Sample records for michael reaction acceptors

  1. Physalins with anti-inflammatory activity are present in Physalis alkekengi var. franchetii and can function as Michael reaction acceptors.

    Ji, Long; Yuan, Yonglei; Luo, Liping; Chen, Zhe; Ma, Xiaoqiong; Ma, Zhongjun; Cheng, Lin


    Michael reaction acceptors (MRAs) are a class of active molecules that are directly or indirectly involved in various cellular processes, including the regulation of many signaling pathways. In this study, the inducible nitric oxide synthase (iNOS) assay was used to demonstrate that the dichloromethane extract of Physalis alkekengi var. franchetii (DCEP) possesses anti-inflammatory activity that might be attributed to the modification of key cysteine residues in IKKβ by the MRAs in DCEP. To isolate these MRAs, glutathione (GSH) was employed, and a simple ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) screening method was developed to investigate the GSH conjugates with potential MRAs. Five physalins, including one new compound isophysalin A (2), together with four known steroidal compounds, physalin A (1), physalin O (3), physalin L (4) and physalin G (5), were isolated to evaluate the GSH conjugating abilities, and it was indicated that compounds 1, 2 and 3, which had a common α,β-unsaturated ketone moiety, exhibited conjugating abilities with GSH and also showed significant nitric oxide (NO) production inhibiting activities. The anti-inflammatory activities of compounds 1, 2 and 3 might be attributed to their targeting multiple cysteine residues on IKKβ; therefore, the alkylation of IKKβ by compound 1 was further studied by micrOTOF-MS. The result showed that six cysteine residues (C(59), C(179), C(299), C(370), C(412), and C(618)) were alkylated, which indicated that IKKβ is a potential target for the anti-inflammatory activity of physalin A.

  2. Glutathione Adduct Patterns of Michael-Acceptor Carbonyls.

    Slawik, Christian; Rickmeyer, Christiane; Brehm, Martin; Böhme, Alexander; Schüürmann, Gerrit


    Glutathione (GSH) has so far been considered to facilitate detoxification of soft organic electrophiles through covalent binding at its cysteine (Cys) thiol group, followed by stepwise catalyzed degradation and eventual elimination along the mercapturic acid pathway. Here we show that in contrast to expectation from HSAB theory, Michael-acceptor ketones, aldehydes and esters may form also single, double and triple adducts with GSH involving β-carbon attack at the much harder N-terminus of the γ-glutamyl (Glu) unit of GSH. In particular, formation of the GSH-N single adduct contradicts the traditional view that S alkylation always forms the initial reaction of GSH with Michael-acceptor carbonyls. To this end, chemoassay analyses of the adduct formation of GSH with nine α,β-unsaturated carbonyls employing high performance liquid chromatography and tandem mass spectrometry have been performed. Besides enriching the GSH adductome and potential biomarker applications, electrophilic N-terminus functio-nalization is likely to impair GSH homeostasis substantially through blocking the γ-glutamyl transferase catalysis of the first breakdown step of modified GSH, and thus its timely reconstitution. The discussion includes a comparison with cyclic adducts of GSH and furan metabolites as reported in literature, and quantum chemically calculated thermodynamics of hard-hard, hard-soft and soft-soft adducts.

  3. Organocatalytic aza-Michael/retro-aza-Michael reaction: pronounced chirality amplification in aza-Michael reaction and racemization via retro-aza-Michael reaction.

    Cai, Yong-Feng; Li, Li; Luo, Meng-Xian; Yang, Ke-Fang; Lai, Guo-Qiao; Jiang, Jian-Xiong; Xu, Li-Wen


    A detailed experimental investigation of an aza-Michael reaction of aniline and chalcone is presented. A series of Cinchona alkaloid-derived organocatalysts with different functional groups were prepared and used in the aza-Michael and retro-aza-Michael reaction. There was an interesting finding that a complete reversal of stereoselectivity when a benzoyl group was introduced to the cinchonine and cinchonidine. The chirality amplification vs. time proceeds in the quinine-derived organocatalyst containing silicon-based bulky group, QN-TBS, -catalyzed aza-Michael reaction under solvent-free conditions. In addition, we have demonstrated for the first time that racemization was occurred in suitable solvents under mild conditions due to retro-aza-Michael reaction of the Michael adduct of aniline with chalcone. These indicate the equilibrium of retro-aza-Michael reaction and aza-Michael reaction produce the happening of chirality amplification in aza-Michael reaction and racemization via retro-aza-Michael reaction under different conditions, which would be beneficial to the development of novel chiral catalysts for the aza-Michael reactions.

  4. Enantioselective Synthesis of β-(3-Hydroxypyrazol-1-yl)ketones Using An Organocatalyzed Michael Addition Reaction

    Gogoi, Sanjib; Zhao, Cong-Gui; Ding, Derong


    β-(3-Hydroxypyrazol-1-yl)ketones have been prepared in high yields and excellent enantioselectivities (94–98% ee) via a Michael addition reaction between 2-pyrazolin-5-ones and aliphatic acyclic α,β-unsaturated ketones using 9-epi-9-amino-9-deoxyquinine as the catalyst. These results account for the first example of an aza-Michael addition of the ambident 2-pyrazolin-5-one anion to a Michael acceptor. PMID:19415906

  5. Insight into the Mechanism of the Michael Reaction.

    Giraldo, Carolina; Gómez, Sara; Weinhold, Frank; Restrepo, Albeiro


    The mechanism for the nucleophilic addition step of the Michael reaction between methanethiol as a model Michael donor and several α-substituted methyl acrylates (X=F, Cl, Me, H, CN, NO2 ) as model Michael acceptors is described in detail. We suggest a novel way to condense electrophilic Fukui functions at specific atoms in terms of the contributions from the atomic orbitals to the LUMO or, more generally, to the orbital controlling the reaction. This procedure correctly associates activation energies to local electrophilic Fukui indices for the cases treated in this work. The calculated reaction barriers strongly depend on the nature of the substituent. As a general rule, activation energies are governed by structural changes, although electronic factors are significant for electron-withdrawing groups. Nucleophilic addition to Michael receptors is best described as a highly nonsynchronous process, in which the geometry of the transition state comprises a nonplanar six-membered ring. Formation of the S⋅⋅⋅C bond, which defines the interaction between the reactants, progresses ahead of all other primitive processes in the early stages of the transformation. In view of our results, we postulate that highly complex chemical reactions, as is the case for the nucleophilic addition step studied herein, that involve cleavage/formation of a total of six bonds, lower their activation energies by favoring nonsynchronicity, that is, for these types of systems, primitive changes should advance at different rates.

  6. Copper-catalyzed asymmetric conjugate addition of organometallic reagents to extended Michael acceptors

    Thibault E. Schmid


    Full Text Available The copper-catalyzed asymmetric conjugate addition (ACA of nucleophiles onto polyenic Michael acceptors represents an attractive and powerful methodology for the synthesis of relevant chiral molecules, as it enables in a straightforward manner the sequential generation of two or more stereogenic centers. In the last decade, various chiral copper-based catalysts were evaluated in combination with different nucleophiles and Michael acceptors, and have unambiguously demonstrated their usefulness in the control of the regio- and enantioselectivity of the addition. The aim of this review is to report recent breakthroughs achieved in this challenging field.

  7. Phthalimides as exceptionally efficient single electron transfer acceptors in reductive coupling reactions promoted by samarium diiodide.

    Vacas, Tatiana; Alvarez, Eleuterio; Chiara, Jose Luis


    Experimental and theoretical evidence shows that phthalimides are highly efficient single electron transfer acceptors in reactions promoted by samarium diiodide, affording ketyl radical anion intermediates, which participate in high-yielding inter- and intramolecular reductive coupling processes with different radicophiles including imides, oxime ethers, nitrones, and Michael acceptors.

  8. Rh(III)-Catalyzed C-H Bond Addition/Amine-Mediated Cyclization of Bis-Michael Acceptors.

    Potter, Tyler J; Ellman, Jonathan A


    A Rh(III)-catalyzed C-H bond addition/primary amine-promoted cyclization of bis-Michael acceptors is reported. The C-H bond addition step occurs with high chemoselectivity, and the subsequent intramolecular Michael addition, mediated by a primary amine catalyst, sets three contiguous stereocenters with high diastereoselectivity. A broad range of directing groups and both aromatic and alkenyl C-H bonds were shown to be effective in this transformation, affording functionalized piperidines, tetrahydropyrans, and cyclohexanes.

  9. Aza‐Michael addition reaction: Post‐polymerization modification and preparation of PEI/PEG‐based polyester hydrogels from enzymatically synthesized reactive polymers

    Hoffmann, Christian; Stuparu, Mihaiela C.; Daugaard, Anders Egede


    monomers provides the polyesters, which carry an activated carbon‐carbon double bond in the polymer backbone. These electron deficient alkenes represent suitable aza‐Michael acceptors and can be engaged in a nucleophilic addition reaction with small molecular mono‐amines (aza‐Michael donors) to yield...

  10. The reaction of choline dehydrogenase with some electron acceptors.

    Barrett, M C; Dawson, A P


    1. The choline dehydrogenase (EC WAS SOLUBILIZED FROM ACETONE-DRIED POWDERS OF RAT LIVER MITOCHONDRIA BY TREATMENT WITH Naja naja venom. 2. The kinetics of the reaction of enzyme with phenazine methosulphate and ubiquinone-2 as electron acceptors were investigated. 3. With both electron acceptors the reaction mechanism appears to involve a free, modified-enzyme intermediate. 4. With some electron acceptors the maximum velocity of the reaction is independent of the nature of the acceptor. With phenazine methosulphate and ubiquinone-2 as acceptors the Km value for choline is also independent of the nature of the acceptor molecule. 5. The mechanism of the Triton X-100-solubilized enzyme is apparently the smae as that for the snake venom solubilized enzyme.

  11. Covalent Modifiers: A Chemical Perspective on the Reactivity of α,β-Unsaturated Carbonyls with Thiols via Hetero-Michael Addition Reactions.

    Jackson, Paul A; Widen, John C; Harki, Daniel A; Brummond, Kay M


    Although Michael acceptors display a potent and broad spectrum of bioactivity, they have largely been ignored in drug discovery because of their presumed indiscriminate reactivity. As such, a dearth of information exists relevant to the thiol reactivity of natural products and their analogues possessing this moiety. In the midst of recently approved acrylamide-containing drugs, it is clear that a good understanding of the hetero-Michael addition reaction and the relative reactivities of biological thiols with Michael acceptors under physiological conditions is needed for the design and use of these compounds as biological tools and potential therapeutics. This Perspective provides information that will contribute to this understanding, such as kinetics of thiol addition reactions, bioactivities, as well as steric and electronic factors that influence the electrophilicity and reversibility of Michael acceptors. This Perspective is focused on α,β-unsaturated carbonyls given their preponderance in bioactive natural products.

  12. Lipase-Catalyzed Aza-Michael Reaction on Acrylate Derivatives

    Steunenberg, P.; Sijm, M.; Zuilhof, H.; Sanders, J.P.M.; Scott, E.L.; Franssen, M.C.R.


    A methodology has been developed for an efficient and selective lipase-catalyzed aza-Michael reaction of various amines (primary and secondary) with a series of acrylates and alkylacrylates. Reaction parameters were tuned, and under the optimal conditions it was found that Pseudomonas stutzeri lipas

  13. Aza-Michael Reaction for an Undergraduate Organic Chemistry Laboratory

    Nigam, Manisha; Rush, Brittney; Patel, Jay; Castillo, Raul; Dhar, Preeti


    A green, aza-Michael reaction is described that can be used to teach undergraduate students conjugate addition of nitrogen nucleophile to an a,ß-unsaturated ester. Students analyze spectral data of the product obtained from the assigned reaction to determine product structure and propose the mechanism of its formation. The experiment requires…

  14. Aza-Michael Reaction for an Undergraduate Organic Chemistry Laboratory

    Nigam, Manisha; Rush, Brittney; Patel, Jay; Castillo, Raul; Dhar, Preeti


    A green, aza-Michael reaction is described that can be used to teach undergraduate students conjugate addition of nitrogen nucleophile to an a,ß-unsaturated ester. Students analyze spectral data of the product obtained from the assigned reaction to determine product structure and propose the mechanism of its formation. The experiment requires…

  15. Double Michael Addition Reaction of Bischalcone under Ultrasound

    LI,Ji-Tai; XU,Wen-Zhi; CHEN,Guo-Feng; LI,Tong-Shuang


    @@ The Michael addition of 1,5-diaryl-1,4-pentadien-3-ones with active methylene compounds has been the subjects of many investigations. Ultrasound has increasingly been used in organic synthesis in the last three decades. Compared with traditional methods, this method is more convenient and easily controlled. A large number of organic reactions can be carried out in higher yield, shorter reaction time or milder conditions under ultrasonic irradiation. KF/Al2O3 as a useful solid supported catalyst has received considerable attention because of their high level of chemoselectivity and environmental compatibility as well as simplicity of operation and their ready availability at low cost. Herein we report the double Michael addition of dibenzalacetone with active methlene compounds such as dimethyl malonate, diethyl malonate,methyl cyanoacetate and ethyl cyanoacetate catalyzed by KF/Al2O3 under ultrasound irradiation.

