials were identified by IR, 1H NMR, 13C NMR, and mass spectroscopies, and elemental analysis.

  3. Synthesis and electrochemical studies of phenylazo substituted tetraaza macrocyclic complexes of Ni(II)

    Randhir Singh; Suresh Kumar; Amarendra Bhattacharya


    Synthesis and characterization of some phenyl azo substituted tetraaza macrocyclic complexes of Ni(II) are reported. Electrochemical behaviour of these macrocyclic complexes has been examined using polarographic, voltammetric and spectroscopic techniques. These studies show that both the ligand and the metal are electrochemically active. The electrochemical behaviour of the azo function has been shown to occur through a single four-electron process. When a nitro group is also present, the nitro function of the azo moiety is reduced in a six-electron cathodic wave.

  4. [2+2+2] Cycloaddition Reactions of Macrocyclic Systems Catalyzed by Transition Metals. A Review

    Anna Roglans


    Full Text Available Polyalkyne and enediyne azamacrocycles are prepared from arenesulfonamides and various alkyne and alkene derivatives either under basic or neutral conditions. The new family of macrocyclic substrates is tested in the [2+2+2] cycloaddition reaction. Several catalysts are used for the cycloisomerization reaction, and their enantioinduction is evaluated as appropriate. The effect of the structural features of the macrocycles, namely the ring size, substituents in precise positions and the number and type of unsaturations, on the [2+2+2] cycloaddition reaction has also been studied.

  5. Synthesis, Structure, and Molecular Recognition of S6 - and (SO2 )6 -Corona[6](het)arenes: Control of Macrocyclic Conformation and Properties by the Oxidation State of the Bridging Heteroatoms.

    Guo, Qing-Hui; Zhao, Liang; Wang, Mei-Xiang


    We report herein the synthesis, structure, and molecular recognition of S6 - and (SO2 )6 -corona[6](het)arenes, and demonstrate a unique and efficient strategy of regulating macrocyclic conformation and properties by adjusting the oxidation state of the heteroatom linkages. The one-pot nucleophilic aromatic substitution reaction of 1,4-benzenedithiol derivatives, biphenyl-4,4'-dithiol and 9,9-dipropyl-9H-fluorene-2,7-dithiol with 3,6-dichlorotetrazine afforded S6 -corona[3]arene[3]tetrazines. These compounds underwent inverse-electron-demand Diels-Alder reaction with enamines and norbornadiene to produce S6 -corona[3]arene[3]pyridazines. Facile oxidation of sulfide linkages yielded (SO2 )6 -corona[3]arene[3]pyridazines. All corona[6](het)arenes adopted generally hexagonal macrocyclic ring structures; however, their electronic properties and conformation could be fine-tuned by altering the oxidation state of the sulfur linkages. Whereas (SO2 )6 -corona[3]arene[3]pyridazines were electron-deficient, S6 -corona[3]arene[3]pyridazines acted as electron-rich macrocyclic hosts that recognized various organic cations in both aqueous and organic solutions.

  6. Dinuclear cobalt(II) and copper(II) complexes with a Py2N4S2 macrocyclic ligand.

    Núñez, Cristina; Bastida, Rufina; Lezama, Luis; Macías, Alejandro; Pérez-Lourido, Paulo; Valencia, Laura


    The interaction between Co(II) and Cu(II) ions with a Py(2)N(4)S(2)-coordinating octadentate macrocyclic ligand (L) to afford dinuclear compounds has been investigated. The complexes were characterized by microanalysis, conductivity measurements, IR spectroscopy and liquid secondary ion mass spectrometry. The crystal structure of the compounds [H(4)L](NO(3))(4), [Cu(2)LCl(2)](NO(3))(2) (5), [Cu(2)L(NO(3))(2)](NO(3))(2) (6), and [Cu(2)L(μ-OH)](ClO(4))(3)·H(2)O (7) was also determined by single-crystal X-ray diffraction. The [H(4)L](4+) cation crystal structure presents two different conformations, planar and step, with intermolecular face-to-face π,π-stacking interactions between the pyridinic rings. Complexes 5 and 6 show the metal ions in a slightly distorted square-pyramidal coordination geometry. In the case of complex 7, the crystal structure presents the two metal ions joined by a μ-hydroxo bridge and the Cu(II) centers in a slightly distorted square plane or a tetragonally distorted octahedral geometry, taking into account weak interactions in axial positions. Electron paramagnetic resonance spectroscopy is in accordance with the dinuclear nature of the complexes, with an octahedral environment for the cobalt(II) compounds and square-pyramidal or tetragonally elongated octahedral geometries for the copper(II) compounds. The magnetic behavior is consistent with the existence of antiferromagnetic interactions between the ions for cobalt(II) and copper(II) complexes, while for the Co(II) ones, this behavior could also be explained by spin-orbit coupling.

  7. Studies of Flerovium and Element 115 Homologs with Macrocyclic Extractants

    Despotopulos, John D. [Univ. of Nevada, Las Vegas, NV (United States)


    Study of the chemistry of the heaviest elements, Z ≥ 104, poses a unique challenge due to their low production cross-sections and short half-lives. Chemistry also must be studied on the one-atom-at-a-time scale, requiring automated, fast, and very efficient chemical schemes. Recent studies of the chemical behavior of copernicium (Cn, element 112) and flerovium (Fl, element 114) together with the discovery of isotopes of these elements with half-lives suitable for chemical studies have spurred a renewed interest in the development of rapid systems designed to study the chemical properties of elements with Z ≥ 114. This dissertation explores both extraction chromatography and solvent extraction as methods for development of a rapid chemical separation scheme for the homologs of flerovium (Pb, Sn, Hg) and element 115 (Bi, Sb), with the goal of developing a chemical scheme that, in the future, can be applied to on-line chemistry of both Fl and element 115. Carrier-free radionuclides, used in these studies, of the homologs of Fl and element 115 were obtained by proton activation of high-purity metal foils at the Lawrence Livermore National Laboratory (LLNL) Center for Accelerator Mass Spectrometry (CAMS): natIn(p,n)113Sn, natSn(p,n)124Sb, and Au(p,n)197m,gHg. The carrier-free activity was separated from the foils by novel separation schemes based on ion exchange and extraction chromatography techniques. Carrier-free Pb and Bi isotopes were obtained from development of a novel generator based on cation exchange chromatography using the 232U parent to generate 212Pb and 212Bi. Macrocyclic extractants, specifically crown ethers and their derivatives, were chosen for these studies; crown ethers show high selectivity for metal ions. Finally. a potential chemical system for Fl was established based on the Eichrom Pb resin, and insight to an improved system based on thiacrown ethers is

  8. Sceliphrolactam, a polyene macrocyclic lactam from a wasp-associated Streptomyces sp

    Oh, Dong-Chan; Poulsen, Michael; Currie, Cameron R


    A previously unreported 26-membered polyene macrocyclic lactam, sceliphrolactam, was isolated from an actinomycete, Streptomyces sp., associated with the mud dauber, Sceliphron caementarium. Sceliphrolactam's structure was determined by 1D- and 2D-NMR, MS, UV, and IR spectral analysis. Sceliphrol...

  9. Haemonchus contortus P-glycoprotein-2: in situ localisation and characterisation of macrocyclic lactone transport.

    Godoy, Pablo; Lian, Jing; Beech, Robin N; Prichard, Roger K


    Haemonchus contortus is a veterinary nematode that infects small ruminants, causing serious decreases in animal production worldwide. Effective control through anthelmintic treatment has been compromised by the development of resistance to these drugs, including the macrocyclic lactones. The mechanisms of resistance in H. contortus have yet to be established but may involve efflux of the macrocyclic lactones by nematode ATP-binding-cassette transporters such as P-glycoproteins. Here we report the expression and functional activity of H. contortus P-glycoprotein 2 expressed in mammalian cells and characterise its interaction with the macrocyclic lactones, ivermectin, abamectin and moxidectin. The ability of H. contortus P-glycoprotein 2 to transport different fluorophore substrates was markedly inhibited by ivermectin and abamectin in a dose-dependent and saturable way. The profile of transport inhibition by moxidectin was markedly different. H. contortus P-glycoprotein 2 was expressed in the pharynx, the first portion of the worm's intestine and perhaps in adjacent nervous tissue, suggesting a role for this gene in regulating the uptake of avermectins and in protecting nematode tissues from the effects of macrocyclic lactone anthelmintic drugs. H. contortus P-glycoprotein 2 may thus contribute to resistance to these drugs in H. contortus.

  10. New Cleft-like Molecules and Macrocycles from Phosphonate Substituted Spirobisindanol

    Paolo Finocchiaro


    Full Text Available We have synthetized medium-sized cyclophanes and macrocycles containingphosphonic groups, directly linked to the aromatic rings of the phanes or as pendant arms,for use as specific receptors for the selective complexation of neutral guests or forcomplexing lanthanides, as luminescent sensors and for diagnostic bioassays in medicine.Furthermore, because it would be of great interest for biochemistry as well as forpharmacological studies to dispose of preorganized rigid chiral hosts for biorelevantmolecules we designed inter alia, some new chiral macrocycles capable of a triple bindingmode and we used them for constructing macrocycles that could also be of interest forchiral recognition and chiral separations. Thus, in this paper we shall review the salientaspects of some macrocycles synthetized in our laboratory, all possessing the phosphonatemoiety and a spirobisindanol scaffold and able to act as complexing agents for cations andorganic substrates. In particular, we shall describe their NMR characterization, theirstereochemistry in solution and in the solid state, and their use as chiral receptors forbiorelevant molecules. Chiral HPLC resolution of some of them is also reported.

  11. Structural and Biochemical Basis for Intracellular Kinase Inhibition by Src-specific Peptidic Macrocycles.

    Aleem, Saadat; Georghiou, George; Kleiner, Ralph E; Guja, Kip; Craddock, Barbara P; Lyczek, Agatha; Chan, Alix I; Garcia-Diaz, Miguel; Miller, W Todd; Liu, David R; Seeliger, Markus A


    Protein kinases are attractive therapeutic targets because their dysregulation underlies many diseases, including cancer. The high conservation of the kinase domain and the evolution of drug resistance, however, pose major challenges to the development of specific kinase inhibitors. We recently discovered selective Src kinase inhibitors from a DNA-templated macrocycle library. Here, we reveal the structural basis for how these inhibitors retain activity against a disease-relevant, drug-resistant kinase mutant, while maintaining Src specificity. We find that these macrocycles display a degree of modularity: two of their three variable groups interact with sites on the kinase that confer selectivity, while the third group interacts with the universally conserved catalytic lysine and thereby retains the ability to inhibit the "gatekeeper" kinase mutant. We also show that these macrocycles inhibit migration of MDA-MB-231 breast tumor cells. Our findings establish intracellular kinase inhibition by peptidic macrocycles, and inform the development of potent and specific kinase inhibitors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Photoswitchable Dihydroazulene Macrocycles for Solar Energy Storage: The Effects of Ring Strain.

    Vlasceanu, Alexandru; Frandsen, Benjamin N; Skov, Anders B; Hansen, Anne Schou; Rasmussen, Mads Georg; Kjaergaard, Henrik G; Mikkelsen, Kurt V; Nielsen, Mogens Brøndsted


    Efficient energy storage and release are two major challenges of solar energy harvesting technologies. The development of molecular solar thermal systems presents one approach to address these issues by tuning the isomerization reactions of photo/thermoswitches. Here we show that the incorporation of photoswitches into macrocyclic structures is a particularly attractive solution for increasing the storage time. We present the synthesis and properties of a series of macrocycles incorporating two dihydroazulene (DHA) photoswitching subunits, bridged by linkers of varying chain length. Independent of ring size, all macrocycles exhibit stepwise, light-induced, ring-opening reactions (DHA-DHA to DHA-VHF to VHF-VHF; VHF = vinylheptafulvene) with the first DHA undergoing isomerization with a similar efficiency as the uncyclized parent system while the second (DHA-VHF to VHF-VHF) is significantly slower. The energy-releasing, VHF-to-DHA, ring closures also occur in a stepwise manner and are systematically found to proceed slower in the more strained (smaller) cycles, but in all cases with a remarkably slow conversion of the second VHF to DHA. We managed to increase the half-life of the second VHF-to-DHA conversion from 65 to 202 h at room temperature by simply decreasing the ring size. A computational study reveals the smallest macrocycle to have the most energetic VHF-VHF state and hence highest energy density.


    Lavinia Tofan


    Full Text Available The obtained results concerning the Ga (III ion retention on flexible open cell polyurethane foam of polyether type pretreated with tri-n-butyl phosphate are presented. The influence of solution acidity, phases contact time, Ga (III concentration and solution temperature have been investigated. The parameters of Ga (III batch sorption have been optimized. On the basis of Langmuir isotherms, the sorption constants and the thermodynamic parameters, ∆G, ∆Η and ∆S have been calculated.

  14. Improvement of the water selectivity of ULTEM poly(ether imide) pervaporation films by an allylamine-plasma-polymerized layer

    Kaba, Meriyam; Raklaoui, Nabil; Guimon, Marie Françoise; Mas, André


    International audience; The wettability and surface energy of extruded ULTEM poly(ether imide) films strongly increased (the water contact angle varied from 75 to 38° and the surface energy varied from 45.3 to 59.5 mJ m-2, respectively) with the deposition of an allylamine-plasma-polymerized layer and were characterized with X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy according to the experimental parameters. Pervaporation tests for dehydrating ...

  15. Tren centered tris-macrocycles as polytopic ligands for Cu(II) and Ni(II).

    Siegfried, Liselotte; McMahon, C Niamh; Kaden, Thomas A; Palivan, Cornelia; Gescheidt, Georg


    Two novel symmetric polytopic ligands L(1) and L(2) have been synthesized. They are composed of three 1,4,8,11-tetraazacyclotetradecane macrocycles which are connected to a central tren moiety via an ethylene and a trimethylene bridge, respectively. The complexation potential and the speciation diagrams of L(1) and L(2) towards Cu(2+) and Ni(2+) were determined by spectrophotometric and potentiometric titrations. Insight into the geometry of the Cu(2+) complexes is provided by UV-VIS and EPR spectroscopy. The simplified ligands L(3) and L(4) are utilized as references for an aminoethyl- and a tren-substituted tetraaza macrocycle to help assign the EPR spectra of the polytopic ligands L(1) and L(2). At a metal-to-ligand ratio of 3 : 1, the metal cations are preferentially bound to the tetraaza macrocycles of L(1) and L(2) in a square planar geometry. At high pH values, a nitrogen atom of the tren moiety in L(1) serves as an additional ligand in an axial position leading to a square pyramidal coordination around Cu(2+), whereas in L(2) no such geometry change is observed. At a metal-to-ligand ratio of 4 : 1, the additional metal cation resides in the central tren moiety of L(1) and L(2). However, in contrast to the typical trigonal bipyramidal geometry found in the [Cutren](2+) complex, the fourth Cu(2+) has a square pyramidal coordination caused by the interaction with the Cu(2+) cations in the macrocycles (as evidenced by EPR spectra). Since the sequence of metal complexation is such that the first three metal ions always bind to the three macrocycles of L(1) and L(2) and the fourth to the tren unit, it is possible to prepare heteronuclear complexes such as [Cu(3)NiL](8+) or [Ni(3)CuL](8+), which can be unambiguously identified by their spectral properties.

  16. Synthesis and Crystal Structure of a Novel 1D Mercury(II) Iodide Coordination Polymer Containing 40-Membered Macrocycle%Synthesis and Crystal Structure of a Novel 1D Mercury(II) Iodide Coordination Polymer Containing 40-Membered Macrocycle

    GAN Xiao-Ping; KONG Ling; WU Peng; LV Chen; TU Yu-Long; CHEN Yi-Xin; ZHOU Hong-Ping; WU Jie-Ying; TIAN Yu-Peng


    A mercury coordination polymer [Hg3(TizT)216]n (Mr = 1921.72, TizT = 2,4,6- tri(imidazole- 1-yl)- 1,3,5-triazine) containing a 40-membered macrocycle which was constructed by four TizT ligands and four mercury(II) iodide molecules had been synthesized by the reaction of HgI2 with TizT. The complex was characterized by elemental analysis, FT-IR, ^1H NMR spectra and X-ray crystallography. The crystal of the complex belongs to the monoclinic system and C2/c space group with a = 35.840(5), b = 8.169(5), c = 14.980(5) A, β = 104.466(5)°, Z= 4, V= 4247(3) A^3, De = 3.006 g·cm^-3, μ= 15.223 mm^-1, F(000) = 3384, Rint = 0.0504, wR = 0.0833 and constructs a chair-like conformation of cyclohexane one by one, which forms a 1-D polymer through the fashion of fused ring aromatic hydrocarbon. The hydrogen bonds and π-π interactions shape the 2-D network structure. The two compounds excited weak fluorescence.

  17. Cyano-bridged structures based on [MnIIN3O2-macrocycle)]2+: a synthetic, structural, and magnetic study.

    Bonadio, Federica; Senna, Maria-Cristina; Ensling, Jürgen; Sieber, Andreas; Neels, Antonia; Stoeckli-Evans, Helen; Decurtins, Silvio


    Reactions between the complex [MnII(L)]2+, where L is a N3O2 macrocyclic ligand, and different cyanometalate precursors such as [M(CN)n]m- (M(III) = Cr, Fe; M(II) = Fe, Ni, Pd, Pt) lead to cyano-bridged molecular assemblies exhibiting a variety of structural topologies. The reaction between [MnII(L)]2+ and [FeII(CN)6]4- forms a trinuclear complex with formula [(MnII(L)(H2O))2(FeII(micro-CN)2(CN)4)] x 2MeOH x 10H2O (1) which crystallizes in the triclinic space group P1. The reaction between [MnII(L)]2+ and [M(II)(CN)4]2-, where M(II) = Ni (2), Pd (3), Pt (4), gives rise to three isostructural linear chain compounds with stoichiometry [(MnII(L))(M(II)(micro-CN)2(CN)2)]n and which crystallize in the monoclinic space group C2/c. The self-assembly between [MnII(L)]2+ with [M(III)(CN)6]3-, where M(III) = Cr (5), Fe (6, 7, 8), forms three types of compounds. Compounds 5 and 6 are isostructural (monoclinic, space group P2(1)/n), and the structures comprise anionic linear chains [(MnII(L))(M(III)(micro-CN)2(CN)4)]n(n-) with cationic trinuclear complexes [(MnII(L)(H2O))2(M(III)(micro-CN)2(CN)4)]+ as counterions. Using an excess of K3[FeIII(CN)6], an analogous compound to 6 but with K+ as counterion is obtained (7), which crystallizes in the triclinic space group P1. Compound 8 consists of 2-D layers with formula [(MnII(L))3(FeIII(micro-CN)4(CN)2)(FeIII(micro-CN)2(CN)4)]n x 2nMeOH; it crystallizes in the monoclinic space group P2(1)/n. The magnetic properties were investigated for all samples. In particular, compound 5, which shows antiferromagnetic exchange interactions between Mn(II) and Cr(III) ions through cyanide bridging ligands, has been studied in detail; the magnetic exchange parameter amounts to J = -7.5(7) cm(-1). Compound 8 shows a magnetically ordered phase below 6.4 K which is confirmed by Mössbauer spectroscopy; two hyperfine split spectra were observed below Tc from which IJI values of 2.1 and 1.6 cm(-1) could be deduced.

  18. Metátese de olefinas aplicada ao fechamento de anéis: uma ferramenta poderosa para a síntese de macrociclos naturais Ring-closing olefin metathesis: a powerful tool for the synthesis of natural macrocycles

    Anderson Rouge dos Santos


    Full Text Available For a quarter of a century, metathesis has become indispensable for the synthesis of natural and non-natural products, particularly of biologically active compounds. This review illustrates through a maximum of appropriate examples the power and the versatility of the metathesis ring-closure (RCM reaction as a key ring-closure methodology for the synthesis of natural macrocycles. Its high functional group compatibility as well as the possibility of further transformations makes this reaction a powerful tool in the cases where the structural framework and function requirements are difficult to meet.

  19. Influence of the carbohydrate fragment position in the macrocycle of chlorine e6 trimethyl ester glycosylated derivatives on their in vitro photo- induced activity

    R. I. Yakubovskaya


    Full Text Available The physicochemical and photophysical properties, as well as photo-induced activity, of glycoconjugates based on chlorine е6 trimethyl ether with various positions of carbohydrate fragment in the macrocycle have been studied. The photo-induced activity was investigated in the human (HEp2, A549 and HT29 and animal (LLC cell lines. The tested compounds showed in vitro both high photo-induced activity and high stability in the dark. The photosensitizer with galactose in the A pirrole ring demonstrated the highest activity (the half maximal inhibitory concentration (ИК50 varied from 27±2 nM to 75±5 nM in tests on different cell lines. Dyes with sugar substitutes in the C pirrole ring were 5–10 times less active. 

  20. Shape-persistent macrocycles functionalised with coumarin dyes: acid-controlled energy- and electron-transfer processes.

    Giansante, Carlo; Ceroni, Paola; Venturi, Margherita; Balzani, Vincenzo; Sakamoto, Junji; Schlüter, A Dieter


    We have investigated the spectroscopic properties (absorption spectra, emission spectra, emission lifetimes) of three triads in CH(2)Cl(2): C2-M-C2, C343-M-C343, and C2-M-C343, in which M is a shape-persistent macrocyclic hexagonal backbone composed of two 2,2'-bipyridine (bpy) units embedded in opposing sides, and C2 and C343 are coumarin 2 and coumarin 343, respectively. All the components are strongly fluorescent species (Phi=0.90, 0.79, and 0.93 for M, C2, and C343, respectively, as established by investigating suitable model compounds). In each triad excitation of M leads to almost quantitative energy transfer to the lowest coumarin-localised excited state. Upon addition of acid, the two bpy units of the M component undergo independent protonation leading to monoprotonated (e.g., C2-MH(+)-C2) and diprotonated (e.g., C2-M2 H(+)-C2) species. Further addition of acid leads to protonation of the coumarin component so that each triad is involved in four protonation equilibria. Protonation causes strong (and reversible, upon addition of base) changes in the absorption and fluorescence properties of the triads because of inversion of the excited-state order and/or the occurrence of electron-transfer quenching processes.

  1. Chemical evolution on planetary surfaces: from simple gases to organic macrocycles

    Fox, Stefan; Strasdeit, Henry

    It is generally accepted that α-amino acids existed in the primordial ocean on the Hadean / early Archean Earth. They had been abiotically synthesized from smaller molecules such as H2 , CH4 , H2 O, NH3 , HCN, aldehydes, ketones, and alcohols [1-3]. Once the amino acids had been formed, they probably reacted to more complex molecules. One possibility is the thermal transformation at hot volcanic coasts. In a first step, amino acid-containing seawater evaporated in the vicinity of lava streams. A salt crust remained in which amino acids were embedded. In a second step, these embedded amino acids were thermally transformed to new compounds. In order to simulate this hot-volcanic-coast scenario artificial salt crusts with embedded amino acids were prepared and heated to 300-800 ° C in a slow stream of nitrogen gas. We found that in the salt crusts glycine, DL-alanine and -aminoisobutyric acid were chemically bonded to calcium or magnesium ions. This metal coordination prevents the sublimation of the amino acids and permits the thermal formation of pyridines, piperazine-2,5-diones, polycyclic aromatic hydrocarbons, and especially several alkylated pyrroles. Thus an abiotic source of pyrroles on young Earth-like planets may exist. Amino acids and pyrroles are building blocks of important biomolecules. It might seem plausible that amino acids formed peptides on the early Earth. However, in aqueous solution the condensation reaction is unfavorable, and even if short peptides would have formed they would have tended to hydrolyze. This argument is equally true for nucleic acid components [4]. In contrast to that, it is known that pyrrole, in aqueous HCl solutions, reacts with formaldehyde to form oligopyrroles [5]. Prebiotic oligopyrroles and their metal complexes may have been utilized by primitive metabolizing systems and later modified into porphyrin-like macrocycles such as chlorophyll. [1] Miller, S. L. (1953) Science, 117, 528. [2] Johnson, A. P., Cleaves, H. J

  2. Thermally stable hyperbranched polyether-based polymer electrolyte for lithium-ion batteries

    Wu Feng; Feng Ting; Wu Chuan; Bai Ying; Chen Junzheng [School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing 10081 (China); Ye Lin, E-mail: [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 10081 (China)


    A thermally stable polymer matrix, comprising hyperbranched polyether PHEMO (poly(3-{l_brace}2-[2-(2-hydroxyethoxy) ethoxy] ethoxy{r_brace}methyl-3'-methyloxetane)) and PVDF-HFP (poly(vinylidene fluoride-hexafluoropropylene)), has been successfully prepared for applications in lithium-ion batteries. This type of polymer electrolyte has been made by adding different amounts of lithium bis(oxalate)borate (LiBOB) to the polymer matrix. Its thermal and structural properties were measured using differential scanning calorimetry and x-ray diffraction. Experimental results show that the polymer electrolyte system possesses good thermal stability, with a decomposition temperature above 420 {sup 0}C. The ionic conductivity of the polymer electrolyte system is dependent on the lithium salt content, reaching a maximum of 1.1 x 10{sup -5} S cm{sup -1} at 30 {sup 0}C and 2.3 x 10{sup -4} S cm{sup -1} at 80 {sup 0}C when doped with 10 wt% LiBOB.

  3. Zinc ion conducting polymer electrolytes based on oligomeric polyether/PVDF-HFP blends

    Ye, Hui; Xu, Jun John

    Here we report novel zinc ion conducting polymer electrolytes based on oligomeric polyether/PVDF-HFP blends with or without the incorporation of a small amount of organic carbonates. Their thermal properties, ionic conductivity and electrochemical properties are characterized and the effect of different Zn salts and incorporation of a small amount of organic carbonates are investigated. These polymer electrolyte membranes exhibit essentially no or very low volatility, high thermal stability, high ionic conductivity, wide electrochemical stability window, acceptable interfacial resistance with zinc, and the capability for reversible Zn plating/stripping. Particularly promising are electrolyte systems based on the combination of low lattice energy zinc imide salt and a special co-solvent of oligomeric poly(ethylene glycol) dimethyl ether (PEGDME) mixed with a small amount of ethylene carbonate (EC), dimensionally stabilized with PVDF-HFP. Such novel polymer electrolyte membranes could lead to the development of new kinds of electrochemical energy storage devices based on zinc electrochemistry, including solid-state, thin-film rechargeable zinc/air cells envisaged.

  4. Zinc ion conducting polymer electrolytes based on oligomeric polyether/PVDF-HFP blends

    Ye, Hui; Xu, Jun John [Department of Materials Science and Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ 08854 (United States)


    Here we report novel zinc ion conducting polymer electrolytes based on oligomeric polyether/PVDF-HFP blends with or without the incorporation of a small amount of organic carbonates. Their thermal properties, ionic conductivity and electrochemical properties are characterized and the effect of different Zn salts and incorporation of a small amount of organic carbonates are investigated. These polymer electrolyte membranes exhibit essentially no or very low volatility, high thermal stability, high ionic conductivity, wide electrochemical stability window, acceptable interfacial resistance with zinc, and the capability for reversible Zn plating/stripping. Particularly promising are electrolyte systems based on the combination of low lattice energy zinc imide salt and a special co-solvent of oligomeric poly(ethylene glycol) dimethyl ether (PEGDME) mixed with a small amount of ethylene carbonate (EC), dimensionally stabilized with PVDF-HFP. Such novel polymer electrolyte membranes could lead to the development of new kinds of electrochemical energy storage devices based on zinc electrochemistry, including solid-state, thin-film rechargeable zinc/air cells envisaged. (author)

  5. The Effects of Sulfonated Poly(ether ether ketone Ion Exchange Preparation Conditions on Membrane Properties

    Rebecca S. L. Yee


    Full Text Available A low cost cation exchange membrane to be used in a specific bioelectrochemical system has been developed using poly(ether ether ketone (PEEK. This material is presented as an alternative to current commercial ion exchange membranes that have been primarily designed for fuel cell applications. To increase the hydrophilicity and ion transport of the PEEK material, charged groups are introduced through sulfonation. The effect of sulfonation and casting conditions on membrane performance has been systematically determined by producing a series of membranes synthesized over an array of reaction and casting conditions. Optimal reaction and casting conditions for producing SPEEK ion exchange membranes with appropriate performance characteristics have been established by this uniquely systematic experimental series. Membrane materials were characterized by ion exchange capacity, water uptake, swelling, potential difference and NMR analysis. Testing this extensive membranes series established that the most appropriate sulfonation conditions were 60 °C for 6 h. For mechanical stability and ease of handling, SPEEK membranes cast from solvent casting concentrations of 15%–25% with a resulting thickness of 30–50 µm were also found to be most suitable from the series of tested casting conditions. Drying conditions did not have any apparent impact on the measured parameters in this study. The conductivity of SPEEK membranes was found to be in the range of 10−3 S cm−1, which is suitable for use as a low cost membrane in the intended bioelectrochemical systems.

  6. Electrospun sulfonated poly(ether ketone) nanofibers as proton conductive reinforcement for durable Nafion composite membranes

    Klose, Carolin; Breitwieser, Matthias; Vierrath, Severin; Klingele, Matthias; Cho, Hyeongrae; Büchler, Andreas; Kerres, Jochen; Thiele, Simon


    We show that the combination of direct membrane deposition with proton conductive nanofiber reinforcement yields highly durable and high power density fuel cells. Sulfonated poly(ether ketone) (SPEK) was directly electrospun onto gas diffusion electrodes and then filled with Nafion by inkjet-printing resulting in a 12 μm thin membrane. The ionic membrane resistance (30 mΩ*cm2) was well below that of a directly deposited membrane reinforced with chemically inert (PVDF-HFP) nanofibers (47 mΩ*cm2) of comparable thickness. The power density of the fuel cell with SPEK reinforced membrane (2.04 W/cm2) is 30% higher than that of the PVDF-HFP reinforced reference sample (1.57 W/cm2). During humidity cycling and open circuit voltage (OCV) hold, the SPEK reinforced Nafion membrane showed no measurable degradation in terms of H2 crossover current density, thus fulfilling the target of 2 mA/cm2 of the DOE after degradation. The chemical accelerated stress test (100 h OCV hold at 90 °C, 30% RH, H2/air, 50/50 kPa) revealed a degradation rate of about 0.8 mV/h for the fuel cell with SPEK reinforced membrane, compared to 1.0 mV/h for the PVDF-HFP reinforced membrane.

  7. Adsorption capacity of poly(ether imide) microparticles to uremic toxins.

    Tetali, Sarada D; Jankowski, Vera; Luetzow, Karola; Kratz, Karl; Lendlein, Andreas; Jankowski, Joachim


    Uremia is a phenomenon caused by retention of uremic toxins in the plasma due to functional impairment of kidneys in the elimination of urinary waste products. Uremia is presently treated by dialysis techniques like hemofiltration, dialysis or hemodiafiltration. However, these techniques in use are more favorable towards removing hydrophilic than hydrophobic uremic toxins. Hydrophobic uremic toxins, such as hydroxy hipuric acid (OH-HPA), phenylacetic acid (PAA), indoxyl sulfate (IDS) and p-cresylsulfate (pCRS), contribute substantially to the progression of chronic kidney disease (CKD) and cardiovascular disease. Therefore, objective of the present study is to test adsorption capacity of highly porous microparticles prepared from poly(ether imide) (PEI) as an alternative technique for the removal of uremic toxins. Two types of nanoporous, spherically shaped microparticles were prepared from PEI by a spraying/coagulation process.PEI particles were packed into a preparative HPLC column to which a mixture of the four types of uremic toxins was injected and eluted with ethanol. Eluted toxins were quantified by analytical HPLC. PEI particles were able to adsorb all four toxins, with the highest affinity for PAA and pCR. IDS and OH-HPA showed a partially non-reversible binding. In summary, PEI particles are interesting candidates to be explored for future application in CKD.

  8. Influence of nanoporous poly(ether imide) particle extracts on human aortic endothelial cells (HAECs).

    Kumar, Reddi K; Basu, Sayantani; Lemke, Horst-Dieter; Jankowski, Joachim; Kratz, Karl; Lendlein, Andreas; Tetali, Sarada D


    Accumulated uremic toxins like indoxyl sulphate, hippuric acid and p-cresyl sulphates in renal failure patients stimulate proinflammatory effects, and consequently kidney and cardiovascular diseases. Low clearance rate of these uremic toxins from the blood of uremic patients by conventional techniques like hemodialysis is due to their strong covalent albumin binding (greater than 95%) and hydrophobic nature, which led to alternatives like usage of hydrophobic adsorber's in removing these toxins from the plasma of kidney patients. Polymers like polyethylene, polyurethane, polymethylmethacrylate, cellophane and polytetrafluoroethylene were already in use as substitutes for metal devices as dialysis membranes. Among new synthetic polymers, one such ideal adsorber material are highly porous microparticles of poly(ether imide) (PEI) with diameters in the range from 50-180μm and a porosity around 88±2% prepared by a spraying and coagulation process.It is essential to make sure that these synthetic polymers should not evoke any inflammatory or apoptotic response during dialysis. Therefore in our study we evaluated in vitro effect of PEI microparticle extracts in human aortic endothelial cells (HEACs) concerning toxicity, inflammation and apoptosis. No cell toxicity was observed when HAECs were treated with PEI extracts and inflammatory/apoptotic markers were not upregulated in presence of PEI extracts. Our results ensure biocompatibility of PEI particles and further hemocompatibility of particles will be tested.

  9. Research on Influence Factors of Surfactivity of Polyester Polyether Block Copolymer

    WU Ming-hua; LIN He-ming


    Polyester polyether block copolymer (PPBC) was synthesized by ester-exchange and polycodensation reactions using dimethyl terephthalate (DMT), ethylene glycol (EG) and polyethylene glycol (PEG) as monomer. The effects of PEG molecular weight, mol ratio of DMT to PEG (nDMT/nPEG), temperature and time of polycondensation reaction and vacuum degree in the reaction system on the surface tension and critical micelle concentration (CMC) of PPBC aqueous solution were studied. It was found that both the molecular weight and the concentration of PEG can affect PPBC'S surface activity obviously, and the optimum synthesis condition of PPBC used as surfactant is as follows: PEG molecular weight is 1500, mol ratio of DMT to PEG is 3, temperature and time of polycondensation reaction is 260°C×1h, vacuum degree of condensation reaction is 0.03-0.05 MPa. It was proved by surface tension measurement of PPBC aqueous solution that the PPBC synthesized in this condition is a good surfactant with excellent surfactivity.

  10. Molecular sieve/sulfonated poly(ether ketone ether sulfone) composite membrane as proton exchange membrane

    Changkhamchom, Sairung; Sirivat, Anuvat


    A proton exchange membrane (PEM) is an electrolyte membrane used in both polymer electrolyte membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFCs). Currently, PEMs typically used for PEMFCs are mainly the commercially available Nafion^ membranes, which is high cost and loss of proton conductivity at elevated temperature. In this work, the Sulfonated poly(ether ketone ether sulfone), (S-PEKES), was synthesized by the nucleophilic aromatic substitution polycondensation between bisphenol S and 4,4'-dichlorobenzophenone, and followed by the sulfonation reaction with concentrated sulfuric acid. The molecular sieve was added in the S-PEKES matrix at various ratios to form composite membranes to be the candidate for PEM. Properties of both pure sulfonated polymer and composite membranes were compared with the commercial Nafion^ 117 membrane from Dupont. S-PEKES membranes cast from these materials were evaluated as a polymer electrolyte membrane for direct methanol fuel cells. The main properties investigated were the proton conductivity, methanol permeability, thermal, chemical, oxidative, and mechanical stabilities by using a LCR meter, Gas Chromatography, Thermogravimetric Analysis, Fourier Transform Infrared Spectroscopy, Fenton's reagent, and Universal Testing Machine. The addition of the molecular sieve helped to increase both the proton conductivity and the methanol stability. These composite membranes are shown as to be potential candidates for use as a Proton Exchange Membrane (PEM).

  11. In Vitro Evaluation of Bioactivity of Chemically Deposited Hydroxyapatite on Polyether Ether Ketone

    D. Almasi


    Full Text Available Polyether ether ketone (PEEK is considered the best alternative material for titanium for spinal fusion cage implants due to its low elasticity modulus and radiolucent property. The main problem of PEEK is its bioinert properties. Coating with hydroxyapatite (HA showed very good improvement in bioactivity of the PEEK implants. However the existing methods for deposition of HA have some disadvantages and damage the PEEK substrate. In our previous study a new method for deposition of HA on PEEK was presented. In this study cell proliferation of mesenchymal stem cell and apatite formation in simulated body fluid (SBF tests were conducted to probe the effect of this new method in improvement of the bioactivity of PEEK. The mesenchymal stem cell proliferation result showed better cells proliferation on the treated layer in comparison with untreated PEEK. The apatite formation results showed the growth of the HA on the treated PEEK but there was not any sight of the growth of HA on the untreated PEEK even after 2 weeks. The results showed the new method of the HA deposition improved the bioactivity of the treated PEEK in comparison with the bare PEEK.

  12. UV-induced Self-initiated Graft Polymerization of Acrylamide onto Poly(ether ether ketone)

    CHEN Rui-chao; SUN Hui; LI Ang; XU Guo-zhi


    Photo-grafting of hydrophilic monomer was used to enhance the hydrophilicity of poly(ether ether ketone)(PEEK) with the aim of extending its applications to biological fields.PEEK sheets were surface modified by grafting of acrylamide(AAm) with ultraviolet(UV) irradiation in the presence or absence of benzophenone(BP).The effects of BP,irradiation time and monomer concentration on the surface wettability of PEEK were investigated.Characterization of modified PEEK using scanning electron microscopy(SEM),energy-disperse spectrometer(EDS) and water contact angle measurements shows that AAm was successfully grafted on PEEK surface both in presence and absence of BP.With the increase in irradiation time and monomer concentration,contact angles decrease to as low as 30°,demonstrating a significant improvement of surface hydrophilicity.In agreement with the decrease in contact angle,under identical conditions,the nitrogen concentration increases,suggesting the increase in grafting degree of the grafting polymerization.This investigation demonstrates a self-initiation of PEEK due to its BP-like structure in the backbone of the polymer.Though the graft polymerization proceeds more readily in the presence of BP,the self-initiated graft polymerization is clearly observed.

  13. Positively charged and bipolar layered poly(ether imide) nanofiltration membranes for water softening applications

    Gassara, S.; Abdelkafi, A.; Quémener, D.; Amar, R. Ben; Deratani, A.


    Poly(ether imide) (PEI) ultrafiltration membranes were chemically modified with branched poly(ethyleneimine) to obtain nanofiltration (NF) membrane Cat PEI with a positive charge in the pH range below 9. An oppositely charged polyelectrolyte layer was deposited on the resulting membrane surface by using sodium polystyrene sulfonate (PSSNa) and sodium polyvinyl sulfonate (PVSNa) to prepare a bipolar layered membrane NF Cat PEI_PSS and Cat PEI_PVS having a negatively charged surface and positively charged pores. Cat PEI exhibited good performance to remove multivalent cations (more than 90% of Ca2+) from single salt solutions except in presence of sulfate ions. Adding an anionic polyelectrolyte layer onto the positively charged surface resulted in a significant enhancement of rejection performance even in presence of sulfate anions. Application of the prepared membranes in water softening of natural complex mixtures was successful for the different studied membranes and a large decrease of hardness was obtained. Moreover, Cat PEI_PSS showed a good selectivity for nitrate removal. Fouling experiments were carried out with bovine serum albumin, as model protein foulant. Cat PEI_PSS showed much better fouling resistance than Cat PEI with a quantitative flux recovery ratio.

  14. Morphology Effect on Proton Dynamics in Nafion® 117 and Sulfonated Polyether Ether Ketone

    Leong, Jun Xing; Diño, Wilson Agerico; Ahmad, Azizan; Daud, Wan Ramli Wan; Kasai, Hideaki


    We report results of our experimental and theoretical studies on the dynamics of proton conductivity in Nafion® 117 and self-fabricated sulfonated polyether ether ketone (SPEEK) membranes. Knowing that the presence of water molecules in the diffusion process results in a lower energy barrier, we determined the diffusion barriers and corresponding tunneling probabilities of Nafion® 117 and SPEEK system using a simple theoretical model that excludes the medium (water molecules) in the initial calculations. We then propose an equation that relates the membrane conductivity to the tunneling probability. We recover the effect of the medium by introducing a correction term into the proposed equation, which takes into account the effect of the proton diffusion distance and the hydration level. We have also experimentally verified that the proposed equation correctly explain the difference in conductivity between Nafion® 117 and SPEEK. We found that membranes that are to be operated in low hydration environments (high temperatures) need to be designed with short diffusion distances to enhance and maintain high conductivity.

  15. Preparation of composite poly(ether block amide) membrane for CO2 capture

    Lianjun Wang; Yang Li; Shuguang Li; Pengfei Ji; Chengzhang Jiang


    In this study, a poly(ether block amide) (Pebax 1657) composite membrane applied for CO2 capture was prepared by coating Pebax 1657 solution on polyacrylonitrile (PAN) ultrafiltration membrane. Ethanol/water mixture was used as the solvent of Pebax and the effects of ethanol/water mass ratios and Pebax concentration on the permeation properties of composite membrane were studied. To enhance the com-posite membrane permeance, the gutter layer, made from reactive amino silicone crosslinking with polydimethylsiloxane (PDMS), was de-signed. The influence of crosslinking degree of the gutter layer on membrane performance was investigated. As a result, a Pebax/amino-PDMS/PAN multilayer membrane with hexane resistance was developed, showing CO2 permeance of 350 GPU and CO2/N2 selectivity over 50. The blend of polyethylene glycol dimethyl ether (PEG-DME) with Pebax as coating material was studied to further improve the membrane performance. After being combined with PEG-DME additive, CO2 permeance of the final Pebax-PEG-DME/amino-PDMS/PAN composite membrane reached 400 GPU above with CO2/N2 selectivity over 65.

  16. Crosslinked poly(ether block amide) composite membranes for organic solvent nanofiltration applications

    Aburabie, Jamaliah


    Poly(ether block amide) – Pebax® – based membranes are well described for gas separation applications. But only a few publications exist for their application in pressure driven liquid applications like ultrafiltration and nanofiltration. Here we use the commercially available Pebax® 1657 for the preparation of membranes for the filtration of organic solvents. Porous polyacrylonitrile membranes were coated with Pebax® 1657 which was then crosslinked. Toluene diisocyanate (TDI) was used as a crosslinker agent for the coating. Reaction time and crosslinker concentration were optimized for the aimed application. The Pebax® coating and the impact of the TDI on the resulting crosslinked membranes were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). SEM analysis shows a uniform thin coating of the PEBAX that covers the pores of the PAN membranes. FTIR and DSC analysis confirm the crosslinking reaction. Crosslinked Pebax® membranes show high stability toward ethanol propanol, acetone and even dimethylformamide (DMF). In the case of DMF applications, the standard PAN was replaced by crosslinked PAN developed in our laboratory. In order to increase the membranes permeances, graphene oxide (GO) nanosheets were incorporated in the Pebax® coating. These GO containing membranes showed strongly increased permeances for selected solvents. © 2016 Elsevier B.V.

  17. Toughening polylactide with polyether-block-amide and thermoplastic starch acetate: Influence of starch esterification degree.

    Zhou, Linyao; Zhao, Guiyan; Feng, Yulin; Yin, Jinghua; Jiang, Wei


    Native corn starch was esterified with acetic anhydride and plasticized with glycerol to give the thermoplastic starch acetate (TPSA). TPSA was blended with polylactide (PLA) and polyether-block-amide-graft-glycidyl methacrylate (PEBA-g-GMA) to obtain biodegradable PLA/PEBA-g-GMA/TPSA blends with high notched impact resistance and low cost. Compared with PLA/PEBA-g-GMA blends, as much as 9 wt% expensive PEBA-g-GMA elastomer could be substituted by the slightly acetylated thermoplastic starch while retaining high impact strength. The mechanical properties depended on the esterification degree of starch acetate. The impact strength, tensile strength and elongation at break increased to the peak value with increasing the esterification degree from 0 to 0.04, thereafter they decreased on further increasing the esterification degree. The morphological results showed that the TPSA particles were smaller and more uniform at the optimum esterification degree of 0.04, leading to the peak value of the mechanical properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. An SEM and EDS study of the microstructure of nitrate ester plasticized polyether propellants



    Full Text Available To probe the microstructures of nitrate ester plasticized polyether (NEPE composite propellants and observe the morphology of each constitute in the propellant, the microstructure and elemental constitutes of NEPE propellants were investigated using scanning electron microscopy and energy dispersive X-ray spectroscopy. The ammonium perchlorate (AP grains had a scraggy surface and were difficult to disperse uniformly. The compatibility between the AP grains and the polymer binder was poor, especially for large grains. The size distribution range of the AP and octogen (HMX grains in propellants varied from several to several hundreds μm for the former while for the latter from several to several tens μm. Contrasting images before and after dissolution the propellant in trichloromethane showed that the degree of crosslinking of the polymer binder was low since non-crosslinked binder on the surface areas was easily removed by the solvent, and that the plasticizer was near the HMX grains and contributed more O to the element analysis of HMX.

  19. Comparative study to evaluate the accuracy of polyether occlusal bite registration material and occlusal registration wax as a guide for occlusal reduction during tooth preparation

    Niranjan Joshi


    Objective: The objective of this study was to compare and evaluate the reliability of the most commonly used occlusal registration wax that with polyether bite registration material as a guide for occlusal reduction required during tooth preparations. Materials and Methods: For the purpose of this study, 25 abutment teeth requiring tooth preparation for fixed prosthesis were selected and tooth preparations carried out. Modeling wax strips of specific dimensions were placed onto the cast of prepared tooth, which was mounted on maximum intercuspation on the articulator and the articulator was closed. The thickness of the wax registration was measured at three zones namely two functional cusps and central fossa. Similar measurements were made using the polyether bite registration material and prosthesis at the same zones. The data was tabulated and was subjected to statistical analysis using anova test and Tukey honestly significant difference test. Results: The differences in thickness between wax record and prosthesis by 0.1346 mm, whereas the difference between polyether and prosthesis was 0.02 mm with a P value of 0.042, which is statistically significant. This means that the wax record was 8.25% larger than the prosthesis while polyether was just 1.27% larger than the prosthesis. Conclusion: The clinical significance of the above analysis is that Ramitec polyether bite registration material is most suitable material when compared with commonly used modeling wax during the tooth preparation.

  20. The addition of a second lanthanide ion to increase the luminescence of europium(III) macrocyclic complexes

    Bromm, A.J. Jr.; Vallarino, L.M. [Virginia Commonwealth Univ., Richmond, VA (United States). Dept. of Chemistry; Leif, R.C. [Newport Instruments, San Diego, CA (United States); Quagliano, J.R. [Los Alamos National Lab., NM (United States)


    At present, the microscopic visualization of luminescent labels containing lanthanide(III) ions, primarily europium(III), as light-emitting centers is best performed with time-gated instrumentation, which by virtually eliminating the background fluorescence results in an improved signal to noise ratio. However, the use of the europium(III) macrocycle, Quantum Dye{trademark}, in conjunction with the strong luminescence enhancing effect (cofluorescence) of yttrium(III) or gadolinium(III), can eliminate the need for such specialized instrumentation. In the presence of Gd(III), the luminescence of the Eu(III)-macrocycles can be conveniently observed with conventional fluorescence instrumentation at previously unattainable low levels. The Eu(III) {sup 5}D{sub 0} {r_arrow} {sup 7}F{sub 2} emission of the Eu(III)-macrocycles was observed as an extremely sharp band with a maximum at 619 nm and a clearly resolved characteristic pattern. At very low Eu(III)-macrocycle concentrations, another sharp emission was detected at 614 nm, arising from traces of Eu(III) present in even the purest commercially available gadolinium products. Discrimination of the resolved emissions of the Eu(III)-macrocycle and Eu(III) contaminant should provide a means to further lower the limit of detection of the Eu(III)-macrocycle.

  1. Review on calixarene-type macrocycles and metal extraction data

    Ludwig, R. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    This paper gives an overview on the current state of solvent extraction studies with derivatized [1.n]-metacyclophanes and related compounds. 122 References from the last ten years are discussed and data on extractability, extraction equilibria, and complex formation are presented in graphical form. (author) 122 refs.

  2. Planning and periodization in swimming: An example of a macrocycle for an adapted swimming group

    A. Querido


    Full Text Available The planning of the training process in is commonly recognized as a fundamental aspect for the correct and harmonious development of the capacities and to improve sports results. The aim of this paper was to present an example of a macrocyle of training in a group of adapted swimmers. The group includes 5 swimmers, being 4 male and 1 female: three swimmers with Down syndrome, one swimmer with intellectual disability and one swimmer with autism. The macrocycle of training was subdivided in 23 weeks: 15 belonging to the General Preparation Period, 4 to the Specific Preparation Period, 2 to the Competitive Period, culminating with the Winter National Championships, and 2 to the Transition Period trying. At the Winter National Championships, the most important competition of this macrocycle, these swimmers obtained 7 national titles, 4 national vice-champions titles and 2 third places. These results gave the swimmers an important incentive to keep up the good work.

  3. Planning and periodization in swimming: An example of a macrocycle for an adapted swimming group

    A. Querido


    Full Text Available The planning of the training process in is commonly recognized as a fundamental aspect for the correct and harmonious development of the capacities and to improve sports results. The aim of this paper was to present an example of a macrocyle of training in a group of adapted swimmers. The group includes 5 swimmers, being 4 male and 1 female: three swimmers with Down syndrome, one swimmer with intellectual disability and one swimmer with autism. The macrocycle of training was subdivided in 23 weeks: 15 belonging to the General Preparation Period, 4 to the Specific Preparation Period, 2 to the Competitive Period, culminating with the Winter National Championships, and 2 to the Transition Period trying. At the Winter National Championships, the most important competition of this macrocycle, these swimmers obtained 7 national titles, 4 national vice-champions titles and 2 third places. These results gave the swimmers an important incentive to keep up the good work.

  4. Uranyl-selective PVC membrane electrodes based on some recently synthesized benzo-substituted macrocyclic diamides.

    Shamsipur, Mojtaba; Soleymanpour, Ahmad; Akhond, Morteza; Sharghi, Hashem; Massah, Ahmad Reza


    Four different recently synthesized macrocyclic diamides were studied to characterize their abilities as uranyl ion carriers in PVC membrane electrodes. The electrodes based on macrocycle 1,18-diaza-3,4;15,16-dibenzo-5,8,11,14,21,24-hexaoxacyclohexaeicosane-2,17-dione resulted in a Nernstian response for UO(2)(2+) ion over wide concentration ranges. The linear concentration range for the polymeric membrane electrode (PME) is 3.0x10(-6)-8.2x10(-3) M with a detection limit of 2.2x10(-6) and that for the coated graphite electrode (CGE) is 5.0x10(-7)-1.5x10(-3) M with a detection limit of 3.5x10(-7) M. The electrodes manifest advantages of low resistance, very fast response and, most importantly, good selectivities relative to a wide variety of other cations.

  5. Synthesis and anion recognition properties of shape-persistent binaphthyl-containing chiral macrocyclic amides

    Marco Caricato


    Full Text Available We report on the synthesis and characterization of novel shape-persistent, optically active arylamide macrocycles, which can be obtained using a one-pot methodology. Resolved, axially chiral binol scaffolds, which incorporate either methoxy or acetoxy functionalities in the 2,2' positions and carboxylic functionalities in the external 3,3' positions, were used as the source of chirality. Two of these binaphthyls are joined through amidation reactions using rigid diaryl amines of differing shapes, to give homochiral tetraamidic macrocycles. The recognition properties of these supramolecular receptors have been analyzed, and the results indicate a modulation of binding affinities towards dicarboxylate anions, with a drastic change of binding mode depending on the steric and electronic features of the functional groups in the 2,2' positions.

  6. A bambusuril macrocycle that binds anions in water with high affinity and selectivity.

    Yawer, Mirza Arfan; Havel, Vaclav; Sindelar, Vladimir


    Synthetic receptors that function in water are important for the qualitative and quantitative detection of anions, which may act as pollutants in the environment or play important roles in biological processes. Neutral receptors are particularly appealing because they are often more selective than positively charged receptors; however, their affinity towards anions in pure water is only in range of 1-10(3)  L mol(-1) . The anion-templated synthesis of a water-soluble bambusuril derivative is shown to be an outstanding receptor for various inorganic anions in pure water, with association constants of up to 10(7)  L mol(-1) . Furthermore, the macrocycle discriminates between anions with unprecedented selectivity (up to 500 000-fold). We anticipate that the combination of remarkable affinity and selectivity of this macrocycle will enable the efficient detection and isolation of diverse anions in aqueous solutions, which is not possible with current supramolecular systems.

  7. New Copper and Oxomolybdate Robson-Type Polynuclear Macrocyclic Complexes: Structure, Spectroscopy, and Electrochemical Properties

    Marcelo Carpes Nunes


    Full Text Available The polynuclear complexes [Mo3O8(tidf]·dmso·2H2O (1 and [{Cu2(tidf}2(μ-Mo8O24] (2 (tidf2− is a symmetrical tetraiminodiphenolate Robson-type macrocyclic ligand were prepared from equimolar combinations of [Mg2(tidf](NO32·4H2O, [MoO2Cl2(dmso2] (for 1 and complex 1 and Cu(ClO42·4H2O (for 2 in acetonitrile. Molecular structures of both complexes were determined and showed atypical modes of coordination. A significant observation was the remarkable flexibility of the macrocycle ligand that effectively accommodated the steric demands of metal cations and the packing forces and showed a unique mode of coordination. Spectroscopic (UV-vis and FTIR and redox properties are discussed.

  8. STM visualisation of counterions and the effect of charges on self-assembled monolayers of macrocycles.

    Kudernac, Tibor; Shabelina, Natalia; Mamdouh, Wael; Höger, Sigurd; De Feyter, Steven


    Despite their importance in self-assembly processes, the influence of charged counterions on the geometry of self-assembled organic monolayers and their direct localisation within the monolayers has been given little attention. Recently, various examples of self-assembled monolayers composed of charged molecules on surfaces have been reported, but no effort has been made to prove the presence of counterions within the monolayer. Here we show that visualisation and exact localisation of counterions within self-assembled monolayers can be achieved with scanning tunnelling microscopy (STM). The presence of charges on the studied shape-persistent macrocycles is shown to have a profound effect on the self-assembly process at the liquid-solid interface. Furthermore, preferential adsorption was observed for the uncharged analogue of the macrocycle on a surface.

  9. A Novel Cobalt(Ⅲ) Complex with Macrocyclic Triamine Ligand for High Capacity Hydrogen Adsorption

    ZHU Hai-Yan; GUO Hui; LI Sai


    The coordination complex of Co(Ⅲ) based on a macrocyclic triamine ligand 1,4-diacetate-1,4,7-triazacyclodecane (L) has been synthesized and characterized. The metal cation is bonded with three nitrogen atoms and two oxygen atoms of L and one chloride ion to form a distorted octahedral geometry. This complex coordinated with macrocyclic ligand possesses large pore volume that will be contributed to observe high H2 adsorption. With respect to the first-principles electronic structure calculations, the feasibility to store hydrogen in the complex is explored. Indeed, the complex has shown a very high total H2 adsorption of 7.2 wt% (wt% = (weight of adsorbed H2)/(weight of host material)), with a binding energy of 0.03 eV/H2

  10. A comprehensive electronic structure description of a biscyanotetraazacobalt(III) macrocyclic complex.

    Ishiruji, Fabiana Hitomi Ono; Nunes, Fábio Souza


    Molecular modeling and a detailed spectroscopic characterization of the macrocyclic complex [Co(meso)(CN)(2)](+) (meso = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) is herein presented. Structural, electronic and vibrational features are discussed and assignments were proposed on the basis of semi-empirical (molecular mechanics (MM+), ZINDO/S and PM3) quantum-mechanics calculations. The energy and the composition of the molecular orbitals of the complex were calculated and a quantitative diagram was constructed. The simulated UV-vis spectrum exhibited a reasonably good accordance with the experimental one and fully assignments of seven bands were made. An optimized configuration of the complex showed a strong cobalt-cyanide axial bond in agreement with the major contribution of the cyanide to the composition of the molecular orbitals in contrast to a discrete participation of the macrocyclic meso to the ground state of the complex.

  11. mRNA display: from basic principles to macrocycle drug discovery.

    Josephson, Kristopher; Ricardo, Alonso; Szostak, Jack W


    We describe a new discovery technology that uses mRNA-display to rapidly synthesize and screen macrocyclic peptide libraries to explore a valuable region of chemical space typified by natural products. This technology allows high-affinity peptidic macrocycles containing modified backbones and unnatural side chains to be readily selected based on target binding. Success stories covering the first examples of these libraries suggest that they could be used for the discovery of intracellular protein-protein interaction inhibitors, highly selective enzyme inhibitors or synthetic replacements for monoclonal antibodies. The review concludes with a look to the future regarding how this technology might be improved with respect to library design for cell permeability and bioavailability.

  12. Biodegradable polyester-based eco-composites containing hemp fibers modified with macrocyclic oligomers

    Conzatti, Lucia; Utzeri, Roberto; Hodge, Philip; Stagnaro, Paola


    An original compatibilizing pathway for hemp fibers/poly(1,4-butylene adipate-co-terephtalate) (PBAT) eco-composites was explored exploiting the capability of macrocyclic oligomers (MCOs), obtained by cyclodepolymerization (CDP) of PBAT at high dilution, of being re-converted into linear chains by entropically-driven ring-opening polymerization (ED-ROP) that occurs simply heating the MCOS in the bulk. CDP reaction of PBAT was carried out varying solvent, catalyst and reaction time. Selected MCOs were used to adjust the conditions of the ED-ROP reaction. The best experimental conditions were then adopted to modify hemp fibers. Eco-composites based on PBAT and hemp fibers as obtained or modified with PBAT macrocyclics or oligomers were prepared by different process strategies. The best fiber-PBAT compatibility was observed when the fibers were modified with PBAT oligomers before incorporation in the polyester matrix.

  13. Template synthesis of macrocyclic complexes and their spectroscopic and antibacterial studies.

    Singh, D P; Grover, Vidhi; Kumar, Ramesh; Jain, Kiran


    A new series of macrocyclic complexes of type [M(TML)X]X(2), where M = Cr(III), Fe(III), TML is tetradentate macrocyclic ligand, and X = Cl(-), NO(3)(-), CH(3)COO(-), have been synthesized by condensation of isatin and ethylenediamine in the presence of metal salt. The complexes were synthesized by both conventional and microwave methods. The complexes have been characterized with the help of elemental analysis, conductance measurement, magnetic measurement, and infrared, far infrared, and electronic spectral studies. Molar conductance values indicate them to be 1:2 electrolytes. Electronic spectra along with magnetic moments suggest five-coordinate square pyramidal geometry for these complexes. The complexes were also tested for their in vitro antibacterial activity. Some of the complexes showed satisfactory antibacterial activitiy.

  14. The Click Reaction as an Efficient Tool for the Construction of Macrocyclic Structures

    Dario Pasini


    Full Text Available The Cu(I-catalyzed azide-alkyne cycloaddition (CuAAC, known as the click reaction is an established tool used for the construction of complex molecular architectures. Given its efficiency it has been widely applied for bioconjugation, polymer and dendrimer synthesis. More recently, this reaction has been utilized for the efficient formation of rigid or shape-persistent, preorganized macrocyclic species. This strategy also allows the installment of useful functionalities, in the form of polar and function-rich 1,2,3-triazole moieties, directly embedded in the macrocyclic structures. This review analyzes the state of the art in this context, and provides some elements of perspective for future applications.

  15. Special physical preparation of skilled wrestlers during a macrocycle in the conditions of higher educational establishment.

    Ogar' G.O.


    Full Text Available It is developed and experimentally grounded efficiency and methods of improvement of the special physical preparedness of skilled fighters. It is certain that a method parts on a few stages of preparation of training macrocycle and optimized for sportsmen which parallel study in higher educational establishment. It is set that the educational training process of skilled fighters must take into account the specific of organization of educational process of educational establishment and answer the calendar of competitions on a CY.

  16. Lead Diversification through a Prins-Driven Macrocyclization Strategy: Application to C13-Diversified Bryostatin Analogues.

    Wender, Paul A; Billingsley, Kelvin L


    The design, synthesis, and biological evaluation of a novel class of C13-diversified bryostatin analogues are described. An innovative and general strategy based on a Prins macrocyclization-nucleophilic trapping cascade was used to achieve late-stage diversification. In vitro analysis of selected library members revealed that modification at the C13 position of the bryostatin scaffold can be used as a diversification handle to regulate biological activity.

  17. Ligand and Metalloligand Design for Macrocycles, Multimetallic Arrays, Coordination Polymers and Assemblies

    E. C. Constable; Housecroft, C. E.


    This overview of ligand design focuses on three areas: (i) principles of ligand binding, the formation of complexes, and popular strategies for ligand synthesis; (ii) ligand design in macrocyclic complexes, coordination polymers and networks and metallopolygons, and assembly strategies based upon the use of metalloligand building blocks; (iii) ligand design for the extraction and transport of metals. This area of coordination chemistry is too large to permit a comprehensive survey in the spac...

  18. Syntheses of Macrocyclic Amides from L-Amino Acid Esters by RCM


    A series of succinate-derived macrocyclic amides( 1 ) was synthesized via ring-closing metathesis (RCM) as the key step. The substrate included 12 to 15 members. The metathesis precursors were obtained from the amide coupling of tert-butyl 3-carboxyhex-5-enoate(2) with numerous side-chain alkenylated amino acid esters of general type(3)derived from L-lysine and L-ornithine.

  19. Macrocyclic hexaoxazoles: Influence of aminoalkyl substituents on RNA and DNA G-quadruplex stabilization and cytotoxicity.

    Satyanarayana, Mavurapu; Kim, Young-Ah; Rzuczek, Suzanne G; Pilch, Daniel S; Liu, Angela A; Liu, Leroy F; Rice, Joseph E; LaVoie, Edmond J


    A series of 24-membered macrocyclic hexaoxazoles containing one or two aminoalkyl substituents was synthesized and evaluated for cytotoxicity and for their ability to selectively stabilize G-quadruplex DNA and RNA. The most cytotoxic analog 4a, with IC(50) values of 25 and 130 nM using KB3-1 and RPMI 8402 cells, is efficacious in vivo in athymic nude mice with a human tumor xenograft from the breast cancer cell line MDA-MB-435.

  20. Synthesis, spectral and extended spectrum beta-lactamase studies of transition metal tetraaza macrocyclic complexes.

    Kumar, Dinesh; Sharma, Nutan; Nair, Manjula


    Urinary tract infections commonly occur in humans due to microbial pathogens invading the urinary tract, which can bring about a range of clinical symptoms and potentially fatal sequelae. The present study is aimed at addressing the development of a new antimicrobial agent against extended spectrum beta lactamase (ESBL) producing E. coli bacteria. We have synthesised some biologically potent (NNNN) donor macrocycles (L 1  = dibenzo[f,n]dipyrido[3,4-b:4',3'-j][1,4,9,12]tetraazacyclohexadecine-6,11,18,23(5H,12H, 7H, 24H)-tetraone, and L 2  = 6,12,19,25-tetraoxo-4,6,11,12,16,18,23,24-octahydrotetrabenzo [b,g,k,p][1,5,10,14]tetra azacyclooctadecine-2,13-dicarboxylic acid) and their Ti and Zr metal complexes in alcoholic media using microwave protocol. Macrocyclic ligands were synthesised by incorporating of 3,5-diaminobenzoic acid, phthalic acid and 3,4-diaminopyridine in 1:1:1 molar ratio. The macrocyclic ligands and their metal complexes have been characterised by elemental analysis, conductance measurement, magnetic measurement and their structure configurations have been determined by various spectroscopic (FTIR, (1)H/(13)C NMR, UV-Vis, LC-MS mass, XRD and TGA) techniques. [ZrL2Cl2]Cl2 metal complex shows excellent antibacterial activity against ESBLs. A zone of inhibition and minimum inhibitory concentration was determined by McFarland and the dilution method, respectively. The spectral studies confirm the binding sites of the nitrogen atom of the macrocycles. An octahedral geometry has been assigned to the metal complexes based on the findings.

  1. Macrocycle peptides delineate locked-open inhibition mechanism for microorganism phosphoglycerate mutases

    Yu, Hao; Dranchak, Patricia; Li, Zhiru; MacArthur, Ryan; Munson, Matthew S.; Mehzabeen, Nurjahan; Baird, Nathan J.; Battalie, Kevin P.; Ross, David; Lovell, Scott; Carlow, Clotilde K.S.; Suga, Hiroaki; Inglese, James (U of Tokyo); (NEB); (Kansas); (NIH); (NIST); (HHMI)


    Glycolytic interconversion of phosphoglycerate isomers is catalysed in numerous pathogenic microorganisms by a cofactor-independent mutase (iPGM) structurally distinct from the mammalian cofactor-dependent (dPGM) isozyme. The iPGM active site dynamically assembles through substrate-triggered movement of phosphatase and transferase domains creating a solvent inaccessible cavity. Here we identify alternate ligand binding regions using nematode iPGM to select and enrich lariat-like ligands from an mRNA-display macrocyclic peptide library containing >1012 members. Functional analysis of the ligands, named ipglycermides, demonstrates sub-nanomolar inhibition of iPGM with complete selectivity over dPGM. The crystal structure of an iPGM macrocyclic peptide complex illuminated an allosteric, locked-open inhibition mechanism placing the cyclic peptide at the bi-domain interface. This binding mode aligns the pendant lariat cysteine thiolate for coordination with the iPGM transition metal ion cluster. The extended charged, hydrophilic binding surface interaction rationalizes the persistent challenges these enzymes have presented to small-molecule screening efforts highlighting the important roles of macrocyclic peptides in expanding chemical diversity for ligand discovery.

  2. Redox-Active Tetraruthenium Macrocycles Built from 1,4-Divinylphenylene-Bridged Diruthenium Complexes.

    Scheerer, Stefan; Linseis, Michael; Wuttke, Evelyn; Weickert, Sabrina; Drescher, Malte; Tröppner, Oliver; Ivanović-Burmazović, Ivana; Irmler, Andreas; Pauly, Fabian; Winter, Rainer F


    Metallamacrocylic tetraruthenium complexes were generated by treatment of 1,4-divinylphenylene-bridged diruthenium complexes with functionalized 1,3-benzene dicarboxylic acids and characterized by HR ESI-MS and multinuclear NMR spectroscopy. Every divinylphenylene diruthenium subunit is oxidized in two consecutive one-electron steps with half-wave potential splittings in the range of 250 to 330 mV. Additional, smaller redox-splittings between the +/2+ and 0/+ and the 3+/4+ and 2+/3+ redox processes, corresponding to the first and the second oxidations of every divinylphenylene diruthenium entity, are due to electrostatic effects. The lack of electronic coupling through bond or through space is explained by the nodal properties of the relevant molecular orbitals and the lateral side-by-side arrangement of the divinylphenylene linkers. The polyelectrochromic behavior of the divinylphenylene diruthenium precursors is retained and even amplified in these metallamacrocyclic structures. EPR studies down to T=4 K indicate that the dications 1-H(2+) and 1-OBu(2+) are paramagnetic. The dications and the tetracation of macrocycle 3-H display intense (dications) or weak (3-H(4+) ) EPR signals. Quantum chemical calculations indicate that the four most stable conformers of the macrocycles are largely devoid of strain. Bond parameters, energies as well as charge and spin density distributions of model macrocycle 5-H(Me) were calculated for the different charge and spin states.