  16. Photoredox radical conjugate addition of dithiane-2-carboxylate promoted by an iridium(iii) phenyl-tetrazole complex: a formal radical methylation of Michael acceptors.

    Gualandi, Andrea; Matteucci, Elia; Monti, Filippo; Baschieri, Andrea; Armaroli, Nicola; Sambri, Letizia; Cozzi, Pier Giorgio


    A readily accessible iridium(iii) phenyl-tetrazole complex ([Ir(ptrz)2(tBu-bpy)](+), 2; Hptrz = 2-methyl-5-phenyl-tetrazole; tBu-bpy = 4,4'-di-tert-butyl-2,2'-bipyridine) is shown to be a versatile catalyst for a new photocatalytic Michael reaction. Under light irradiation in the presence of 2, a dithiane 2-carboxylic acid, obtained by simple hydrolysis of a commercially available ethyl ester, generates a 1,3-dithiane radical capable of performing addition to a variety of Michael acceptors (e.g., unsaturated ketones, esters, amides and malonates). This broad scope reaction with high yields is a formal photo-redox addition of the elusive methyl radical and the adducts obtained can be starting materials for a variety of functionalized products. The excited-state oxidation potential of catalyst 2 allows selective formation of radicals only from α-heterosubstituted carboxylates. Chemical modification of this metal complex can tune the electrochemical properties, opening a route to new highly selective catalytic photo-oxidation reactions.

  17. Chemistry of sulfonylmethyl isocyanides. 45. A direct synthesis of 2-(trimethylstannyl)pyrroles from Michael acceptors and stannylated tosylmethyl isocyanide

    Dijkstra, HP; ten Have, Ronald; van Leusen, A.M.


    A series of 2-(trimethylstannyl)pyrroles 3, with substituents at the 3- and 4-positions, is synthesized efficiently by a base-induced reaction of stannylated TosMIC with Michael accepters. Stills cross-couplings with bromobenzene and double cross-couplings with 1,4-dibromobenzene have been achieved

  18. Proline Based Chiral Ionic Liquids for Enantioselective Michael Reaction

    Kaoru Nobuoka


    Full Text Available Chiral ionic liquids, starting from (S-proline, have been prepared and evaluated the ability of a chiral catalyst. In Michael reaction of trans-β-nitrostyrene and cyclohexanone, all the reactions were carried out under homogeneous conditions without any solvent except for excess cyclohexanone. The chiral ionic liquid catalyst with the positive charge delocalized bulky pyrrolidinium cation shows excellent yields (up to 92%, diastereoselectivities (syn/anti = 96/4, and enantioselectivities (up to 95% ee and could be reused at least three times without any loss of its catalytic activity. Such results demonstrated a promising new approach for green and economic chiral synthesis by using the chiral ionic liquids as a chiral catalyst and a chiral medium.

  19. Solvent-free Michael addition reaction of fluorene with chalcon

    Fu Feng


    A series of novel Michael addition products of fluorene to chalcone were obtained in the presence of sodium hydroxide under solvent-free condition. The advantages of this procedure were mild reaction conditions, simple protocol, and high yields. The structures of the products were characterized by IR, 1H NMR, MS and X-ray diffraction. The crystal of the new compound 3 h is y= 64.2440(10)°, V = 2.4137(3) nm3, Z= 4, Dc=1.220 g/cm3, μ = 0.286 mm-1, F(000) = 920, R = 0.0656 and wR = 0.1554 for 5664 observed reflection with I > 2σ(I).

  20. Asymmetric Michael Reaction of Malononitrile Catalyzed by Chiral Ru(Ⅱ) Complex and Achiral Base

    MA Ya-Ping; XING Zhi-Kui; ZHU Jin; CUI Xin; CUN Lin-Feng; DENG Jin-Gen


    @@ Michael addition reactions represent one of the most important carbon-carbon bond forming reactions in modern synthetic organic chemistry. [1 ~3] We achieved catalytic enantioselective Michael addition reactions of malononitrile with chiral vicinal diamine-Ru(Ⅱ) complex in the presence of achiral base. High yields and moderate ee were observed.

  1. Asymmetric synthesis of α-amino acids via homologation of Ni(II) complexes of glycine Schiff bases. Part 3: Michael addition reactions and miscellaneous transformations.

    Aceña, José Luis; Sorochinsky, Alexander E; Soloshonok, Vadim


    The major goal of this review is a critical discussion of the literature data on asymmetric synthesis of α-amino acids via Michael addition reactions involving Ni(II)-complexes of amino acids. The material covered is divided into two conceptually different groups dealing with applications of: (a) Ni(II)-complexes of glycine as C-nucleophiles and (b) Ni(II)-complexes of dehydroalanine as Michael acceptors. The first group is significantly larger and consequently subdivided into four chapters based on the source of stereocontrolling element. Thus, a chiral auxiliary can be used as a part of nucleophilic glycine Ni(II) complex, Michael acceptor or both, leading to the conditions of matching vs. mismatching stereochemical preferences. The particular focus of the review is made on the practical aspects of the methodology under discussion and mechanistic considerations.

  2. Domino Michael-Michael and Aldol-Aldol Reactions: Diastereoselective Synthesis of Functionalized Cyclohexanone Derivatives Containing Quaternary Carbon Center.

    Ghorai, Manas K; Halder, Sandipan; Das, Subhomoy


    A simple strategy for the synthesis of highly functionalized cyclohexanone derivatives containing an all-carbon quaternary center from α-(aryl/alkyl)methylidene-β-keto esters or β-diketones via a K-enolate mediated domino Michael-Michael reaction sequence with moderate to good yield and excellent diastereoselectivity (de > 99%) is described. Interestingly, Li-base mediated reaction of α-arylmethylidene-β-diketones affords functionalized 3,5-dihydroxy cyclohexane derivatives as the kinetically controlled products via a domino aldol-aldol reaction sequence with excellent diastereoselectivity. Li-enolates of the β-keto esters or β-diketones undergo facile domino Michael-Michael reaction with nitro-olefins to afford the corresponding nitrocyclohexane derivatives in good yields and excellent diastereoselectivity (de > 99%). The formation of the products and the observed stereoselectivity were explained by plausible mechanisms and supported by extensive computational study. An asymmetric version of the protocol was explored with (L)-menthol derived nonracemic substrates, and the corresponding nonracemic cyclohexanone derivatives containing an all-carbon quaternary center were obtained with excellent stereoselectivity (de, ee > 99%).

  3. Synthesis, chemical reactivity as Michael acceptors, and biological potency of monocyclic cyanoenones, novel and highly potent anti-inflammatory and cytoprotective agents.

    Zheng, Suqing; Santosh Laxmi, Y R; David, Emilie; Dinkova-Kostova, Albena T; Shiavoni, Katherine H; Ren, Yanqing; Zheng, Ying; Trevino, Isaac; Bumeister, Ronald; Ojima, Iwao; Wigley, W Christian; Bliska, James B; Mierke, Dale F; Honda, Tadashi


    Novel monocyclic cyanoenones examined to date display unique features regarding chemical reactivity as Michael acceptors and biological potency. Remarkably, in some biological assays, the simple structure is more potent than pentacyclic triterpenoids (e.g., CDDO and bardoxolone methyl) and tricycles (e.g., TBE-31). Among monocyclic cyanoenones, 1 is a highly reactive Michael acceptor with thiol nucleophiles. Furthermore, an important feature of 1 is that its Michael addition is reversible. For the inhibition of NO production, 1 shows the highest potency. Notably, its potency is about three times higher than CDDO, whose methyl ester (bardoxolone methyl) is presently in phase III clinical trials. For the induction of NQO1, 1 also demonstrated the highest potency. These results suggest that the reactivity of these Michael acceptors is closely related to their biological potency. Interestingly, in LPS-stimulated macrophages, 1 causes apoptosis and inhibits secretion of TNF-α and IL-1β with potencies that are higher than those of bardoxolone methyl and TBE-31.

  4. Domino Mukaiyama-Michael reactions in the synthesis of polycyclic systems

    Sarabèr, F.C.E.; Dratch, S.; Bosselaar, G.; Jansen, B.J.M.; Groot, de Æ.


    Good results were obtained in the Mukaiyama-Michael reaction of the silyl enol ether of cyclohexanone with 2-methyl-2cyclopentenone and carvone, with transfer of the silyl group to the receiving enone and with TrSbCl6 as catalyst. A second Mukaiyama-Michael reaction of this new silyl enol ether with

  5. Domino Mukaiyama-Michael reactions in the synthesis of polycyclic systems

    Sarabèr, F.C.E.; Dratch, S.; Bosselaar, G.; Jansen, B.J.M.; Groot, de Æ.


    Good results were obtained in the Mukaiyama-Michael reaction of the silyl enol ether of cyclohexanone with 2-methyl-2cyclopentenone and carvone, with transfer of the silyl group to the receiving enone and with TrSbCl6 as catalyst. A second Mukaiyama-Michael reaction of this new silyl enol ether with

  6. Structure-based design, synthesis, and biological evaluation of irreversible human rhinovirus 3C protease inhibitors. 1. Michael acceptor structure-activity studies.

    Dragovich, P S; Webber, S E; Babine, R E; Fuhrman, S A; Patick, A K; Matthews, D A; Lee, C A; Reich, S H; Prins, T J; Marakovits, J T; Littlefield, E S; Zhou, R; Tikhe, J; Ford, C E; Wallace, M B; Meador, J W; Ferre, R A; Brown, E L; Binford, S L; Harr, J E; DeLisle, D M; Worland, S T


    The structure-based design, chemical synthesis, and biological evaluation of peptide-derived human rhinovirus (HRV) 3C protease (3CP) inhibitors are described. These compounds incorporate various Michael acceptor moieties and are shown to irreversibly bind to HRV serotype 14 3CP with inhibition activities (kobs/[I]) ranging from 100 to 600 000 M-1 s-1. These inhibitors are also shown to exhibit antiviral activity when tested against HRV-14-infected H1-HeLa cells with EC50's approaching 0.50 microM. Extensive structure-activity relationships developed by Michael acceptor alteration are reported along with the evaluation of several compounds against HRV serotypes other than 14. A 2.0 A crystal structure of a peptide-derived inhibitor complexed with HRV-2 3CP is also detailed.

  7. Aza-peptidyl Michael acceptor and epoxide inhibitors--potent and selective inhibitors of Schistosoma mansoni and Ixodes ricinus legumains (asparaginyl endopeptidases).

    Ovat, Asli; Muindi, Fanuel; Fagan, Crystal; Brouner, Michelle; Hansell, Elizabeth; Dvorák, Jan; Sojka, Daniel; Kopácek, Petr; McKerrow, James H; Caffrey, Conor R; Powers, James C


    Aza-peptide Michael acceptors and epoxides with the general structure of YCO-Ala-Ala-AAsn-trans-CH horizontal lineCHCOR and YCO-Ala-Ala-AAsn-EP-COR, respectively, are shown to be potent inhibitors of asparaginyl endopeptidases (legumains) from the bloodfluke, Schistosoma mansoni (SmAE), and the hard tick, Ixodes ricinus (IrAE). Structure-activity relationships (SARs) were determined for a set of 41 aza-peptide Michael acceptors and eight aza-peptide epoxides. Both enzymes prefer disubstituted amides to monosubstituted amides in the P1' position, and potency increased as we increased the hydrophobicity of the inhibitor in this position. Extending the inhibitor to P5 resulted in increased potency, especially against IrAE, and both enzymes prefer small over large hydrophobic residues at P2. Aza-peptide Michael acceptor inhibitors are more potent than aza-peptide epoxide inhibitors, and for some of these compounds, second-order inhibiton rate constants are the fastest yet discovered. Given the central functions of these enzymes in both parasites, the data presented here may facilitate the eventual design of selective antiparasitic drugs.

  8. Trimethylsilylethynyl ketones as surrogates for ethynyl ketones in the double Michael reaction.

    Holeman, Derrick S; Rasne, Ravindra M; Grossman, Robert B


    Trimethylsilylethynyl ketones can be desilylated in the presence of a tethered carbon diacid and induced to undergo a double Michael reaction in situ. The trimethylsilylethynyl ketones can serve as surrogates of ethynyl ketones that are difficult to prepare or isolate.

  9. Solvent-free microwave-mediated Michael addition reactions

    H Surya Prakash Rao; S Jothilingam


    Facile Michael addition of active methylene compounds to ,-unsaturated carbonyl compounds takes place on the surface of potassium carbonate under microwave irradiation. Further studies on microwave-mediated Robinson annulations reveal a convenient and facile method for condensation of chalcone with methylene compounds to furnish cyclohexenones.