  3. History of avermectin and ivermectin, with notes on the history of other macrocyclic lactone antiparasitic agents.

    Campbell, William C


    The macrocyclic lactones enjoy a position of prominence in the control of parasites, and their history may be of interest, and even of use, in an age in which the search for chemotherapeutic agents has been transformed by modern technology. Much of their history has been recorded piecemeal in a wide variety of publications. The present review provides additional detail, and offers a personal perspective on the history of ivermectin and related avermectins. Brief notes are included on the subsequent development of other macrocyclic lactones. Milbemycin preceded the avermectins as a macrocyclic lactone of agricultural importance, but was used for a different purpose. Development of the avermectins arose from the isolation, in the laboratories of the Kitasato Institute, of a novel soil-dwelling bacterium and its transmittal (in 1974) to the laboratories of Merck & Co., Inc. There it was found (in 1975) to produce a potent anthelmintic substance, which was then identified and transmuted by interdisciplinary research into an antiparasitic product. Initially the focus was on its applicability to veterinary science and animal husbandry; and after developmental research by many scientific teams, the product was introduced commercially (in 1981) for the control of endoparasitic nematodes and ectoparasitic arthropods in livestock. Subsequently, special applications in human medicine were developed, and were successfully implemented in partnership with World Health Organization and several non-governmental organizations (NGOs).

  4. Heartworms, macrocyclic lactones, and the specter of resistance to prevention in the United States

    Bowman Dwight D


    Full Text Available Abstract In order to provide a background to current concerns relative to the possible resistance of heartworms to macrocyclic lactones, this review summarizes various studies in which lack of efficacies (LOEs have been observed in dogs on macrocyclic lactone preventives relative to the United States of America. Some of these studies have been published in the peer-reviewed literature, others have appeared in various reports to the Center for Veterinary Medicine (CVM of the Food and Drug Administration (FDA of the USA as New Animal Drug Application (NADA summaries, and one appeared as a letter to US veterinarians. This review also discusses reports relating to the potential problem of heartworm resistance in microfilariae and third-stage larvae, as well as molecular markers associated with resistance to macrocyclic lactones within Dirofilaria immitis. As more work is being done in this area of great concern relative to the protection of dogs from infection using this class of preventives, it seems timely to summarize what is known about heartworms, their potential resistance to treatment, and the means of selecting for resistance genes in populations of this helminth in the laboratory and in the field.

  5. Increasing AIP Macrocycle Size Reveals Key Features of agr Activation in Staphylococcus aureus.

    Johnson, Jeffrey G; Wang, Boyuan; Debelouchina, Galia T; Novick, Richard P; Muir, Tom W


    The agr locus in the commensal human pathogen, Staphylococcus aureus, is a two-promoter regulon with allelic variability that produces a quorum-sensing circuit involved in regulating virulence within the bacterium. Secretion of unique autoinducing peptides (AIPs) and detection of their concentrations by AgrC, a transmembrane receptor histidine kinase, coordinates local bacterial population density with global changes in gene expression. The finding that staphylococcal virulence can be inhibited through antagonism of this quorum-sensing pathway has fueled tremendous interest in understanding the structure-activity relationships underlying the AIP-AgrC interaction. The defining structural feature of the AIP is a 16-membered, thiolactone-containing macrocycle. Surprisingly, the importance of ring size on agr activation or inhibition has not been explored. In this study, we address this deficiency through the synthesis and functional analysis of AIP analogues featuring enlarged and reduced macrocycles. Notably, this study is the first to interrogate AIP function by using both established cell-based reporter gene assays and newly developed in vitro AgrC-I binding and autophosphorylation activity assays. Based on our data, we present a model for robust agr activation involving a cooperative, three-points-of-contact interaction between the AIP macrocycle and AgrC.

  6. Dethreading of Tetraalkylsuccinamide-Based [2]Rotaxanes for Preparing Benzylic Amide Macrocycles.

    Martinez-Cuezva, Alberto; Rodrigues, Leticia V; Navarro, Cristian; Carro-Guillen, Fernando; Buriol, Lilian; Frizzo, Clarissa P; Martins, Marcos A P; Alajarin, Mateo; Berna, Jose


    The dethreading of a series of succinamide-based [2]rotaxanes bearing benzylic amide macrocycles is reported herein. These transformations proceeded quantitatively either under flash vacuum pyrolysis, conventional heating, or microwave irradiation. Studying the size complementarity of the stoppers at the ends of the thread and the cavity of the macrocycle allowed us to set up the best substituents for implementing the extrusion of the thread from the interlocked precursors. A variety of (1)H NMR kinetic experiments were carried out in order to evaluate the rate constants of the dethreading process, the half-life times of the rotaxanes, and the influence of temperature and solvents on these processes. The use of dibutylamino groups as stoppers yielded the rotaxane precursor in a reasonable yield and allowed the quantitative deslipping of the rotaxane. The overall process, including the rotaxane formation and its further dethreading, has been exploited for preparing benzylic amide macrocycles enhancing, in most cases, the results of the classical (2 + 2) condensation and other reported stepwise syntheses. The kinetics of the dethreading process is fairly sensitive to the electronic effects of the substituents on the isophthalamide unit or to the electronic nature of the pyridine rings through a conformational equilibrium expanding or contracting the cavity of the interlocked precursor.

  7. Moisture effect on polyether and polyvinylsiloxane dimensional accuracy and detail reproduction.

    Walker, Mary P; Petrie, Cynthia S; Haj-Ali, Reem; Spencer, Paulette; Dumas, Chris; Williams, Karen


    This investigation evaluated and compared the dimensional accuracy and surface detail reproduction of two hydrophilic polyvinylsiloxane (PVS) and two polyether (PE) impression materials when used under dry and moist conditions. Impressions were made of stainless steel dies as described in ANSI/ADA specification no. 19, with two vertical and three horizontal lines inscribed on the die superior surface. Impressions were made under dry and moist conditions (17 impressions per condition for each material). Dimensional accuracy was measured by comparing the average length of the middle horizontal line in each impression with the same line on the metal die using a measuring microscope with an accuracy of 0.001 mm. Surface detail reproduction was evaluated by using criteria similar to ADA specification no. 19: continuous replication of at least two of the three horizontal lines. The mean percent dimensional change and SD values ranged from -0.135% (0.035) to 0.053% (0.031). A two-way analysis of variance (ANOVA) indicated that moisture did not cause significant adverse effects on the dimensional accuracy of any material (p > 0.05); however, significant differences were found between the materials (p Aquasil and Genie Ultra PVS impressions produced satisfactory detail reproduction, while 100% of Permadyne Garant and Impregum Penta Soft PE impressions still met the surface detail criteria. Although moisture may not adversely affect the dimensional accuracy of either PE or hydrophilic PVS material, the evidence suggests that PE material is more likely to produce impressions with superior detail reproduction in the presence of moisture.

  8. Synthesis, characterization and properties of yellow-light-emitting polyethers containing bis(styryl)anthracene units

    Gioti, M., E-mail:; Pitsalidis, C., E-mail:; Tzounis, L.; Logothetidis, S., E-mail: [Laboratory for Thin Films-Nanosystems and Nanometrology (LTFN), Physics Department, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Andreopoulou, A. K.; Kallitsis, J. K. [Department of Chemistry, University of Patras, University Campus, Rio-Patras GR26504, Greece and Foundation for Research and Technology Hellas, Institute of Chemical Engineering Sciences (FORTH/ICE-HT), Platani Str., Patras GR26504 (Greece); Mparmpoutsis, E. [Department of Chemistry, University of Patras, University Campus, Rio-Patras GR26504 (Greece)


    Aromatic aliphatic polyethers containing bis(styryl)anthracene units in the main chain separated by flexible spacer of 11 (AND52) or 12 (AND53) methylene units, were synthesized and characterized aiming to be applied as emitting materials in polymer light emitting diode (PLED) devices. The polymers are soluble in common organic solvents and have average molecular weight of about 15kDa. Differentiations owing to an odd-even number of methylene units (χ=11 vs χ=12) are observed in their optical properties in solid state. Thin films as well as PLED devices were fabricated via conventional spin-coating process. Initially, various parameters have been investigated concerning the solubility of the polymers, the effect of film thickness on the electrical properties, and their thermal stability. The optical properties of the two polymers were investigated by NIR-Vis-far UV spectroscopic ellipsometry (SE). The accurate determination of the thickness and the optical constants (refractive index and dielectric function as a function of wavelength) were derived. These provide substantial insights into the final design of the optimum final multi-layer structure of the PLEDs, if we take into account that the external quantum efficiency (EQE) of electroluminescence (EL) strongly depends on the optical interference of the beams of emitted light that have been multiply reflected from the layer interfaces. The morphological characterization of the AND52 and AND53 polymeric thin films was carried out using atomic force microscopy (AFM), while current density-voltage (J-V) characteristics of the devices were studied by electrical measurements. The single PLED devices were switched on at relatively low operation voltages, showing the potential as backplanes for active matrix PLED applications. In this perspective, it can be assumed that further studies of the presented materials will enable the development of flexible PLEDs with the possibility to scale up their dimensions for bigger

  9. Synthesis and Characterization of a New Network Polymer Electrolyte Containing Polyether in the Main Chains and Side Chains

    Wang; Cheng-chien; Chen; Chuh-yung


    1 Results A new network polymer electrolyte matrix with polyether in the side chains and main chains was synthesized by the azo-macroinitiator method and urethane reaction.The macroinitiator,polymer and network polymer were confirmed by Fourier-transform infrared (FT-IR) spectroscopy and 1H NMR.FT-IR was also used to study the environment of lithium ions doped in these network polymer electrolytes.Three important groups are considered: N-H,carbonyl,and ether groups.The thermal properties of the polymer ...

  10. Quantum dots-hyperbranched polyether hybrid nanospheres towards delivery and real-time detection of nitric oxide

    Liu, Shuiping; Gu, Tianxun; Fu, Jiajia;


    In this work, novel hybrid nanosphere vehicles were synthesized for nitric oxide (NO) donating and real-time detection. The hybrid nanosphere vehicles consist of cadmium selenide quantum dots (CdSe QDs) as NO fluorescent probes, and the modified hyperbranched polyether (mHP)-based diazeniumdiolat...... mechanism. The low cell-toxicity of QDs-mHP-NO nanospheres was verified by means of MTT assay on L929 cells viability. The QDs-mHP-NO nanospheres provide perspectives for designing a new class of biocompatible NO donating and imaging systems....

  11. Incorporation of trinuclear lanthanide(III) hydroxo bridged clusters in macrocyclic frameworks.

    Kobyłka, Michał J; Ślepokura, Katarzyna; Acebrón Rodicio, Maria; Paluch, Marta; Lisowski, Jerzy


    A cluster of lanthanide(III) or yttrium(III) ions, Ln3(μ3-OH)2, (Ln(III) = Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Yb(III), or Y(III)) can be bound in the center of a chiral macrocyclic amines H3L1(R), H3L1(S), and H3L2(S) obtained in a reduction of a 3 + 3 condensation product of (1R,2R)- or (1S,2S)-1,2-diaminocyclohexane and 2,6-diformyl-4-methylphenol or 2,6-diformyl-4-tertbutylphenol. X-ray crystal structures of the Nd(III), Sm(III), Gd(III), Dy(III), and Y(III) complexes reveal trinuclear complexes with Ln(III) ions bridged by the phenolate oxygen atoms of the macrocycle as well as by μ3-hydroxo bridges. In the case of the Nd(III) ion, another complex form can be obtained, whose X-ray crystal structure reveals two trinuclear macrocyclic units additionally bridged by hydroxide anions, corresponding to a [Ln3(μ3-OH)]2(μ2-OH)2 cluster encapsulated by two macrocycles. The formation of trinuclear complexes is confirmed additionally by (1)H NMR, electrospray ionization mass spectrometry (ESI MS), and elemental analyses. Titrations of free macrocycles with Sm(III) or Y(III) salts and KOH also indicate that a trinuclear complex is formed in solution. On the other hand, analogous titrations with La(III) salt indicate that this kind of complex is not formed even with the excess of La(III) salt. The magnetic data for the trinuclear Gd(III) indicate weak antiferromagnetic coupling (J = -0.17 cm(-1)) between the Gd(III) ions. For the trinuclear Dy(III) and Tb(III) complexes the χ(M)T vs T plots indicate a more complicated dependence, resulting from the combination of thermal depopulation of mJ sublevels, magnetic anisotropy, and possibly weak antiferromagnetic and ferromagnetic interactions.

  12. Enantiomeric self-recognition in homo- and heterodinuclear macrocyclic lanthanide(III) complexes.

    Lisowski, Jerzy


    The controlled formation of lanthanide(III) dinuclear μ-hydroxo-bridged [Ln(2)L(2)(μ-OH)(2)X(2)](n+) complexes (where X = H(2)O, NO(3)(-), or Cl(-)) of the enantiopure chiral macrocycle L is reported. The (1)H and (13)C NMR resonances of these complexes have been assigned on the basis of COSY, NOESY, TOCSY, and HMQC spectra. The observed NOE connectivities confirm that the dimeric solid-state structure is retained in solution. The enantiomeric nature of the obtained chiral complexes and binding of hydroxide anions are reflected in their CD spectra. The formation of the dimeric complexes is accompanied by a complete enantiomeric self-recognition of the chiral macrocyclic units. The reaction of NaOH with a mixture of two different mononuclear lanthanide(III) complexes, [Ln(1)L](3+) and [Ln(2)L](3+), results in formation of the heterodinuclear [Ln(1)Ln(2)L(2)(μ-OH)(2)X(2)](n+) complexes as well as the corresponding homodinuclear complexes. The formation of the heterodinuclear complex is directly confirmed by the NOESY spectra of [EuLuL(2)(μ-OH)(2)(H(2)O)(2)](4+), which reveal close contacts between the macrocyclic unit containing the Eu(III) ion and the macrocyclic unit containing the Lu(III) ion. While the relative amounts of homo- and heterodinuclear complexes are statistical for the two lanthanide(III) ions of similar radii, a clear preference for the formation of heterodinuclear species is observed when the two mononuclear complexes contain lanthanide(III) ions of markedly different sizes, e.g., La(III) and Yb(III). The formation of heterodinuclear complexes is accompanied by the self-sorting of the chiral macrocyclic units based on their chirality. The reactions of NaOH with a pair of homochiral or racemic mononuclear complexes, [Ln(1)L(RRRR)](3+)/[Ln(2)L(RRRR)](3+), [Ln(1)L(SSSS)](3+)/[Ln(2)L(SSSS)](3+), or [Ln(1)L(rac)](3+)/[Ln(2)L(rac)](3+), results in mixtures of homochiral, homodinuclear and homochiral, heterodinuclear complexes. On the contrary, no

  13. Effect of the chemical modification of a macrocycle and the acidity of a medium on the spectral properties and basicity of tetraphenylporphyrin in HCl- N, N-dimethylformamide system at 298 K

    Ivanova, Yu. B.; Razgonyaev, O. V.; Semeikin, A. S.; Mamardashvili, N. Zh.


    Spectrophotometric titration is used to study the basicity of tetraphenylporphine and its derivatives with electron-donor and electron-acceptor substituents in the 4-positions of meso-aryl fragments (5,10,15,20-tetra(4-R-phenyl)porphine, R:-OH,-NH2,-COOH,-Cl) in a system HCl- N, N-dimethylformamide at 298 K. An equation for calculating the dependence of the Hammett constant ( H 0) on the HCl concentration in a HCl- N, N-dimethylformamide system at 298 K is proposed. It is found that protonation of the intracycle nitrogen atoms of tetrapyrrole macrocycles of the indicated compounds occurs in two stages in this system. The corresponding ionization constants and concentration ranges of the existence of mono- and doubly-protonated dication forms of the indicated compounds are determined. It is found that both the introduction of strong substituents into the macrocycle of porphyrin and the properties of the medium facilitate the formation of mono- and doubly-protonated forms of porphyrins in solutions.

  14. Modified nanocrystal cellulose/fluorene-containing sulfonated poly(ether ether ketone ketone) composites for proton exchange membranes

    Wei, Yingcong; Shang, Yabei; Ni, Chuangjiang; Zhang, Hanyu; Li, Xiaobai; Liu, Baijun; Men, Yongfeng; Zhang, Mingyao; Hu, Wei


    Highly sulfonated poly(ether ether ketone ketone)s (SFPEEKKs) with sulfonation degrees of 2.34 (SFPEEKK5) and 2.48 (SFPEEKK10) were synthesized through the direct sulfonation of a fluorene-containing poly(ether ether ketone ketone) under a relatively mild reaction condition. Using the solution blending method, sulfonated nanocrystal cellulose (sNCC)-enhanced SFPEEKK composites (SFPEEKK/sNCC) were successfully prepared for investigation as proton exchange membranes. Transmission electron microscopy showed that sNCC was uniformly distributed in the composite membranes. The properties of the composite membranes, including thermal stability, mechanical properties, water uptake, swelling ratio, oxidative stability and proton conductivity were thoroughly evaluated. Results indicated that the insertion of sNCC could contribute to water management and improve the mechanical performance of the membranes. Notably, the proton conductivity of SFPEEKK5/sNCC-5 was as high as 0.242 S cm-1 at 80 °C. All data proved the potential of SFPEEKK/sNCC composites for proton exchange membranes in medium-temperature fuel cells.

  15. Dimensional Stability of Polyether, Alginate, and Silicone Impression Materials After Disinfection With 2% Sanosil Through the Immersion Technique



    Full Text Available Background To prevent diseases transmission, infection control in dental offices without reducing the accuracy and dimensional stability of impression materials is very important. Objectives The aim of this study was to evaluate the effects of Sanosil disinfectants on the dimensional stability of some usual impression materials. Materials and Methods Three types of impression material, namely, alginate, condensational silicone, and polyether, were used in this study. Impressions were obtained from the master steel model. Fifteen impressions of each material (control group were immersed in water for ten minutes and impressions of study groups were disinfected by immersion in 2% Sanosil for ten minutes. Then impressions were poured by type III gypsum according to the manufacture's instruction. Dimensions of casts in the two anterior dimensions, i.e. interval between the anterior abutments and interval between anterior-posterior abutments, were recorded by a digital caliper with the accuracy of 0.01 mm. Data were analyzed with SPSS through two-way ANOVA test. Results The results showed that there was no significant difference in the mean dimension of casts prepared by different impression materials in anterior and anterior-posterior dimensions in comparison to the original model after disinfection with Sanosil. Conclusions The study revealed that disinfection with 2% Sanosil has no significant effect on casts dimensions of alginate, silicone, and polyether impression and dimensional stability is maintained.

  16. Hydrophilic modification of poly(ether sulfone) ultrafiltration membrane surface by self-assembly of TiO 2 nanoparticles

    Luo, Ming-Liang; Zhao, Jian-Qing; Tang, Wu; Pu, Chun-Sheng


    Membrane fouling is one of the major obstacles for reaching the ultimate goal, which realizes high flux over a prolonged period of ultrafiltration (UF) operation. In this paper, TiO 2 nanoparticles of a quantum size (40 nm or less) in anatase crystal structure were prepared from the controlled hydrolysis of titanium tetraisopropoxide and characterized by X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). The hydrophilic modification of poly(ether sulfone) UF membrane was performed by self-assembly of the hydroxyl group of TiO 2 nanoparticle surface and the sulfone group and ether bond in poly(ether sulfone) structure through coordination and hydrogen bond interaction, which was ascertained by X-ray photoelectron spectroscopy (XPS). The morphology and hydrophilicity were characterized by scanning electron microscopy (SEM) and contact angle test, respectively. The composite UF membrane was also characterized in terms of separation behavior for polyethylene glycol-5000 solute. The experimental results show that the composite UF membrane has good separation performance and offers a strong potential for possible use as a new type of anti-fouling UF membrane.

  17. Characterization of a poly(ether urethane)-based controlled release membrane system for delivery of ketoprofen

    Macocinschi, Doina, E-mail: [Department of Physical Chemistry of Polymers, ' Petru Poni' Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41 A, 700487 Iasi (Romania); Filip, Daniela; Vlad, Stelian; Oprea, Ana Maria [Department of Physical Chemistry of Polymers, ' Petru Poni' Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41 A, 700487 Iasi (Romania); Gafitanu, Carmen Anatolia [Faculty of Pharmacy, ' Gr. T. Popa' University of Medicine and Pharmacy, Universitatii 16, 700115 Iasi (Romania)


    Highlights: Black-Right-Pointing-Pointer Ketoprofen incorporation in poly(ether urethane) microporous membrane. Black-Right-Pointing-Pointer Moisture sorption properties of as-cast membrane. Black-Right-Pointing-Pointer Drug release mechanisms in function of pH and composition of membranes. - Abstract: A poly(ether urethane) based on polytetrahydrofuran containing hydroxypropyl cellulose for biomedical applications was tested for its biocompatibility. Ketoprofen was incorporated (3% and 6%) in the polyurethane matrix as an anti-inflammatory drug. Kinetic and drug release mechanisms were studied. The pore size and pore size distribution of the polyurethane membranes were investigated by scanning electron microscopy. Surface tension characteristics as well as moisture sorption properties such as diffusion coefficients and equilibrium moisture contents of the membrane material were studied. It was found that kinetics and release mechanisms are in function of medium pH, composition of polymer-drug system, pore morphology and pore size distribution. Prolonged nature of release of ketoprofen is assured by low amount of drug in polyurethane membrane and physiological pH.

  18. Synthesis and characterization of sulfonated poly(ether sulfone)s containing mesonaphthobifluorene for polymer electrolyte membrane fuel cell.

    Lim, Youngdon; Seo, Dongwan; Lee, Soonho; Hossain, Md Awlad; Lim, Jinseong; Lee, Sangyoung; Hong, Taehoon; Kim, Whangi


    The novel sulfonated poly(ether sulfone)s containing mesonaphthobifluorene (MNF) moiety were synthesized and characterized their properties. The prepared polymers have highly conjugated aromatic structure due to the MNF group which is an allotrope of carbon and one atom thick planar sheets of sp2-bonded carbon atoms. Poly(ether sulfone)s bearing tetraphenylethylene on polymer backbone were synthesized by polycondensation and followed intra-cyclization from tetraphenylethylene to form MNF by Friedel-craft reaction with Lewis acid (FeCl3). The sulfonation was performed selectively on MNF units with conc. sulfuric acid. The structural properties of the sulfonated polymers were investigated by 1H-NMR spectroscopy. The membranes were studied by ion exchange capacity (IEC), water uptake, and proton conductivity. The synthesized polymer electrolyte membranes showed better thermal and dimensional stabilities owing to the inducted highly conjugated aromatic structure in the polymer backbone. The water uptake of the synthesized membranes ranged from 23-52%, compared with 32.13% for Nafion 211 at 80 degrees C. The synthesized membranes exhibited proton conductivities (80 degrees C, RH 90%) of 74.6-100.4 mS/cm, compared with 102.7 mS/cm for Nafion 211.

  19. Cloud Points of Water—soluble Polyether Phosphites and Their Application in the Biphasic Hydroformylation of Higher Olefins

    LIU,Xiao-Zhong; WANG,Yan-Hua; KONG,Fan-Zhi; JIN,Zi-Lin


    Wate-soluble polyether phosphites alkyl polyethylene glycol ophenylene phosphite(APGPPS)were alcoholysis of phosphorus chloride with plyoxyethylene alkyl ether.With appropriate HLB(hydrophile-lypophile balance),the phosphites possess clear cloud points below 100℃,Addition of some inorganic salts decreases cloud points of the phosphites.When the phosphiites have long polyether chain binding to short-chain alkyl group,their cloud points could be extrapolated from figure of dependece of cloud points on addition of inorganic salts.Utilizing octylpolyglycol-phenylene-phosphite(OPGPP)(APGPP,R:Octyl)/Rh complex formed in situ as catalyst,over 90% conversion of 1-decene was obtained ,avoiding the limitation of water insolubility of substrates.Preliminary results indicated that micellar catalysis and thermoregulated phase-transfer catalysis(TRPTC)coexist in the reaction system.Below cloud point,micellar catalysis induced by plyether phosphites may be existed.When temperature is increased to above cloud point of the phosphies,this reaction works mainly in TRPTC.The catalysts could be easily spearated by simple decantation,but followed by considerable loss in activity after three successive reaction runs.Preliminary results indicated hydrolysis of OPGPP happened during the reaction.which may explain for the bad loss in activity.The catalyst was reused up to seven times with-out clear decrease in activity when OPGPP/Rh ratio was increased to 50.

  20. Synthesis, crystal structures and properties of two novel macrocyclic nickel(II) and copper(II) complexes

    Su, Yan-Hui; Liu, Jie; Li, Jia; Si, Xue-Zhi


    Two new 14-membered hexaaza macrocyclic complexes with the formulae [NiL](ClO 4) 2·CH 3COCH 3 ( 1) and [CuL](ClO 4) 2·CH 3COCH 3 ( 2), where L = 3,10-bis(2-thiophenemethyl)-1,3,5,8,10,12-hexaazacyclotetradecane, have been synthesized and characterized by elemental analyses, single-crystal X-ray diffraction analyses, electronic spectra, IR and TG-DTA. In 1, the nickel(II) ion is four-coordinated with four nitrogen atoms from the macrocycle and forms a square-planar coordination geometry. In 2, the copper(II) ion is six-coordinated with four nitrogen atoms from the macrocyclic ligand in the equatorial plane and two oxygen atoms from the perchlorate anions in the axial position exhibiting an elongated octahedron coordination geometry. The two complexes present two different molecular arrangements in which the [ML] 2+ (M = Ni, Cu) cation arrays in the manner of M(1)M(2)M(1)… in sequence. The pendant thiophene groups of the neighboring macrocycles have no π⋯π interactions. All the ClO4- anions and acetone molecules are involved in hydrogen-bonding interactions with the macrocyclic ligand.

  1. Intercalation compounds involving inorganic layered structures



    Full Text Available Two-dimensional inorganic networks can shown intracrystalline reactivity, i.e., simple ions, large species as Keggin ions, organic species, coordination compounds or organometallics can be incorporated in the interlayer region. The host-guest interaction usually causes changes in their chemical, catalytic, electronic and optical properties. The isolation of materials with interesting properties and making use of soft chemistry routes have given rise the possibility of industrial and technological applications of these compounds. We have been using several synthetic approaches to intercalate porphyrins and phthalocyanines into inorganic materials: smectite clays, layered double hydroxides and layered niobates. The isolated materials have been characterized by elemental and thermal analysis, X-ray diffraction, surface area measurements, scanning electronic microscopy, electronic and resonance Raman spectroscopies and EPR. The degree of layer stacking and the charge density of the matrices as well their acid-base nature were considered in our studies on the interaction between the macrocycles and inorganic hosts.

  2. Patterns of venom production and temporal polyethism in workers of Jerdon's jumping ant, Harpegnathos saltator.

    Haight, Kevin L


    Ants are chemical factories, and among their more noticeable products are their venoms. Though many studies have addressed the properties and activities of ant venoms, basic venom-related physiological questions, such as how venom production and replacement may vary with age, are rarely addressed. The answers to these questions are fundamental to understanding the physiological capabilities of these organisms, as well as the parameters within which potential optimization of their investment in venom production must take place. The only previous investigation into venom production in ants found it to be limited to early life in workers of the fire ant, Solenopsis invicta (Haight and Tschinkel, 2003). Because similar studies have not been conducted for comparison, it is unclear whether or not this is a common physiological pattern in ants. As a parsimonious way to address this question, and, more generally, to increase the currently scant information available regarding the venom-producing capabilities of ants, the longevity, temporal polyethism, age-related venom production, and age-related venom replacement capabilities of workers of Jerdon's jumping ant, Harpegnathos saltator were investigated. Longevity varied from 10 days to nearly 2 years, with a median lifespan of 206 days. Workers remained in the nest when young, transitioned to outside work (foraging) after 50 days of age, and reached a plateau in their tendency to be outside the nest at 74 days of age. They eclosed with empty venom sacs, filled them by about 57 days of age, and were able to replace venom at all three ages tested (though at a higher rate when aged 100 days than 30 and 206). So, venom-production ability is not limited to early life in H. saltator workers, and aspects of venom physiology and exploratory behavior appear to coincide in a manner likely to result in foraging efficiency benefits; venom sacs reach fullness around the age workers begin their foraging careers, and venom replacement

  3. Template Syntheses and Crystal Structures of Hexaaza Macrocyclic Complexes with C-Methyl Substituents


    Two new macrocyclic complexes with C-methyl substituents on the framework,namely, [CuL](ClO4)2 (L = 5,12-dimethyl- 1,8-dihydroxyethyl- 1,3,6,8,10,13-hexaazacyclotetradecane) 1 and [NiL](ClO4)2 2, have been synthesized and structurally characterized through X-ray diffraction analysis. Also, crystal structure of [CuL1](ClO4)2 (L1 = 1,8-dimethyl- 1,3,6,8,10,13- hexaazacyclotetradecane) 3 has been determined. Crystal data for 1: C14H32C12CuN6O10, Mr = 578.90,monoclinic, P21In, a = 8.3529(11), b = 10.8105(17), c = 13.3709(17) A, β = 105.189(10)°, V =1165.2(3) A3, Z = 2, Dc = 1.650 g/cm3, F(000) = 602, λ(MoKα) = 0.71073 A,μ = 1.229 mm-1, R =0.0474 and wR = 0.0895 for 2771 observed reflections (I > 2σ(I)). Crystal data for 2:C14H32C12N6NiO10, Mr = 574.07, monoclinic, P21/c, a = 8.3636(12), b = 12.997(2), c = 10.764(2) A,β = 99.31 (2)°, V = 1154.7(3) A3, Z = 2, Dc = 1.651 g/cm3, F(000) = 600, λ(MoKα) = 0.71073 A,μ =1.134 mm-1, R = 0.0380 and wR = 0.0796 for 2670 observed reflections (I > 2σ(Ⅰ)). Crystal data for 3. C10H26Cl2CuN6O8, Mr = 492.81, monoclinic, P21/n, a = 8.4860(17), b = 8.6320(17), c = 12.662(3)A, β = 103.40(3)°, V = 902.2(3) A3, Z = 2, Dc = 1.814 g/cm3, F(000) = 510, λ(MoKα) = 0.71073 A,μ = 1.562 mm - 1, R = 0.0505 and wR = 0. 1 061 for 1967 observed reflections (I > 2σ(Ⅰ)). Complexes 1 and 2 are isostructural with the metal ions situated at the inversion center. Hydrogen bonds between O atoms of pendant and perchlorate anion give rise to a two-dimensional supramolecular layer. The Cu(Ⅱ) ions of compounds 1 and 3 adopt distorted axially-elongated octahedral coordinate geometry, and the nickel(Ⅱ) ion in complex 2 is four-coordinated with a square-planar configuration.

  4. Peptide Macrocycles Featuring a Backbone Secondary Amine: A Convenient Strategy for the Synthesis of Lipidated Cyclic and Bicyclic Peptides on Solid Support

    Oddo, Alberto; Münzker, Lena; Hansen, Paul Robert


    A convenient strategy for the on-resin synthesis of macrocyclic peptides (3- to 13-mers) via intramolecular halide substitution by a diamino acid is described. The method is compatible with standard Fmoc/tBu SPPS and affords a tail-to-side-chain macrocyclic peptide featuring an endocyclic secondary...

  5. Synthesis, morphology and properties of segmented poly(ether ester amide)s comprising uniform glycine or β-alanine extended bisoxalamide hard segments

    Sijbrandi, N.J.; Kimenai, A.J.; Mes, E.P.C.; Broos, R.; Bar, G.; Rosenthal, M.; Odarchenko, Y.; Ivanov, D.A.; Feijen, J.; Dijkstra, P.J.


    Segmented poly(ether ester amide)s comprising glycine or β-alanine extended bisoxalamide hard segments are highly phase separated thermoplastic elastomers with a broad temperature independent rubber plateau. These materials with molecular weights, Mn, exceeding 30 × 103 g mol−1 are conveniently prep

  6. The importance of orientation in proton transport of a polymer film based on an oriented self-organized columnar liquid-crystalline polyether

    Tylkowski, Bartosz; Castelao, Nuria [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain); Giamberini, Marta, E-mail: [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain); Garcia-Valls, Ricard [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain); Reina, Jose Antonio [Departament de Quimica Analitica i Quimica Organica, Universitat Rovira i Virgili, Carrer Domingo s/n, E-43007, Tarragona (Spain); Gumi, Tania [Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paiesos Catalans, 26, E-43007, Tarragona (Spain)


    We prepared membranes based on a liquid-crystalline side-chain polyether obtained by chemical modification of commercial poly(epichlorohydrin) (PECH) with dendrons. This polymer exhibited a columnar structure, which could form an ion channel in the inner part. The columns were successfully oriented by taking advantage of surface interactions between the polymer and hydrophilic substrates, as confirmed by X-ray diffraction analysis (XRD), environmental scanning electron microscopy (ESEM) and optical microscopy between crossed polars (POM). Column orientation was found to be crucial for effective transport: the oriented membranes exhibited proton transport comparable to that of Nafion Registered-Sign N117 and no water uptake. An increase in sodium ion concentration in the feed phase suggested a proton/cation antiport. On the contrary, no proton transport was detected on unoriented membranes based on the same liquid-crystalline side-chain polyether or on unmodified PECH. - Highlights: Black-Right-Pointing-Pointer We prepared oriented membranes based on a liquid crystalline columnar polyether. Black-Right-Pointing-Pointer In this structure, the inner polyether chain could work as an ion channel. Black-Right-Pointing-Pointer We obtained membranes by casting a chloroform solution in the presence of water. Black-Right-Pointing-Pointer Membranes showed good proton permeability due to the presence of oriented channels.