  10. KF-Montmorillonite-catalyzed Michael Addition Reaction of Malononitrile to α,β-Unsaturated Ketones

    SHI Daqing; WU Nan; ZHUANG Qiya


    The Michael addition reaction of α,β-unsaturated ketones with malononitrile catalyzed by KF-montmorillonite was investigated. It was interesting to note that at different reaction temperatures the addition and cycloaddition re-action products were obtained. This method has the advantages of good yields, mild reaction conditions, easy work-up and inexpensive reagents over the existing procedures.

  11. Crystallisation and preliminary X-ray diffraction analysis of the protease from Southampton norovirus complexed with a Michael-acceptor inhibitor

    Coates, Leighton [ORNL; Cooper, Jon [University of Southampton, England; Hussey, Robert [University of Southampton, England


    Noroviruses are the predominant cause of human epidemic nonbacterial gastroenteritis. Viral replication requires a cysteine protease that cleaves a 200 kDa viral polyprotein into its constituent functional parts. Here, the crystallization of the recombinant protease from the Southampton norovirus is described. While the native crystals were found to diffract only to medium resolution (2.9 {angstrom}), cocrystals of an inhibitor complex diffracted X-rays to 1.7 {angstrom} resolution. The polypeptide inhibitor (Ac-EFQLQ-propenyl ethyl ester) possesses an amino-acid sequence designed to match the substrate specificity of the enzyme, but was synthesized with a reactive Michael acceptor group at the C-terminal end.

  12. Hexafluorobenzene: A powerful solvent for a noncovalent stereoselective organocatalytic Michael addition reaction

    Lattanzi, Alessandra


    A dramatic enhancement of the diastereo- and enantioselectivity in the nitro-Michael addition reaction organocatalysed by a commercially available α,α-l-diaryl prolinol was disclosed when performing the reaction in unconventional hexafluorobenzene as a medium. DFT calculations were performed to clarify the origin of stereoselectivity and the role of C 6F 6. © The Royal Society of Chemistry 2012.

  13. Novel chiral thioureas for highly enantioselective Michael reactions of malonates to nitroalkenes

    Li Jun Yan; Quan Zhong Liu; Xue Lian Wang


    Highly efficient Michael addition reactions of malonates to nitroalkenes catalyzed by novel chiral thioureas derived from optically pure BINOL and amino acids are reported. Various trans-nitroalkenes reacted with malonates affording the desired products in up to 95% yield with excellent enantioselectivities (up to 97% ee).

  14. Guanidinium Lactate Ionic Liquid:An Efficient and Recycling Catalyst for Michael Addition Reaction

    LIANG Da-peng; XIN Xin; GAO Han; DUAN Hai-feng; LIN Ying-jie


    A facile and efficient 1,4-conjungate addition(Michael addition) reaction of active methylene compounds to a,β-unsaturated compounds,catalyzed by guanidinium lactate ionic liquid(IL9),has been developed.A range of chaicones and nitroaikenes together with active methylene compounds have been converted smoothly to the corresponding products in high yields.

  15. Aza-Michael reaction of 12-N-carboxamide of (-)-cytisine under high pressure conditions.

    Tsypysheva, Inna P; Lobov, Alexander N; Kovalskaya, Alena V; Petrova, Polina R; Ivanov, Sergey P; Rameev, Shamil A; Borisevich, Sophia S; Safiullin, Rustam L; Yunusov, Marat S


    The first example of aza-Michael reaction of 12-N-carboxamide of quinolizidine alkaloid (-)-cytisine with α,β-unsaturated ketones, dimethyl acetylenedicarboxylate and β-nitrostyrene under high pressure condition has been described. It has been shown that the [4+2]-cycloaddition takes place in the case with N-phenylmaleimide.

  16. catalysis of the michael reactions by n,n'-dimethylaminopropyl ...


    In each case the templates were recovered and reused in ... reaction mixture that had pH similar to that of the catalyst-water suspension, the pH of the mixture was ... The shoulders are likely to be due to residual -OEt groups which have been.

  17. Efficient Lewis Acids Catalyzed Aza-Michael Reactions of Enones with Carbamates

    XIA Chun-Gu; XU Li-Wen


    The a-amino carbonyl functionality is not only a segment of biologically important natural products but also a versatile intermediate for the synthesis of nitrogen-containing compounds.1 The development of novel synthetic methods leading to a-amino ketone, a-amino acids or their derivatives has attracted much attention in organic synthesis.2 Among the traditional methods for generating a-amino carbonyl compounds, Mannich-type reaction is one of the classical and powerful methods.3 However, the classic Mannich reaction presents serious disadvantages, for example, there is still a drawback in that the silyl enolates have to be prepared from the corresponding carbonyl compounds. Alternatively, aza-Michael additions can be used to create carbon-heteroatom bonds by reaction of a,a-unsaturated carbonyl compounds with amines. Although recent advances have made this route more attractive, development of cheaper, simpler, and more efficient metal catalyst, especially which can be applied to chalcone, is highly desirable.In this paper, we demonstrated that the first aza-Michael reaction of chalcone with a less nucleophilic carbamates can be accomplished on Me3SiCFFeCl3 catalyst system under very mild conditions. Apart from experimental simplicity, the advantages of this methodology are the use of a very cheap Lewis acid catalyst and the insensitivity of the reaction mixture towards air and moisture.catalyst for aza-Michael reaction of chalcone and cyclic enones with carbamates. And with the cyclic enones with carbamates in dichloromethane at room temperature were also investigated. In this conjugate addition reaction, good to excellent yields of a-amino ketones were obtained with system could also mediates aza-Michael addition of carbamates to chalcone and derivatives.These new strategies opened efficient procedures for the synthesis of a-amino ketones under mild conditions.

  18. Michael addition reactions of cyclanones with acrylamides: Producing 2-carbamoylethyl derivatives or ene-lactams


    The electron-withdrawing groups (EWGs) in the electrophilic alkenes employed in the Michael addition reaction are almost only CO2R, CN, COR, NO2, and SO2Ph. Although amides (CONR1R2) are also typical electron-withdrawing groups and are of great importance in organic synthesis, they are scarcely em-ployed as the EWGs of the electrophilic alkenes in the Michael addition reaction. In this work, the Mi-chael reactions of acrylamide and its derivatives with cyclanones were successfully carried out in the presence of enough radical inhibitors. The amide groups play a key role in producing the preferred products. The N-substituted acrylamides, including N-monosubstituted and N,N-disubstituted acryla-mides could react with cyclohexanone (CHn) to give the expected 2-carbamoylethyl derivatives; how-ever, acrylamide reacting with cyclohexanone only produced ene-lactam. Cyclanones also have effects on the products, while the ring size of cyclanones influences the reaction yield and the α-substituent decides the ratio of resulting isomeric ene-lactams.

  19. Induction of NAD(P)H:quinone oxidoreductase 1 (NQO1) by Glycyrrhiza species used for women's health: differential effects of the Michael acceptors isoliquiritigenin and licochalcone A

    Hajirahimkhan, Atieh; Simmler, Charlotte; Dong, Huali; Lantvit, Daniel D.; Li, Guannan; Chen, Shao-Nong; Nikolić, Dejan; Pauli, Guido F.; van Breemen, Richard B.; Dietz, Birgit M.; Bolton, Judy L.


    For the alleviation of menopausal symptoms, women frequently turn to botanical dietary supplements, such as licorice and hops. In addition to estrogenic properties, these botanicals could also have chemopreventive effects. We have previously shown that hops and its Michael acceptor xanthohumol (XH) induced the chemoprevention enzyme, NAD(P)H:quinone oxidoreductase 1 (NQO1), in vitro and in vivo. Licorice species could also induce NQO1, as they contain the Michael acceptors isoliquiritigenin (LigC) found in Glycyrrhiza glabra (GG), G. uralensis (GU), and G. inflata (GI) and licochalcone A (LicA) which is only found in GI. These licorice species and hops induced NQO1 activity in murine hepatoma (Hepa1c1c7) cells; hops >> GI > GG ≅ GU. Similar to the known chemopreventive compounds curcumin (turmeric), sulforaphane (broccoli), and XH, LigC and LicA were active dose-dependently; sulforaphane >> XH > LigC > LicA ≅ curcumin >> LigF. Induction of the antioxidant response element-luciferase in human hepatoma (Hep-G2-ARE-C8) cells suggested involvement of the Keap1-Nrf2 pathway. GG, GU, and LigC also induced NQO1 in non-tumorigenic breast epithelial MCF-10A cells. In female Sprague-Dawley rats treated with GG and GU, LigC and LigF were detected in the liver and mammary gland. GG weakly enhanced NQO1 activity in the mammary tissue but not in the liver. Treatment with LigC alone did not induce NQO1 in vivo most likely due to its conversion to LigF, extensive metabolism, and its low bioavailability in vivo. These data show the chemopreventive potential of licorice species in vitro could be due to LigC and LicA and emphasize the importance of chemical and biological standardization of botanicals used as dietary supplements. Although the in vivo effects in the rat model after four day treatment are minimal, it must be emphasized that menopausal women take these supplements for extended periods of time and long-term beneficial effects are quite possible. PMID:26473469

  20. Asymmetric Synthesis of Fully Substituted Cyclopentane-Oxindoles through an Organocatalytic Triple Michael Domino Reaction

    Zou, Liang-Hua; Philipps, Arne R; Raabe, Gerhard; Enders, Dieter


    An efficient, highly stereoselective asymmetric synthesis of fully functionalized cyclopentanes bearing an oxindole moiety and several other functional groups in one pot has been developed. Key step is an organocatalytic triple Michael domino reaction forming three C–C bonds and six stereocenters, including a quaternary one. Starting from equimolar amounts of simple substrates, a high molecular complexity can be reached after a Wittig olefination in one pot. The new protocol can easily be scaled up to gram amounts. PMID:25470781

  1. Tetramethylguanidium Lactate Ionic Liquid:Catalyst-free Medium for Michael Addition Reaction


    A catalyst-free, facile and efficient Michael addition reaction of active methylene compounds as well as nitromethane with chalcones catalyzed by guanidinium lactate ionic liquid was done. A series of chalcones,nitromethane, and active methylene compounds were converted smoothly to the corresponding products in high yields.The simple procedure, very mild conditions, high yields, and reuse of the IL without any loss of catalytic activity make this protocol considerably attractive for academic researches and practical applications.

  2. On the relative preference of enamine/iminium pathways in an organocatalytic Michael addition reaction.

    Patil, Mahendra P; Sunoj, Raghavan B


    The mechanism of the organocatalyzed Michael addition between propanal and methyl vinyl ketone is investigated using the density functional and ab intio methods. Different modes of substrate activation offered by a secondary amine (pyrrolidine) organocatalyst are reported. The electrophilic activation of enone (P-I) through the formation of an iminium ion, and nucleophilic activation of propanal (P-II) in the form of enamine have been examined by identifying the corresponding transition states. The kinetic preference for the formation of key intermediates is established in an effort to identify the competing pathways associated with the title reaction. A comparison of barriers associated with different pathways as well as intermediate formation allows us to provide a suitable mechanistic rationale for Michael addition reactions catalyzed by a secondary amine. The overall barriers for the C-C bond formation pathways involving enol or iminium intermediates are identified as higher than the enamine pathway. Additionally, the generation of iminium is found to be less favored as compared to enamine formation. The effect of co-catalyst/protic solvent on the energetics of the overall reaction is also studied using the cluster continuum approach. Significant reduction in the activation energies for each step of the reaction is predicted for the solvent-assisted models. The co-catalyst assisted addition of propanal-enamine to methyl vinyl ketone is identified as the most preferred pathway (P-IV) for the Michael addition reaction. The results are in concurrence with the available experimental reports on the rate acceleration by the use of a co-catalyst in this reaction.

  3. Michael Acceptor Approach to the Design of New Salvinorin A-based High Affinity Ligands for the Kappa-Opioid Receptor

    Polepally, Prabhakar R.; Huben, Krzysztof; Vardy, Eyal; Setola, Vincent; Mosier, Philip D.; Roth, Bryan L.; Zjawiony, Jordan K.


    The neoclerodane diterpenoid salvinorin A is a major secondary metabolite isolated from the psychoactive plant Salvia divinorum. Salvinorin A has been shown to have high affinity and selectivity for the κ-opioid receptor (KOR). To study the ligand–receptor interactions that occur between salvinorin A and the KOR, a new series of salvinorin A derivatives bearing potentially reactive Michael acceptor functional groups at C-2 was synthesized and used to probe the salvinorin A binding site. The κ-, δ-, and μ-opioid receptor (KOR, DOR and MOR, respectively) binding affinities and KOR efficacies were measured for the new compounds. Although none showed wash-resistant irreversible binding, most of them showed high affinity for the KOR, and some exhibited dual affinity to KOR and MOR. Molecular modeling techniques based on the recently-determined crystal structure of the KOR combined with results from mutagenesis studies, competitive binding, functional assays and structure–activity relationships, and previous salvinorin A–KOR interaction models were used to identify putative interaction modes of the new compounds with the KOR and MOR. PMID:25193297

  4. Michael acceptor approach to the design of new salvinorin A-based high affinity ligands for the kappa-opioid receptor.