  7. Single-molecule phenyl-acetylene-macrocycle-based optoelectronic switch functioning as a quantum-interference-effect transistor.

    Hsu, Liang-Yan; Rabitz, Herschel


    This work proposes a new type of optoelectronic switch, the phenyl-acetylene-macrocycle-based single-molecule transistor, which utilizes photon-assisted tunneling and destructive quantum interference. The analysis uses single-particle Green's functions along with Floquet theory. Without the optical field, phenyl-acetylene-macrocycle exhibits a wide range of strong antiresonance between its frontier orbitals. The simulations show large on-off ratios (over 10(4)) and measurable currents (~10(-11) A) enabled by photon-assisted tunneling in a weak optical field (~2 × 10(5) V/cm) and at a small source-drain voltage (~0.05 V). Field amplitude power scaling laws and a range of field intensities are given for operating one- and two-photon assisted tunneling in phenyl-acetylene-macrocycle-based single-molecule transistors. This development opens up a new direction for creating molecular switches.

  8. Highly efficient synthesis of monodisperse poly(ethylene glycols) and derivatives through macrocyclization of oligo(ethylene glycols).

    Zhang, Hua; Li, Xuefei; Shi, Qiuyan; Li, Yu; Xia, Guiquan; Chen, Long; Yang, Zhigang; Jiang, Zhong-Xing


    A macrocyclic sulfate (MCS)-based approach to monodisperse poly(ethylene glycols) (M-PEGs) and their monofunctionalized derivatives has been developed. Macrocyclization of oligo(ethylene glycols) (OEGs) provides MCS (up to a 62-membered macrocycle) as versatile precursors for a range of monofunctionalized M-PEGs. Through iterative nucleophilic ring-opening reactions of MCS without performing group protection and activation, a series of M-PEGs, including the unprecedented 64-mer (2850 Da), can be readily prepared. Synthetic simplicity coupled with versatility of this new strategy may pave the way for broader applications of M-PEGs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Discovery and Optimization of Macrocyclic Quinoxaline-pyrrolo-dihydropiperidinones as Potent Pim-1/2 Kinase Inhibitors.

    Cee, Victor J; Chavez, Frank; Herberich, Bradley; Lanman, Brian A; Pettus, Liping H; Reed, Anthony B; Wu, Bin; Wurz, Ryan P; Andrews, Kristin L; Chen, Jie; Hickman, Dean; Laszlo, Jimmy; Lee, Matthew R; Guerrero, Nadia; Mattson, Bethany K; Nguyen, Yen; Mohr, Christopher; Rex, Karen; Sastri, Christine E; Wang, Paul; Wu, Qiong; Wu, Tian; Xu, Yang; Zhou, Yihong; Winston, Jeffrey T; Lipford, J Russell; Tasker, Andrew S; Wang, Hui-Ling


    The identification of Pim-1/2 kinase overexpression in B-cell malignancies suggests that Pim kinase inhibitors will have utility in the treatment of lymphoma, leukemia, and multiple myeloma. Starting from a moderately potent quinoxaline-dihydropyrrolopiperidinone lead, we recognized the potential for macrocyclization and developed a series of 13-membered macrocycles. The structure-activity relationships of the macrocyclic linker were systematically explored, leading to the identification of 9c as a potent, subnanomolar inhibitor of Pim-1 and -2. This molecule also potently inhibited Pim kinase activity in KMS-12-BM, a multiple myeloma cell line with relatively high endogenous levels of Pim-1/2, both in vitro (pBAD IC50 = 25 nM) and in vivo (pBAD EC50 = 30 nM, unbound), and a 100 mg/kg daily dose was found to completely arrest the growth of KMS-12-BM xenografts in mice.

  10. Immobilized copper(II) macrocyclic complex on MWCNTs with antibacterial activity

    Tarlani, Aliakbar, E-mail: [Inorganic Nanostructures and Catalysts Research Lab., Chemistry & Chemical Engineering Research Center of Iran, Pajoohesh Blvd., km 17, Karaj Hwy, Tehran 14968-13151 (Iran, Islamic Republic of); Narimani, Khashayar [Inorganic Nanostructures and Catalysts Research Lab., Chemistry & Chemical Engineering Research Center of Iran, Pajoohesh Blvd., km 17, Karaj Hwy, Tehran 14968-13151 (Iran, Islamic Republic of); Mohammadipanah, Fatemeh; Hamedi, Javad [Department of Microbial Biotechnology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran 14155-6455 (Iran, Islamic Republic of); University of Tehran Biocompound Collection (UTBC), Microbial Technology and Products Research Center, University of Tehran, Tehran (Iran, Islamic Republic of); Tahermansouri, Hasan [Department of Chemistry, Ayatollah Amoli Branch, Islamic Azad University, Amol (Iran, Islamic Republic of); Amini, Mostafa M. [Department of Chemistry, Shahid Behshti University, 1983963113, Tehran (Iran, Islamic Republic of)


    Graphical abstract: In an antibacterial test, grafted copper(II) macrocyclic complex on the surface of MWCNT showed higher antibacterial activity against Bacillus subtilis compared to the individual MWCNT-COOH and the complex. - Highlights: • Copper(II) tetraaza macrocyclic complex covalently bonded to modified MWCNT. • Grafting of the complex carried out via an interaction between −C(=O)Cl group and NH of the ligand. • The samples were subjected in an antibacterial assessment to compare their activity. • Immobilized complex showed higher antibacterial activity against Bacillus subtilis ATCC 6633 compared to separately MWCNT-C(C=O)-OH and CuTAM. - Abstract: In a new approach, a copper(II) tetraaza macrocyclic complex (CuTAM) was covalently bonded on modified multi-walled carbon nanotubes (MWCNTs). To achieve this purpose, MWCNTs were converted to MWCNT-COCl and then reacted to NH groups of TAM ligand. The prepared material was characterized by Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, thermal gravimetric analysis (TGA), and FESEM (field emission scanning electron microscopy). FT-IR and TGA demonstrated the presence of the organic moieties, and XRD proved that the structure of MWCNTs remained intact during the three modification steps. An increase in the I{sub D}/I{sub G} ratio in Raman spectra confirmed the surface modifications. Finally, the samples were subjected to an antibacterial assessment to compare their biological activity. The antibacterial test showed that the grafted complex on the surface of the nanotube (MWCNT-CO-CuTAM) has higher antibacterial activity against Bacillus subtilis ATCC 6633 than the MWCNT-COOH and CuTAM with 1000 and 2000 μg/mL.

  11. Kinetic Analysis for Macrocyclizations Involving Anionic Template at the Transition State

    Vicente Martí-Centelles


    competitive oligomerization/polymerization processes yielding undesired oligomeric/polymeric byproducts. The effect of anions has also been included in the kinetic models, as they can act as catalytic templates in the transition state reducing and stabilizing the transition state. The corresponding differential equation systems for each kinetic model can be solved numerically. Through a comprehensive analysis of these results, it is possible to obtain a better understanding of the different parameters that are involved in the macrocyclization reaction mechanism and to develop strategies for the optimization of the desired processes.

  12. A flexible cyclophane: Design, synthesis, and structure of a multibridged tris-tetrathiafulvalene (TTF) macrocycle

    Takimiya, K.; Thorup, Niels; Becher, J.


    that the neutral molecules include two (3a) or one chloroform molecule (3b) as solvent of crystallization inside the cavity, whereas the I-3(-) salt of 3b, obtained by electrocrystallization, has a molecular structure which is different from that of the neutral molecule in that the cavity has completely collapsed.......The tris-tetrathiafulvalene (TTF) macrocycles 3 with a large end-cavity were effectively synthesized from the readily available tetrakis(cyanoethylthio)TTF by means of a selective deprotection/realkylation sequence followed by an intramolecular coupling reaction. Crystal structure analyses revealed...

  13. Biomechanical Assessment of the Strength of Volleyball Players in Different Stages of the Training Macrocycle

    Śliwa Marcin


    Full Text Available Introduction. In order to help volleyball players achieve superior results, their coaches are constantly seeking new training methods. One of the methods used to improve the effectiveness of the training that is being implemented is conducting tests which make it possible to assess the player’s locomotor system in terms of its motor and biomechanical functions. The aim of the study was to determine the torque of the knee flexor and extensor muscles of volleyball players in three stages of the annual macrocycle.

  14. Synthesis of NLO polycarbonates via the ring-opening polymerization of macrocyclic prepolymers

    Kulig, Joseph B.; Moore, Collin G.; Brittain, William J.; Gilmour, Sandra; Perry, Joseph W.


    The synthesis and characterization of polycarbonates and polyformals is described. Copolymers of bisphenol A (BPA) and either a triphenyloxazole (1) or phenylquinoxaline (2) monomer were prepared. The polycarbonate copolymers were prepared by ring-opening polymerization of macrocyclic prepolymers using a solvent-free process. Preliminary electro- optic measurements have been performed on the polycarbonate copolymers of BPA and 1. Polyformals have also been prepared by a conventional polymerization process involving the reaction of dichloromethane with different feed ratios of BPA and either 1 or 2. The glass transition temperature of either the polyformals or polycarbonates is dramatically increased by increasing mole fractions of monomers 1 and 2.

  15. "Cyclamen Red" colors based on a macrocyclic anthocyanin in carnation flowers.

    Gonnet, J F; Fenet, B


    The "cyclamen" red (or pink) colors in carnation flowers-cultivars Red Rox and eight others-are based on the presence of a new macrocyclic anthocyanin, pelargonidin 3,5-di-O-beta-glucoside(6' ', 6' "-malyl diester) identified by spectroscopic methods. The instability of the bridging malyl group with sugars in acidic medium readily causes the formation of the opened ring form, 3-O-(6' '-O-malylglucoside)-5-O-glucoside. The issue of cyclamen colors based in carnations on this original acylated pelargonidin derivative simulating those based on simpler cyanidin glycosides in Rosa cultivars is discussed using CIELAB colorimetric coordinates.

  16. Catalytic Hydrolysis of Phosphate Diester with Metal Complexesof Macrocyclic Tetraamine in Comicellar Solution

    XIANG Qing-Xiang; YU Xiao-Qi; YOU Jing-Song; YAN Qian-Shun; XIE Ru-Gang


    Four novel pyridine or benzene ring-containing pendant macrocyclic dioxotetraanines 2,6-dioxo-1,4,7,10-tetraazacy-clododeane ligands have been synthesized.Their metal com-plexes have been investigated as catalysts for the hydrolysis of bis(p-nitrophenyl) phosphate (BNPP) in aqueous comicellar solution.The results indicate that the hydrophobic interaction between substrate and metal complex, the nature of transition metal ion, and the micellar microenvironment are important factors for the hydrolysis, of BNPP.Large rate enhancement (up to over two-three orders magnitude) employing 5 hasbeen observed.

  17. Neighbor-directed histidine N(τ) alkylation. A route to imidazolium-containing phosphopeptide macrocycles

    Qian, Wen-Jian [National Cancer Inst., Frederick, MD (United States); Park, Jung-Eun [National Cancer Inst., Bethesda, MD (United States); Grant, Robert [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Lai, Christopher C. [National Cancer Inst., Frederick, MD (United States); Kelley, James A. [National Cancer Inst., Frederick, MD (United States); Yaffe, Michael B. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Lee, Kyung S. [National Cancer Inst., Bethesda, MD (United States); Burke, Terrence R. [National Cancer Inst., Frederick, MD (United States)


    Our recently discovered, selective, on-resin route to N(τ)-alkylated imidazolium-containing histidine residues affords new strategies for peptide mimetic design. In this, we demonstrate the use of this chemistry to prepare a series of macrocyclic phosphopeptides, in which imidazolium groups serve as ring-forming junctions. These cationic moieties subsequently serve to charge-mask the phosphoamino acid group that directed their formation. Furthermore, neighbor-directed histidine N(τ)-alkylation opens the door to new families of phosphopeptidomimetics for use in a range of chemical biology contexts.

  18. Molecular Rearrangement of an Aza-Scorpiand Macrocycle Induced by pH: A Computational Study

    Jesus Vicente De Julián-Ortiz


    Full Text Available Rearrangements and their control are a hot topic in supramolecular chemistry due to the possibilities that these phenomena open in the design of synthetic receptors and molecular machines. Macrocycle aza-scorpiands constitute an interesting system that can reorganize their spatial structure depending on pH variations or the presence of metal cations. In this study, the relative stabilities of these conformations were predicted computationally by semi-empirical and density functional theory approximations, and the reorganization from closed to open conformations was simulated by using the Monte Carlo multiple minimum method.


    SUN Qiang; ZHANG Jinlan; XU Jiping


    Chelating resin with macrocyclic mercaptal group supported on macroporous polystyrene beads was synthesized, which showed good selectivity to Hg2+: its complexing capacity amounted to 30-60 mg Hg2+/g resin, two orders of magnitude greater than for other metal ions such as Ca2+, Zn2+,Cd2+, Pb2+ etc. This resin could restore the activity of urease which had been deactivated by poisoning with Hg2+. Its restoring power was far better than that of the mercapto-resin and common anionic exchange resins. It showed some promising use as an oral polymeric detoxifying drug for mercury poisoning.

  20. Carbohydrate-based aza-macrocycles by Richman-Atkins cyclization of glucopyranose precursors.

    Rathjens, Andreas; Thiem, Joachim


    2, 3-Di-ω-halo- as well as 2, 3-di-ω-toluenesulfonamide-alkylated glucopyranoside derivatives were prepared. Their condensation with α,ω-bis-toluenesulfonamide components under varying Richman-Atkins conditions with alkali carbonate in DMF led to carbohydrate-linked aza-macrocycles displaying 14-, 17-, 18-, 21-, 24-, and 25-membered ring structures. Isomeric aza-macrocylic coronands of 20- as well as 30-membered ring size containing two saccharides could be obtained employing Richman-Atkins condensations of two functionalized sugar building units.

  1. Kinetics of oxidation of nickel(II) aza macrocycles by peroxydisulphate in aqueous media

    J Lalitham; V R Vijayaraghavan


    The kinetics of the oxidation of nickel (II) hexaaza and nickel (II) pentaaza macrocycles by the peroxydisulphate anion, S2O8 2-, were studied in aqueous media. Effect of H on reaction rate was also studied. The rate increases with increase of S2OO8 2- concentration. Rates are almost independent of acid between H 4 and 2, giving overall a relatively simple second-order rate law followed by oxidation within the ion pair solvent shell. Using rate = +1/2 d[Ni(L)3+]/dt = k[Ni(L)2+][S2O8 2-], oxidation rate constants were determined.

  2. Application of Calixarenes as Macrocyclic Ligands for Uranium(VI: A Review

    Katarzyna Kiegiel


    Full Text Available Calixarenes represent a well-known family of macrocyclic molecules with broad range of potential applications in chemical, analytical, and engineering materials fields. This paper covers the use of calixarenes as complexing agents for uranium(VI. The high effectiveness of calix[6]arenes in comparison to other calixarenes in uranium(VI separation process is also presented. Processes such as liquid-liquid extraction (LLE, liquid membrane (LM separation, and ion exchange are considered as potential fields for application of calixarenes as useful agents for binding UO22+ for effective separation from aqueous solutions containing other metal components.

  3. Efficient macrocyclization of U-turn preorganized peptidomimetics: the role of intramolecular H-bond and solvophobic effects.

    Becerril, Jorge; Bolte, Michael; Burguete, M Isabel; Galindo, Francisco; García-España, Enrique; Luis, Santiago V; Miravet, Juan F


    Simple peptidomimetic molecules derived from amino acids were reacted with meta- and para-bis(bromomethyl)benzene in acetonitrile to very efficiently yield macrocyclic structures. The cyclization reaction does not require high dilution techniques and seems to be insensitive to the size of the formed macrocycle. The analysis of data obtained by (1)H NMR, single-crystal X-ray diffraction, fluorescence measurements, and molecular mechanics indicate that folded conformations can preorganize the system for an efficient cyclization. The role played by intramolecular hydrogen-bonding and solvophobic effects in the presence of folded conformations is analyzed.

  4. Cyclooctane metathesis catalyzed by silica-supported tungsten pentamethyl [(ΞSiO)W(Me)5]: Distribution of macrocyclic alkanes

    Riache, Nassima


    Metathesis of cyclic alkanes catalyzed by the new surface complex [(ΞSiO)W(Me)5] affords a wide distribution of cyclic and macrocyclic alkanes. The major products with the formula CnH2n are the result of either a ring contraction or ring expansion of cyclooctane leading to lower unsubstituted cyclic alkanes (5≤n≤7) and to an unprecedented distribution of unsubstituted macrocyclic alkanes (12≤n≤40), respectively, identified by GC/MS and by NMR spectroscopies.

  5. Self-Assembly of a 1D Hydrogen-Bonded Polymer from a Hexamethyltetraaza Macrocyclic Nickel(II Complex and Isophthalic Acid

    In-Taek Lim


    Full Text Available The compound [Ni(L(isoph2][Ni(L]·8H2O (1; L = C-meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane; H2-isoph = isophthalic acid has been synthesized and structurally characterized. Complex 1 exhibits a geometrically symmetric core with a {4/6} coordination number set. The coordination environment around the Ni(1 ion is a distorted octahedron, while the geometry around the four-coordinate Ni(2 is depicted as square planar in 1D hydrogen-bonded infinite chain. The compound crystallizes in the triclinic system P-1 with a = 8.602(2, b = 10.684(7, c = 16.550(3 Å, a = 91.04(4, b = 94.09(2, g = 111.09(4°, V = 1413.9(10 Å3, Z = 1. The cyclic voltammogram of 1 undergoes one-electron wave corresponding to NiII/NiI process. The electronic spectra, electrochemical and TGA behavior of the complex are significantly affected by the nature of the hexamethyltetraaza macrocycle and the axial isoph2− ligand.

  6. High efficiency, narrow particle size distribution, sub-2 μm based macrocyclic glycopeptide chiral stationary phases in HPLC and SFC.

    Barhate, Chandan L; Wahab, M Farooq; Breitbach, Zachary S; Bell, David S; Armstrong, Daniel W


    State of the art chiral chromatography still employs 3-5 μm bonded or immobilized chiral selectors in 10-25 cm columns. With the availability of 1.9 μm narrow particle size distribution (NPSD) silica, it is now possible to make ever shorter, high efficiency columns practical for sub-minute chiral separations. Three macrocyclic glycopeptides (teicoplanin, teicoplanin aglycone, and vancomycin) were bonded onto 1.9 μm NPSD particles. Such packed columns had ∼80% lower backpressure as compared to polydisperse (PD) 1.7 μm silica materials when using the same mobile phase. The decreased backpressure allowed for diminution of frictional heating and allowed for the use of the 1.9 μm NPSD particle based columns at high flow rates. The 1.9 μm NPSD particle based columns showed up to 190,000 plates m(-1) for chiral molecules and 210,000 plates m(-1) for achiral probes. Representative enantiomeric separations are shown for wide classes of compounds, including different types of amino acids, β-blockers, and pharmaceutically important heterocyclic compounds such as oxazolidinones. Applications in three liquid chromatography modes, namely, reversed phase, polar organic mode and normal phase chiral separations were shown with resolution values ranging from 1.5 to 5.7. Additionally, the same columns were used with supercritical fluid chromatography (SFC) for ultrafast separations.

  7. Temperature effects on the rheological properties of current polyether and polysiloxane impression materials during setting.

    Berg, John C; Johnson, Glen H; Lepe, Xavier; Adán-Plaza, Sergio


    Rheological tests of elastomeric impression materials during setting have been most often conducted at room temperature rather than at intraoral temperature. Because temperature may affect properties and the setting kinetics, clinically relevant inferences may not be accurate with studies conducted at room temperature. The purpose of this study was to determine the viscoelastic properties of new low- and medium-viscosity elastomeric impression materials during setting at 33 degrees C and to evaluate the medium-viscosity materials at 3 additional temperatures. The impression materials investigated at 33 degrees C were 2 polyvinylsiloxanes (PVS) (Aquasil Deca and Aquasil LV) and 5 polyethers (PE) (Impregum Penta, Impregum Penta Soft H, Impregum Penta Soft L, Impregum Garant Soft L, and Permadyne Garant L). Three impression materials (Aquasil Deca, Impregum Penta, and Impregum Penta Soft H) were also investigated at 25 degrees, 29 degrees, and 37 degrees C. Time-dependent oscillatory rheometry was carried out on these materials (n=3) with a rheometer with a 25-mm diameter parallel plate cell. The storage modulus (G') and the loss tangent (tandelta) were determined as functions of time over a period from 0 seconds to 900 seconds, commencing 40 seconds after mixing. Induction time (t(ind)) or initial setting time and tandelta, the relative liquidlike behavior, were also computed. A single-factor analysis of variance (ANOVA) was used for the properties determined at 33 degrees C and a 2-factor ANOVA was used for the temperature studies, with hypothesis testing at alpha=.05. The G'(t) curves for all materials displayed the expected sigmoidal shape with time, with the solid-like behavior rising slowly, then more rapidly, and again slowly to final set. The initial setting time (t(ind)) was found to be approximately 2.8 minutes for the PVS materials and for Impregum Penta and Impregum Penta Soft H, but was significantly longer for the remaining 3 PE low viscosity materials

  8. Effect of cervical relining of acrylic resin copings on the accuracy of stone dies obtained using a polyether impression material

    André Tomazini Gomes de Sá


    Full Text Available The purpose of this study was to evaluate the accuracy of the respective dies after polyether elastomeric procedure in the presence or absence of cervical contact of the acrylic resin shell with the cervical region, establishing a comparison to dies obtained with stock trays. This study consisted of three groups with 10 specimens each: 1 acrylic copings without cervical contact, (cn; 2 acrylic copings with cervical contact (cc; 3 perforated stock tray, (st. The accuracy of the resulting dies was verified with the aid of a master crown, precisely fit to the master steel die. ANOVA test found statistically significant differences among groups (p<0.001. Tukey's test found that the smallest discrepancy occurred in group cn, followed by cc, while the st group presented the highest difference (cc x cn: p=0.007; st x cn: p<0.001; st x cc: p<0.001.

  9. Expression of the Foraging Gene Is Associated with Age Polyethism, Not Task Preference, in the Ant Cardiocondyla obscurior

    Oettler, Jan; Nachtigal, Anna-Lena; Schrader, Lukas


    One of the fundamental principles of social organization, age polyethism, describes behavioral maturation of workers leading to switches in task preference. Here we present a system that allows for studying division of labor (DOL) by taking advantage of the relative short life of Cardiocondyla obscurior workers and thereby the pace of behavioral transitions. By challenging same-age young and older age cohorts to de novo establish DOL into nurse and foraging tasks and by forcing nurses to precociously become foragers and vice versa we studied expression patterns of one of the best known candidates for social insect worker behavior, the foraging gene. Contrary to our expectations we found that foraging gene expression correlates with age, but not with the task foraging per se. This suggests that this nutrition-related gene, and the pathways it is embedded in, correlates with physiological changes over time and potentially primes, but not determines task preference of individual workers. PMID:26650238

  10. Rheological and electrical percolation in melt-processed poly(ether ether ketone)/multi-wall carbon nanotube composites

    Bangarusampath, D. S.; Ruckdäschel, Holger; Altstädt, Volker; Sandler, Jan K. W.; Garray, Didier; Shaffer, Milo S. P.


    Multi-wall carbon nanotubes were dispersed homogeneously throughout a poly(ether ether ketone) matrix by melt processing. The influence of nanotube content on both rheological and electrical properties was analysed. The dynamic storage modulus, G', shows a characteristic solid-like behavior above 1 wt% nanotubes. A sharp transition from an electrically insulating to a conductive composite was observed between 1 and 1.5 wt%. By applying a power-law relation, the rheological and electrical percolation thresholds were found to be 0.9 wt%, and 1.3 wt%, respectively. Considering this data, Guth's filler reinforcement theory provides a valuable estimation of the aspect ratio of the nanotubes after processing and indicates substantial length degradation during the dispersion process.

  11. Characterization of a poly(ether urethane)-based controlled release membrane system for delivery of ketoprofen

    Macocinschi, Doina; Filip, Daniela; Vlad, Stelian; Oprea, Ana Maria; Gafitanu, Carmen Anatolia


    A poly(ether urethane) based on polytetrahydrofuran containing hydroxypropyl cellulose for biomedical applications was tested for its biocompatibility. Ketoprofen was incorporated (3% and 6%) in the polyurethane matrix as an anti-inflammatory drug. Kinetic and drug release mechanisms were studied. The pore size and pore size distribution of the polyurethane membranes were investigated by scanning electron microscopy. Surface tension characteristics as well as moisture sorption properties such as diffusion coefficients and equilibrium moisture contents of the membrane material were studied. It was found that kinetics and release mechanisms are in function of medium pH, composition of polymer-drug system, pore morphology and pore size distribution. Prolonged nature of release of ketoprofen is assured by low amount of drug in polyurethane membrane and physiological pH.

  12. Expression of the Foraging Gene Is Associated with Age Polyethism, Not Task Preference, in the Ant Cardiocondyla obscurior.

    Oettler, Jan; Nachtigal, Anna-Lena; Schrader, Lukas


    One of the fundamental principles of social organization, age polyethism, describes behavioral maturation of workers leading to switches in task preference. Here we present a system that allows for studying division of labor (DOL) by taking advantage of the relative short life of Cardiocondyla obscurior workers and thereby the pace of behavioral transitions. By challenging same-age young and older age cohorts to de novo establish DOL into nurse and foraging tasks and by forcing nurses to precociously become foragers and vice versa we studied expression patterns of one of the best known candidates for social insect worker behavior, the foraging gene. Contrary to our expectations we found that foraging gene expression correlates with age, but not with the task foraging per se. This suggests that this nutrition-related gene, and the pathways it is embedded in, correlates with physiological changes over time and potentially primes, but not determines task preference of individual workers.

  13. Expression of the Foraging Gene Is Associated with Age Polyethism, Not Task Preference, in the Ant Cardiocondyla obscurior.

    Jan Oettler

    Full Text Available One of the fundamental principles of social organization, age polyethism, describes behavioral maturation of workers leading to switches in task preference. Here we present a system that allows for studying division of labor (DOL by taking advantage of the relative short life of Cardiocondyla obscurior workers and thereby the pace of behavioral transitions. By challenging same-age young and older age cohorts to de novo establish DOL into nurse and foraging tasks and by forcing nurses to precociously become foragers and vice versa we studied expression patterns of one of the best known candidates for social insect worker behavior, the foraging gene. Contrary to our expectations we found that foraging gene expression correlates with age, but not with the task foraging per se. This suggests that this nutrition-related gene, and the pathways it is embedded in, correlates with physiological changes over time and potentially primes, but not determines task preference of individual workers.

  14. Studies on microdomain structure in segmented polyether polyurethaneureas by positron annihilation lifetime and small—angle X—ray scattering

    YinChuan-Yuan; GuQing-Chao; 等


    The microdomain structure of segmented polyether polyurethaneureas is investigated by means of positron annihilation lifetime spectroscopy,small-angle X-ray scattering and differential scanning calorimetry.The experimental results show that the decrease in the domain volume and free volume results from the increase in the hard segment (polyurethaneurea segment)contents as the number-average molecular weight Mn of the soft segments (polyethylene glycol segments)is the same,and that the increase in domain volume and free volume result from the increase in the Mn of the soft segments when the hard segment content is the same or nearly the same.These results demonstrate that positron annihilation lifetime spectroscopy is a sensitive technique to probe the microdomain structure in polymers.

  15. Preparation of poly(ether ether ketone)-based polymer electrolytes for fuel cell membranes using grafting technique

    Hasegawa, Shin; Suzuki, Yasuyuki [Conducting Polymer Materials Group, Environment and Industrial Materials Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370 1292 (Japan); Maekawa, Yasunari [Conducting Polymer Materials Group, Environment and Industrial Materials Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370 1292 (Japan)], E-mail:


    Poly(ether ether ketone) (PEEK)-based polymer electrolyte membranes (PEMs) was successfully prepared by radiation grafting of a styrene monomer into PEEK films and the consequent selective sulfonation of the grafting chains in the film state. Using milder sulfonation, the sulfonation reactions proceeded at the grafted chains in preference to the phenylene rings of PEEK main chains; as a result, the grafted films could successfully transform to a PEM with conductivity of more than 0.1 S/cm. The ion exchange capacity (IEC) and conductivity of the grafted PEEK electrolyte membranes were controlled to the ranges of 1.2-2.9 mmol/g and 0.03-0.18 S/cm by changing the grafting degree. It should be noted that this is the first example of directly transforming super-engineering plastic films into a PEM using radiation grafting.

  16. A study on the microstructure of a nitrate ester plasticized polyether propellant dissolved in HCl and KOH solutions



    Full Text Available Understanding of how the properties and performance of nitrate ester plasticized polyether (NEPE propellants relate to microstructure is complicated by numerous components that have different characteristics. One approach to alleviating these complications is to observe a microstructure that has lost one or several components. This article examines the dissolution process, mass loss and change of the ion concentration of propellants in acid and alkali solutions. A scanning electron microscope was used to observe the dissolved residual of the propellants. The results revealed that the main constituents of NEPE propellant have different dissolving properties in solutions of HCl and KOH. By monitoring the dissolution process of NEPE propellant in HCl and KOH solutions, it was found that the microstructure of the propellant is generally compact and the polymer binder not only binds all the other components, but also protects the inner part of the propellant in solution.

  17. Response of Critical Speed to Different Macrocycle Phases during Linear Periodization on Young Swimmers

    João Bartholomeu NETO


    Full Text Available Sport training programs to young swimmers have to aggregate different physical stimulus to collaborate with overall physical development, which can lead to reach best results in competitions. Linear periodization seems to be a powerful tool that allow the organization of these stimulus. However, this model has been not studied. Regarding physical capacities, aerobic fitness is inversely related with fatigue and exercise performance. Although aerobic capacity evaluation used to be expensive, critical speed (CS is easy and non - expensive tool capable to make this measurement. Thus, the aim of this study was evaluate the effects of linear periodization in CS on well - trained young swimmers. Sixteen athletes (age: 14.06  1.22 years, height: 163.52  10.99 cm, weight: 57.4  12.7 kg, body mass index: 21.24  37; 7 ♀, were underwent to a linear macrocycle training with 23 weeks divided in four mesocycles: general endurance (i.e., 4 weeks, specific endurance (i.e., 8 weeks, competitive (i.e., 7 weeks and taper (i.e., 4 weeks. Results showed significantly improve on CS after competitive and taper mesocycle phases, which was composed by higher training intensity in comparison with other macrocycle phases. Therefore, the results of the present study indicate a collaboration of mesocycle intensity on the cumulative effects of linear periodization in CS improve on young swimmers.

  18. Tiered analytics for purity assessment of macrocyclic peptides in drug discovery: Analytical consideration and method development.

    Qian Cutrone, Jingfang Jenny; Huang, Xiaohua Stella; Kozlowski, Edward S; Bao, Ye; Wang, Yingzi; Poronsky, Christopher S; Drexler, Dieter M; Tymiak, Adrienne A


    Synthetic macrocyclic peptides with natural and unnatural amino acids have gained considerable attention from a number of pharmaceutical/biopharmaceutical companies in recent years as a promising approach to drug discovery, particularly for targets involving protein-protein or protein-peptide interactions. Analytical scientists charged with characterizing these leads face multiple challenges including dealing with a class of complex molecules with the potential for multiple isomers and variable charge states and no established standards for acceptable analytical characterization of materials used in drug discovery. In addition, due to the lack of intermediate purification during solid phase peptide synthesis, the final products usually contain a complex profile of impurities. In this paper, practical analytical strategies and methodologies were developed to address these challenges, including a tiered approach to assessing the purity of macrocyclic peptides at different stages of drug discovery. Our results also showed that successful progression and characterization of a new drug discovery modality benefited from active analytical engagement, focusing on fit-for-purpose analyses and leveraging a broad palette of analytical technologies and resources.

  19. Gold-catalyzed Synthesis of Pyridine Containing Macrocycles, Related to Porphyrin

    DYKER,Gerald; LIU,Jian-Hui; MERZ,Klaus


    @@ Porphyrins are very important substances used in a wide range of model systems in many areas, such as biomimic chemistry and material science. This kind of macrocycle generally consists of 5-membered ring to form a cyclic extended aromatic network. Recently much work have been done concerning the modification of porphyrins core structures, and many kinds of analogues have been recorded. One of the important aspects was the research of the porphyrinogen ligand.These macrocycles bear functional resemblance to certain kind of polydentate ligand, and provide a variety of tri-dimensional binding cavities for metal ions. In addition, some other kinds of analogues have been recorded, involving the introduction of a CH unit to replace one of the nitrogen atoms. We also notice the fact that pyridine is a very effective ligand, and it can coordinate with many kinds of metals. Based on these observations, we would like to design and synthesize a new porphyrinogen (5) analogue containing a NNNN core, two of the N atoms from pyrrole and the other two N from pyridine. Such core modifications may alter the electronic structure of the ring and provide variable cavity for metal coordination.

  20. A supramolecular ruthenium macrocycle with high catalytic activity for water oxidation that mechanistically mimics photosystem II

    Schulze, Marcus; Kunz, Valentin; Frischmann, Peter D.; Würthner, Frank


    Mimicking the ingenuity of nature and exploiting the billions of years over which natural selection has developed numerous effective biochemical conversions is one of the most successful strategies in a chemist's toolbox. However, an inability to replicate the elegance and efficiency of the oxygen-evolving complex of photosystem II (OEC-PSII) in its oxidation of water into O2 is a significant bottleneck in the development of a closed-loop sustainable energy cycle. Here, we present an artificial metallosupramolecular macrocycle that gathers three Ru(bda) centres (bda = 2,2‧-bipyridine-6,6‧-dicarboxylic acid) that catalyses water oxidation. The macrocyclic architecture accelerates the rate of water oxidation via a water nucleophilic attack mechanism, similar to the mechanism exhibited by OEC-PSII, and reaches remarkable catalytic turnover frequencies >100 s-1. Photo-driven water oxidation yields outstanding activity, even in the nM concentration regime, with a turnover number of >1,255 and turnover frequency of >13.1 s-1.