    Polepally, Prabhakar R; Huben, Krzysztof; Vardy, Eyal; Setola, Vincent; Mosier, Philip D; Roth, Bryan L; Zjawiony, Jordan K


    The neoclerodane diterpenoid salvinorin A is a major secondary metabolite isolated from the psychoactive plant Salvia divinorum. Salvinorin A has been shown to have high affinity and selectivity for the κ-opioid receptor (KOR). To study the ligand-receptor interactions that occur between salvinorin A and the KOR, a new series of salvinorin A derivatives bearing potentially reactive Michael acceptor functional groups at C-2 was synthesized and used to probe the salvinorin A binding site. The κ-, δ-, and μ-opioid receptor (KOR, DOR and MOR, respectively) binding affinities and KOR efficacies were measured for the new compounds. Although none showed wash-resistant irreversible binding, most of them showed high affinity for the KOR, and some exhibited dual affinity to KOR and MOR. Molecular modeling techniques based on the recently-determined crystal structure of the KOR combined with results from mutagenesis studies, competitive binding, functional assays and structure-activity relationships, and previous salvinorin A-KOR interaction models were used to identify putative interaction modes of the new compounds with the KOR and MOR.

  5. TDDFT Study on Different Sensing Mechanisms of Similar Cyanide Sensors Based on Michael Addition Reaction

    Guang-yue Li; Ping Song; Guo-zhong He


    The solvents and substituents of two similar fluorescent sensors for cyanide, 7-diethylamino-3-formylcoumarin (sensor a) and 7-diethylamino-3-(2-nitrovinyl)coumarin (sensor b), are proposed to account for their distinct sensing mechanisms and experimental phenomena.The time-dependent density functional theory has been applied to investigate the ground states and the first singlet excited electronic states of the sensor as well as their possible Michael reaction products with cyanide, with a view to monitoring their geometries and photophysical properties. The theoretical study indicates that the protic water solvent could lead to final Michael addition product of sensor a in the ground state, while the aprotic acetonitrile solvent could lead to carbanion as the final product of sensor b. Furthermore,the Michael reaction product of sensor a has been proved to have a torsion structure in its first singlet excited state. Correspondingly, sensor b also has a torsion structure around the nitrovinyl moiety in its first singlet excited state, while not in its carbanion structure. This could explain the observed strong fluorescence for sensor a and the quenching fluorescencefor the sensor b upon the addition of the cyanide anions in the relevant sensing mechanisms.

  6. Asymmetric Michael Addition of Activated Alkenes to Nitro Alkenes Catalyzed by Organic Catalyst

    XUE Dong; CHEN Yong-Chun; CUI Xin; WANG Qi-Wei; ZHU Jin; DENG Jin-Gen


    @@ Enantioselective Michael addition is one of the most powerfulbond-forming reaction in organic synthesis. [1] A mong the Michael acceptors, nitro alkenes are very attractive, because the nitro group is the most electron-withdrawing group known and it can serve as masked functionality to be further transformed after the addition has taken place. [2] Recently, asymmetric Michael reactions catalyzed by organic catalyst have draw much attention.[3

  7. Catalytic reaction of cytokinin dehydrogenase : preference for quinones as electron acceptors

    Frébortová, Jitka; Fraaije, Marco W.; Galuszka, Petr; Šebela, Marek; Peč, Pavel; Hrbáč, Jan; Novák, Ondřej; Bilyeu, Kristin D.; English, James T.; Frébort, Ivo; Sebela, M.; Pec, P.; Hrbac, J.; Frebort, [No Value


    The catalytic reaction of cytokinin oxidase/dehydrogenase (EC was studied in detail using the recombinant flavoenzyme from maize. Determination of the redox potential of the covalently linked flavin cofactor revealed a relatively high potential dictating the type of electron acceptor that

  8. Asymmetric synthesis of fully substituted cyclopentane-oxindoles through an organocatalytic triple Michael domino reaction.

    Zou, Liang-Hua; Philipps, Arne R; Raabe, Gerhard; Enders, Dieter


    An efficient, highly stereoselective asymmetric synthesis of fully functionalized cyclopentanes bearing an oxindole moiety and several other functional groups in one pot has been developed. Key step is an organocatalytic triple Michael domino reaction forming three C-C bonds and six stereocenters, including a quaternary one. Starting from equimolar amounts of simple substrates, a high molecular complexity can be reached after a Wittig olefination in one pot. The new protocol can easily be scaled up to gram amounts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. The role of noninnocent solvent molecules in organocatalyzed asymmetric Michael addition reactions.

    Patil, Mahendra P; Sunoj, Raghavan B


    A proline-catalyzed asymmetric Michael addition between ketones and trans-beta-nitrostyrene was studied by using the density-functional theory with mPW1PW91 and B3LYP functionals. Improved insight into the enantio- and diastereoselective formation of gamma-nitroketones/-aldehydes is obtained through transition-state analysis. Consideration of the activation parameters obtained from gas-phase calculations and continuum solvation models failed to reproduce the reported experimental stereoselectivities for the reaction between cyclohexanone and 3-pentanone with trans-beta-nitrostyrene. The correct diastereo- and enantioselectivites were obtained only upon explicit inclusion of solvent molecules in the diastereomeric transition states that pertain to the C--C bond formation. Among the several transition-state models that were examined, the one that exhibits cooperative hydrogen-bonding interactions with two molecules of methanol could explain the correct stereochemical outcome of the Michael reaction. The change in differential stabilization that arises as a result of electrostatic and hydrogen-bonding interactions in the key transition states is identified as the contributing factor toward obtaining the correct diastereomer. This study establishes the importance of including explicit solvent molecules in situations in which the gas-phase and continuum models are inadequate in obtaining meaningful insight regarding experimental stereoselectivities.

  10. Nitro-fatty acid reaction with glutathione and cysteine. Kinetic analysis of thiol alkylation by a Michael addition reaction.

    Baker, Laura M S; Baker, Paul R S; Golin-Bisello, Franca; Schopfer, Francisco J; Fink, Mitchell; Woodcock, Steven R; Branchaud, Bruce P; Radi, Rafael; Freeman, Bruce A


    Fatty acid nitration by nitric oxide-derived species yields electrophilic products that adduct protein thiols, inducing changes in protein function and distribution. Nitro-fatty acid adducts of protein and reduced glutathione (GSH) are detected in healthy human blood. Kinetic and mass spectrometric analyses reveal that nitroalkene derivatives of oleic acid (OA-NO2) and linoleic acid (LNO2) rapidly react with GSH and Cys via Michael addition reaction. Rates of OA-NO2 and LNO2 reaction with GSH, determined via stopped flow spectrophotometry, displayed second-order rate constants of 183 M(-1)S(-1) and 355 M(-1)S(-1), respectively, at pH 7.4 and 37 degrees C. These reaction rates are significantly greater than those for GSH reaction with hydrogen peroxide and non-nitrated electrophilic fatty acids including 8-iso-prostaglandin A2 and 15-deoxy-Delta(12,14)-prostaglandin J2. Increasing reaction pH from 7.4 to 8.9 enhanced apparent second-order rate constants for the thiol reaction with OA-NO2 and LNO2, showing dependence on the thiolate anion of GSH for reactivity. Rates of nitroalkene reaction with thiols decreased as the pKa of target thiols increased. Increasing concentrations of the detergent octyl-beta-d-glucopyranoside decreased rates of nitroalkene reaction with GSH, indicating that the organization of nitro-fatty acids into micellar or membrane structures can limit Michael reactivity with more polar nucleophilic targets. In aggregate, these results reveal that the reversible adduction of thiols by nitro-fatty acids is a mechanism for reversible post-translational regulation of protein function by nitro-fatty acids.

  11. Phospha-Michael Addition as a New Click Reaction for Protein Functionalization.

    Lee, Yan-Jiun; Kurra, Yadagiri; Liu, Wenshe R


    A new type of click reaction between an alkyl phosphine and acrylamide was developed and applied for site-specific protein labeling in vitro and in live cells. Acrylamide is a small electrophilic olefin that readily undergoes phospha-Michael addition with an alkyl phosphine. Our kinetic study indicated a second-order rate constant of 0.07 m(-1)  s(-1) for the reaction between tris(2-carboxyethyl)phosphine and acrylamide at pH 7.4. To demonstrate its application in protein functionalization, we used a dansyl-phosphine conjugate to successfully label proteins that were site-specifically installed with N(ɛ) -acryloyl-l-lysine and employed a biotin-phosphine conjugate to selectively probe human proteins that were metabolically labeled with N-acryloyl-galactosamine. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Green Aza-Michael Reaction of Aliphatic Amines to á,(a)-Unsaturated Compounds in Water

    XU Li-Wen; XIA Chun-Gu


    The hydroamination of olefins is a long-standing goal for transition metal catalysis. And the metal-catalyzed addition of amines to carbon-carbon double bonds is an unsolved, synthetically important problem. Although recent advances have made using lanthanide and precious metal complexes, there are few excellent catalyst that display broad functional group tolerance and useful rates for an intermolecular aza-Michael addition. As such, the development of efficient synthetic methods leading to a-amino carbonyl compounds and derivatives has attracted much attention in organic synthesis. Although recent advances have made this route more attractive, development of cheaper, simpler, and more efficient metal catalyst is highly desirable. We also have been interested in developing a reaction that uses catalytic quantities of minimally toxic, readily available, economic reagent should greatly contribute to the creation of environmental benign processes.The recent interest in aqueous medium metal-mediated carbon-carbon and carbon-heteroatom and formations led to the contributors for such reactions. Furthermore, development of organic reactions in water will contribute to the progress of green and quasi-nature catalysis chemistry. Surprisingly however, there is few report on conjugate additions of amines to a,a-unsaturated carbonyl compounds in water.Herein, we report a new protocol that employs air stable copper salts as efficient catalyst in the aza-Michael reaction under mild reaction conditions. Advantages of the protocol include high-yielding reactions that can be conducted at ambient temperature; the use of readily available and stable copper salts as the catalyst, and the reaction was successfully performed in environmental benign solvent, water.Finally, we have utilized a variety of aliphatic amines successfully with different á,(a)-unsaturated compounds catalyzed by simple hydrophilic ionic liquid, bmimBF4 in water. Interestingly, all the aliphatic amines gave

  13. Click and chemically triggered declick reactions through reversible amine and thiol coupling via a conjugate acceptor

    Diehl, Katharine L.; Kolesnichenko, Igor V.; Robotham, Scott A.; Bachman, J. Logan; Zhong, Ye; Brodbelt, Jennifer S.; Anslyn, Eric V.


    The coupling and decoupling of molecular units is a fundamental undertaking of organic chemistry. Herein we report the use of a very simple conjugate acceptor, derived from Meldrum's acid, for the sequential ‘clicking’ together of an amine and a thiol in aqueous conditions at neutral pH. Subsequently, this linkage can be ‘declicked’ by a chemical trigger to release the original amine and thiol undisturbed. The reactivity differs from that of other crosslinking agents because the selectivity for sequential functionalization derives from an altering of the electrophilicity of the conjugate acceptor on the addition of the amine. We describe the use of the procedure to modify proteins, create multicomponent libraries and synthesize oligomers, all of which can be declicked to their starting components in a controlled fashion when desired. Owing to the mild reaction conditions and ease of use in a variety of applications, the method is predicted to have wide utility.

  14. Organocatalytically Generated Donor-Acceptor Cyclopropanes in Domino Reactions. One-Step Enantioselective Synthesis of Pyrrolo[1,2-a]quinolines.

    Sanchez-Diez, Eduardo; Vesga, Diana L; Reyes, Efraim; Uria, Uxue; Carrillo, Luisa; Vicario, Jose L


    An easy and straightforward procedure has been developed for the synthesis of highly enantioenriched pyrrolo[1,2-a]quinolines through a one-pot process that comprises a domino cyclopropane ring opening/aza-Michael/aldol reaction followed by acid-promoted lactamization. The key feature of the synthetic approach relies on the ability of conveniently functionalized cyclopropaneacetaldehydes to undergo organocatalytic activation by a chiral secondary amine that enables the catalytic generation of a donor-acceptor cyclopropane. This intermediate has the potential to undergo a ring opening that generates an electrophilic α,β-unsaturated iminium ion that subsequently reacts through the already mentioned domino sequence and in which stereochemical information is very efficiently transferred from the amine catalyst to the final products. Moreover, one of the alkoxycarbonyl moieties can be easily removed by standard hydrolysis/decarboxylation, providing access to the target adducts as single stereoisomers.

  15. N-Heterocyclic-Carbene-Catalysed Diastereoselective Vinylogous Mukaiyama/Michael Reaction of 2-(Trimethylsilyloxy)furan and Enones

    Wang, Ying


    N-heterocyclic carbenes have been utilised as highly efficient nucleophilic organocatalysts to mediate vinylogous Mukaiyama/Michael reactions of 2-(trimethylsilyloxy)furan with enones to afford γ-substituted butenolides in 44-99% yield with 3:1-32:1 diastereoselectivity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Enantioselective synthesis of benzofurans and benzoxazines via an olefin cross-metathesis-intramolecular oxo-Michael reaction.

    Zhang, Jun-Wei; Cai, Quan; Gu, Qing; Shi, Xiao-Xin; You, Shu-Li


    Chiral phosphoric acid and Hoveyda-Grubbs II were found to catalyze an olefin cross-metathesis-intramolecular oxo-Michael cascade reaction of the ortho-allylphenols and enones to provide a variety of benzofuran and benzoxazine derivatives in moderate to good yields and enantioselectivity.

  17. Organocatalytic Asymmetric Domino Michael/Henry Reaction of Indolin-3-ones with o-Formyl-β-nitrostyrenes.

    Mahajan, Suruchi; Chauhan, Pankaj; Loh, Charles C J; Uzungelis, Server; Raabe, Gerhard; Enders, Dieter


    A highly diastereo- and enantioselective domino Michael/Henry reaction of 1-acetylindolin-3-ones with o-formyl-(E)-β-nitrostyrenes catalyzed by low loading of a quinine-derived amine-squaramide provides the corresponding indolin-3-one derivatives bearing four adjacent stereogenic centers in good to high yields and with excellent stereoselectivities.

  18. A polystyrene-supported 9-amino(9-deoxy)epi quinine derivative for continuous flow asymmetric Michael reactions.

    Izquierdo, Javier; Ayats, Carles; Henseler, Andrea H; Pericàs, Miquel A


    A polystyrene (PS)-supported 9-amino(9-deoxy)epi quinine derivative catalyzes Michael reactions affording excellent levels of conversion and enantioselectivity using different nucleophiles and structurally diverse enones. The highly recyclable, immobilized catalyst has been used to implement a single-pass, continuous flow process (residence time: 40 min) that can be operated for 21 hours without significant decrease in conversion and with improved enantioselectivity with respect to batch operation. The flow process has also been used for the sequential preparation of a small library of enantioenriched Michael adducts.

  19. Organocatalytic Asymmetric Synthesis of Functionalized 1,3,5-Triarylpyrrolidin-2-ones via an Aza-Michael/Aldol Domino Reaction.

    Joie, Céline; Deckers, Kristina; Enders, Dieter


    The organocatalytic asymmetric synthesis of functionalized 1,3,5-triarylpyrrolidin-2-ones bearing three contiguous stereocenters through an aza-Michael/aldol domino reaction of α-ketoamides with α,β-unsaturated aldehydes is described. The domino products were further derivatized by aldehyde olefination under one-pot conditions. The reaction proceeds with excellent diastereoselectivities (>20:1) and good to excellent enantioselectivities (60-96% ee).

  20. Synthesis of the Hemoglobin-Conjugated Polymer Micelles by Thiol Michael Addition Reactions.

    Qi, Yanxin; Li, Taihang; Wang, Yupeng; Wei, Xing; Li, Bin; Chen, Xuesi; Xie, Zhigang; Jing, Xiabin; Huang, Yubin


    Amphiphilic triblock copolymers mPEG-b-PMAC-b-PCL are synthesized using methoxyl poly(ethylene glycol), cyclic carbonic ester monomer including acryloyl group, and ε-caprolactone. Copolymers are self-assembled into core-shell micelles in aqueous solution. Thiolated hemoglobin (Hb) is conjugated with micelles sufficiently through thiol Michael addition reaction to form hemoglobin nanoparticles (HbNs) with 200 nm in diameter. The conjugation of Hb onto the micelle surface is further confirmed by X-ray photoelectron spectroscopy. Feeding ratio of copolymer micelles to Hb at 1:3 would lead to the highest hemoglobin loading efficiency 36.7 wt%. The UV results demonstrate that the gas transporting capacity of HbNs is well remained after Hb is conjugated with polymeric micelles. Furthermore, the obtained HbNs have no obvious detrimental effects on blood components in vitro. This system may thus have great potential as one of the candidates to be developed as oxygen carriers and provide a reference for the modification of protein drugs.

  1. Studies on NaI/DMSO induced retro-Michael addition (RMA) reactions on some 1,5-dicarbonyl compounds

    H Surya Prakash Rao; S Jothilingam


    Studies on the reaction of some 1,5-ketodiesters/1,5-diketones with NaX (X = Cl/Br/I)/DMSO have shown that under microwave/thermal conditions, facile retro-Michael addition (RMA) reaction takes place instead of formation of the expected Krapcho products. Mechanistic studies have shown that the NaI/DMSO system is a better system than NaCl/DMSO or NaBr/DMSO to promote the RMA pathway and DMSO is an essential requirement. The electrophilic halide ion could be involved in this fragmentation reaction.

  2. Aza-Michael addition reactions between nitroolefins and benzotriazole catalyzed by MCM-41 immobilized heteropoly acids in water

    Shao-Lei Xie; Yong-Hai Hui; Xiang-Ju Long; Chang-Chun Wang; Zheng-Feng Xie


    MCM-41 supported heteropoly acids (HPAs) catalysts were synthesized,characterized and their catalytic activity was evaluated in an aza-Michael addition reaction between nitroolefins and benzotriazole in water at room temperature.50 wt% PW/MCM-41 showed the highest activity (up to 96% yield).The catalyst was used in six consecutive experiments without obvious loss of activity,confirming the success of the anchoring process and the catalyst stability.

  3. Functionalization of Polydopamine via the Aza-Michael Reaction for Antimicrobial Interfaces.

    Liu, Chia-Yu; Huang, Chun-Jen


    Polydopamine (pDA) coatings afford tremendous versatility due to their capabilities to provide substrate-independent functionalization with a wide range of amine- and thiol-containing molecules. In this work, we developed a new and facile conjugation approach to the formation of β-amino carbonyl linkages between pDA and acrylate/acrylamide molecules via the aza-Michael reaction. Sulfobetaine acrylamide (SBAA), sulfobetaine methacrylate (SBMA), and poly(ethylene glycol) methacrylate (PEGMA) were employed to graft onto pDA films, giving rise to formation of antifouling coatings. Because of the universal adhesive property of pDA, the coating strategy was applied to different substrates, including TiO2, gold, SiO2, Nitinol alloy, polystyrene, and poly(dimethylsiloxane). The variation of surface chemistry and surface wettability upon pDA modification and subsequent conjugation was monitored with X-ray photoelectron spectroscopy (XPS) and water contact angle measurements. Antifouling properties of coatings were challenged by three common Gram-negative and Gram-positive bacteria. Cytocompatibility of the coatings with NIH-3T3 fibroblasts was accessed using MTT assay. The results showed that pDA coatings grafted with SBAA exhibited superhydrophilicity and excellent fouling resistance likely due to the high chemical reactivity of acrylamide, leading to high grafting density. In addition, dual functional coatings containing passive and active antibacterial components were constructed through the in situ deposition of antimicrobial agent, silver nanoparticles, in pDA, followed by the grafting of SBAA for bacterial repellence. The composite coatings allowed reducing adsorption of E. coli by >95%, while killing attached bacteria by up to 98% upon the releasing of Ag(+) ions as measured by inductively coupled plasma mass spectrometry. Consequently, this work paves a new avenue to the grafting strategy to engineer pDA and to the functional bioinspired antifouling interfaces in

  4. Organocatalytic Domino Oxa-Michael/1,6-Addition Reactions: Asymmetric Synthesis of Chromans Bearing Oxindole Scaffolds.

    Zhao, Kun; Zhi, Ying; Shu, Tao; Valkonen, Arto; Rissanen, Kari; Enders, Dieter


    An asymmetric organocatalytic domino oxa-Michael/1,6-addition reaction of ortho-hydroxyphenyl-substituted para-quinone methides and isatin-derived enoates has been developed. In the presence of 5 mol % of a bifunctional thiourea organocatalyst, this scalable domino reaction affords 4-phenyl-substituted chromans bearing spiro-connected oxindole scaffolds and three adjacent stereogenic centers in good to excellent yields (up to 98 %) and with very high stereoselectivities (up to >20:1 d.r., >99 % ee). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Elucidation of inorganic reaction mechanisms in ionic liquids: the important role of solvent donor and acceptor properties.

    Schmeisser, Matthias; van Eldik, Rudi


    In this article, we focus on the important role of solvent donor and acceptor properties of ionic liquids in the elucidation of inorganic reaction mechanisms. For this purpose, mechanistic and structural studies on typical inorganic reactions, performed in ionic liquids, have been conducted. The presented systems range from simple complex-formation and ligand-substitution reactions to the activation of small molecules by catalytically active complexes. The data obtained for the reactions in ionic liquids are compared with those for the same reactions carried out in conventional solvents, and are discussed with respect to the donor and acceptor properties of the applied ionic liquids. The intention of this perspective is to gain more insight into the role of ILs as solvents and their interaction with metal ions and complexes in solution.

  6. Synthesis of β3-Amino Acids via Catalyst- and Solvent-Free Aza-Michael Reaction


    A safe, environmentally friendly and cost-effective method for the synthesis of β-amino acid derivatives has been developed. Treatment of α,β-unsaturated compounds with aliphatic amines furnishes β-amino acid derivatives in good to excellent yields via a catalyst- and solvent-free aza-Michael addition.

  7. Optimum Conditions for Introducing Free Radical Polymerizable Methacrylate Groups on the MWCNT Surface by Michael Addition Reaction

    Kim, Sunghoon; Park, Seonghwan; Kwon, Jaebeom; Ha, KiRyong [Keimyung University, Daegu (Korea, Republic of)


    In this study, we investigated optimum conditions for the introduction of a lot of free radical polymerizable methacrylate groups on the multi-walled carbon nanotube (MWCNT) surface. Carboxyl groups were introduced first on MWCNT surfaces by treating with a mixture of sulfuric acid and nitric acid with ultrasonic bath for 2 hours, and oxidized MWCNTs were reacted further with thionyl chloride followed by triethylenetetramine (TETA) to introduce amino groups on the oxidized MWCNT surface, to make MWCNT-NH{sub 2}. To introduce free radical polymerizable methacrylate groups on the MWCNT-NH{sub 2}, MWCNT-NH{sub 2} was reacted with 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM) by Michael addition reaction. We investigated progress of modification reactions for MWCNT by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and elemental analysis (EA). We found maximum degree of Michael addition reactions between AHM and TETA grafted on MWCNT-NH{sub 2} for 10:1 mol ratio and 8 hour reaction time in our reaction conditions.

  8. Refined transition-state models for proline-catalyzed asymmetric Michael reactions under basic and base-free conditions.

    Sharma, Akhilesh K; Sunoj, Raghavan B


    The stereocontrolling transition state (TS) models for C-C bond formation relying on hydrogen bonding have generally been successful in proline-catalyzed aldol, Mannich, α-amination, and α-aminoxylation reactions. However, the suitability of the hydrogen-bonding model in protic and aprotic conditions as well as under basic and base-free conditions has not been well established for Michael reactions. Through a comprehensive density functional theory investigation, we herein analyze different TS models for the stereocontrolling C-C bond formation, both in the presence and absence of a base in an aprotic solvent (THF). A refined stereocontrolling TS for the Michael reaction between cyclohexanone and nitrostyrene is proposed. The new TS devoid of hydrogen bonding between the nitro group of nitrostyrene and carboxylic acid of proline, under base-free conditions, is found to be more preferred over the conventional hydrogen-bonding model besides being able to reproduce the experimentally observed stereochemical outcome. A DBU-bound TS is identified as more suitable for rationalizing the origin of asymmetric induction under basic reaction conditions. In both cases, the most preferred approach of nitrostyrene is identified as occurring from the face anti to the carboxylic acid of proline-enamine. The predicted enantio- and diastereoselectivities are in very good agreement with the experimental observations.

  9. EPR characterisation of the triplet state in photosystem II reaction centers with singly reduced primary acceptor Q(A).