  1. Synthesis, characterization, and photoactivated DNA cleavage by copper (II)/cobalt (II) mediated macrocyclic complexes.

    Naik, H R Prakash; Naik, H S Bhojya; Aravinda, T; Lamani, D S


    We report the synthesis of new photonuclease consisting of two Co(II)/Cu(II) complexes of macrocyclic fused quinoline. Metal complexes are [MLX(2)], type where M = Co(II) (5), Cu(II) (6), and X = Cl, and are well characterized by elemental analysis, Fourier transform infrared spectroscopy, (1)H-NMR and electronic spectra. We have shown that photocleavage of plasmid DNA is markedly enhanced when this ligand is irradiated in the presence of Cu(II), and more so than that of cobalt. The chemistry of ternary and binary Co(II) complexes showing efficient light induced (360 nm) DNA cleavage activity is summarized. The role of the metal in photoinduced DNA cleavage reactions is explored by designing complex molecules having macrocyclic structure. The mechanistic pathways are found to be concentration dependent on Co(II)/Cu(II) complexes and the photoexcitation energy photoredox chemistry. Highly effective DNA cleavage ability of 6 is attributed to the effective cooperation of the metal moiety.

  2. Does a water-training macrocycle really create imbalances in swimmers' shoulder rotator muscles?

    Batalha, Nuno; Marmeleira, José; Garrido, Nuno; Silva, António J


    The continuous execution of swimming techniques may cause muscle imbalances in shoulder rotators leading to injury. However, there is a lack of published research studies on this topic. The aim of this study was to analyze the influence of a competitive swim period on the shoulder rotator-cuff balance in young swimmers. A randomized controlled pretest-posttest design was used, with two measurements performed during the first macrocycle of the swimming season (baseline and 16 weeks). Twenty-seven young male swimmers (experimental group) and 22 male students who were not involved in swim training (control group) with the same characteristics were evaluated. Peak torque of shoulder internal and external rotators was assessed. Concentric action at 1.04 rad s(-1) (3 repetitions) and 3.14 rad s(-1) (20 repetitions) was measured using an isokinetic dynamometer (Biodex System 3). External/internal rotators strength ratios were also obtained. For both protocols, there were significant training effects on internal rotator strength and external/internal rotator ratios (p ≤ .05). This trend was the same for both shoulders. Within-group analysis showed significant changes from baseline to 16 weeks for internal rotators strength and unilateral ratios of the experimental group. Swimmers' internal rotator strength levels increased significantly. In contrast, a significant decrease of the unilateral ratios was observed. Findings suggest that a competitive swim macrocycle leads to an increase in muscular imbalances in the shoulder rotators of young competitive swimmers. Swimming coaches should consider implementing a compensatory strength-training program.

  3. A comparison of the accuracy of polyether, polyvinyl siloxane, and plaster impressions for long-span implant-supported prostheses.

    Hoods-Moonsammy, Vyonne J; Owen, Peter; Howes, Dale G


    The purpose of this study was to compare the capacity of different impression materials to accurately reproduce the positions of five implant analogs on a master model by comparing the resulting cast with the stainless steel master model. The study was motivated by the knowledge that distortions can occur during impression making and the pouring of casts and that this distortion may produce inaccuracies of subsequent restorations, especially long-span castings for implant superstructures. The master model was a stainless steel model with five implant analogs. The impression materials used were impression plaster (Plastogum, Harry J Bosworth), a polyether (Impregum Penta, 3M ESPE), and two polyvinyl siloxane (PVS) materials (Aquasil Monophase and Aquasil putty with light-body wash, Dentsply). Five impressions were made with each impression material and cast in die stone under strictly controlled laboratory conditions. The positions of the implants on the master model, the impression copings, and the implant analogs in the subsequent casts were measured using a coordinate measuring machine that measures within 4 μm of accuracy. Statistical analyses indicated that distortion occurred in all of the impression materials, but inconsistently. The PVS monophase material reproduced the master model most accurately. Although there was no significant distortion between the impressions and the master model or between the impressions and their casts, there were distortions between the master model and the master casts, which highlighted the cumulative effects of the distortions. The polyether material proved to be the most reliable in terms of predictability. The impression plaster displayed cumulative distortion, and the PVS putty with light body showed the least reliability. Some of the distortions observed are of clinical significance and likely to contribute to a lack of passive fit of any superstructure. The inaccuracy of these analog materials and procedures suggested

  4. Expression patterns of a circadian clock gene are associated with age-related polyethism in harvester ants, Pogonomyrmex occidentalis

    Ingram Krista K


    Full Text Available Abstract Background Recent advances in sociogenomics allow for comparative analyses of molecular mechanisms regulating the development of social behavior. In eusocial insects, one key aspect of their sociality, the division of labor, has received the most attention. Age-related polyethism, a derived form of division of labor in ants and bees where colony tasks are allocated among distinct behavioral phenotypes, has traditionally been assumed to be a product of convergent evolution. Previous work has shown that the circadian clock is associated with the development of behavior and division of labor in honeybee societies. We cloned the ortholog of the clock gene, period, from a harvester ant (Pogonomyrmex occidentalis and examined circadian rhythms and daily activity patterns in a species that represents an evolutionary origin of eusociality independent of the honeybee. Results Using real time qPCR analyses, we determined that harvester ants have a daily cyclic expression of period and this rhythm is endogenous (free-running under dark-dark conditions. Cyclic expression of period is task-specific; foragers have strong daily fluctuations but nest workers inside the nest do not. These patterns correspond to differences in behavior as activity levels of foragers show a diurnal pattern while nest workers tend to exhibit continuous locomotor activity at lower levels. In addition, we found that foragers collected in the early fall (relative warm, long days exhibit a delay in the nightly peak of period expression relative to foragers collected in the early spring (relative cold, short days. Conclusion The association of period mRNA expression levels with harvester ant task behaviors suggests that the development of circadian rhythms is associated with the behavioral development of ants. Thus, the circadian clock pathway may represent a conserved 'genetic toolkit' that has facilitated the parallel evolution of age-related polyethism and task allocation in

  5. Supramolecular polymers constructed from macrocycle-based host-guest molecular recognition motifs.

    Dong, Shengyi; Zheng, Bo; Wang, Feng; Huang, Feihe


    /physical properties, including stimuli responsiveness, self-healing, and environmental adaptation. It has been reported that macrocycle-based supramolecular polymers can respond to pH change, photoirradition, anions, cations, temperature, and solvent. Macrocycle-based supramolecular polymers have been prepared in solution, in gel, and in the solid state. Furthermore, the solvent has a very important influence on the formation of these supramolecular polymers. Crown ether- and pillararene-based supramolecular polymers have mainly formed in organic solvents, such as chloroform, acetone, and acetonitrile, while cyclodextrin- and cucurbituril-based supramolecular polymerizations have been usually observed in aqueous solutions. For calixarenes, both organic solvents and water have been used as suitable media for supramolecular polymerization. With the development of supramolecular chemistry and polymer science, various methods, such as nuclear magnetic resonance spectroscopy, X-ray techniques, electron microscopies, and theoretical calculation and computer simulation, have been applied for characterizing supramolecular polymers. The fabrication of macrocycle-based supramolecular polymers has become a currently hot research topic. In this Account, we summarize recent results in the investigation of supramolecular polymers constructed from macrocycle-based host-guest molecular recognition motifs. These supramolecular polymers are classified based on the different macrocycles used in them. Their monomer design, structure control, stimuli-responsiveness, and applications in various areas are discussed, and future research directions are proposed. It is expected that the development of supramolecular polymers will not only change the way we live and work but also exert significant influence on scientific research.

  6. Diverse organo-peptide macrocycles via a fast and catalyst-free oxime/intein-mediated dual ligation.

    Satyanarayana, Maragani; Vitali, Francesca; Frost, John R; Fasan, Rudi


    Macrocyclic Organo-Peptide Hybrids (MOrPHs) can be prepared from genetically encoded polypeptides via a chemoselective and catalyst-free reaction between a trifunctional oxyamino/amino-thiol synthetic precursor and an intein-fusion protein incorporating a bioorthogonal keto group.

  7. The role of macrocyclic ligands in the peroxo/superoxo nature of Ni-O2 biomimetic complexes.

    Zapata-Rivera, Jhon; Caballol, Rosa; Calzado, Carmen J


    The impact of the macrocyclic ligand on the electronic structure of two LNi-O2 biomimetic adducts, [Ni(12-TMC)O2](+) (12-TMC = 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane) and [Ni(14-TMC)O2](+) (14-TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), has been inspected by means of difference-dedicated configuration interaction calculations and a valence bond reading of the wavefunction. The system containing the 12-membered macrocyclic ligand has been experimentally described as a side-on nickel(III)-peroxo complex, whereas the 14-membered one has been characterized as an end-on nickel(II)-superoxide. Our results put in evidence the relationship between the steric effect of the macrocyclic ligand, the O2 coordination mode and the charge transfer extent between the Ni center and the O2 molecule. The 12-membered macrocyclic ligand favors a side-on coordination, a most efficient overlap between Ni 3d and O2 π* orbitals and, consequently, a larger charge transfer from LNi fragment to O2 molecule. The analysis of the ground-state electronic structure shows an enhancement of the peroxide nature of the Ni-O2 interaction for [Ni(12-TMC)O2](+), although a dominant superoxide character is found for both systems.

  8. Isonitrile iron(II) complexes with chiral N2P2 macrocycles in the enantioselective transfer hydrogenation of ketones.

    Bigler, Raphael; Mezzetti, Antonio


    Bis(isonitrile) iron(II) complexes bearing a C2-symmetric N2P2 macrocyclic ligand, which are easily prepared from the corresponding bis(acetonitrile) analogue, catalyze the asymmetric transfer hydrogenation (ATH) of a broad scope of ketones in excellent yields (up to 98%) and with high enantioselectivity (up to 91% ee).

  9. Thermodynamics of the sorption of organic compounds on polyethylene glycol 400-permethylated β-cyclodextrin stationary phase and its enantioselectivity in gas chromatography

    Kuraeva, Yu. G.; Onuchak, L. A.; Evdokimova, M. A.


    The thermodynamic characteristics of sorption of 24 organic compounds of various classes from the gas phase on the binary stationary phase based on polyethylene glycol 400 and permethylated β-cyclodextrin were determined. The influence of geometrical structure and optical activity of organic compounds on the possibility of forming sorbate-macrocycle complexes was examined. It was found that the studied stationary phase shows the enantioselectivity towards low-polar terpenes under the conditions of gas chromatography.

  10. Efficient access to new chemical space through flow--construction of druglike macrocycles through copper-surface-catalyzed azide-alkyne cycloaddition reactions.

    Bogdan, Andrew R; James, Keith


    A series of 12- to 22-membered macrocycles, with druglike functionality and properties, have been generated by using a simple and efficient copper-catalyzed azide-acetylene cycloaddition reaction, conducted in flow in high-temperature copper tubing, under environmentally friendly conditions. The triazole-containing macrocycles have been generated in up to 90 % yield in a 5 min reaction, without resorting to the high-dilution conditions typical of macrocyclization reactions. This approach represents a very efficient method for constructing this important class of molecules, in terms of yield, concentration, and environmental considerations.

  11. A Macrocyclic 1,4-Diketone Enables the Synthesis of a p-Phenylene Ring That Is More Strained than a Monomer Unit of [4]Cycloparaphenylene.

    Mitra, Nirmal K; Corzo, Hector H; Merner, Bradley L


    The synthesis of a p-terphenyl-based macrocycle, containing a p-phenylene unit with 42.6 kcal/mol of strain energy (SE), is reported. The conversion of a macrocyclic 1,4-diketone to a highly strained arene system takes place over five synthetic steps, featuring iterative dehydrative reactions in the aromatization protocol. Spectroscopic data of the deformed benzenoid macrocycle are in excellent agreement with other homologues that have been reported, indicating that the central p-phenylene ring of 9 is aromatic.

  12. Water encapsulation in a polyoxapolyaza macrobicyclic compound.

    Mateus, Pedro; Delgado, Rita; Groves, Patrick; Campos, Sara R R; Baptista, António M; Brandão, Paula; Félix, Vítor


    A new heteroditopic macrobicyclic compound (t(2)pN(5)O(3)) containing two separate polyoxa and polyaza compartments was synthesized in good yield through a [1 + 1] "tripod-tripod coupling" strategy. The X-ray crystal structure of H(3)t(2)pN(5)O(3)(3+) revealed the presence of one encapsulated water molecule accepting two hydrogen bonds from two protonated secondary amines and donating a hydrogen bond to one amino group. The acid-base behavior of the compound was studied by potentiometry at 298.2 K in aqueous solution and at ionic strength 0.10 M in KCl. The results revealed unusual protonation behavior, namely a surprisingly low fourth protonation constant contrary to what was expected for the compound. (1)H NMR and DOSY experiments, as well as molecular modeling studies, showed that the water encapsulation and the conformation observed in the solid state are retained in solution. The strong binding of the encapsulated water molecule, reinforced by the cooperative occurrence of a trifurcated hydrogen bond at the polyether compartment of the macrobicycle, account for the very low log K(4)(H) value obtained.

  13. Kinetics and mechanism of the stepwise complex formation of Cu(II) with tren-centered tris-macrocycles.

    Soibinet, Matthieu; Gusmeroli, Deborah; Siegfried, Liselotte; Kaden, Thomas A; Palivan, Cornelia; Schweiger, Arthur


    The stepwise complexation kinetics of Cu2+ with three tetratopic ligands L1, L2 and L3, tren-centred macrocycles with different bridges connecting the 14-membered macrocycles with the tren unit, have been measured by stopped-flow photodiode array techniques at 25 degrees C, I= 0.5 M (KNO3), and pH = 4.96. The reaction between the first Cu2+ and the ligand consists of several steps. In a rapid reaction Cu2+ first binds to the flexible and more reactive tren-unit. In this intermediate a translocation from the tren unit to the macrocyclic ring, which forms the thermodynamic more stable complex, takes place. This species can react further with a second Cu2+ to give a heterotopic dinuclear species with one Cu2+ bound by the tren-unit and the other coordinated by the macrocycle. A further translocation occurs to give the homoditopic species with two Cu2+ in the macrocycles. Finally a slow rearrangement of the dinuclear complex gives the final species. The rates of the translocation are dependent on the length and rigidity of the bridge, whereas the complexation rates with the tren unit are little affected by it. VIS spectra of the species obtained by fitting the kinetic results, EPR-spectra taken during the reaction, and ES mass spectra of the products confirm the proposed mechanism. The addition of a second, third and fourth equivalent of Cu2+ proceeds in an analogous way, but is complicated by the fact that we start and end with a mixture of species. These steps were evaluated in a qualitative way only.

  14. "Carbo-aromaticity" and novel carbo-aromatic compounds.

    Cocq, Kévin; Lepetit, Christine; Maraval, Valérie; Chauvin, Remi


    While the concept of aromaticity is being more and more precisely delineated, the category of "aromatic compounds" is being more and more expanded. This is illustrated by an introductory highlight of the various types of "aromaticity" previously invoked, and by a focus on the recently proposed "aromatic character" of the "two-membered rings" of the acetylene and butatriene molecules. This serves as a general foundation for the definition of "carbo-aromaticity", the relevance of which is surveyed through recent results in the synthetic, physical, and theoretical chemistry of carbo-mers and in particular macrocyclic-polycyclic representatives constituting a natural family of "novel aromatic compounds". With respect to their parent molecules, carbo-mers are constitutionally defined as "carbon-enriched", and can also be functionally regarded as "π-electron-enriched". This is exemplified by recent experimental and theoretical results on functional, aromatic, rigid, σ,π-macrocyclic carbo-benzene archetypes of various substitution patterns, with emphasis on the quadrupolar pattern. For the purpose of comparison, several types of non-aromatic references of carbo-benzenes are then considered, i.e. freely rotating σ,π-acyclic carbo-n-butadienes and flexible σ-cyclic, π-acyclic carbo-cyclohexadienes, and to "pro-aromatic" congeners, i.e. rigid σ,π-macrocyclic carbo-quinoids. It is shown that functional carbo-mers are entering the field of "molecular materials" for properties such as linear or nonlinear optical properties (e.g. dichromism and two-photon absorption) and single molecule conductivity. Since total or partial carbo-mers of aromatic carbon-allotropes of infinite size such as graphene (graphynes and graphdiynes) and graphite ("graphitynes") have long been addressed at the theoretical or conceptual level, recent predictive advances on the electrical, optical and mechanical properties of such carbo-materials are surveyed. Very preliminary experimental results

  15. Synthesis and characterization of polyether urethane acrylate -LiCF{sub 3}SO{sub 3}-based polymer electrolytes by UV-curing in lithium batteries

    Kim, Cheon Soo; Kim, Bo Hyun; Kim, Keon [Korea Univ., Seoul (Korea). Dept. of Chemistry


    The prepolymers of polyether urethane acrylate (PEUA) were synthesized from polyether polyol (polyethylene glycol (PEG) or polypropylene glycol (PPG)), diisocyanate (hexamethylene diisocyanate (HMDI) or toluene, 2,4-diisocyanate (TDI)), and the caprolactone-modified hydroxyethyl acrylate (FA2D) using the catalyst (dibutyltin dilaurate (DBTDL)) by stepwise addition reaction. Lithium triflate (LiCF{sub 3}SO{sub 3}) was dissolved in PEUA prepolymers, and plasticizer (propylene carbonate (PC)) was added into prepolymer and salt mixtures. Then photoinitiator (Irgacure 184) was also dissolved in the mixtures. Thin films were prepared by casting on the glass plate, and then by curing the plasticized prepolymer and salt mixtures under UV radiation. Electrochemical and electrical properties of PEUA-LiCF{sub 3}SO{sub 3}-based polymer electrolytes were evaluated and discussed to be used in lithium batteries. (orig.)

  16. Synthesis and characterization of polyether urethane acrylate-LiCF 3SO 3-based polymer electrolytes by UV-curing in lithium batteries

    Kim, Cheon-Soo; Kim, Bo-Hyun; Kim, Keon

    The prepolymers of polyether urethane acrylate (PEUA) were synthesized from polyether polyol (polyethylene glycol (PEG) or polypropylene glycol (PPG)), diisocyanate (hexamethylene diisocyanate (HMDI) or toluene 2,4-diisocyanate (TDI)), and the caprolactone-modified hydroxyethyl acrylate (FA2D) using the catalyst (dibutyltin dilaurate (DBTDL)) by stepwise addition reaction. Lithium triflate (LiCF 3SO 3) was dissolved in PEUA prepolymers, and plasticizer (propylene carbonate (PC)) was added into prepolymer and salt mixtures. Then photoinitiator (Irgacure 184) was also dissolved in the mixtures. Thin films were prepared by casting on the glass plate, and then by curing the plasticized prepolymer and salt mixtures under UV radiation. Electrochemical and electrical properties of PEUA-LiCF 3SO 3-based polymer electrolytes were evaluated and discussed to be used in lithium batteries.

  17. Evaluation of surface detail reproduction, dimensional stability and gypsum compatibility of monophase polyvinyl-siloxane and polyether elastomeric impression materials under dry and moist conditions

    Vadapalli, Sriharsha Babu; Atluri, Kaleswararao; Putcha, Madhu Sudhan; Kondreddi, Sirisha; Kumar, N. Suman; Tadi, Durga Prasad


    Objectives: This in vitro study was designed to compare polyvinyl-siloxane (PVS) monophase and polyether (PE) monophase materials under dry and moist conditions for properties such as surface detail reproduction, dimensional stability, and gypsum compatibility. Materials and Methods: Surface detail reproduction was evaluated using two criteria. Dimensional stability was evaluated according to American Dental Association (ADA) specification no. 19. Gypsum compatibility was assessed by two crit...

  18. Discovery of a Highly Potent, Cell-Permeable Macrocyclic Peptidomimetic (MM-589) Targeting the WD Repeat Domain 5 Protein (WDR5)–Mixed Lineage Leukemia (MLL) Protein–Protein Interaction

    Karatas, Hacer; Li, Yangbing; Liu, Liu; Ji, Jiao; Lee, Shirley; Chen, Yong; Yang, Jiuling; Huang, Liyue; Bernard, Denzil; Xu, Jing; Townsend, Elizabeth C.; Cao, Fang; Ran, Xu; Li, Xiaoqin; Wen, Bo; Sun, Duxin; Stuckey, Jeanne A; Lei, Ming; Dou, Yali; Wang, Shaomeng (Michigan)


    We report herein the design, synthesis, and evaluation of macrocyclic peptidomimetics that bind to WD repeat domain 5 (WDR5) and block the WDR5–mixed lineage leukemia (MLL) protein–protein interaction. Compound 18 (MM-589) binds to WDR5 with an IC50 value of 0.90 nM (Ki value <1 nM) and inhibits the MLL H3K4 methyltransferase (HMT) activity with an IC50 value of 12.7 nM. Compound 18 potently and selectively inhibits cell growth in human leukemia cell lines harboring MLL translocations and is >40 times better than the previously reported compound MM-401. Cocrystal structures of 16 and 18 complexed with WDR5 provide structural basis for their high affinity binding to WDR5. Additionally, we have developed and optimized a new AlphaLISA-based MLL HMT functional assay to facilitate the functional evaluation of these designed compounds. Compound 18 represents the most potent inhibitor of the WDR5–MLL interaction reported to date, and further optimization of 18 may yield a new therapy for acute leukemia.

  19. One-Dimensional Hydrogen-Bonded Infinite Chain from Nickel(II Tetraaza Macrocyclic Complex and 1,2-Cyclopentanedicarboxylate Ligand

    Ki-Young Choi


    Full Text Available The reaction of [Ni(L]Cl2·2H2O (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo [14,4,01.18,07.12]docosane with trans-1,2-cyclopentanedicarboxylic acid (H2-cpdc yields a 1D hydrogen-bonded infinite chain with formula [Ni(L(H-cpdc-2] (1. This complex has been characterized by X-ray crystallography, spectroscopy and cyclic voltammetry. The crystal structure of 1 exhibits a distorted octahedral geometry about Ni atom with four nitrogen atoms of the macrocycle and two oxygen atoms of the H-cpdc- ligand at the axial position. Compound 1 crystallizes in the monoclinic system P21/c with a = 8.7429(17, b = 10.488(2, c = 18.929(4 Å, β = 91.82(2, V = 1734.8(6 Å3, Z = 2. Electronic spectrum of 1 reveals a high-spin octahedral environment. Cyclic voltammetry of 1 undergoes two waves of a one-electron transfer corresponding to NiII/NiIII and NiII/NiI processes.

  20. The macrocyclic peptide antibiotic micrococcin P(1) is secreted by the food-borne bacterium Staphylococcus equorum WS 2733 and inhibits Listeria monocytogenes on soft cheese.

    Carnio, M C; Höltzel, A; Rudolf, M; Henle, T; Jung, G; Scherer, S


    Staphylococcus equorum WS 2733 was found to produce a substance exhibiting a bacteriostatic effect on a variety of gram-positive bacteria. The metabolite was purified to homogeneity by ammonium sulfate precipitation and semipreparative reversed-phase high-performance liquid chromatography. Electrospray mass spectrometry confirmed the high purity of the compound and revealed a molecular mass of 1,143 Da. By two-dimensional nuclear magnetic resonance spectroscopy the substance was identified as micrococcin P(1) which is a macrocyclic peptide antibiotic that has not yet been reported for the genus Staphylococcus. A total of 95 out of 95 Listeria strains and 130 out of 135 other gram-positive bacteria were inhibited by this substance, while none of 37 gram-negative bacteria were affected. The antilisterial potential of this food-grade strain as a protective starter culture was evaluated by its in situ application in cheese-ripening experiments under laboratory conditions. A remarkable growth reduction of Listeria monocytogenes could be achieved compared to control cheese ripened with a nonbacteriocinogenic type strain of Staphylococcus equorum. In order to prove that inhibition was due to micrococcin P(1), a micrococcin-deficient mutant was constructed which did not inhibit L. monocytogenes in cheese-ripening experiments.

  1. The Macrocyclic Peptide Antibiotic Micrococcin P1 Is Secreted by the Food-Borne Bacterium Staphylococcus equorum WS 2733 and Inhibits Listeria monocytogenes on Soft Cheese

    Carnio, Markus C.; Höltzel, Alexandra; Rudolf, Melanie; Henle, Thomas; Jung, Günther; Scherer, Siegfried


    Staphylococcus equorum WS 2733 was found to produce a substance exhibiting a bacteriostatic effect on a variety of gram-positive bacteria. The metabolite was purified to homogeneity by ammonium sulfate precipitation and semipreparative reversed-phase high-performance liquid chromatography. Electrospray mass spectrometry confirmed the high purity of the compound and revealed a molecular mass of 1,143 Da. By two-dimensional nuclear magnetic resonance spectroscopy the substance was identified as micrococcin P1 which is a macrocyclic peptide antibiotic that has not yet been reported for the genus Staphylococcus. A total of 95 out of 95 Listeria strains and 130 out of 135 other gram-positive bacteria were inhibited by this substance, while none of 37 gram-negative bacteria were affected. The antilisterial potential of this food-grade strain as a protective starter culture was evaluated by its in situ application in cheese-ripening experiments under laboratory conditions. A remarkable growth reduction of Listeria monocytogenes could be achieved compared to control cheese ripened with a nonbacteriocinogenic type strain of Staphylococcus equorum. In order to prove that inhibition was due to micrococcin P1, a micrococcin-deficient mutant was constructed which did not inhibit L. monocytogenes in cheese-ripening experiments. PMID:10831414

  2. Blue copper protein analogue: synthesis and characterization of copper complexes of the N2S2 macrocycle 1,8-dithia-4,11-diazacyclotetradecane.

    Walker, Tia L; Mula, Sam; Malasi, Wilhelm; Engle, James T; Ziegler, Christopher J; van der Est, Art; Modarelli, Jody; Taschner, Michael J


    To improve understanding of copper at the active site of Type 1 copper proteins, Cu(I) and Cu(II) complexes of 1,8-dithia-4,11-diazacyclotetradecane, shown in , have been successfully isolated and structurally characterized by X-ray crystallography. In these compounds, both Cu(I) and Cu(II) are centered in the plane of the macrocycle containing two sulphur and two nitrogen heteroatoms comprising the distorted tetrahedral/square planar coordination geometry. The UV/VIS spectra, electrochemistry and EPR properties have been obtained for the Cu(II) complex 2. Three absorption bands at 295 nm, 354 nm, and 545 nm are observed in aqueous solution at a pH of 5. These bands have been assigned to the N → Cu(II) and S → Cu(II) charge transfer bands and the d-d transitions respectively. The Cu(I/II) redox midpoint potential of complex 2 in CH3CN is +403 mV versus NHE.

  3. Total synthesis and biological evaluation of a series of macrocyclic hybrids and analogues of the antimitotic natural products dictyostatin, discodermolide, and taxol.

    Paterson, Ian; Naylor, Guy J; Gardner, Nicola M; Guzmán, Esther; Wright, Amy E


    The design, synthesis, and biological evaluation of a series of hybrids and analogues of the microtubule-stabilizing anticancer agents dictyostatin, discodermolide, and taxol is described. A 22-membered macrolide scaffold was prepared by adapting earlier synthetic routes directed towards dictyostatin and discodermolide, taking advantage of the distinctive structural and stereochemical similarities between these two polyketide-derived marine natural products. Initial endeavors towards accessing novel discodermolide/dictyostatin hybrids led to the adoption of a late-stage diversification strategy and the construction of a small library of methyl-ether derivatives, along with the first triple hybrids bearing the side-chain of taxol or taxotere attached through an ester linkage. Biological assays of the anti-proliferative activity of these compounds in a series of human cancer cell lines, including the taxol-resistant NCI/ADR-Res cell line, allowed the proposal of various structure-activity relationships. This led to the identification of a potent macrocyclic discodermolide/dictyostatin hybrid 12 and its C9 methoxy derivative 38, accessible by an efficient total synthesis and with a similar biological profile to dictyostatin.


    Ethiop.,3(1), 17-24 (1 939), ... Binucleating copper(II) and cobaltilll complexes of the ligand,. 4,16,20 ... to serve as simple model for multi-metal centered catalysts. ... catalysis in the four electron reduction of dioxygen to water (11,12).

  5. Metal-macrocycle framework (MMF): supramolecular nano-channel surfaces with shape sorting capability.

    Tashiro, Shohei; Kubota, Ryou; Shionoya, Mitsuhiko


    Hollow nanostructures for the functional assembly of chemical groups with inner surface geometry and regulable stoichiometry enable steric design of interior reaction centers. Herein we report a metal-macrocycle framework (MMF) that forms single-crystalline nanochannels with five distinct enantiomeric pairs of guest binding pockets. During crystal-soaking experiments, the MMF crystals can encapsulate aromatic molecules with high site selectivity. First, constitutional isomers of dibromobenzene are captured and sorted into different binding pockets. Second, each of the optical isomers of (1R/1S)-1-(3-chlorophenyl)ethanol is included diastereoselectively into one of an enantiomeric pair of binding pockets. An advantage of this strategy is that the interior walls can be "repainted" via replacement of the trapped molecules with alternatives. Such guest uptake behaviors would allow highly regioselective or stereoselective reactions within the nanochannel.

  6. Strontium-selective membrane electrodes based on some recently synthesized benzo-substituted macrocyclic diamides.

    Shamsipur, M; Rouhani, S; Sharghi, H; Ganjali, M R; Eshghi, H


    Eight different recently synthesized macrocyclic diamides were studied to characterize their abilities as strontium ion carriers in PVC membrane electrodes. The electrode based on 1,13-diaza-2,3;11,12-dibenzo-4,7,10-trioxacyclopentadecane-14,15-dione exhibits a Nernstian response for Sr(2+) ions over a wide concentration range (1.0 × 10(-)(1)-3.2 × 10(-)(5) M) with a limit of detection of 8.0 × 10(-)(6) M (0.7 ppm). The response time of the sensor is ∼10 s, and the membrane can be used for more than three months without observing any deviation. The electrode revealed comparatively good selectivities with respect to many alkali, alkaline earth, and transition metal ions. It was used as an indicator electrode in potentiometric titration of carbonate ions with a strontium ion solution.

  7. Cobalt(II)-selective membrane electrode based on a recently synthesized benzo-substituted macrocyclic diamide.

    Shamsipur, M; Poursaberi, T; Rouhani, S; Niknam, K; Sharghi, H; Ganjali, M R


    A PVC-membrane electrode based on a recently synthesized 18-membered macrocyclic diamide is presented. The electrode reveals a Nernstian potentiometric response for Co2+ over a wide concentration range (2.0 x 10(-6)-1.0 x 10(-2) M). The electrode has a response time of about 10 s and can be used for at least 2 months without any divergence. The proposed sensor revealed very good selectivities for Co2+ over a wide variety of other metal ions, and could be used over a wide pH range (3.0-8.0). The detection limit of the sensor is 6.0 x 10(-7) M. It was successfully applied to the direct determination and potentiometric titration of cobalt ion.

  8. Tetranuclear manganese(II) complexes of sulfonylcalix[4]arene macrocycles: synthesis, structure, spectroscopic and magnetic properties.

    Lamouchi, Meriem; Jeanneau, Erwann; Pillonnet, Anne; Brioude, Arnaud; Martini, Matteo; Stéphan, Olivier; Meganem, Faouzi; Novitchi, Ghenadie; Luneau, Dominique; Desroches, Cédric


    Two tetranuclear manganese(II) complexes {K(+)[Mn(4)(ThiaSO(2))(2)(OH)](-)} (1) and {K(+)[Mn(4)(ThiaSO(2))(2)(F)](-)} (2) have been synthesized under solvothermal conditions in methanol with p-tert-butylsulfonylcalix[4]arene (ThiaSO(2)). For both complexes, the structure has been established from single-crystal X-ray diffraction. The two complexes are best described as manganese squares sandwiched between two thiacalixarene macrocycles. In both complexes, in the center of the square formed by the four manganese(II) atoms, the unexpected presence of μ(4)-OH(-) or μ(4)-F(-) gives a negative charge to the cluster. The two tetranuclear complexes exhibit strong orange luminescence behavior resulting from the symbiosis between the ThiaSO(2) and the Mn(2+). Despite similar chemical formulation, (1) and (2) present difference in emission intensity and lifetime τ.

  9. Synthesis of Macrocyclic Ionophore for the Development of Highly Selective Chloride Sensor

    Sameena Mehtab


    Full Text Available The macrocyclic ligands 3,8,12,17-tetramethyl-2,18,9,11-bipyridyl-1,4,7,10,13,16-hexaazacyclooctadecanetetrahydro bromide has been synthesized and explored as suitable ionophores for chloride selective membrane sensors. It displays Nernstian behavior (59.2 mV decade-1 across the range of 4.1 × 10-8 to 1.0 × 10-2 M. The detection limit of the electrode is ~ 15 nM and the response time and life times are 14 s and eight weeks respectively over a wide pH range (3.5 - 9.5. Interference from other anions is very low and it can be used as indicator electrode in the potentiometric titration of chloride ions and to determine chloride in agricultural soil water samples.

  10. Graphene supported non-precious metal-macrocycle catalysts for oxygen reduction reaction in fuel cells

    Choi, Hyun-Jung; Ashok Kumar, Nanjundan; Baek, Jong-Beom


    Fuel cells are promising alternative energy devices owing to their high efficiency and eco-friendliness. While platinum is generally used as a catalyst for the oxygen reduction reaction (ORR) in a typical fuel cell, limited reserves and prohibitively high costs limit its future use. The development of non-precious and durable metal catalysts is being constantly conceived. Graphene has been widely used as a substrate for metal catalysts due to its unique properties, thus improving stability and ORR activities. In this feature, we present an overview on the electrochemical characteristics of graphene supported non-precious metal containing macrocycle catalysts that include metal porphyrin and phthalocyanine derivatives. Suggested research and future development directions are discussed.