    Feikema, W Onno; Gast, Peter; Klenina, Irina B; Proskuryakov, Ivan I


    The triplet states of photosystem II core particles from spinach were studied using time-resolved cw EPR technique at different reduction states of the iron--quinone complex of the reaction center primary electron acceptor. With doubly reduced primary acceptor, the well-known photosystem II triplet state characterised by zero-field splitting parameters |D|=0.0286 cm(-1), |E|=0.0044 cm(-1) was detected. When the primary acceptor was singly reduced either chemically or photochemically, a triplet state of a different spectral shape was observed, bearing the same D and E values and characteristic spin polarization pattern arising from RC radical pair recombination. The latter triplet state was strongly temperature dependent disappearing at T=100 K, and had a much faster decay than the former one. Based on its properties, this triplet state was also ascribed to the photosystem II reaction center. A sequence of electron-transfer events in the reaction centers is proposed that explains the dependence of the triplet state properties on the reduction state of the iron--quinone primary acceptor complex.

  10. Catalytic enantioselective Michael addition reactions of alpha-nitroesters to alpha,beta-unsaturated ketones

    Keller, E; Veldman, N; Spek, AL; Feringa, BL


    Enantioselective Michael additions of alpha-nitroesters 2a-d with alpha,beta-unsaturated ketones were carried out in the presence of a catalytic amount of chiral Al-Li-(R,R')-2,2'-dihydroxy-1,1'-binaphthyl ('AlLiBINOL') complex prepared in situ from LiAlH4 and 2.45 equiv. of (R,R')-BINOL. The enanti

  11. Catalytic enantioselective Michael addition reactions of α-nitroesters to α,β-unsaturated ketones

    Keller, Erik; Veldman, Nora; Spek, Anthony L.; Feringa, Bernard


    Enantioselective Michael additions of α-nitroesters 2a-d with α,β-unsaturated ketones were carried out in the presence of a catalytic amount of chiral Al-Li-(R,R')-2,2'-dihydroxy-1,1'-binaphthyl (‘AlLiBINOL’) complex prepared in situ from LiAlH4 and 2.45 equiv. of (R,R')-BINOL. The enantioselectivit

  12. Aza-Michael Mono-addition Using Acidic Alumina under Solventless Conditions

    Giovanna Bosica


    Full Text Available Aza-Michael reactions between primary aliphatic and aromatic amines and various Michael acceptors have been performed under environmentally-friendly solventless conditions using acidic alumina as a heterogeneous catalyst to selectively obtain the corresponding mono-adducts in high yields. Ethyl acrylate was the main acceptor used, although others such as acrylonitrile, methyl acrylate and acrylamide were also utilized successfully. Bi-functional amines also gave the mono-adducts in good to excellent yields. Such compounds can serve as intermediates for the synthesis of anti-cancer and antibiotic drugs.

  13. Application of a Double Aza-Michael Reaction in a ‘Click, Click, Cy-Click’ Strategy: From Bench to Flow

    Zang, Qin; Javed, Salim; ULLAH, FARMAN; Zhou, Aihua; Knudtson, Christopher A.; Bi, Danse; Basha, Fatima Z.; Organ, Michael G.; Hanson, Paul R.


    The development of a ‘click, click, cy-click’ process utilizing a double aza-Michael reaction to generate functionalized 1,2,5-thiadiazepane 1,1-dioxides is reported. Optimization in flow, followed by scale out of the inter-/intramolecular double aza-Michael addition has also been realized using a microwave-assisted, continuous flow organic synthesis platform (MACOS). In addition, a facile one-pot, sequential strategy employing in situ Huisgen cycloaddition post-double aza-Michael has been ac...

  14. Michael-type addition reactions for the in situ formation of poly(vinyl alcohol)-based hydrogels.

    Tortora, Mariarosaria; Cavalieri, Francesca; Chiessi, Ester; Paradossi, Gaio


    Michael-type addition reactions offer the possibility to obtain in situ formation of polymeric hydrogels in the absence of a radical mechanism for the networking process. We explored such a synthetic route for obtaining a poly(vinyl alcohol) (PVA)-based hydrogel as a potential biomaterial for applications in vitro-retinal replacement surgery. The presence of radicals in the reaction medium can represent a risk for in situ surgical treatment. To circumvent this problem we have applied nucleophilic addition to ad hoc modified PVA macromers. The gel formation has been studied with respect to the timing required in this surgery and in terms of the structural characteristics of the obtained network.

  15. A New Strategy for Enantioselective Construction of Multisubstituted Five-Membered Oxygen Heterocycles via a Domino Michael/Hemiketalization Reaction.

    Hua, Yuan-Zhao; Liu, Meng-Meng; Huang, Pei-Jin; Song, Xixi; Wang, Min-Can; Chang, Jun-Biao


    A new highly enantioselective domino Michael/hemiketalization reaction of α-hydroxyacetophenone with β,γ-unsaturated α-keto esters for the synthesis of 2,2,4,5-tetrasubstituted chiral tetrahydrofurans is reported. With 2 mol % intramolecular dinuclear zinc-AzePhenol complex prepared in situ from the reaction of multidentate semi-azacrown ether ligand with ZnEt2 , the corresponding anti-multisubstituted tetrahydrofuran products were obtained in up to 90 % yields, and 98 % enantiomeric excess (ee) at 0 °C for 45 min. Moreover, the products were easily converted to 2,3,5-trisubstituted 2,3-dihydrofurans without any loss in optical activity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Switchable Diastereoselectivity in the Fluoride Promoted Vinylogous Mukaiyama-Michael Reaction of 2-Trimethylsilyloxyfuran Catalyzed by Crown Ethers

    Della Sala, Giorgio


    The fluoride promoted vinylogous Mukaiyama-Michael reaction (VMMR) of 2-trimethylsilyloxyfuran with diverse α,β-unsaturated ketones is described. The TBAF catalyzed VMMR afforded high anti-diastereoselectivity irrespective of the solvents used. The KF/crown ethers catalytic systems proved to be highly efficient in terms of yields and resulted in a highly diastereoselective unprecedented solvent/catalyst switchable reaction. Anti-adducts were obtained as single diastereomers or with excellent diastereoselectivities when benzo-15-crown-5 in CH2Cl2 was employed. On the other hand, high syn-diastereoselectivities (from 76:24 to 96:4) were achieved by employing dicyclohexane-18-crown-6 in toluene. Based on DFT calculations, the catalysts/solvents-dependent switchable diastereoselectivities are proposed to be the result of loose or tight cation-dienolate ion pairs.

  17. A dual arylboronic acid--aminothiourea catalytic system for the asymmetric intramolecular hetero-Michael reaction of α,β-unsaturated carboxylic acids.

    Azuma, Takumi; Murata, Akihiro; Kobayashi, Yusuke; Inokuma, Tsubasa; Takemoto, Yoshiji


    A bifunctional aminoboronic acid has been used to facilitate for the first time the intramolecular aza- and oxa-Michael reactions of α,β-unsaturated carboxylic acids. The combination of an arylboronic acid with a chiral aminothiourea allowed for these reactions to proceed successfully in an enantioselective manner to afford the desired heterocycles in high yields and ee's (up to 96% ee). The overall utility of this dual catalytic system was demonstrated by a one-pot enantioselective synthesis of (+)-erythrococcamide B, which proceeded via sequential Michael and amidation reactions.

  18. Theoretical and Experimental Investigation of Thermodynamics and Kinetics of Thiol-Michael Addition Reactions: A Case Study of Reversible Fluorescent Probes for Glutathione Imaging in Single Cells.

    Chen, Jianwei; Jiang, Xiqian; Carroll, Shaina L; Huang, Jia; Wang, Jin


    Density functional theory (DFT) was applied to study the thermodynamics and kinetics of reversible thiol-Michael addition reactions. M06-2X/6-31G(d) with the SMD solvation model can reliably predict the Gibbs free energy changes (ΔG) of thiol-Michael addition reactions with an error of less than 1 kcal·mol(-1) compared with the experimental benchmarks. Taking advantage of this computational model, the first reversible reaction-based fluorescent probe was developed that can monitor the changes in glutathione levels in single living cells.

  19. Enantioselective Cu-II-Catalyzed Diels-Alder and Michael Addition Reactions in Water Using Bio-Inspired Triazacyclophane-Based Ligands

    Albada, H. Bauke; Rosati, Fiora; Coquiere, David; Roelfes, Gerard; Liskamp, Rob M. J.


    A triazacyclophane (TAC) scaffold decorated with three histidine amino acid residues was used as a tridentate ligand in asymmetric copper(II)-catalysed Diels-Alder and Michael addition reactions in water. Enantiomeric excesses up to 55% were obtained in Diels-Alder reactions using ligands in which t

  20. Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

    Tatyana E. Shubina


    Full Text Available A new guanidine-thiourea organocatalyst has been developed and applied as bifunctional organocatalyst in the Michael addition reaction of diethyl malonate to trans-β-nitrostyrene. Extensive DFT calculations, including solvent effects and dispersion corrections, as well as ab initio calculations provide a plausible description of the reaction mechanism.

  1. Enantioselective Cu-II-Catalyzed Diels-Alder and Michael Addition Reactions in Water Using Bio-Inspired Triazacyclophane-Based Ligands

    Albada, H. Bauke; Rosati, Fiora; Coquiere, David; Roelfes, Gerard; Liskamp, Rob M. J.

    A triazacyclophane (TAC) scaffold decorated with three histidine amino acid residues was used as a tridentate ligand in asymmetric copper(II)-catalysed Diels-Alder and Michael addition reactions in water. Enantiomeric excesses up to 55% were obtained in Diels-Alder reactions using ligands in which

  2. Eco-friendly polyethylene glycol promoted Michael addition reactions of α,β-unsaturated carbonyl compounds

    Abstract- Intra- and inter-nucleophilic addition reactions of different unsaturated compounds were found to be highly effective without any additives in PEG-400 as a recyclable reaction medium under neutral conditions.

  3. A Greener, Efficient Approach to Michael Addition of Barbituric Acid to Nitroalkene in Aqueous Diethylamine Medium

    Hany J. Al-Najjar


    Full Text Available An efficient method for the synthesis of a variety of pyrimidine derivatives 3a–t by reaction of barbituric acids 1a,b as Michael donor with nitroalkenes 2a–k as Michael acceptor using an aqueous medium and diethylamine is described. This 1,4-addition strategy offers several advantages, such as using an economic and environmentally benign reaction media, high yields, versatility, and shorter reaction times. The synthesized compounds were identified by 1H-NMR, 13C-NMR, CHN, IR, and MS. The structure of compound 3a was further confirmed by single crystal X-ray structure determination.

  4. One-pot cascade michael.cyclization reactions of ο-hydroxycinnamaldehydes: Synthesis of functionalized 2,3-dihydrobenzofuranes

    Gwon, Sung Hyuk; Kim, Sunggon [Kyonggi Univ., Suwon (Korea, Republic of)


    We described the cascade Michael.cyclization reaction of o-hydroxycinnamaldehydes with diethyl α-bromomalonate promoted by potassium carbonate. The reactions provided functionalized 2,3-dihydrobenzofurans in good yields for a variety of o-hydroxyaromatic α,β-unsaturated aldehydes. Current work focuses on expanding the scope of this reaction to other substrates such as sulfur yields, and on developing an efficient catalytic asymmetric variant. 2,3-Dihydrobenzofurans are found in numerous biologically active natural products and synthetic compounds. These are an attractive type of oxygenated compound because their basic core skeleton is present in neolignans, pterocarpans, and synthetic drugs used in the treatment of pulmonary hypertension, atherosclerotic peripheral arterial disease, and central nervous system trauma and ischemia. Owing to the importance of their structures, numerous synthetic methods for 2,3-dihydrobenzofurans have been developed, primarily: radical cyclizations, Lewis acid promoted reactions, anionic cyclizations, and transition-metal catalyzed processes. However, these methods cannot be generalized as much as is desirable, and they yielded poor chemo- and/or stereoselectivities. Hence, the development of an efficient enantioselective synthetic method for obtaining 2,3-dihydrobenzofuran scaffolds attracted our attention.

  5. Facile construction of macroporous hybrid monoliths via thiol-methacrylate Michael addition click reaction for capillary liquid chromatography.

    Lin, Hui; Ou, Junjie; Liu, Zhongshan; Wang, Hongwei; Dong, Jing; Zou, Hanfa


    A facile approach based on thiol-methacrylate Michael addition click reaction was developed for construction of porous hybrid monolithic materials. Three hybrid monoliths were prepared via thiol-methacrylate click polymerization by using methacrylate-polyhedral oligomeric silsesquioxane (POSS) (cage mixture, n=8, 10, 12, POSS-MA) and three multi-thiol crosslinkers, 1,6-hexanedithiol (HDT), trimethylolpropane tris(3-mercaptopropionate) (TPTM) and pentaerythritol tetrakis(3-mercaptopropionate) (PTM), respectively, in the presence of porogenic solvents (n-propanol and PEG 200) and a catalyst (dimethylphenylphosphine, DMPP). The obtained monoliths possessed high thermal and chemical stabilities. Besides, they all exhibited high column efficiencies and excellent separation abilities in capillary liquid chromatography (cLC). The highest column efficiency could reach ca. 195,000N/m for butylbenzene on the monolith prepared with POSS-MA and TPTM (monolith POSS-TPTM) in reversed-phase (RP) mode at 0.64mm/s. Good chromatographic performance were all achieved in the separations of polycyclic aromatic hydrocarbons (PAHs), phenols, anilines, EPA 610 as well as bovine serum albumin (BSA) digest. The high column efficiencies in the range of 51,400-117,000N/m (achieved on the monolith POSS-PTM in RP mode) convincingly demonstrated the high separation abilities of these thiol-methacrylate based hybrid monoliths. All the results demonstrated the feasibility of the phosphines catalyzed thiol-methacrylate Michael addition click reaction in fabrication of monolithic columns with high efficiency for cLC applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Polyphosphoester-Camptothecin Prodrug with Reduction-Response Prepared via Michael Addition Polymerization and Click Reaction.

    Du, Xueqiong; Sun, Yue; Zhang, Mingzu; He, Jinlin; Ni, Peihong


    Polyphosphoesters (PPEs), as potential candidates for biocompatible and biodegradable polymers, play an important role in material science. Various synthetic methods have been employed in the preparation of PPEs such as polycondensation, polyaddition, ring-opening polymerization, and olefin metathesis polymerization. In this study, a series of linear PPEs has been prepared via one-step Michael addition polymerization. Subsequently, camptothecin (CPT) derivatives containing disulfide bonds and azido groups were linked onto the side chain of the PPE through Cu(I)-catalyzed azidealkyne cyclo-addition "click" chemistry to yield a reduction-responsive polymeric prodrug P(EAEP-PPA)-g-ss-CPT. The chemical structures were characterized by nuclear magnetic resonance spectroscopy, gel permeation chromatography, Fourier transform infrared, ultraviolet-visible spectrophotometer, and high performance liquid chromatograph analyses, respectively. The amphiphilic prodrug could self-assemble into micelles in aqueous solution. The average particle size and morphology of the prodrug micelles were measured by dynamic light scattering and transmission electron microscopy, respectively. The results of size change under different conditions indicate that the micelles possess a favorable stability in physiological conditions and can be degraded in reductive medium. Moreover, the studies of in vitro drug release behavior confirm the reduction-responsive degradation of the prodrug micelles. A methyl thiazolyl tetrazolium assay verifies the good biocompatibility of P(EAEP-PPA) not only for normal cells, but also for tumor cells. The results of cytotoxicity and the intracellular uptake about prodrug micelles further demonstrate that the prodrug micelles can efficiently release CPT into 4T1 or HepG2 cells to inhibit the cell proliferation. All these results show that the polyphosphoester-based prodrug can be used for triggered drug delivery system in cancer treatment.

  7. Donor-acceptor graphene-based hybrid materials facilitating photo-induced electron-transfer reactions.

    Stergiou, Anastasios; Pagona, Georgia; Tagmatarchis, Nikos


    Graphene research and in particular the topic of chemical functionalization of graphene has exploded in the last decade. The main aim is to increase the solubility and thereby enhance the processability of the material, which is otherwise insoluble and inapplicable for technological applications when stacked in the form of graphite. To this end, initially, graphite was oxidized under harsh conditions to yield exfoliated graphene oxide sheets that are soluble in aqueous media and amenable to chemical modifications due to the presence of carboxylic acid groups at the edges of the lattice. However, it was obvious that the high-defect framework of graphene oxide cannot be readily utilized in applications that are governed by charge-transfer processes, for example, in solar cells. Alternatively, exfoliated graphene has been applied toward the realization of some donor-acceptor hybrid materials with photo- and/or electro-active components. The main body of research regarding obtaining donor-acceptor hybrid materials based on graphene to facilitate charge-transfer phenomena, which is reviewed here, concerns the incorporation of porphyrins and phthalocyanines onto graphene sheets. Through illustrative schemes, the preparation and most importantly the photophysical properties of such graphene-based ensembles will be described. Important parameters, such as the generation of the charge-separated state upon photoexcitation of the organic electron donor, the lifetimes of the charge-separation and charge-recombination as well as the incident-photon-to-current efficiency value for some donor-acceptor graphene-based hybrids, will be discussed.

  8. Michael Thonet


    Saksa päritolu austria mööblidisaineri ja mööblitöösturi Michael Thonet' (1796-1871) disainiloomingust. 1859. a. Michael Thonet' loodud tool nr. 14 on endiselt tootmises ja on tuntud ka Viini toolina. 2 ill

  9. Michael Thonet


    Saksa päritolu austria mööblidisaineri ja mööblitöösturi Michael Thonet' (1796-1871) disainiloomingust. 1859. a. Michael Thonet' loodud tool nr. 14 on endiselt tootmises ja on tuntud ka Viini toolina. 2 ill

  10. Tandem halogenation/Michael-initiated ring-closing reaction of α,β-unsaturated nitriles and activated methylene compounds: one-pot diastereoselective synthesis of functionalized cyclopropanes.

    Xin, Xiaoqing; Zhang, Qian; Liang, Yongjiu; Zhang, Rui; Dong, Dewen


    An efficient one-pot synthetic route to highly substituted cyclopropanes has been developed from readily available α,β-unsaturated nitriles and doubly activated methylene compounds under very mild conditions in a highly diastereoselective manner, which involves halogenation, Michael addition and intramolecular ring-closing reaction sequences.

  11. Un-catalyzed tandem Knoevenagel-Michael reaction for the synthesis of 4,4'-(arylmethylene)bis(7H-pyrazol-5-ols) in aqueous medium

    Nilesh P. Tale; Girdharilal B. Tiwari; Nandkishor N. Karade


    An environmentally benign un-catalyzed one-pot synthesis of 4,4'-(arylmethylene)bis(7H-pyrazol-5-ols) has been reported via tandem Knoevenagel-Michael reaction of aldehydes with two equivalents of 3-methyl-l-phenyl-lH-pyrazol-5(4H)-one in aqueous medium.

  12. Preparation of a Rapidly Forming Poly(ferrocenylsilane)-Poly(ethylene glycol)-based Hydrogel by a Thiol–Michael Addition Click Reaction

    Sui, Xiaofeng; van Ingen, Lennard; Hempenius, Mark A.; Vancso, Gyula J.


    The synthesis of a rapidly forming redox responsive poly(ferrocenylsilane)-poly(ethylene glycol) (PFS-PEG)-based hydrogel is described, achieved by a thiol-Michael addition click reaction. PFS bearing acrylate side groups (PFS-acryl) was synthesized by side group modification of

  13. Donor–acceptor graphene-based hybrid materials facilitating photo-induced electron-transfer reactions

    Anastasios Stergiou


    Full Text Available Graphene research and in particular the topic of chemical functionalization of graphene has exploded in the last decade. The main aim is to increase the solubility and thereby enhance the processability of the material, which is otherwise insoluble and inapplicable for technological applications when stacked in the form of graphite. To this end, initially, graphite was oxidized under harsh conditions to yield exfoliated graphene oxide sheets that are soluble in aqueous media and amenable to chemical modifications due to the presence of carboxylic acid groups at the edges of the lattice. However, it was obvious that the high-defect framework of graphene oxide cannot be readily utilized in applications that are governed by charge-transfer processes, for example, in solar cells. Alternatively, exfoliated graphene has been applied toward the realization of some donor–acceptor hybrid materials with photo- and/or electro-active components. The main body of research regarding obtaining donor–acceptor hybrid materials based on graphene to facilitate charge-transfer phenomena, which is reviewed here, concerns the incorporation of porphyrins and phthalocyanines onto graphene sheets. Through illustrative schemes, the preparation and most importantly the photophysical properties of such graphene-based ensembles will be described. Important parameters, such as the generation of the charge-separated state upon photoexcitation of the organic electron donor, the lifetimes of the charge-separation and charge-recombination as well as the incident-photon-to-current efficiency value for some donor–acceptor graphene-based hybrids, will be discussed.

  14. Enantioselective organocatalyzed Oxa-Michael-Aldol cascade reactions: Construction of chiral 4H-chromenes with a trifluoromethylated tetrasubstituted carbon stereocenter

    Zhang, Jing


    The first organocatalytic asymmetric synthesis of 4H-chromenes bearing a trifluoromethylated tetrasubstituted carbon center is presented. Chiral secondary amines promote the oxa-Michael-aldol cascade reaction between alkynals and 2-trifluoroacetylphenols via iminium-allenamine activation to produce pharmaceutically important heterocycles with excellent enantioselectivities. The proposed reaction can be scaled-up easily with maintenance of the excellent enantioselectivity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Transglycosylation reactions of Bacillus stearothermophilus maltogenic amylase with acarbose and various acceptors

    Hwa Park, K.; Jeong Kim, M.; Seob Lee, H.; Kim, D. [Department of Food Science and Technology and Research Center for New Bio-Materials in Agriculture, Seoul National University, Suwon (Korea, Republic of); Soo Han, N.; Robyt, J.F. [Laboratory for Carbohydrate Chemistry and Enzymology, Department of Biochemistry and Biophysics, Iowa State University, Ames, IA (United States)


    It was observed that Bacillus stearothermophilus maltogenic amylase cleaved the first glycosidic bond of acarbose to produce glucose and a pseudotrisaccharide (PTS) that was transferred to C-6 of the glucose to give an {alpha}-(1-6) glycosidic linkage and the formation of isoacarbose. The addition of a number of different carbohydrates to the digest gave transfer products in which PTS was primarily attached {alpha}-(1-6) to d-glucose, d-mannose, d-galactose, and methyl {alpha}-d-glucopyranoside. With d-fructopyranose and d-xylopyranose, PTS was linked {alpha}-(1-5) and {alpha}-(1-4), respectively. PTS was primarily transferred to C-6 of the nonreducing residue of maltose, cellobiose, lactose, and gentiobiose. Lesser amounts of {alpha}-(1-3) and/or {alpha}-(1-4) transfer products were also observed for these carbohydrate acceptors. The major transfer product to sucrose gave PTS linked {alpha}-(1-4) to the glucose residue. {alpha},{alpha}-Trehalose gave two major products with PTS linked {alpha}-(1-6) and {alpha}-(1-4). Maltitol gave two major products with PTS linked {alpha}-(1-6) and {alpha}-(1-4) to the glucopyranose residue. Raffinose gave two major products with PTS linked {alpha}-(1-6) and {alpha}-(1-4) to the d-galactopyranose residue. Maltotriose gave two major products with PTS linked {alpha}-(1-6) and {alpha}-(1-4) to the nonreducing end glucopyranose residue. Xylitol gave PTS linked {alpha}-(1-5) as the major product and d-glucitol gave PTS linked {alpha}-(1-6) as the only product. The structures of the transfer products were determined using thin layer-chromatography, high-performance ion chromatography, enzyme hydrolysis, methylation analysis and {sup 13}C NMR spectroscopy. The best acceptor was gentiobiose, followed closely by maltose and cellobiose, and the weakest acceptor was d-glucitol. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  16. Bifunctional Molecular Photoswitches Based on Overcrowded Alkenes for Dynamic Control of Catalytic Activity in Michael Addition Reactions.

    Pizzolato, Stefano F; Collins, Beatrice S L; van Leeuwen, Thomas; Feringa, Ben L


    The emerging field of artificial photoswitchable catalysis has recently shown striking examples of functional light-responsive systems allowing for dynamic control of activity and selectivity in organocatalysis and metal-catalysed transformations. While our group has already disclosed systems featuring first generation molecular motors as the switchable central core, a design based on second generation molecular motors is lacking. Here, the syntheses of two bifunctionalised molecular switches based on a photoresponsive tetrasubstituted alkene core are reported. They feature a thiourea substituent as hydrogen-donor moiety in the upper half and a basic dimethylamine group in the lower half. This combination of functional groups offers the possibility for application of these molecules in photoswitchable catalytic processes. The light-responsive central cores were synthesized by a Barton-Kellogg coupling of the prefunctionalized upper and lower halves. Derivatization using Buchwald-Hartwig amination and subsequent introduction of the thiourea substituent afforded the target compounds. Control of catalytic activity in the Michael addition reaction between (E)-3-bromo-β-nitrostyrene and 2,4-pentanedione is achieved upon irradiation of stable-(E) and stable-(Z) isomers of the bifunctional catalyst 1. Both isomers display a decrease in catalytic activity upon irradiation to the metastable state, providing systems with the potential to be applied as ON/OFF catalytic photoswitches. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Diversity-Oriented Synthesis Based on the DPPP-Catalyzed Mixed Double-Michael Reactions of Electron-Deficient Acetylenes and β-Amino Alcohols

    Yi Chiao Fan


    Full Text Available In this study, we prepared oxizolidines through 1,3-bis(diphenylphosphino-propane (DPPP–catalyzed mixed double-Michael reactions of b-amino alcohols with electron-deficient acetylenes. These reactions are very suitable for the diversity-oriented parallel syntheses of oxizolidines because: (i they are performed under mild metal-free conditions and (ii the products are isolated without complicated work-up. To demonstrate the applicability of mixed double-Michael reactions for the preparation of five-membered-ring heterocycles, we prepared 60 distinct oxazolidines from five β-amino alcohols and 12 electron-deficient acetylenes. We synthesized 36 of these 60 oxazolidines in enantiomerically pure form from proteinogenic amino acid–derived β-amino alcohols.