  11. Tunable photophysical processes of porphyrin macrocycles on the surface of ZnO nanoparticles

    Parida, Manas R.


    We investigated the impact of the molecular structure of cationic porphyrins on the degree of electrostatic interactions with zinc oxide nanoparticles (ZnO NPs) using steady-state and time-resolved fluorescence and transient absorption spectroscopy. Our results demonstrate that the number of cationic pyridinium units has a crucial impact on the photophysics of the porphyrin macrocycle. Fluorescence enhancement, relative to initial free porphyrin fluorescence, was found to be tuned from 3.4 to 1.3 times higher by reducing the number of cationic substituents on the porphyrin from 4 to 2. The resulting enhancement of the intensity of the fluorescence is attributed to the decrease in the intramolecular charge transfer (ICT) character between the porphyrin cavity and its meso substituent. The novel findings reported in this work provide an understanding of the key variables involved in nanoassembly, paving the way toward optimizing the interfacial chemistry of porphyrin-ZnO NP assembly for photodynamic therapy and energy conversion.

  12. HPLC Enantioseparation of Phenylcarbamic Acid Derivatives by Using Macrocyclic Chiral Stationary Phases

    Hroboňová Katarína


    Full Text Available The HPLC by using chiral stationary phases based on macrocyclic antibiotics, dimethylphenyl carbamate cyklofructan 7 and β-cyclodextrin in terms of polar-organic separation mode (mobile phase methanol/acetonitrile/acetic acid/triethylamine were used for enantioseparation of alkoxy derivatives of phenylcarbamic acid. The effect of the analyte structures on the efficiency of enantioseparation was investigated. The most suitable stationary phase was teicoplanin aglycone, where the separations of the enantiomers were obtained (the resolution value from 0.65 to 2.90, depending on the structure of the analyte. Significant effect on the resolution of the enantiomers has position of alkoxy substituent in the hydrophobic part of the molecule. The enantiorecognition was achieved for 3-alkoxysubstituted derivatives.

  13. Validation of a screening method for rapid control of macrocyclic lactone mycotoxins in maize flour samples.

    Zougagh, Mohammed; Téllez, Helena; Sánchez, Alberto; Chicharro, Manuel; Ríos, Angel


    A procedure for the analytical validation of a rapid supercritical fluid extraction amperometric screening method for controlling macrocyclic lactone mycotoxins in maize flour samples has been developed. The limit established by European legislation (0.2 mg kg(-1)), in reference to zearalenone (ZON) mycotoxin, was taken as the reference threshold to validate the proposed method. Natural ZON metabolites were also included in this study to characterize the final screening method. The objective was the reliable classification of samples as positive or negative samples. The cut-off level was fixed at a global concentration of mycotoxins of 0.17 mg kg(-1). An expanded unreliability zone between 0.16 and 0.23 mg kg(-1) characterized the screening method for classifying the samples. A set of 30 samples was used for the final demonstration of the reliability and usefulness of the method.

  14. The Crystal and Molecular Structure of a New Macrocyclic Ligand, (H6BDBPH)Br6·4H2O


    The hexahydro-bromide salt of a new 24-membered hexaaza diphenol macrocyclic ligand, (H6BDBPH)Br6·4H2O (C26H56N6O6Br6, M, = 1028.23), crystallizes in the monoclinic system, space group P21/c, with cell parameters: a = 14. 441(5), b=11.482(4), c=12.090(6)A, β=96.92°, V= 1990 (1)A3, Z=2, Dc=1. 716 g/cm3; F(000) = 1024. MoKa radiation, λ= 0. 71013A ), R = 0.0643 and wR = 0. 1356 for 3507 independent reflections with I > 2σ (I). The macrocyclic ligand adapts chair form, and the crystallographic inversion center is located in the macrocyclic cavity, and the six bromide ions and four water molecules are situated symmetrically outside the macrocyclic cavity.

  15. Diversity-oriented approach to macrocyclic cyclophane derivatives by Suzuki-Miyaura cross-coupling and olefin metathesis as key steps.

    Kotha, Sambasivarao; Chavan, Arjun S; Shaikh, Mobin


    Palladium-catalyzed Suzuki-Miyaura (SM) cross-coupling reaction with allylboronic acid pinacol ester and titanium assisted cross-metathesis (CM)/ring-closing metathesis (RCM) cascade has been used to synthesize macrocyclic cyclophane derivatives.

  16. Synthesis of a TREN in which the aryl substituents are part of a 45 atom macrocycle.

    Cain, Matthew F; Forrest, William P; Peryshkov, Dmitry V; Schrock, Richard R; Müller, Peter


    A substituted TREN has been prepared in which the aryl groups in (ArylNHCH2CH2)3N are substituted at the 3- and 5-positions with a total of six OCH2(CH2)nCH═CH2 groups (n = 1, 2, 3). Molybdenum nitride complexes, [(ArylNCH2CH2)3N]Mo(N), have been isolated as adducts that contain B(C6F5)3 bound to the nitride. Two of these [(ArylNCH2CH2)3N]Mo(NB(C6F5)3) complexes (n = 1 and 3) were crystallographically characterized. After removal of the borane from [(ArylNCH2CH2)3N]Mo(NB(C6F5)3) with PMe3, ring-closing olefin metathesis (RCM) was employed to join the aryl rings with OCH2(CH2)nCH═CH(CH2)nCH2O links (n = 1-3) between them. RCM worked best with a W(O)(CHCMe3)(Me2Pyr)(OHMT)(PMe2Ph) catalyst (OHMT = hexamethylterphenoxide, Me2Pyr = 2,5-dimethylpyrrolide) and n = 3. The macrocyclic ligand was removed from the metal through hydrolysis and isolated in 70-75% yields relative to the borane adducts. Crystallographic characterization showed that the macrocyclic TREN ligand in which n = 3 contains three cis double bonds. Hydrogenation produced a TREN in which the three links are saturated, i.e., O(CH2)10O.

  17. Virtual libraries of tetrapyrrole macrocycles. Combinatorics, isomers, product distributions, and data mining.

    Taniguchi, Masahiko; Du, Hai; Lindsey, Jonathan S


    A software program (PorphyrinViLiGe) has been developed to enumerate the type and relative amounts of substituted tetrapyrrole macrocycles in a virtual library formed by one of four different classes of reactions. The classes include (1) 4-fold reaction of n disubstituted heterocycles (e.g., pyrroles or diiminoisoindolines) to form β-substituted porphyrins, β-substituted tetraazaporphyrins, or α- or β-substituted phthalocyanines; (2) combination of m aminoketones and n diones to form m × n pyrroles, which upon 4-fold reaction give β-substituted porphyrins; (3) derivatization of an 8-point tetrapyrrole scaffold with n reagents, and (4) 4-fold reaction of n aldehydes and pyrrole to form meso-substituted porphyrins. The program accommodates variable ratios of reactants, reversible or irreversible reaction (reaction classes 1 and 2), and degenerate modes of formation. Pólya's theorem (for enumeration of cyclic entities) has also been implemented and provides validation for reaction classes 3 and 4. The output includes the number and identity of distinct reaction-accessible substituent combinations, the number and identity of isomers thereof, and the theoretical mass spectrum. Provisions for data mining enable assessment of the number of products having a chosen pattern of substituents. Examples include derivatization of an octa-substituted phthalocyanine with eight reagents to afford a library of 2,099,728 members (yet only 6435 distinct substituent combinations) and reversible reaction of six distinct disubstituted pyrroles to afford 2649 members (yet only 126 distinct substituent combinations). In general, libraries of substituted tetrapyrrole macrocycles occupy a synthetically accessible region of chemical space that is rich in isomers (>99% or 95% for the two examples, respectively).

  18. Macrocyclic nickel(II) complexes: Synthesis, characterization, superoxide scavenging activity and DNA-binding

    Ramadan, Abd El-Motaleb M.


    A new series of nickel(II) complexes with the tetraaza macrocyclic ligand have been synthesized as possible functional models for nickel-superoxide dismutase enzyme. The reaction of 5-amino-3-methyl-1-phenylpyrazole-4-carbaldehyde (AMPC) with itself in the presence of nickel(II) ion yields, the new macrocyclic cationic complex, [NiL(NO3)2], containing a ligand composed of the self-condensed AMPC (4 mol) bound to a single nickel(II) ion. A series of metathetical reactions have led to the isolation of a number of newly complexes of the types [NiL]X2; X = ClO4 and BF4, [NiLX2], X = Cl and Br (Scheme 1). Structures and characterizations of these complexes were achieved by several physicochemical methods namely, elemental analysis, magnetic moment, conductivity, and spectral (IR and UV-Vis) measurements. The electrochemical properties and thermal behaviors of these chelates were investigated by using cyclic voltammetry and thermogravimetric analysis (TGA and DTG) techniques. A distorted octahedral stereochemistry has been proposed for the six-coordinate nitrato, and halogeno complexes. For the four-coordinate, perchlorate and fluoroborate, complex species a square-planar geometry is proposed. The measured superoxide dismutase mimetic activities of the complexes indicated that they are potent NiSOD mimics and their activities are compared with those obtained previously for nickel(II) complexes. The probable mechanistic implications of the catalytic dismutation of O2rad - by the synthesized nickel(II) complexes are discussed. The DNA-binding properties of representative complexes [NiLCl2] and [NiL](PF4)2 have been investigated by the electronic absorption and fluorescence measurements. The results obtained suggest that these complexes bind to DNA via an intercalation binding mode and the binding affinity for DNA follows the order: [NiLCl2] □ [NiL](PF4)2.

  19. Macrocyclic beta-sheet peptides that mimic protein quaternary structure through intermolecular beta-sheet interactions.

    Khakshoor, Omid; Demeler, Borries; Nowick, James S


    This paper reports the design, synthesis, and characterization of a family of cyclic peptides that mimic protein quaternary structure through beta-sheet interactions. These peptides are 54-membered-ring macrocycles comprising an extended heptapeptide beta-strand, two Hao beta-strand mimics [JACS 2000, 122, 7654] joined by one additional alpha-amino acid, and two delta-linked ornithine beta-turn mimics [JACS 2003, 125, 876]. Peptide 3a, as the representative of these cyclic peptides, contains a heptapeptide sequence (TSFTYTS) adapted from the dimerization interface of protein NuG2 [PDB ID: 1mio]. 1H NMR studies of aqueous solutions of peptide 3a show a partially folded monomer in slow exchange with a strongly folded oligomer. NOE studies clearly show that the peptide self-associates through edge-to-edge beta-sheet dimerization. Pulsed-field gradient (PFG) NMR diffusion coefficient measurements and analytical ultracentrifugation (AUC) studies establish that the oligomer is a tetramer. Collectively, these experiments suggest a model in which cyclic peptide 3a oligomerizes to form a dimer of beta-sheet dimers. In this tetrameric beta-sheet sandwich, the macrocyclic peptide 3a is folded to form a beta-sheet, the beta-sheet is dimerized through edge-to-edge interactions, and this dimer is further dimerized through hydrophobic face-to-face interactions involving the Phe and Tyr groups. Further studies of peptides 3b-3n, which are homologues of peptide 3a with 1-6 variations in the heptapeptide sequence, elucidate the importance of the heptapeptide sequence in the folding and oligomerization of this family of cyclic peptides. Studies of peptides 3b-3g show that aromatic residues across from Hao improve folding of the peptide, while studies of peptides 3h-3n indicate that hydrophobic residues at positions R3 and R5 of the heptapeptide sequence are important in oligomerization.

  20. Peptide macrocycles featuring a backbone secondary amine: a convenient strategy for the synthesis of lipidated cyclic and bicyclic peptides on solid support.

    Oddo, Alberto; Münzker, Lena; Hansen, Paul R


    A convenient strategy for the on-resin synthesis of macrocyclic peptides (3- to 13-mers) via intramolecular halide substitution by a diamino acid is described. The method is compatible with standard Fmoc/tBu SPPS and affords a tail-to-side-chain macrocyclic peptide featuring an endocyclic secondary amine. This functional group is still reactive toward acylation, allowing for the continuation of the synthesis. An application to the synthesis of lipidated cyclic and bicyclic antimicrobial peptides is presented.

  1. 含氟聚醚多元醇的研究进展%The Research Progress of Fluorine-Containing Polyether Polyol

    张英强; 徐微; 李烨


    Compared with conventional hydroxyl-terminated polyethers, the fluorine-containing polyether polyols can be used to prepare polymers with better performances, such as water repellent and oil repellent, self-cleaning, self-lubricating, and resistant to heat, UV light, weathering, corrosion, chemical, solvent and so on. Therefore it has a wide range of potential applications and development prospects. In this article, preparation technical approaches and chemical structure features of fluorine-containing polyether polyols at home and abroad have been reviewed in detail. Research progresses on fluorine-containing polyether polyol used in polyurethane elastmers, coatings and other application areas are briefly introduced. It is pointed out that the main directions of fluorine-containing polyether polyols for the future research and development should focus on lowering products costs, developing green high performance technical process, simplifying preparation techniques, optimizing the process conditions, and developing new products.%与常规羟基聚醚相比,含氟聚醚多元醇可被用来制备具有耐热、耐UV光、耐候、耐腐蚀、耐化学品、耐溶剂、拒油拒水、自清洁、自润滑等优良性能的高分子,因此具有多种潜在应用领域和发展前景。本文综述了国内外含氟聚醚多元醇的制备技术途径、结构类型特点,并阐述了其在聚氨酯弹性体、涂料及其它应用领域的研究进展。指出降低成本、开发绿色高效的制备技术、简化工艺路线、优化工艺条件、研发新产品为未来发展含氟聚醚多元醇的主要研发方向。

  2. Surface modification of poly(ether ether ketone) with methacryloyl-functionalized phospholipid polymers via self-initiation graft polymerization.

    Kawasaki, Yoshihiro; Iwasaki, Yasuhiko


    To improve blood compatibility of poly(ether ether ketone) (PEEK), surface modification with methacryloyl-functionalized phospholipid polymers was performed through self-initiation graft polymerization. The copolymers (PMA) of 2-methacryloyloxyethyl phosphorylcholine (MPC) and 2-aminoethyl methacrylate hydrochloride were synthesized by conventional free radical polymerization. The PMA was then immobilized with pentafluorophenyl methacrylate to obtain methacryloyl-functionalized MPC polymers (PMAMA). The degree of substitution of the methacryloyl group into the copolymer was nearly completed. The PMAMA was dissolved in 1-butanol and the solution was dropped on PEEK. UV light (350±50 nm) was subsequently irradiated on PEEK for various periods. Elemental analysis of the PEEK surface was performed by X-ray photoelectron spectroscopy and phosphorus and nitrogen signals due to the MPC units on PEEK were observed. The surface wettability of PEEK was also improved by immobilization of PMAMA. Plasma protein adsorption was effectively reduced on the PMAMA-immobilized surface regardless of the type of protein. Furthermore, PMAMA immobilization was also useful in reducing platelet adhesion on PEEK. In conclusion, methacryloyl-functionalized MPC polymers could be immobilized on PEEK by simple photo-irradiation, resulting in significant improvement in blood compatibility.

  3. Highly stable ionic-covalent cross-linked sulfonated poly(ether ether ketone) for direct methanol fuel cells

    Lei, Linfeng; Zhu, Xingye; Xu, Jianfeng; Qian, Huidong; Zou, Zhiqing; Yang, Hui


    A novel ionic cross-linked sulfonated poly(ether ether ketone) containing equal content of sulfonic acid and pendant tertiary amine groups (TA-SPEEK) has been initially synthesized for the application in direct methanol fuel cells (DMFCs). By adjusting the ratio of p-xylene dibromide to tertiary amine groups of TA-SPEEK, a series of ionic-covalent cross-linked membranes (C-SPEEK-x) with tunable degree of cross-linking are prepared. Compared with the pristine membrane, the ionic and ionic-covalent cross-linked proton exchange membranes (PEMs) exhibit reduced methanol permeability and improved mechanical properties, dimensional and oxidative stability. The proton conductivity and methanol selectivity of protonated TA-SPEEK and C-SPEEK-x at 25 °C is up to 0.109 S cm-1 and 3.88 × 105 S s cm-3, respectively, which are higher than that of Nafion 115. The DMFC incorporating C-SPEEK-25 exhibits a maximum power density as high as 35.3 mW cm-2 with 4 M MeOH at 25 °C (31.8 mW cm-2 for Nafion 115). Due to the highly oxidative stability of the membrane, no obvious performance degradation of the DMFC is observed after more than 400 h operation, indicating such cost-effective ionic-covalent cross-linked membranes have substantial potential as alternative PEMs for DMFC applications.

  4. Macromolecular Engineering: New Routes Towards the Synthesis of Well-??Defined Polyethers/Polyesters Co/Terpolymers with Different Architectures

    Alamri, Haleema


    The primary objective of this research was to develop a new and efficient pathway for well-defined multicomponent homo/co/terpolymers of cyclic esters/ethers using an organocatalytic approach with an emphasis on the macromolecular engineering aspects of the overall synthesis. Macromolecular engineering (as discussed in the first chapter) of homo/copolymers refers to the specific tailoring of these materials for achieving an easy and reproducible synthesis that results in precise molecular characteristics, i.e. molecular weight and polydispersity, as well as specific structure and end?group choices. Precise control of these molecular characteristics will provide access to new materials that can be used for pre-targeted purposes such as biomedical applications. Among the most commonly used engineering materials are polyesters (biocompatible and biodegradable) and polyethers (biocompatible), either as homopolymers or when or copolymers with linear structures. The ability to create non-linear structures, for example stars, will open new horizons in the applications of these important polymeric materials. The second part of this thesis describes the synthesis of aliphatic polyesters, particularly polycaprolactone and polylactide, using a metal-free initiator/catalyst system. A phosphazene base (t?BuP2) was used as the catalyst for the ring-opening copolymerization of ?-aprolactone (??CL) and L,Lactide (LLA) at room temperature with a variety of protic initiators in different solvents. These studies provided important information for the design of a metal-free route toward the synthesis of polyester?based (bio) materials. The third part of the thesis describes a novel route for the one?pot synthesis of polyether-b polyester block copolymers with either a linear or a specific macromolecular architecture. Poly (styrene oxide)?b?poly(caprolactone)?b?poly(L,lactide) was prepared using this method with the goal of synthesizing poly(styrene oxide)-based materials since this

  5. Electrochemical investigation of sulfonated poly(ether ether ketone)/clay nanocomposite membranes for moderate temperature fuel cell applications

    Hasani-Sadrabadi, Mohammad Mahdi [Polymer Engineering Department, Amirkabir University of Technology, Tehran (Iran); Biomedical Engineering Department, Amirkabir University of Technology, Tehran (Iran); Dashtimoghadam, Erfan; Sarikhani, Kaveh [Polymer Engineering Department, Amirkabir University of Technology, Tehran (Iran); Majedi, Fatemeh S. [Biomedical Engineering Department, Amirkabir University of Technology, Tehran (Iran); Khanbabaei, Ghader [Polymer Science and Technology Division, Research Institute of Petroleum Industry, Tehran (Iran)


    In the present study, polyelectrolyte membranes based on partially sulfonated poly(ether ether ketone) (sPEEK) with various degrees of sulfonation are prepared. The optimum degree of sulfonation is determined according to the transport properties and hydrolytic stability of the membranes. Subsequently, various amounts of the organically modified montmorillonite (MMT) are introduced into the sPEEK matrices via the solution intercalation technique. The proton conductivity and methanol permeability measurements of the fabricated composite membranes reveal a high proton to methanol selectivity, even at elevated temperatures. Membrane based on sPEEK and 1 wt% of MMT, as the optimum nanoclay composition, exhibits a high selectivity and power density at the concentrated methanol feed. Moreover, it is found that the optimum nanocomposite membrane not only provides higher performance compared to the neat sPEEK and Nafion {sup registered} 117 membranes, but also exhibits a high open circuit voltage (OCV) at the elevated methanol concentration. Owing to the high proton conductivity, reduced methanol permeability, high power density, convenient processability and low cost, sPEEK/MMT nanocomposite membranes could be considered as the alternative membranes for moderate temperature direct methanol fuel cell applications. (author)

  6. Shape Memory Composites Based on Electrospun Poly(vinyl alcohol) Fibers and a Thermoplastic Polyether Block Amide Elastomer.

    Shirole, Anuja; Sapkota, Janak; Foster, E Johan; Weder, Christoph


    The present study aimed at developing new thermally responsive shape-memory composites, that were fabricated by compacting mats of electrospun poly(vinyl alcohol) (PVA) fibers and sheets of a thermoplastic polyether block amide elastomer (PEBA). This design was based on the expectation that the combination of the rubber elasticity of the PEBA matrix and the mechanical switching exploitable through the reversible glass transition temperature (Tg) of the PVA filler could be combined to create materials that display shape memory characteristics as an emergent effect. Dynamic mechanical analyses (DMA) show that, upon introduction of 10-20% w/w PVA fibers, the room-temperature storage modulus (E') increased by a factor of 4-5 in comparison to the neat PEBA, and they reveal a stepwise reduction of E' around the Tg of PVA (85 °C). This transition could indeed be utilized to fix a temporary shape and recover the permanent shape. At low strain, the fixity was 66 ± 14% and the recovery was 98 ± 2%. Overall, the data validate a simple and practical strategy for the fabrication of shape memory composites that involves a melt compaction process and employs two commercially available polymers.

  7. Friedel-Crafts Crosslinked Highly Sulfonated Polyether Ether Ketone (SPEEK) Membranes for a Vanadium/Air Redox Flow Battery.

    Merle, Géraldine; Ioana, Filipoi Carmen; Demco, Dan Eugen; Saakes, Michel; Hosseiny, Seyed Schwan


    Highly conductive and low vanadium permeable crosslinked sulfonated poly(ether ether ketone) (cSPEEK) membranes were prepared by electrophilic aromatic substitution for a Vanadium/Air Redox Flow Battery (Vanadium/Air-RFB) application. Membranes were synthesized from ethanol solution and crosslinked under different temperatures with 1,4-benzenedimethanol and ZnCl2 via the Friedel-Crafts crosslinking route. The crosslinking mechanism under different temperatures indicated two crosslinking pathways: (a) crosslinking on the sulfonic acid groups; and (b) crosslinking on the backbone. It was observed that membranes crosslinked at a temperature of 150 °C lead to low proton conductive membranes, whereas an increase in crosslinking temperature and time would lead to high proton conductive membranes. High temperature crosslinking also resulted in an increase in anisotropy and water diffusion. Furthermore, the membranes were investigated for a Vanadium/Air Redox Flow Battery application. Membranes crosslinked at 200 °C for 30 min with a molar ratio between 2:1 (mol repeat unit:mol benzenedimethanol) showed a proton conductivity of 27.9 mS/cm and a 100 times lower VO2+ crossover compared to Nafion.

  8. Friedel–Crafts Crosslinked Highly Sulfonated Polyether Ether Ketone (SPEEK Membranes for a Vanadium/Air Redox Flow Battery

    Géraldine Merle


    Full Text Available Highly conductive and low vanadium permeable crosslinked sulfonated poly(ether ether ketone (cSPEEK membranes were prepared by electrophilic aromatic substitution for a Vanadium/Air Redox Flow Battery (Vanadium/Air-RFB application. Membranes were synthesized from ethanol solution and crosslinked under different temperatures with 1,4-benzenedimethanol and ZnCl2 via the Friedel–Crafts crosslinking route. The crosslinking mechanism under different temperatures indicated two crosslinking pathways: (a crosslinking on the sulfonic acid groups; and (b crosslinking on the backbone. It was observed that membranes crosslinked at a temperature of 150 °C lead to low proton conductive membranes, whereas an increase in crosslinking temperature and time would lead to high proton conductive membranes. High temperature crosslinking also resulted in an increase in anisotropy and water diffusion. Furthermore, the membranes were investigated for a Vanadium/Air Redox Flow Battery application. Membranes crosslinked at 200 °C for 30 min with a molar ratio between 2:1 (mol repeat unit:mol benzenedimethanol showed a proton conductivity of 27.9 mS/cm and a 100 times lower VO2+ crossover compared to Nafion.

  9. Highly charged proton-exchange membrane. Sulfonated poly(ether sulfone)-silica polyelectrolyte composite membranes for fuel cells

    Shahi, Vinod K. [Electro-Membrane Processes Division, Central Salt and Marine Chemicals Research Institute, Bhavnagar-364002, Gujarat (India)


    Sulfonation of poly(ether sulfone) was carried out with chlorosulphonic acid in chloroform and its composite proton-exchange membrane was prepared using aminopropyltriethoxysilane as inorganic precursor by sol-gel in acidic medium. These membranes were further subjected to phosphorylation with phosphorous acid for introducing phosphonic acid functionality at inorganic segment. Extent of sulphonation was estimated by {sup 1}H-NMR spectroscopy while introduction of phosphonic acid groups was confirmed by FTIR spectroscopy and ion-exchange capacity studies. Different membranes, with varied silica content without and with phosphorylation, were characterized for their thermal and mechanical stabilities, physicochemical and electrochemical properties using thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), aq. methanol uptake studies, proton conductivity and methanol permeability measurements. The silica content in the membrane matrix and effect of phosphorylation was optimized as a function of membrane properties. Activation energy required for the proton transport across the membrane was also estimated and found to be comparable with Nafion 117 membrane. From the frictional interpretation and estimation of selectivity parameter it was observed that SPS-Si composite phosphorylated membrane with 20% silica content (SPS-Si(P)/20) resulted in the best proton-exchange membrane, which exhibited quite higher selectivity parameter in comparison to Nafion 117 for direct methanol fuel cell applications. Also, current-voltage polarization characteristics of SPS-Si(P)/20 membrane measured in direct methanol fuel cell, were found to be comparable to the Nafion 117 membrane. (author)

  10. Quantum dots-hyperbranched polyether hybrid nanospheres towards delivery and real-time detection of nitric oxide

    Liu, Shuiping; Gu, Tianxun; Fu, Jiajia [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China); Li, Xiaoqiang, E-mail: [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China); Technical University of Denmark, DTU Food, Søltofts plads, B227, 2800 Kgs. Lyngby (Denmark); Chronakis, Ioannis S. [Technical University of Denmark, DTU Food, Søltofts plads, B227, 2800 Kgs. Lyngby (Denmark); Ge, Mingqiao [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China)


    In this work, novel hybrid nanosphere vehicles were synthesized for nitric oxide (NO) donating and real-time detection. The hybrid nanosphere vehicles consist of cadmium selenide quantum dots (CdSe QDs) as NO fluorescent probes, and the modified hyperbranched polyether (mHP)-based diazeniumdiolates as NO donors, respectively. The nanospheres have spherical outline with dimension of ∼ 127 nm. The data of systematic characterization demonstrated that the mHP-based hybrid nanosphere vehicles (QDs-mHP-NO) can release and real-time detect NO with the low limit of 25 nM, based on fluorescence quenching mechanism. The low cell-toxicity of QDs-mHP-NO nanospheres was verified by means of MTT assay on L929 cells viability. The QDs-mHP-NO nanospheres provide perspectives for designing a new class of biocompatible NO donating and imaging systems. - Highlights: • QDs-mHP-NO fluorescent probe was prepared. • The QDs-mHP-NO probe is capable of releasing NO. • The QDs-mHP-NO probe can quantitatively detecting the release of NO in real time. • The low cell-toxicity of QDs-mHP-NO nanospheres was verified.

  11. Friedel–Crafts Crosslinked Highly Sulfonated Polyether Ether Ketone (SPEEK) Membranes for a Vanadium/Air Redox Flow Battery

    Merle, Géraldine; Ioana, Filipoi Carmen; Demco, Dan Eugen; Saakes, Michel; Hosseiny, Seyed Schwan


    Highly conductive and low vanadium permeable crosslinked sulfonated poly(ether ether ketone) (cSPEEK) membranes were prepared by electrophilic aromatic substitution for a Vanadium/Air Redox Flow Battery (Vanadium/Air-RFB) application. Membranes were synthesized from ethanol solution and crosslinked under different temperatures with 1,4-benzenedimethanol and ZnCl2 via the Friedel–Crafts crosslinking route. The crosslinking mechanism under different temperatures indicated two crosslinking pathways: (a) crosslinking on the sulfonic acid groups; and (b) crosslinking on the backbone. It was observed that membranes crosslinked at a temperature of 150 °C lead to low proton conductive membranes, whereas an increase in crosslinking temperature and time would lead to high proton conductive membranes. High temperature crosslinking also resulted in an increase in anisotropy and water diffusion. Furthermore, the membranes were investigated for a Vanadium/Air Redox Flow Battery application. Membranes crosslinked at 200 °C for 30 min with a molar ratio between 2:1 (mol repeat unit:mol benzenedimethanol) showed a proton conductivity of 27.9 mS/cm and a 100 times lower VO2+ crossover compared to Nafion. PMID:24957118

  12. Sulfonated poly(ether ether ketone)/mesoporous silica hybrid membrane for high performance vanadium redox flow battery

    Li, Zhaohua; Dai, Wenjing; Yu, Lihong; Xi, Jingyu; Qiu, Xinping; Chen, Liquan


    Hybrid membranes of sulfonated poly(ether ether ketone) (SPEEK) and mesoporous silica SBA-15 are prepared with various mass ratios for vanadium redox flow battery (VRB) application and investigated in detail. The hybrid membranes are dense and homogeneous with no visible hole as the SEM and EDX images shown. With the increasing of SBA-15 mass ratio, the physicochemical property, VO2+ permeability, mechanical property and thermal stability of hybrid membranes exhibit good trends, which can be attributed to the interaction between SPEEK and SBA-15. The hybrid membrane with 20 wt.% SBA-15 (termed as S/SBA-15 20) shows the VRB single cell performance of CE 96.3% and EE 88.1% at 60 mA cm-2 due to its good balance of proton conductivity and VO2+ permeability, while Nafion 117 membrane shows the cell performance of CE 92.2% and EE 81.0%. Besides, the S/SBA-15 20 membrane shows stable cell performance of highly stable efficiency and slower discharge capacity decline during 120 cycles at 60 mA cm-2. Therefore, the SPEEK/SBA-15 hybrid membranes with optimized mass ratio and excellent VRB performance can be achieved, exhibiting good potential usage in VRB systems.

  13. Through-space electronic communication of zinc phthalocyanine with substituted [60]Fullerene bearing O2Nxaza-crown macrocyclic ligands

    Ghanbari, Bahram; Shahhoseini, Leila; Mahlooji, Niloofar; Gholamnezhad, Parisa; Taheri Rizi, Zahra


    Two new macrocyclic ligands containing 17- and 19-membered O2N3-donor aza-crowns anchored to [60]Fullerene were synthesized and characterized by employing HPLC, electrospray ionization mass (ESI-MS), 1H and 13C NMR, UV-vis, IR spectroscopies, as well as powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA) in solid state. TGA measurements revealed that upon linking each of these macrocycle rings to [60]Fullerene, the decomposition point measured for [60]Fullerene moiety was increased, indicating on the promoted stability of [60]Fullerene backbone during binding to these macrocyclic ligands. Moreover, the ground state non-covalent interactions of [60]Fullerene derivatives of O2Nx (x = 2, and 3) aza-crown macrocyclic ligands namely, L1-L4 with zinc phthalocyanine (ZnPc) were also investigated by UV-vis absorption, steady state and time resolved fluorescence spectrophotometry in N-methyl-2-pyrrolidone (NMP). The calculation of Stern-Volmer constants (KSV) indicated on existence of an efficient quenching mechanism comprising of the excited singlet state of ZnPc in the presence of L1-L4. The observation of an appropriate correlation between decrease in fluorescence intensity and lifetime parameters led us to propose the occurrence of a static mechanism for the fluorescence quenching of ZnPc in the presence of L1-L3. The binding constants (KBH) of L1-L4/ZnPc were also determined applying the fluorescence quenching experiments. Meanwhile, the incompatibility of both KSV and KBH values found for L4 was also described in terms of structural features using DFT calculations using the B3LYP functional and 6-31G* basis set.

  14. Increasing the luminescence of lanthanide(III) macrocyclic complexes by the use of polymers and lanthanide enhanced luminescence

    Leif, Robert C.; Becker, Margie C.; Bromm, Alfred J., Jr.; Vallarino, Lidia M.; Williams, Steven A.; Yang, Sean


    A Eu (III)-macrocycle-isothiocyanate, Quantum DyeTM, has been reacted with lysine homo- and hetero-peptides to give polymers with multiple luminescent side chains. Contrary to the concentration quenching that occurs with conventional organic fluorophores, the attachment of multiple Quantum Dyes to a polymer results in a concomitant increase in luminescence. The emission intensity of the peptide-bound Quantum Dye units is approximately linearly related to their number. The attachment of peptides containing multiple lanthanide (III) macrocycles to analyte-binding species is facilitated by employing solid-phase technology. Bead-bound peptides are first labeled with multiple Quantum Dye units, then conjugated to an antibody, and finally released from the bead by specific cleavage with Proteinase K unedr physiological conditions. Since the luminescence of lanthanide(III) macrocycles is enhanced by the presence of GD(III) or Y(III) ions in a micellar system, a significant increase in signal can be achieved by attaching a polymer labeled with multiple Quantum Dye units to an analyte- binding species, such as a monoclonal antibody, or by taking advantage of the luminescence enhancing effects of Gd(III) or Y(III), or by both approaches concomitantly. A comparison between the integrated intensity and lifetime measurements of the Eu(III)-macrocycle under a variety of conditions show that the signal increase caused by Gd(III) can not be explained solely by the increase in lifetime, and must result in significant part from an energy transfer process invloving donors not directly bound to the Eu(III).

  15. Modulation of lipopolysaccharide-induced proinflammatory cytokine production by satratoxins and other macrocyclic trichothecenes in the murine macrophage.

    Chung, Yong-Joo; Jarvis, Bruce; Pestka, James


    The satratoxins and other macrocyclic trichothecene mycotoxins are produced by Stachybotrys, a mold that is often found in water-damaged dwellings and office buildings. To test the potential immunomodulatory effects of these mycotoxins, RAW 264.7 murine macrophage cells were treated with various concentrations of satratoxin G (SG), isosatratoxin F (iSF), satratoxin H (SH), roridin A (RA), and verrucarin A (VA) for 48 h in the presence or absence of suboptimal concentra-tion of lipopolysaccharide (LPS, 50 ng/ml), and tumor necrosis factor-alpha (TNF-alpha ) and interleukin-6 (IL-6) production were assayed by enzyme-linked immunosorbent assay (ELISA). In LPS-stimulated cultures, TNF-alpha supernatant concentrations were significantly increased in the presence of 2.5, 2.5, and 1 ng/ml of SG, SH, and RA, respectively, whereas IL-6 concentrations were not affected by the same concentrations these macrocyclic trichothecenes. When cells that were treated with LPS and SG (2.5 ng/ml) were evaluated by real-time polymerase chain reaction (PCR),TNF-alpha mRNA was found to increase at 24, 36, and 48 h compared to control cells. At higher concentrations, cytokine production and cell viability were markedly impaired in LPS-stimulated cells. Without LPS stimulation, neither TNF-alpha, nor IL-6 was induced. These results indicate that low concentrations of macrocyclic trichothecenes superinduce expression of TNF-alpha, whereas higher concentrations of these toxins are cytotoxic and concurrently reduce cytokine production. The capacity of satratoxins and other macrocyclic trichothecenes to alter cytokine production may play an etiologic role in outbreaks of Stachybotrys-associated human illnesses.

  16. Highly enantioselective transfer hydrogenation of ketones with chiral (NH)2 P2 macrocyclic iron(II) complexes.

    Bigler, Raphael; Huber, Raffael; Mezzetti, Antonio


    Bis(isonitrile) iron(II) complexes bearing a C2 -symmetric diamino (NH)2 P2 macrocyclic ligand efficiently catalyze the hydrogenation of polar bonds of a broad scope of substrates (ketones, enones, and imines) in high yield (up to 99.5 %), excellent enantioselectivity (up to 99 % ee), and with low catalyst loading (generally 0.1 mol %). The catalyst can be easily tuned by modifying the substituents of the isonitrile ligand.

  17. Biomimetic Synthesis of Twenty-four Long-chained Diketones as Precursors for Muscone and Further Macrocyclic Ketones

    GUO,Yuan; CHEN,Kang-yu; LI,Jian-Li; SHI,Zhen


    The one-carbon unit transfer reaction of tetrahydrofolate coenzyme was initiated. Bisbenzimidazolium salts were used as a tetrahydrofolate coenzyme model, and thus the biomimetic synthesis of twenty-four acyclic dike-tones as precursors for macrocyclic ketones was successfully accomplished by using the addition-hydrolysis reac-tion of the bisbenzimidazolium salts with alkyl magnesium halide, wherein six diketones have not been reported in literature. Accordingly, a short route to muscone analogues was provided.

  18. Antiproliferative Activity of Polyether Antibiotic--Cinchona Alkaloid Conjugates Obtained via Click Chemistry.

    Skiera, Iwona; Antoszczak, Michał; Trynda, Justyna; Wietrzyk, Joanna; Boratyński, Przemysław; Kacprzak, Karol; Huczyński, Adam


    A series of eight new conjugates of salinomycin or monensin and Cinchona alkaloids were obtained by the Cu(I)-catalysed 1,3-dipolar Huisgen cycloaddition (click chemistry) of respective N-propargyl amides of salinomycin or monensin with four different Cinchona alkaloid derived azides. In vitro antiproliferative activity of these conjugates evaluated against three cancer cell lines (LoVo, LoVo/DX, HepG2) showed that four of the compounds exhibited high antiproliferative activity (IC50 below 3.00 μm) and appeared to be less toxic and more selective against normal cells than two standard anticancer drugs.

  19. Site-selective functionalization of periodic mesoporous organosilica (PMO) with macrocyclic host for specific and reversible recognition of heavy metal.

    Ye, Gang; Leng, Yuxiao; Bai, Feifei; Wei, Jichao; Wang, Jianchen; Chen, Jing


    A novel kind of macrocyclic-host-functionalized periodic mesoporous organosilica (PMO) with excellent and reversible recognition of Pb(II) was developed. The macrocyclic host molecule cis-dicyclohexano[18]crown-6, with strong affinity to Pb(II), was carefully modified as a bridged precursor to build the PMO material. To break down the limit of the functionalization degree for PMOs incorporated with large-sized moieties, a site-selective post-functionalization method was proposed to further decorate the external surface of the PMO material. The selective recognition ability of the upgraded PMO material towards Pb(II) was remarkably enhanced without destroying the mesoporous ordering. Solid-state (13)C and (29)Si NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), XRD, TEM, and nitrogen adsorption-desorption isotherm measurements were utilized for a full characterization of the structure, micromorphology, and surface properties. Reversible binding of Pb(II) was realized in the binding-elution cycle experiments. The mechanism of the supramolecular interaction between the macrocyclic host and metal ion was discussed. The synthetic strategy can be considered a general way to optimize the properties of PMOs as binding materials for practical use while preserving the mesostructure. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Macrocyclic-, polycyclic-, and nitro musks in cosmetics, household commodities and indoor dusts collected from Japan: implications for their human exposure.

    Nakata, Haruhiko; Hinosaka, Mari; Yanagimoto, Hayato


    This paper reported the occurrence and concentrations of macrocyclic-, polycyclic- and nitro musks in cosmetics and household commodities collected from Japan. The high concentrations and detection frequencies of Musk T, habanolide, and exaltolides were found in commercial products, suggesting their large amounts of production and usage in Japan. Polycyclic musks, HHCB and OTNE, also showed high concentrations in cosmetics and products. The estimated dairy intakes of Musk T and HHCB by the dermal exposure to commercial products were 7.8 and 7.9 μg/kg/day in human, respectively, and perfume and body lotion are dominant exposure sources. We also analyzed synthetic musks in house dusts. Polycyclic musks, HHCB and OTNE, showed high concentrations in samples, but macrocyclic musks were detected only in a few samples, although these types of musks were highly detected in commercial products. This is probably due to easy-degradation of macrocyclic musks in indoor environment. The dairy intakes of HHCB by dust ingestions were 0.22 ng/kg/day in human, which were approximately five orders of magnitudes lower than those of dermal absorption from commercial household commodities.

  1. Synthesis and Crystal Structure of a New Dinuclear Manganese(Ⅱ) Manganese(Ⅲ) Complex of a Macrocyclic Ligand

    JIAN Fang-fang; XIAO Hai-lian; XU Liang-zhong; PANG Lei


    A mixed-valence dinuclear manganese complex, [MnⅡMnⅢL](ClO4)·1/2MeOH, where L is a macrocyclic ligand derived from the cyclocondensation of sodium 2,6-diformyl-4-methylphenolate with N,N-bis(2-aminoethyl)-2-hydroxybenzyl amine, was obtained and its structure was determined by X-ray diffraction. The orange crystal is a monoclinic system with space group P21/c and lattice parameters a=1.1617(4), b=1.4005(3), c=1.4641(3) nm, β=113.03(2)°, and Z=2. The crystal structure shows that each pendant-arm is bonded in a bidentate fashion to the adjacent metal atom and that both the arms are on the same side of the macrocycle. The two Mn atoms are bridged by two μ2-phenoxy oxygen atoms of the tetra-imine macrocycle, and each Mn atom, locating in a trigonal prismatic coordination environment(N3O3), is six-coordinated by the two imine nitrogen atoms, one tertiary nitrogen atom and a pendant phenol moiety apart from the two oxygen atoms.

  2. Accelerated Hydrolysis of p-Nitrophenyl Picolinate Catalyzed by Metallomicelle Made from a Novel Macrocyclic Polyamine Copper(Ⅱ) Complex

    KOU,Xing-Ming; ZHAO,Guo-Po; HUANG,Zhong; TIAN,Yu-Hua; MENG,Xiang-Guang; ZENG Xian-Cheng


    A copper(Ⅱ) complex 1 of a novel macrocyclic polyamine ligand with hydroxylethyl pendant groups, 4,ll-bis(hydroxylethyl)-5,7,7,12,14,14-hexamethyl-l,4,8,11-tetraazacyclotetradecane (L) has been synthesized and characterized. Rate enhancement for hydrolysis of p-nitrophenyl picolinate (PNPP) catalyzed by 1 was studied kinetically under Brij35 micellar condition. For comparision, the catalytic activity of corresponding copper(Ⅱ) complex 2 of non-substituted macrocyclic polyamine ligand, 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraaza-cyclote-tradecane (L1) toward the hydrolysis of PNPP was also investigated. The results indicate that the macrocyclic polyamine copper(Ⅱ) complex 1 effectively catalyzed the hydrolysis of PNPP, and the pendant ligand hydroxyl group or deprotonated pendant ligand hydroxyl group can act as catalytically active species in the reaction. A ternary complex kinetic model involving metal ion, ligand and substrate has been proposed, and the results confirmed the reasonability of such kinetic model.

  3. Dinuclear cadmium(II), zinc(II), and manganese(II), trinuclear nickel(II), and pentanuclear copper(II) complexes with novel macrocyclic and acyclic Schiff-base ligands having enantiopure or racemic camphoric diamine components.

    Jiang, Jue-Chao; Chu, Zhao-Lian; Huang, Wei; Wang, Gang; You, Xiao-Zeng


    Four novel [3 + 3] Schiff-base macrocyclic ligands I-IV condensed from 2,6-diformyl-4-substituted phenols (R = CH(3) or Cl) and enantiopure or racemic camphoric diamines have been synthesized and characterized. Metal-ion complexations of these enantiopure and racemic [3 + 3] macrocyclic ligands with different cadmium(II), zinc(II), manganese(II), nickel(II), and copper(II) salts lead to the cleavage of Schiff-base C horizontal lineN double bonds and subsequent ring contraction of the macrocyclic ligands due to the size effects and the spatial restrictions of the coordination geometry of the central metals, the steric hindrance of ligands, and the counterions used. As a result, five [2 + 2] and one [1 + 2] dinuclear cadmium(II) complexes (1-6), two [2 + 2] dinuclear zinc(II) (7 and 8), and two [2 + 2] dinuclear manganese(II) (9 and 10) complexes together with one [1 + 1] trinuclear nickel(II) complex (11) and one [1 + 2] pentanuclear copper(II) complex (12), bearing enantiopure or racemic ligands, different substituent groups in the phenyl rings, and different anionic ligands (Cl(-), Br(-), OAc(-), and SCN(-)), have been obtained in which the chiral carbon atoms in the camphoric backbones are arranged in different ways (RRSS for the enantiopure ligands in 1, 2, 4, 5, and 7-10 and RSRS for the racemic ligands in 3, 6, 11, and 12). The steric hindrance effects of the methyl group bonded to one of the chiral carbon atoms of camphoric diamine units are believed to play important roles in the formation of the acyclic [1 + 1] trinuclear complex 11 and [1 + 2] dinuclear and pentanuclear complexes 6 and 12. In dinuclear cadmium(II), zinc(II), and manganese(II) complexes 1-10, the sequence of separations between the metal centers is consistent with that of the ionic radii shortened from cadmium(II) to manganese(II) to zinc(II) ions. Furthermore, UV-vis, circular dichroism, (1)H NMR, and fluorescence spectra have been used to characterize and compare the structural

  4. Unsaturated macrocyclic dihydroxamic acid siderophores produced by Shewanella putrefaciens using precursor-directed biosynthesis.

    Soe, Cho Z; Codd, Rachel


    To acquire iron essential for growth, the bacterium Shewanella putrefaciens produces the macrocyclic dihydroxamic acid putrebactin (pbH2; [M + H(+)](+), m/zcalc 373.2) as its native siderophore. The assembly of pbH2 requires endogenous 1,4-diaminobutane (DB), which is produced from the ornithine decarboxylase (ODC)-catalyzed decarboxylation of l-ornithine. In this work, levels of endogenous DB were attenuated in S. putrefaciens cultures by augmenting the medium with the ODC inhibitor 1,4-diamino-2-butanone (DBO). The presence in the medium of DBO together with alternative exogenous non-native diamine substrates, (15)N2-1,4-diaminobutane ((15)N2-DB) or 1,4-diamino-2(E)-butene (E-DBE), resulted in the respective biosynthesis of (15)N-labeled pbH2 ((15)N4-pbH2; [M + H(+)](+), m/zcalc 377.2, m/zobs 377.2) or the unsaturated pbH2 variant, named here: E,E-putrebactene (E,E-pbeH2; [M + H(+)](+), m/zcalc 369.2, m/zobs 369.2). In the latter system, remaining endogenous DB resulted in the parallel biosynthesis of the monounsaturated DB-E-DBE hybrid, E-putrebactene (E-pbxH2; [M + H(+)](+), m/zcalc 371.2, m/zobs 371.2). These are the first identified unsaturated macrocyclic dihydroxamic acid siderophores. LC-MS measurements showed 1:1 complexes formed between Fe(III) and pbH2 ([Fe(pb)](+); [M](+), m/zcalc 426.1, m/zobs 426.2), (15)N4-pbH2 ([Fe((15)N4-pb)](+); [M](+), m/zcalc 430.1, m/zobs 430.1), E,E-pbeH2 ([Fe(E,E-pbe)](+); [M](+), m/zcalc 422.1, m/zobs 422.0), or E-pbxH2 ([Fe(E-pbx)](+); [M](+), m/zcalc 424.1, m/zobs 424.2). The order of the gain in siderophore-mediated Fe(III) solubility, as defined by the difference in retention time between the free ligand and the Fe(III)-loaded complex, was pbH2 (ΔtR = 8.77 min) > E-pbxH2 (ΔtR = 6.95 min) > E,E-pbeH2 (ΔtR = 6.16 min), which suggests one possible reason why nature has selected for saturated rather than unsaturated siderophores as Fe(III) solubilization agents. The potential to conduct multiple types of ex situ chemical

  5. Aza-macrocyclic complexes of the Group 1 cations - synthesis, structures and density functional theory study.

    Dyke, John; Levason, William; Light, Mark E; Pugh, David; Reid, Gillian; Bhakhoa, Hanusha; Ramasami, Ponnadurai; Rhyman, Lydia


    The Group 1 complexes, [M(Me6[18]aneN6)][BAr(F)] (M = Li-Cs; Me6[18]aneN6 = 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane; BAr(F) = tetrakis{3,5-bis(trifluoromethyl)-phenyl}borate), are obtained in high yield by reaction of the macrocycle with M[BAr(F)] in anhydrous CH2Cl2 solution, and characterised spectroscopically ((1)H, (13)C{(1)H}, (7)Li, (23)Na, and (133)Cs NMR), by microanalysis and, for M = Li, K, and Rb, by single crystal X-ray analysis. The structures show N6-coordination to the metal ion; the small ionic radius for Li(+) leads to a puckered conformation. In contrast, the K(+) ion fits well into the N6 plane, with the [BAr(F)](-) anions above and below, leading to two K(+) species in the asymmetric unit (a hexagonal planar [K(Me6[18]aneN6)](+) cation and a '[K(Me6[18]aneN6)(κ(1)-BAr(F))2](-) anion', with long axial KF interactions). The Rb(+) ion sits above the N6 plane, with two long axial RbF interactions in one cation and two long, mutually cis RbF interactions in the other. The unusual sandwich cations, [M(Me3tacn)2](+) (M = Na, K; distorted octahedral, N6 donor set) and half-sandwich cations [Li(Me3tacn)(thf)](+) (distorted tetrahedron, N3O donor set), [Li(Me4cyclen)(OH2)](+), and [Na(Me4cyclen)(thf)](+) (both distorted square pyramids with N4O donor sets) were also prepared (Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane, Me4cyclen = 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane). Density functional theory (DFT) calculations, using the BP86 and B3LYP functionals, show that the accessibility of the [M(Me3tacn)2](+) sandwich cations depends strongly on the M(+) ionic radius, such that it is sufficiently large to avoid steric clashing between the Me groups of the two rings, and small enough to avoid very acute N-M-N chelate angles. The calculations also show that coordination to the Group 1 cation involves significant donation of electron density from the p-orbitals on the N atoms of the macrocycle, rather than purely

  6. Biomechanical Assessment of Motor Abilities in Male Handball Players During the Annual Training Macrocycle

    Sacewicz Tomasz


    Full Text Available Introduction. The aim of the study was to determine the torque of the knee extensors and flexors of the lead lower limb, the torque of the shoulder extensors and flexors of the dominant upper limb, and the torque generated by the muscles of the kinematic chain going from the trail lower limb to the hand of the dominant limb in male handball players during the annual training macrocycle. Changes in jump height and throwing velocity were also investigated. Material and methods. The study involved 13 handball players from a Polish second-league team. The measurements were performed four times: at the beginning of the preparation period, at the beginning of the season, at the end of the first part of the season, and at the end of the second part of the season. Torque was measured in isokinetic and isometric conditions. Jumping ability was tested using a piezoelectric platform, and throwing velocity was measured with a speed radar gun. Results. The study found statistically significant differences between the relative torque values of the knee extensors (p < 0.002 and flexors (p < 0.003 of the lead leg measured in isokinetic conditions between the first three measurements and the final one. Isokinetic measurement of the torque of the muscles of the kinematic chain going from the trail leg to the hand of the dominant arm decreased in a statistically significant way at the end of the season. As for the results of the measurement of the torque of the shoulder extensors and flexors in static conditions, no statistically significant differences were observed between the four measurements. However, statistically significant differences were noted in jumping ability and throwing velocity in the annual training macrocycle. Conclusions. The results of the study indicate that there is a need to perform regular assessments of players’ strength and jumping ability during the competition period. There is a need to modify the training methods used during the

  7. Next generation macrocyclic and acyclic cationic lipids for gene transfer: Synthesis and in vitro evaluation.

    Jubeli, Emile; Maginty, Amanda B; Abdul Khalique, Nada; Raju, Liji; Abdulhai, Mohamad; Nicholson, David G; Larsen, Helge; Pungente, Michael D; Goldring, William P D


    Previously we reported the synthesis and in vitro evaluation of four novel, short-chain cationic lipid gene delivery vectors, characterized by acyclic or macrocyclic hydrophobic regions composed of, or derived from, two 7-carbon chains. Herein we describe a revised synthesis of an expanded library of related cationic lipids to include extended chain analogues, their formulation with plasmid DNA (pDNA) and in vitro delivery into Chinese hamster ovarian (CHO-K1) cells. The formulations were evaluated against each other based on structural differences in the hydrophobic domain and headgroup. Structurally the library is divided into four sets based on lipids derived from two 7- or two 11-carbon hydrophobic chains, C7 and C11 respectively, which possess either a dimethylamine or a trimethylamine derived headgroup. Each set includes four cationic lipids based on an acyclic or macrocyclic, saturated or unsaturated hydrophobic domain. All lipids were co-formulated with the commercial cationic lipid 1,2-dimyristoyl-sn-glycero-3-ethylphosphocholine (EPC) in a 1:1 molar ratio, along with one of two distinct neutral co-lipids, cholesterol or 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) in an overall cationic-to-neutral lipid molar ratio of 3:2. Binding of lipid formulations with DNA, and packing morphology associated with the individual lipid-DNA complexes were characterized by gel electrophoresis and small angle X-ray diffraction (SAXD), respectively. As a general trend, lipoplex formulations based on mismatched binary cationic lipids, composed of a shorter C7 lipid and the longer lipid EPC (C14), were generally associated with higher transfection efficiency and lower cytotoxicity than their more closely matched C11/EPC binary lipid formulation counterparts. Furthermore, the cyclic lipids gave transfection levels as high as or greater than their acyclic counterparts, and formulations with cholesterol exhibited higher transfection and lower cytotoxicity than those

  8. Synthesis and anion binding properties of porphyrins and related compounds

    Figueira, Flávio


    Over the last two decades the preparation of pyrrole-based receptors for anion recognition has attracted considerable attention. In this regard porphyrins, phthalocyanines and expanded porphyrins have been used as strong and selective receptors while the combination of those with different techniques and materials can boost their applicability in different applications as chemosensors and extracting systems. Improvements in the field, including the synthesis of this kind of compounds, can contribute to the development of efficient, cheap, and easy-to-prepare anion receptors. Extensive efforts have been made to improve the affinity and selectivity of these compounds and the continuous expansion of related research makes this chemistry even more promising. In this review, we summarize the most recent developments in anion binding studies while outlining the strategies that may be used to synthesize and functionalize these type of macrocycles. © 2016 World Scientific Publishing Company.

  9. Structure-Activity Relationship Studies on a Macrocyclic Agouti-Related Protein (AGRP) Scaffold Reveal Agouti Signaling Protein (ASP) Residue Substitutions Maintain Melanocortin-4 Receptor Antagonist Potency and Result in Inverse Agonist Pharmacology at the Melanocortin-5 Receptor.

    Ericson, Mark D; Freeman, Katie T; Schnell, Sathya M; Fleming, Katlyn A; Haskell-Luevano, Carrie


    The melanocortin system consists of five reported receptors, agonists from the proopiomelanocortin gene transcript, and two antagonists, agouti-signaling protein (ASP) and agouti-related protein (AGRP). For both ASP and AGRP, the hypothesized Arg-Phe-Phe pharmacophores are on exposed β-hairpin loops. In this study, the Asn and Ala positions of a reported AGRP macrocyclic scaffold (c[Pro-Arg-Phe-Phe-Asn-Ala-Phe-DPro]) were explored with 14-compound and 8-compound libraries, respectively, to generate more potent, selective melanocortin receptor antagonists. Substituting diaminopropionic acid (Dap), DDap, and His at the Asn position yielded potent MC4R ligands, while replacing Ala with Ser maintained MC4R potency. Since these substitutions correlate to ASP loop residues, an additional Phe to Ala substitution was synthesized and observed to maintain MC4R potency. Seventeen compounds also possessed inverse agonist activity at the MC5R, the first report of this pharmacology. These findings are useful in developing molecular probes to study negative energy balance conditions and unidentified functions of the MC5R.

  10. Mono- and Dinuclear Macrocyclic Calcium Complexes as Platforms for Mixed-Metal Complexes and Clusters.

    Connolly, Emma A; Leeland, James W; Love, Jason B


    Mono- and dinuclear calcium complexes of the Schiff-base macrocycles H4L have been prepared and characterized spectroscopically and crystallographically. In the formation of Ca(THF)2(H2L(1)), Ca2(THF)2(μ-THF)(L(1)), and Ca2(THF)4(L(2)), the ligand framework adopts a bowl-shaped conformation instead of the conventional wedge, Pacman-shaped structure as seen with the anthracenyl-hinged complex Ca2(py)5(L(3)). The mononuclear calcium complex Ca(THF)2(H2L(1)) reacts with various equivalents of LiN(SiMe3)2 to form calcium/alkali metal clusters and dinuclear transition metal complexes when reacted subsequently with transition metal salts. The dinuclear calcium complex Ca2(THF)2(μ-THF)(L(1)), when reacted with various equivalents of NaOH, is shown to act as a platform for the formation of calcium/alkali metal hydroxide clusters, displaying alternate wedged and bowl-shaped conformations.

  11. Fluensulfone is a nematicide with a mode of action distinct from anticholinesterases and macrocyclic lactones.

    Kearn, James; Ludlow, Elizabeth; Dillon, James; O'Connor, Vincent; Holden-Dye, Lindy


    Plant parasitic nematodes infest crops and present a threat to food security worldwide. Currently available chemical controls e.g. methyl bromide, organophosphates and carbamates have an unacceptable level of toxicity to non-target organisms and are being withdrawn from use. Fluensulfone is a new nematicide of the fluoroalkenyl thioether group that has significantly reduced environmental impact with low toxicity to non-target insects and mammals. Here, we show that the model genetic organism Caenorhabditis elegans is susceptible to the irreversible nematicidal effects of fluensulfone. Whilst the dose required is higher than that which has nematicidal activity against Meloidogyne spp. the profile of effects on motility, egg-hatching and survival is similar to that reported for plant parasitic nematodes. C. elegans thus provides a tractable experimental paradigm to analyse the effects of fluensulfone on nematode behaviour. We find that fluensulfone has pleiotropic actions and inhibits development, egg-laying, egg-hatching, feeding and locomotion. In the case of feeding and locomotion, an early excitation precedes the gross inhibition. The profile of these effects is notably distinct from other classes of anthelmintic and nematicide: the inhibition of motility caused by fluensulfone is not accompanied by the hypercontraction which is characteristic of organophosphates and carbamates and C. elegans mutants that are resistant to the carbamate aldicarb and the macrocyclic lactone ivermectin retain susceptibility to fluensulfone. These data indicate fluensulfone's mode of action is distinct from currently available nematicides and it therefore presents a promising new chemical entity for crop protection.

  12. Grafted chromium 13-membered dioxo-macrocyclic complex into aminopropyl-based nanoporous SBA-15

    Tarlani, Aliakbar, E-mail: [Inorganic Nanostructures and Catalysts Research Laboratory, Chemistry and Chemical Engineering Research Center of Iran, Pajoohesh Boulevard, km 17, Karaj Highway, Tehran 14968-13151 (Iran, Islamic Republic of); Joharian, Monika; Narimani, Khashayar [Inorganic Nanostructures and Catalysts Research Laboratory, Chemistry and Chemical Engineering Research Center of Iran, Pajoohesh Boulevard, km 17, Karaj Highway, Tehran 14968-13151 (Iran, Islamic Republic of); Muzart, Jacques [Institut de Chimie Moléculaire de Reims, CNRS-Université de Reims Champagne-Ardenne, BP 1039, 51687 Reims Cedex 2 (France); Fallah, Mahtab [Inorganic Nanostructures and Catalysts Research Laboratory, Chemistry and Chemical Engineering Research Center of Iran, Pajoohesh Boulevard, km 17, Karaj Highway, Tehran 14968-13151 (Iran, Islamic Republic of)


    In a new approach, chromium (III) tetraaza dioxo ligand was grafted onto functionalized SBA-15 after four step reactions by using coordinating ability of anchored amino functionalized SBA-15. After the termination of each step, the obtained product was characterized by FT-IR, low-angle X-ray diffraction (LA-XRD), N{sub 2} adsorption–desorption isotherms (Brunauer–Emmett–Teller (BET)–Barret–Joyner–Halenda (BJH)) and thermogravimetric analysis (TGA), and used as catalyst for the efficient and regioselective alcoholysis of styrene oxide to 2-alkoxy-1-phenylethanol product at ambient temperature. - Graphical abstract: Chromium (III) tetraaza dioxo ligand was grafted onto functionalized SBA-15 using coordinating ability of anchored amino functionalized SBA-15. Preparation of the catalyst is depicted in Scheme 1. - Highlights: • Dioxo tetraazachromium macrocyclic complex grafted into the SBA-15-NH{sub 2} channels. • The bond is created by coordinating ability of anchored amino functionalized SBA-15. • The prepared nanocatalyst has superior activity in the alcoholysis of styrene oxide. • The catalyst is reusable at ambient temperature for the mentioned reaction.

  13. Synthesis, characterization and biological activity of symmetric dinuclear complexes derived from a novel macrocyclic compartmental ligand

    Mruthyunjayaswamy, B.H.M.; Ijare, Omkar B.; Jadegoud, Y. [Gulbarga University (India). Dept. of Chemistry]. E-mail:


    A phenol based novel macrocyclic binucleating compartmental ligand N,N-bis(2,6-diiminomethyl-4-methyl-1-hydroxyphenyl)malonoyldicarboxamide was prepared. The complexes were prepared by template method by reacting 2,6-diformyl-4-methylphenol, malonoyl dihydrazide and the metal chlorides of Cu(II), Ni(II), Co(II), Cd(II), Zn(II) and Hg(II) in methanol to get a series of dinuclear complexes. The complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibility data, IR, UV-Vis, ESR, NMR and FAB mass spectral data. The dinuclear nature of the complexes was confirmed on the basis of elemental analyses, magnetic susceptibility, ESR and FAB mass spectral data. The ligand as well as Cu(II), Ni(II), Co(II) and Zn(II) complexes were tested for their antibacterial and antifungal properties against Escherichia coli, Staphyloccocus aureus, Aspergillus niger and Fusarium oxysporum. Magnetic susceptibility measurements of Cu(II), Ni(II) and Co(II) complexes reveal that these complexes exhibit antiferromagnetic coupling behavior due to the presence of two metal ions in close proximity. FAB mass spectrum of the Cu(II) complex gave a clear evidence for the dinuclear nature. The ligand and the complexes were found to be less active against the tested bacteria, but the ligand alone was found active against the fungus Fusarium oxysporum. (author)

  14. Immobilized copper(II) macrocyclic complex on MWCNTs with antibacterial activity

    Tarlani, Aliakbar; Narimani, Khashayar; Mohammadipanah, Fatemeh; Hamedi, Javad; Tahermansouri, Hasan; Amini, Mostafa M.


    In a new approach, a copper(II) tetraaza macrocyclic complex (CuTAM) was covalently bonded on modified multi-walled carbon nanotubes (MWCNTs). To achieve this purpose, MWCNTs were converted to MWCNT-COCl and then reacted to NH groups of TAM ligand. The prepared material was characterized by Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, thermal gravimetric analysis (TGA), and FESEM (field emission scanning electron microscopy). FT-IR and TGA demonstrated the presence of the organic moieties, and XRD proved that the structure of MWCNTs remained intact during the three modification steps. An increase in the ID/IG ratio in Raman spectra confirmed the surface modifications. Finally, the samples were subjected to an antibacterial assessment to compare their biological activity. The antibacterial test showed that the grafted complex on the surface of the nanotube (MWCNT-CO-CuTAM) has higher antibacterial activity against Bacillus subtilis ATCC 6633 than the MWCNT-COOH and CuTAM with 1000 and 2000 μg/mL.

  15. Detection of airborne Stachybotrys chartarum macrocyclic trichothecene mycotoxins on particulates smaller than conidia.

    Brasel, T L; Douglas, D R; Wilson, S C; Straus, D C


    Highly respirable particles (diameter, water-damaged buildings. The presence of airborne Stachybotrys chartarum trichothecene mycotoxins on particles smaller than conidia (e.g., fungal fragments) was therefore investigated. Cellulose ceiling tiles with confluent Stachybotrys growth were placed in gas-drying containers through which filtered air was passed. Exiting particulates were collected by using a series of polycarbonate membrane filters with decreasing pore sizes. Scanning electron microscopy was employed to determine the presence of conidia on the filters. A competitive enzyme-linked immunosorbent assay (ELISA) specific for macrocyclic trichothecenes was used to analyze filter extracts. Cross-reactivity to various mycotoxins was examined to confirm the specificity. Statistically significant (P trichothecenes at concentrations of 50 and 5 ng/ml and 500 pg/ml (58.4 to 83.5% inhibition). Of the remaining toxins tested, only verrucarol and diacetylverrucarol (nonmacrocyclic trichothecenes) demonstrated significant binding (18.2 and 51.7% inhibition, respectively) and then only at high concentrations. The results showed that extracts from conidium-free filters demonstrated statistically significant (P trichothecene mycotoxins can become airborne in association with intact conidia or smaller particles. These findings may have important implications for indoor air quality assessment.

  16. Separation of Radioactive Elements Using Nitrogen Oxygen Donor Macrocyclic Ion Exchanger

    Kim, Si Joong; Shim, Min Sook [Korea University, Seoul (Korea, Republic of); Kim, Jeong; Lee, Myung No [Seonam University, Namwon (Korea, Republic of)


    The study for the selective separation and recovery of Pd{sup 2+} ion lead to following results. The four kinds of stationary phase, SGB-NTOE, SGB-NTOT, SGB-NEOD, and SGB-NTOD, were synthesized to react NOTE, NTOT, NEOD, and NTOD with 3-glycidyloxypropyltrimethoxy silane and silica gel. Using these macrocycles, selective separation of Hg(II), Pt(II), and Pd(II) from alkali earth and transition metal ions were possible by column chromatography. Maximum separation capability was appeared in SGB-NTOT and it took 12 hours for complete separation of Pd{sup 2+} ion with the column which inner diameter was 24 cm. The results of the study for the selective separation of Cs{sup +} and Sr{sup 2+} are as follows: Sr{sup 2+} ion was effectively separated through liquid membrane with CR22BB and the relative transport ration of Sr{sup 2+}/Na{sup +} was 15. Cs{sup +} ion was effectively separated through liquid membrane with CR22BB(OH)Ph and the relative transport ration of Cs{sup +}/Na{sup +} was 3.4. 9 refs., 7 tabs., 15 figs. (author)

  17. Ketoprofen encapsulated cucurbit[6]uril nanoparticles: a new exploration of macrocycles for drug delivery

    Hoai, Nguyen To; Tuyen Thi Dao, Phuong; Phu, Quoc Nam; Dam Le, Duy; Nguyen, Tuan Anh; Nguyen, Tai Chi; Chien Dang, Mau


    The aim of this study is (i) to fabricate a nanoparticle formulation of ketoprofen (Keto) using a relatively new family of macrocycles as the carrier for drug delivery: cucurbit[6]uril (CB[6]), (ii) to evaluate its in vitro dissolution and (iii) to investigate its in vivo pharmaceutical property. The CB[6]-Keto nanoparticles were prepared by emulsion solvent evaporation method. Morphology and size of the successfully prepared nanoparticles were then confirmed using a transmission electron microscope and dynamic light scattering. It was shown that they are spherical with hydrodynamic diameter of 200-300 nm. The in vitro dissolution studies of CB[6]-Keto nanoparticles were conducted at pH 1.2 and 7.4. The results indicated that there is a significant increase in Keto concentration at pH 7.4 compared to pH 1.2. For the in vivo assessment, CB[6]-Keto nanoparticles and referential profenid were administered by oral gavages to rabbits. The results implied that CB[6]-Keto nanoparticles remarkably increased area under the curve compared to profenid.

  18. High performance ion chromatography of haloacetic acids on macrocyclic cryptand anion exchanger.

    Bruzzoniti, Maria Concetta; De Carlo, Rosa Maria; Horvath, Krisztian; Perrachon, Daniela; Prelle, Ambra; Tófalvi, Renáta; Sarzanini, Corrado; Hajós, Péter


    A new high performance ion chromatographic method has been developed for the separation of the nine chlorinated-brominated haloacetic acids (HAAs) that are the disinfection by-products of chlorination of drinking water, using a macrocycle-based adjustable-capacity anion-exchange separator column (IonPac Cryptand A1). A gradient method based on theoretical and experimental considerations has been optimized in which 10 mM NaOH-LiOH step gradient was performed at the third minute of the analysis. The optimized method allowed us to separate the nine HAAs and seven possibly interfering inorganic anions in less than 25 min with acceptable resolution. The minimum concentrations detectable for HAAs were between 8.0 (MBA) and 210 (TBA) microg L(-1), with linearity included between 0.9947 (TBA) and 0.9998 (MBA). To increase sensitivity, a 25-fold preconcentration step on a reversed phase substrate (LiChrolut EN) has been coupled. Application of this method to the analysis of haloacetic acids in real tap water samples is illustrated.

  19. Self-assembled benzophenone bis-urea macrocycles facilitate selective oxidations by singlet oxygen.

    Geer, Michael F; Walla, Michael D; Solntsev, Kyril M; Strassert, Cristian A; Shimizu, Linda S


    This manuscript investigates how incorporation of benzophenone, a well-known triplet sensitizer, within a bis-urea macrocycle, which self-assembles into a columnar host, influences its photophysical properties and affects the reactivity of bound guest molecules. We further report the generation of a remarkably stable organic radical. As expected, UV irradiation of the host suspended in oxygenated solvents efficiently generates singlet oxygen similar to the parent benzophenone. In addition, this host can bind guests such as 2-methyl-2-butene and cumene to form stable solid host-guest complexes. Subsequent UV irradiation of these complexes facilitated the selective oxidation of 2-methyl-2-butene into the allylic alcohol, 3-methyl-2-buten-1-ol, at 90% selectivity as well as the selective reaction of cumene to the tertiary alcohol, α,α'-dimethyl benzyl alcohol, at 63% selectivity. However, these products usually arise through radical pathways and are not observed in the presence of benzophenone in solution. In contrast, typical reactions with benzophenone result in the formation of the reactive singlet oxygen that reacts with alkenes to form endoperoxides, diooxetanes, or hydroperoxides, which are not observed in our system. Our results suggest that the confinement, the formation of a stable radical species, and the singlet oxygen photoproduction are responsible for the selective oxidation processes. A greater understanding of the mechanism of this selective oxidation could lead to development of greener oxidants.

  20. Study on the Crystal Structure of a Macrocycle and Tyrosinase Activity of Its Dinuclear Copper Complexes

    周红; 潘志权; 罗勤慧; 梅光泉; 龙德良; 陈久桐


    A ring-contracted form macrocycle, 29,30-dioxo-3,6,9,17,20,23,29,30-octaazapentacyclo[23,3,1,111,15,02,6,016,20]-triacontaneocta- 1 (28),9,11 (12), 13,15(30),23,25(29),26-ene (L) was synthesized by condensation of diethyltriamine with pyridine-1-oxide-2,6-dicarboxaldehyde. A porous three-dimensional layer structure in its crystal was formed by self-assembly through hydrogen bonds and π-π interaction. Its dinuclear copper(I) complex [Cu2L(MeOH)2]-(BF4)2*2H2O and dinuclear-copper(II) complex [Cu2L(MeOH)2](ClO4)4*2H2O were obtained and could oxidize catalytically four phenolic substrates hydroquinone, 2-methyl-hydroquinone, 2,6-di-tert-butylphenol and 2,6-dimethylphenol, in a mixture of methanol and acetonitrile (V : V, 4 : 1). The copper(I) complex reacted with dioxygen to form an oxygenated species as an initial active intermediate for oxidation of the phenols. Oxidation of the substrates by the copper(II) complex produced a copper(I) complex and the oxidation products of the substrates.

  1. Accuracy of implant transfer and surface detail reproduction with polyether and polyvinyl siloxane using closed-tray impression technique

    Marzieh Alikhasi


    Full Text Available   Background and Aims: Making accurate impressions of prepared teeth when they are adjacent to dental implants is of great importance. In these situations, disregarding the selection of appropriate impression material and technique, not only can affect accuracy of transferring of the 3-dimentional spatial status of implant, but also can jeopardize the accurate recording of tooth. In the present study, the accuracy of two impression materials with taper impression copings for recording implant position and surface details was evaluated.   Materials and Methods: One metal reference model with 2 implants (Implantium and a preparation of three grooves on a tooth according to ADA no. 19 standard was fabricated. 10 medium- consistency polyEther (PE impressions using custom trays and 10 polyVinyl Siloxane (PVS putty wash impressions using prefabricated trays with conical impression coping were made. Impressions were poured with ADA type IV stone. A Coordinate Measuring Machine (CMM evaluated x, y and angular displacement of the implant analog heads and also accuracy of groove reproduction were measured using a Video Measuring Machine (VMM. These measurements were compared to the ones from reference model. Data were analyzed using one-way ANOVA and T-test.   Results: Putty wash PVS had less linear discrepancy compared with reference model (P > 0.001. There was no significant difference in the surface detail reproduction (P = 0.15.   Conclusion: Putty wash PVS had better results for linear displacement compared with medium consistency PE. There was no significant difference in surface detail reproduction between the two impression materials.

  2. Sulfonated poly(ether ether ketone)/zirconium tricarboxybutylphosphonate composite proton-exchange membranes for direct methanol fuel cells

    Qijun GAO; Mianyan HUANG; Yuxin WANG; Yuquan CAI; Li XU


    Sulfonated poly(ether ether ketone) (SPEEK) is a very promising alternative membrane material for direct methanol fuel cells. However, with a fairly high degree ofsulfonation (DS), SPEEK membranes can swell excessively and even dissolve at high temperature. This restricts mem-branes from working above a high tolerable temperature to get high proton conductivity. To deal with this contra-dictory situation, insolvable zirconium tricarboxybutyl-phosphonate (Zr(PBTC)) powder was employed to make a composite with SPEEK polymer in an attempt to improve temperature tolerance of the membranes. SPEEK/Zr(PBTC) composite membranes were obtained by casting a homogeneous mixture of Zr(PBTC) and SPEEK in N,N-dimethylacetamide on a glass plate and then evaporating the solvent at 60℃. Many characteristics were investigated, including thermal stability, liquid uptake, methanol permeability and proton conductivity. Results showed significant improvement not only in tem-perature tolerance, but also in methanol resistance of the SPEEK/Zr(PBTC) composite membranes. The mem-branes containing 30 wt-%~40 wt-% of Zr(PBTC) had their methanol permeability around 10-7 cm2·S-1 at room temperature to 80℃, which was one order of magnitudelower than that of Nafion 115. High proton conductivity of the composite membranes, however, could also be achieved from higher temperature applied. At 100% rela-tive humidity, above 90℃ the conductivity of the compo-site membrane containing 40 wt-% of Zr(PBTC) exceeded that of the Nafion 115 membrane and even reached a high value of 0.36 S·cm-1 at 160℃. Improved applicable tem-perature and high conductivity of the composite membrane indicated its promising application in DMFC operations at high temperature.

  3. Dihydrogenimidazole modified silica-sulfonated poly(ether ether ketone) hybrid materials as electrolyte membranes for direct ethanol fuel cells

    Roelofs, Kimball S.; Hirth, Thomas [Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstr. 12, 70569 Stuttgart (Germany); Schiestel, Thomas, E-mail: [Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstr. 12, 70569 Stuttgart (Germany)


    The present study reports on dihydrogenimidazole modified inorganic-organic mixed matrix membranes for possible application as a proton exchange membrane in direct ethanol fuel cells. The polymeric phase consisted mainly of sulfonated poly(ether ether ketone) (sPEEK) with a sulfonation degree of 55%. The inorganic phase was built up from hydrophilic fumed silica particles interconnected with partially hydrolyzed and condensed tetraethoxysilane with a total inorganic loading of 27.3%. This inorganic phase was further modified with N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole (DHIM), which consists of an hydrolyzable inorganic part and a functional organic group. The influence of the modifier on the mixed matrix system was studied by means of various modifier concentrations in various aqueous-ethanolic systems (water, 2 M and 4 M ethanol). Modifier concentration and ethanol concentration of the ethanol-water mixture exhibited significant but opposite effects on the liquid uptake of the mixed matrix membranes. The proton conductivity as well as the proton diffusion coefficient as a function of modifier content showed a linear decrease. The proton conductivity as a function of temperature showed Arrhenius behavior and the activation energy of the mixed matrix membranes was 43.9 {+-} 2.6 kJ mol{sup -1}. High selectivity of proton diffusion coefficient to ethanol permeability coefficient was obtained with high modifier concentrations. At low modifier concentrations, this selectivity was dominated by ethanol permeation and at high modifier concentrations by proton diffusion. The main electrolyte properties can be optimized by setting the DHIM content in mixed matrix membrane. With this approach, tailor-made membranes can be prepared for possible application in direct ethanol fuel cells.

  4. Synthesis and properties of aromatic polyethers containing poly(ethylene oxide) side chains as polymer electrolytes for lithium ion batteries

    Vöge, Andrea, E-mail: [Department of Chemistry, University of Patras, 26500 Patras (Greece); Deimede, Valadoula, E-mail: [Department of Chemistry, University of Patras, 26500 Patras (Greece); Paloukis, Fotis; Neophytides, Stylianos G. [Foundation of Research and Technology – Hellas, Institute of Chemical Engineering Sciences (FORTH/ICE-HT), Patras 26504 (Greece); Kallitsis, Joannis K. [Department of Chemistry, University of Patras, 26500 Patras (Greece)


    Polymer electrolytes consisting of polar pyridine units in the backbone and poly(ethylene oxide) (PEO) side chains are designed for possible application in lithium ion batteries. In particular, aromatic polyethers bearing PEO side chains with varying length are synthesized either by copolymerization of the corresponding PEO based diols with different arylfluorides or by modification of dihydroxyl functionalized precursor polymers with poly(ethylene oxide) methyl ether tosylate. The formation of free standing films is dependent on the PEO content, polymers' composition as well as on the different monomers used. The mechanical properties study shows that the glass transition temperature can be controlled by varying the PEO content. Thermal stability is also influenced by the PEO length: the shorter the PEO side chain, the higher the stability. XRD analysis gives information about the desired amorphous character of these polymers, which is independent of the PEO content. Solid polymer electrolytes prepared by blending the PEO-based polymers with lithium salt and PEO 2000 (used as plasticizer) show ambient temperature conductivities in the range of 10{sup −6} S/cm. To further improve conductivity doping of PEO-based polymers in liquid electrolyte (1 M LiPF{sub 6} in EC/DMC 1/1) in some cases results in high conductivities in the range of 10{sup −3} S cm{sup −1} at 80 °C. - Highlights: • Polymer electrolytes bearing PEO side chains of varying lengths were designed. • DMA and TGA show that T{sub g} and T{sub d} can be controlled by varying the PEO content. • XRD confirms polymers amorphous character, independent of the PEO content. • Membranes doped in liquid electrolyte have high conductivities (10{sup −3} S cm{sup −1}, 80 °C)

  5. State of the water in crosslinked sulfonated poly(ether ether ketone). Two-dimensional differential scanning calorimetry correlation mapping

    Al Lafi, Abdul G. [Department of Chemistry, Atomic Energy Commission, Damascus, P.O. Box 6091 (Syrian Arab Republic); Hay, James N., E-mail: [The School of Metallurgy and Materials, College of Physical Sciences and Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)


    Highlights: • 2D-DSC mapping was applied to analyze the heat flow responses of hydrated crosslinked sPEEK. • Two types of loosely bond water were observed. • The first was bond to the sulfonic acid groups and increased with ion exchange capacity. • The second was attributed to the polar groups introduced by ions irradiation and increased with crosslinking degree. • DSC combined with 2D mapping provides a powerful tool for polymer structural determination. - Abstract: This paper reports the first application of two-dimensional differential scanning calorimetry correlation mapping, 2D-DSC-CM to analyze the heat flow responses of sulphonated poly(ether ether ketone), sPEEK, films having different ion exchange capacity and degrees of crosslinks. With the help of high resolution and high sensitivity of 2D-DSC-CM, it was possible to locate two types of loosely bound water within the structure of crosslinked sPEEK. The first was bound to the sulfonic acid groups and dependent on the ion exchange capacity of the sPEEK. The second was bound to other polar groups, either introduced by irradiation with ions and dependent on the crosslinking degree or present in the polymer such as the carbonyl groups or terminal units. The results suggest that the ability of the sulfonic acid groups in the crosslinked sPEEK membranes to adsorb water molecules is increased by crosslinking, probably due to the better close packing efficiency of the crosslinked samples. DSC combined with 2D correlation mapping provides a fast and powerful tool for polymer structural determination.

  6. Photochemical modification of poly(ether sulfone) ultrafiltration membranes by UV-assisted graft polymerization for the prevention of biofouling

    Pieracci, John Paul

    Membranes are widely used by the biotechnology industry in the separation and recovery of proteins from biological solutions. Fouling of membrane surfaces by irreversible protein adsorption during ultrafiltration causes loss of membrane permeability and can reduce membrane selectivity and lead to significant product loss through denaturation. In this work, low fouling poly(ether sulfone) (PES) ultrafiltration membranes were produced by ultraviolet (UV) assisted graft polymerization of hydrophilic vinyl monomers using a newly developed photochemical dip modification technique. This technique was developed to make the UV modification process more easily adaptable to continuous membrane manufacturing processes. A method was also developed to measure and track the degree of polymer grafting on the membrane surface using attenuated total reflection Fourier transform infrared spectroscopy (FTIR/ATR). Grafting the hydrophilic monomer N-vinyl-2-pyrrolidinone (NVP) onto the membrane surface increased surface wettability and produced membranes with the high wettability of regenerated cellulose membranes. The enhanced surface wettability significantly decreased irreversible adsorptive fouling during the filtration of the protein bovine serum albumin (BSA). In order to maintain the rejection of BSA after modification, PES chain scission was tightly controlled by regulating the UV wavelength range and the light intensity used. The UV reactor system was operated with 300 nm UV lamps and a benzene filter used to remove high energy wavelengths below 275 nm that were determined to cause severe loss of BSA rejection due to pore enlargement from extensive chain scission. Dip modification caused membrane permeability to decrease due to the grafted chains blocking the membrane pores. The use of a chain transfer agent during modification followed by ethanol cleaning increased modified membrane permeability, but BSA rejection was severely decreased. The resultant membranes produced by


    程亮; 李洪伟; 孔令杰; 张东恒


    以氢氧化钾作为催化剂,环氧丙烷与环氧丁烷共聚制备了分别符合黏度级别 OSP-18,OSP-46, OSP-150要求的油溶性聚醚,并通过红外光谱(IR)、核磁共振(NMR)和凝胶渗透色谱(GPC)对其进行表征。利用旋转氧弹测试方法考察了油溶性聚醚的抗氧化性能,结果表明油溶性聚醚本身的抗氧化性能较差。通过考察不同抗氧剂与油溶性聚醚的互配性,开发了α-苯胺与氨基甲酸酯组成的复合抗氧剂,该复合抗氧剂与油溶性聚醚有较好的互配性,可使油溶性聚醚的旋转氧弹时间达到1200 min,复合抗氧剂可使油溶性聚醚在不同配方体系中得到应用。%Oil-soluble polyether (OSP)was prepared by the copolymerization of propylene oxide and butylene oxide using KOH as a catalyst.The viscosity grades of the prepared oil-soluble polyether are OSP-18,OSP-46,OSP-150,respectively.The structures of the products were defined by means of infra-red spectroscopy (IR),nuclear magnetic resonance (NMR)and gel permeation chromatography (GPC). The anti-oxidation performance of OSPs were investigated by rotary oxygen bomb test method (ROBT).The results indicate that the oil-soluble polyether is poor in anti-oxidation with short induc-tion period.However,the performance of the oil-soluble polyether is greatly improved by addition of the composite antioxidant,composed of α-aniline (AOA-4 )and carbamate (AOL-1 ). The ROBT can reach to 1 200 minutes.The performance of this composite antioxidant makes OSP the best application in different formulations.


    DONGShihua; LIUShi; 等


    Six novel resins impregnated with polyether or polythioether oligomers have been synthesized and their extraction properties have also been investigated.Gold(Ⅲ) and /or palladium (Ⅱ) coulld be extracted repidly by the resins with high percentage and capacities from aqueous solution but most of the co-existing base metal ions were remained.The extraction capacities and stripping percentage were approximately unchanged after four extraction-elution cycles and the resins also showed excellent column extraction-elution properties.

  9. Dependence of the chemical properties of macrocyclic [Ni(II)(2)L(μ-O(2)CR)](+) complexes on the basicity of the carboxylato coligands (L(2-) = macrocyclic N(6)S(2) ligand).

    Lehmann, Ulrike; Klingele, Julia; Lozan, Vasile; Steinfeld, Gunther; Klingele, Marco H; Käss, Steffen; Rodenstein, Axel; Kersting, Berthold


    The dependence of the properties of mixed ligand [Ni(II)(2)L(μ-O(2)CR)](+) complexes (where L(2-) represents a 24-membered macrocyclic hexaamine-dithiophenolato ligand) on the basicity of the carboxylato coligands has been examined. For this purpose 19 different [Ni(II)(2)L(μ-O(2)CR)](+) complexes (2-20) incorporating carboxylates with pK(b) values in the range 9 to 14 have been prepared by the reaction of [Ni(II)(2)L(μ-Cl)](+) (1) and the respective sodium or triethylammonium carboxylates. The resulting carboxylato complexes, isolated as ClO(4)(-) or BPh(4)(-) salts, have been fully characterized by elemental analyses, IR, UV/vis spectroscopy, and X-ray crystallography. The possibility of accessing the [Ni(II)(2)L(μ-O(2)CR)](+) complexes by carboxylate exchange reactions has also been examined. The main findings are as follows: (i) Substitution reactions between 1 and NaO(2)CR are not affected by the basicity or the steric hindrance of the carboxylate. (ii) Complexes 2-20 form an isostructural series of bisoctahedral [Ni(II)(2)L(μ-O(2)CR)](+) compounds with a N(3)Ni(μ-SR)(2)(μ-O(2)CR)NiN(3) core. (iii) They are readily identified by their ν(as)(CO) and ν(s)(CO) stretching vibration bands in the ranges 1684-1576 cm(-1) and 1428-1348 cm(-1), respectively. (iv) The spin-allowed (3)A(2g) → (3)T(2g) (ν(1)) transition of the NiOS(2)N(3) chromophore is steadily red-shifted by about 7.5 nm per pK(b) unit with increasing pK(b) of the carboxylate ion. (v) The less basic the carboxylate ion, the more stable the complex. The stability difference across the series, estimated from the difference of the individual ligand field stabilization energies (LFSE), amounts to about 4.2 kJ/mol [Δ(LFSE)(2,18)]. (vi) The "second-sphere stabilization" of the nickel complexes is not reflected in the electronic absorption spectra, as these forces are aligned perpendicularly to the Ni-O bonds. (vii) Coordination of a basic carboxylate donor to the [Ni(II)(2)L](2+) fragment weakens

  10. Polybenzimidazole compounds

    Klaehn, John R.; Peterson, Eric S.; Wertsching, Alan K.; Orme, Christopher J.; Luther, Thomas A.; Jones, Michael G.


    A PBI compound that includes imidazole nitrogens, at least a portion of which are substituted with an organic-inorganic hybrid moiety. At least 85% of the imidazole nitrogens may be substituted. The organic-inorganic hybrid moiety may be an organosilane moiety, for example, (R)Me.sub.2SiCH.sub.2--, where R is selected from among methyl, phenyl, vinyl, and allyl. The PBI compound may exhibit similar thermal properties in comparison to the unsubstituted PBI. The PBI compound may exhibit a solubility in an organic solvent greater than the solubility of the unsubstituted PBI. The PBI compound may be included in separatory media. A substituted PBI synthesis method may include providing a parent PBI in a less than 5 wt % solvent solution. Substituting may occur at about room temperature and/or at about atmospheric pressure. Substituting may use at least five equivalents in relation to the imidazole nitrogens to be substituted or, preferably, about fifteen equivalents.

  11. “One Ring to Bind Them All”—Part I: The Efficiency of the Macrocyclic Scaffold for G-Quadruplex DNA Recognition

    David Monchaud


    Full Text Available Macrocyclic scaffolds are particularly attractive for designing selective G-quadruplex ligands essentially because, on one hand, they show a poor affinity for the “standard” B-DNA conformation and, on the other hand, they fit nicely with the external G-quartets of quadruplexes. Stimulated by the pioneering studies on the cationic porphyrin TMPyP4 and the natural product telomestatin, follow-up studies have developed, rapidly leading to a large diversity of macrocyclic structures with remarkable-quadruplex binding properties and biological activities. In this review we summarize the current state of the art in detailing the three main categories of quadruplex-binding macrocycles described so far (telomestatin-like polyheteroarenes, porphyrins and derivatives, polyammonium cyclophanes, and in addressing both synthetic issues and biological aspects.

  12. Cationic Copolymerization of 3,3-Bis(hydroxymethyl)oxetane and Glycidol: Biocompatible Hyperbranched Polyether Polyols with High Content of Primary Hydroxyl Groups.

    Christ, Eva-Maria; Hobernik, Dominika; Bros, Matthias; Wagner, Manfred; Frey, Holger


    The cationic ring-opening copolymerization of 3,3-bis(hydroxymethyl)oxetane (BHMO) with glycidol using different comonomer ratios (BHMO content from 25 to 90%) and BF3OEt2 as an initiator has been studied. Apparent molecular weights of the resulting hyperbranched polyether copolymers ranged from 1400 to 3300 g mol(-1) (PDI: 1.21-1.48; method: SEC, linear PEG standards). Incorporation of both comonomers is evidenced by MALDI-TOF mass spectroscopy. All hyperbranched polyether polyols with high content of primary hydroxyl groups portray good solubility in water, which correlates with an increasing content of glycerol units. Detailed NMR characterization was employed to elucidate the copolymer microstructures. Kinetic studies via FTIR demonstrated a weak gradient-type character of the copolymers. MTT assays of the copolymers (up to 100 μg mL(-1)) on HEK and fibroblast cell lines (3T3, L929, WEHI) as well as viability tests on the fibroblast cells were carried out to assess the biocompatibility of the materials, confirming excellent biocompatibility. Transfection efficiency characterization by flow cytometry and confocal laser microscopy demonstrated cellular uptake of the copolymers. Antiadhesive properties of the materials on surfaces were assessed by adhesion assays with fibroblast cells.

  13. Intermediates in monensin biosynthesis: A late step in biosynthesis of the polyether ionophore monensin is crucial for the integrity of cation binding

    Wolfgang Hüttel


    Full Text Available Polyether antibiotics such as monensin are biosynthesised via a cascade of directed ring expansions operating on a putative polyepoxide precursor. The resulting structures containing fused cyclic ethers and a lipophilic backbone can form strong ionophoric complexes with certain metal cations. In this work, we demonstrate for monensin biosynthesis that, as well as ether formation, a late-stage hydroxylation step is crucial for the correct formation of the sodium monensin complex. We have investigated the last two steps in monensin biosynthesis, namely hydroxylation catalysed by the P450 monooxygenase MonD and O-methylation catalysed by the methyl-transferase MonE. The corresponding genes were deleted in-frame in a monensin-overproducing strain of Streptomyces cinnamonensis. The mutants produced the expected monensin derivatives in excellent yields (ΔmonD: 1.13 g L−1 dehydroxymonensin; ΔmonE: 0.50 g L−1 demethylmonensin; and double mutant ΔmonDΔmonE: 0.34 g L−1 dehydroxydemethylmonensin. Single crystals were obtained from purified fractions of dehydroxymonensin and demethylmonensin. X-ray structure analysis revealed that the conformation of sodium dimethylmonensin is very similar to that of sodium monensin. In contrast, the coordination of the sodium ion is significantly different in the sodium dehydroxymonensin complex. This shows that the final constitution of the sodium monensin complex requires this tailoring step as well as polyether formation.

  14. 聚醚嵌段改性硅油的合成与应用%Synthesis and Application of Polyether Block Modified Amino Silicone Oil

    刘瑞云; 缪瑶生; 蒋英妹


    将端含氢硅油与烯丙基聚氧烷乙基环氧基醚进行加成反应,再使用端氨基聚醚对其进行氨化反应,得到聚醚嵌段改性硅油.并用于全棉织物、涤棉织物的整理.结果表明:经聚醚嵌段改性硅油整理后的织物具有良好的亲水性、手感、白度等.%Side hydrogen silicone oil was reacted with polyoxyethylene alkyl allyl ether through hydrosily-lation and the product was then aminated with an amino-terminated polyoxypropylene, to afford a polyether block modified amino silicone oil, which was used for the finishing of cotton and polyester fabric. Results showed that the fabric treated with polyether-block modified silicone oil BW has a good performance of hydro-philicity, feel and whiteness.

  15. Intermediates in monensin biosynthesis: A late step in biosynthesis of the polyether ionophore monensin is crucial for the integrity of cation binding

    Spencer, Jonathan B; Leadlay, Peter F


    Summary Polyether antibiotics such as monensin are biosynthesised via a cascade of directed ring expansions operating on a putative polyepoxide precursor. The resulting structures containing fused cyclic ethers and a lipophilic backbone can form strong ionophoric complexes with certain metal cations. In this work, we demonstrate for monensin biosynthesis that, as well as ether formation, a late-stage hydroxylation step is crucial for the correct formation of the sodium monensin complex. We have investigated the last two steps in monensin biosynthesis, namely hydroxylation catalysed by the P450 monooxygenase MonD and O-methylation catalysed by the methyl-transferase MonE. The corresponding genes were deleted in-frame in a monensin-overproducing strain of Streptomyces cinnamonensis. The mutants produced the expected monensin derivatives in excellent yields (ΔmonD: 1.13 g L−1 dehydroxymonensin; ΔmonE: 0.50 g L−1 demethylmonensin; and double mutant ΔmonDΔmonE: 0.34 g L−1 dehydroxydemethylmonensin). Single crystals were obtained from purified fractions of dehydroxymonensin and demethylmonensin. X-ray structure analysis revealed that the conformation of sodium dimethylmonensin is very similar to that of sodium monensin. In contrast, the coordination of the sodium ion is significantly different in the sodium dehydroxymonensin complex. This shows that the final constitution of the sodium monensin complex requires this tailoring step as well as polyether formation. PMID:24605157

  16. μ-Nitrido Diiron Macrocyclic Platform: Particular Structure for Particular Catalysis.

    Afanasiev, Pavel; Sorokin, Alexander B


    The ultimate objective of bioinspired catalysis is the development of efficient and clean chemical processes. Cytochrome P450 and soluble methane monooxygenase enzymes efficiently catalyze many challenging reactions. Extensive research has been performed to mimic their exciting chemistry, aiming to create efficient chemical catalysts for functionalization of strong C-H bonds. Two current biomimetic approaches are based on (i) mononuclear metal porphyrin-like complexes and (ii) iron and diiron non-heme complexes. However, biomimetic catalysts capable of oxidizing CH4 are still to be created. In the search for powerful oxidizing catalysts, we have recently proposed a new bioinspired strategy using N-bridged diiron phthalocyanine and porphyrin complexes. This platform is particularly suitable for stabilization of Fe(IV)Fe(IV) complexes and can be useful to generate high-valent oxidizing active species. Indeed, the possibility of charge delocalization on two iron centers, two macrocyclic ligands, and the nitrogen bridge makes possible the activation of H2O2 and peracids. The ultrahigh-valent diiron-oxo species (L)Fe(IV)-N-Fe(IV)(L(+•))═O (L = porphyrin or phthalocyanine) have been prepared at low temperatures and characterized by cryospray MS, UV-vis, EPR, and Mössbauer techniques. The highly electrophilic (L)Fe(IV)-N-Fe(IV)(L(+•))═O species exhibit remarkable reactivity. In this Account, we describe the catalytic applications of μ-nitrido diiron complexes in the oxidation of methane and benzene, in the transformation of aromatic C-F bonds under oxidative conditions, in oxidative dechlorination, and in the formation of C-C bonds. Importantly, all of these reactions can be performed under mild and clean conditions with high conversions and turnover numbers. μ-Nitrido diiron species retain their binuclear structure during catalysis and show the same mechanistic features (e.g., (18)O labeling, formation of benzene epoxide, and NIH shift in aromatic oxidation

  17. Molecular Assemblies of Porphyrins and Macrocyclic Receptors: Recent Developments in Their Synthesis and Applications

    Abdirahman A. Mohamod


    Full Text Available Metalloporphyrins which form the core of many bioenzymes and natural light harvesting or electron transport systems, exhibit a variety of selective functional properties depending on the state and surroundings with which they exist in biological systems. The specificity and ease with which they function in each of their bio-functions appear to be largely governed by the nature and disposition of the protein globule around the porphyrin reaction center. Synthetic porphyrin frameworks confined within or around a pre-organized molecular entity like the protein network in natural systems have attracted considerable attraction, especially in the field of biomimetic reactions. At the same time a large number of macrocyclic oligomers such as calixarenes, resorcinarenes, spherands, cyclodextrins and crown ethers have been investigated in detail as efficient molecular receptors. These molecular receptors are synthetic host molecules with enclosed interiors, which are designed three dimensionally to ensure strong and precise molecular encapsulation/recognition. Due to their complex structures, enclosed guest molecules reside in an environment isolated from the outside and as a consequence, physical properties and chemical reactions specific to that environment in these guest species can be identified. The facile incorporation of such molecular receptors into the highly photoactive and catalytically efficient porphyrin framework allows for convenient design of useful molecular systems with unique structural and functional properties. Such systems have provided over the years attractive model systems for the study of various biological and chemical processes, and the design of new materials and molecular devices. This review focuses on the recent developments in the synthesis of porphyrin assemblies associated with cyclodextrins, calixarenes and resorcinarenes and their potential applications in the fields of molecular encapsulation/recognition, and

  18. Molecular mechanics approach for design and conformational studies of macrocyclic ligands

    Rohini,; Akbar, Rifat; Kanungo, B. K., E-mail: [Department of Chemistry, Sant Longowal Institute of Engineering & Technology, Longowal-148106 (India)


    Computational Chemistry has revolutionized way of viewing molecules at the quantum mechanical scale by allowing simulating various chemical scenarios that are not possible to study in a laboratory. The remarkable applications of computational chemistry have promoted to design and test of the effectiveness of various methods for searching the conformational space of highly flexible molecules. In this context, we conducted a series of optimization and conformational searches on macrocyclic based ligands, 9N3Me5Ox, (1,4,7-tris(5-methyl-8-hydroxyquinoline)-1,4,7-triazacyclononane) and 12N3Me5Ox, (1,5,9-tris(5-methyl-8-hydroxyquinoline)-1,5,9-triazacyclododecane) and studied their selectivity and coordination behavior with some lanthanide metal ions in molecular mechanics and semiempirical methods. The methods include both systematic and random conformational searches for dihedral angles, torsion angles and Cartesian coordinates. Structural studies were carried out by using geometry optimization, coordination scans and electronic properties were evaluated. The results clearly show that chair-boat conformational isomer of 9N3Me5Ox ligand is more stable due to lower eclipsing ethane interaction and form stronger adduct complexes with lanthanide metal ion. This is because of the fact that, in a central unit of 9N3 of the ligand form six endo type bonds out of nine. The rest of bonds have trans conformation. In contrast, for the adduct of 12N3Me5Ox, two C-C bonds have on eclipsed conformation, and others have synclinal and antiperiplanar confirmations. The distortion of the two eclipsed conformations may affect the yields and the stability of the complexes.

  19. Synthesis of Cycloveratrylene Macrocycles and Benzyl Oligomers Catalysed by Bentonite under Microwave/Infrared and Solvent-Free Conditions

    Manuel Salmón


    Full Text Available Tonsil Actisil FF, which is a commercial bentonitic clay, promotes the formation of cycloveratrylene macrocycles and benzyl oligomers from the corresponding benzyl alcohols in good yields under microwave heating and infrared irradiation in the absence of solvent in both cases. The catalytic reaction is sensitive to the type of substituent on the aromatic ring. Thus, when benzyl alcohol was substituted with a methylenedioxy, two methoxy or three methoxy groups, a cyclooligomerisation process was induced. Unsubstituted, methyl and methoxy benzyl alcohols yielded linear oligomers. In addition, computational chemistry calculations were performed to establish a validated mechanistic pathway to explain the growth of the obtained linear oligomers.

  20. Cationic lipids bearing succinic-based, acyclic and macrocyclic hydrophobic domains: synthetic studies and in vitro gene transfer

    Jubeli, Emile; Maginty, A. B.; Khalique, N. A.;


    a dimethylamine or trimethylamine headgroup, and a macrocyclic or an acyclic hydrophobic domain composed of, or derived from two 16-atom, succinic-based acyl chains. The synthesized lipids and a co-lipid of neutral charge, either cholesterol or 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), were formulated...... within the hydrophobic domain of the cationic lipids was found to improve lipid hydration. The transfection assays revealed a general trend in which mismatched formulations that employed a rigid lipid combined with a non-rigid (or flexible) lipid, outperformed the matched formulations. The results from...