  18. Tandem Knoevenagel–Michael reactions in aqueous diethylamine medium: A greener and efficient approach toward bis-dimedone derivatives

    Abdullah Mohammed Al-Majid


    The use of inexpensive, eco-friendly and readily available reagents, easy work-up, and high purity products makes the procedure a convenient and robust method for the synthesis of tandem Knoevenagel–Michael adducts.

  19. Excited states in electron-transfer reaction products: ultrafast relaxation dynamics of an isolated acceptor radical anion.

    Horke, Daniel A; Roberts, Gareth M; Verlet, Jan R R


    The spectroscopy and ultrafast relaxation dynamics of excited states of the radical anion of a representative charge-transfer acceptor molecule, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, have been studied in the gas phase using time-resolved photoelectron spectroscopy. The photoelectron spectra reveal that at least two anion excited states are bound. Time-resolved studies show that both excited states are very short-lived and internally convert to the anion ground state, with the lower energy state relaxing within 200 fs and a near-threshold valence-excited state relaxing on a 60 fs time scale. These excited states, and in particular the valence-excited state, present efficient pathways for electron-transfer reactions in the highly exergonic inverted region which commonly displays rates exceeding predictions from electron-transfer theory.

  20. Michael Schwantzer



    In the seven years that he has been in China, German-native Michael, Schwantzer has found himself at the sharp end of business,building up a successful enterprise from humble beginnings in a highly competitive market. Michael initially came to China in 1997 to run a Sino-German joint venture supplying the shipbuilding industry in Nanjing. Two years later he joined LAP, starting the company's China operations. Within two years he had helped bring LAP's annual China sales from zero to US$ 5 million, in part through his extensive contacts within the steel industry.Based in Shanghai, where he lives with his wife and two children, Michael has caught the China-bug and has no plans to return to his native Germany. “Why would I?” he says.“Shanghai is the place to be right now.”

  1. Michael Scott

    Ersin Hussein


    Full Text Available Associate Professor Michael Scott is a researcher and lecturer based in the department of Classics and Ancient History at the University of Warwick. He is also President of the Lytham St Annes Classical Association. Prior to his appointment at Warwick, Michael was the Moses and Mary Finley Research Fellow in ancient history at Darwin College, as well as an Affiliated Lecturer in the Faculty of Classics, at Cambridge University.Michael's research and teaching engages with interdisciplinary approaches to the literary, epigraphic and material evidence to investigate ancient Greek and Roman society, particularly focusing on Delphi and Olympia as religious spaces.While Michael has contributed significantly to the field of classics and ancient history by publishing extensively, he has also enjoyed great success in engaging wider audiences with the ancient world. He regularly talks in schools around the country, writes books intended for the popular market as well as articles for national and international newspapers and magazines. Michael's experience in writing and presenting a range of programmes intended for TV and radio audiences has made him a household name. He has written and presented programmes for the National Geographic, History Channel, Nova, and the BBC including Delphi: bellybutton of the ancient world (BBC4; Guilty Pleasures: luxury in the ancient and medieval words (BBC4; Jesus: rise to power (Natural Geographic; Ancient Discoveries (History Channel; Who were the Greeks? (BBC2; The Mystery of the X Tombs (BBC2/Nova; The Greatest Show on Earth (BBC4, in conjunction with the Open University. He has also presented a radio series for BBC Radio 4, Spin the Globe. Michael's most recent programme, Roman Britain from the Air, was aired on ITV in December 2014.In this interview, I talk to him about his engagement with other disciplines within the humanities, his forthcoming book project, and his experiences writing and presenting TV and radio

  2. Green and efficient synthesis of novel bispyrazoles through a tandem Knoevenagel and Michael type reaction using nanowire zinc oxide as a powerful and recyclable catalyst

    ESKANDARI, Khalil; KARAMI, Bahador; Khodabakhshi, Saeed; HOSEINI, SEYYED JAFAR


    Zinc oxide nanowires (ZnO NWs) were prepared and characterized by scanning electron microscopy, powder X-ray diffraction, and transmission electron microscopy analyses. ZnO NWs were then employed as heterogeneous and recyclable catalyst for green synthesis of some new and known bispyrazole derivatives through a tandem Knoevenagel and Michael type addition reaction of aromatic aldehyde and pyrazolone. The synthetic method is operationally simple and affords product with high yields in short re...

  3. Solvent-free Thia-Michael Addition Reactions Using 3-[Bis(alkylthio)methylene]pentane-2,4-diones as Efficient and Odorless Thiol Equivalents

    LIN Chun; ZHAO Xiao-Liang; OUYANG Yan; YU Hai-Feng; DONG De-Wen


    3-[Bis(alkylthio)methylene]pentane-2,4-diones (1a and 1b) have been investigated as nonthiolic and odorless thiol equivalents for thia-Michael addition reactions under solvent-free conditions. Promoted by HCl (aq.), the cleavage of compounds 1 took place, and the in-situ generated thiols underwent facile conjugate addition to α,β-unsaturated carbonyl compounds 2 affording the corresponding β-keto sulfides 3 in high yields.

  4. Lewis Acid Catalyzed Selective Reactions of Donor-Acceptor Cyclopropanes with 2-Naphthols.

    Kaicharla, Trinadh; Roy, Tony; Thangaraj, Manikandan; Gonnade, Rajesh G; Biju, Akkattu T


    Lewis acid-catalyzed reactions of 2-substituted cyclopropane 1,1-dicarboxylates with 2-naphthols is reported. The reaction exhibits tunable selectivity depending on the nature of Lewis acid employed and proceed as a dearomatization/rearomatization sequence. With Bi(OTf)3 as the Lewis acid, a highly selective dehydrative [3+2] cyclopentannulation takes place leading to the formation of naphthalene-fused cyclopentanes. Interestingly, engaging Sc(OTf)3 as the Lewis acid, a Friedel-Crafts-type addition of 2-naphthols to cyclopropanes takes place, thus affording functionalized 2-naphthols. Both reactions furnished the target products in high regioselectivity and moderate to high yields. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Michael Jordan



    Many of us know Michael Jordan is a famous American basketball star. He is perhaps the greatest player in basketball history. Jordan is 1.98m tall. He plays guard(后卫)for the Chicago Bulls. He led his team to six NBA(National Basketball Association ) championships (冠军4).

  6. On Michael Addition Reactions of Chalcones%查尔酮类化合物的 Michael加成反应

    张鹏会; 李艳春; 蒲雯


    A series of chalcones are synthesized from aromatic aldehyde and acetophenone ,with H2 O as the solvent and sodium hydroxide as the catalyst .A series of Michael addition products are obtained from these chalcones and ethyl acetoacetate , catalyzed by sodium hydroxide and anhydrous sodium carbonate under the assistance of ultrasonic irradiation .And the inflences of the addition reaction condition on the yield are studied .The premium condition are determined by followings:the molar ratio of chalcone and ethyl acetoacetate is 1/1.5,sodium hydroxide/anhydrous sodium carbonate is 1/1.5 under PEG -400/H2O in 40oC,the desired product is obtained,and the yield can be up to 91.2%.The method of this syn-thesis has advantages such as simple to operate ,short reaction time and high yield .%以芳香醛与苯乙酮为原料, NaOH 为催化剂,在水相中合成了一系列查尔酮化合物。在超声辅助下,研究了混合碱( NaOH-Na2 CO3)催化查尔酮与三乙(乙酰乙酸乙酯)的 Michael加成反应,合成了一系列Michael加成产物,并对影响反应的因素进行了探究,得出最佳反应条件为:40oC 下,在 PEG -400/H2O 介质中,n查尔酮/n三乙=1/1.5,nNaOH/nNa2CO3=1/1.5,得到目标产物的产率最好,高达91.2%。此方法操作简单,反应时间短,产率高。

  7. N-Heterocyclic Carbene-Catalysed Diastereoselective Vinylogous Michael Addition Reaction of gamma-Substituted deconjugated Butenolides

    Guo, Hao


    An efficient N-heterocyclic carbene (NHC)-catalysed vinylogous Michael addition of deconjugated butenolides was developed. In the presence of 5 mol% of the NHC catalyst, both γ-alkyl and aryl-substituted deconjugated butenolides undergo vinylogous Michael addition with various α, β-unsaturated ketones, esters, or nitriles to afford γ,γ-disubstituted butenolides containing adjacent quaternary and tertiary carbon centers in good to excellent yields with excellent diastereoselectivities. In this process, the free carbene is assumed to act as a strong Brønsted base to promote the conjugate addition.

  8. Nano-organocatalyst: magnetically retrievable ferrite-anchored glutathione for microwave-assisted Paal–Knorr reaction, aza-Michael addition, and pyrazole synthesis

    Polshettiwar, Vivek


    Postsynthetic Surface modification of magnetic nanoparticles by glutathione imparts desirable chemical functionality and enables the generation of catalytic sites on the surfaces of ensuing organocatalysts. In this article, we discuss the developments, unique activity, and high selectivity of nano-organocatalysts for microwave-assisted Paal-Knorr reaction, aza-Michael addition, and pyrazole synthesis. Their insoluble character Coupled with paramagnetic nature enables easy separation of these nano-catalysts from the reaction mixture using external magnet, which eliminates the requirement of catalyst filtration. Published by Elsevier Ltd.

  9. Isoindolinones as Michael Donors under Phase Transfer Catalysis: Enantioselective Synthesis of Phthalimidines Containing a Tetrasubstituted Carbon Stereocenter

    Francesco Scorzelli


    Full Text Available Readily available chiral ammonium salts derived from cinchona alkaloids have proven to be effective phase transfer catalysts in the asymmetric Michael reaction of 3-substituted isoindolinones. This protocol provides a convenient method for the construction of valuable asymmetric 3,3-disubstituted isoindolinones in high yields and  moderate to good enantioselectivity. Diastereoselectivity was also investigated in the construction of contiguous tertiary and quaternary stereocenters. The use of acrolein as Michael acceptor led to an interesting tricyclic derivative, a pyrroloisoindolinone analogue, via a tandem conjugated addition/cyclization reaction.

  10. Structural water cluster as a possible proton acceptor in the adduct decay reaction of oat phototropin 1 LOV2 domain.

    Chan, Ruby H; Bogomolni, Roberto A


    LOV domains (Light, Oxygen, Voltage) are the light-sensory modules of phototropins, the blue-light photoreceptor kinases in plants, and of a wide variety of flavoproteins found in all three domains of life. These 12 kDa modules bind a flavin chromophore (FMN or FAD) noncovalently and undergo a photochemical activation in which the sulfur atom of a conserved cysteine forms an adduct to the C(4a) carbon of the flavin. The adduct breaks spontaneously in a base-catalyzed reaction involving a rate-limiting proton-transfer step, regenerating the dark state in seconds. This photocycle involves chromophore and protein structural changes that activate the C-terminal serine/threonine kinase. Previous studies (Biochemistry 2007, 46, 7016-7021) showed that decreased hydration obtained at high glycerol concentrations stabilizes the adduct state in a manner similar to that attained at low temperatures, resulting in much longer adduct decay times. This kinetic effect was attributed to an increased protein rigidity that hindered structural fluctuations necessary for the decay reaction. In this work, we studied the adduct decay kinetics of oat phototropin 1 (phot1) LOV2 at varying hydration using a specially designed chamber that allowed for measurement of UV-visible and FTIR spectra of the same samples. Therefore, we obtained LOV protein concentrations, adduct decay kinetics, and the different populations of bound water by deconvolution of the broad water absorption peak around 3500 cm(-1). A linear dependence of the adduct decay rate constant on the concentration of double and triple hydrogen-bonded waters strongly suggests that the adduct decay is a pseudo-first-order reaction in which both the adduct and the strongly bound waters are reactants. We suggest that a cluster of strongly bound water functions as the proton acceptor in the rate-limiting step of adduct decay.

  11. Modulating the Redox Potential of the Stable Electron Acceptor, QB, in Mutagenized Photosystem II Reaction Centers.

    Perrine, Zoee [The Ohio State Univ., Columbus, OH (United States); The Donald Danforth Plant Science Center, St. Louis, MO (United States); Sayre, Richard [The Donald Danforth Plant Science Center, St. Louis, MO (United States)


    One of the unique features of electron transfer processes in photosystem II (PSII) reaction centers (RC) is the exclusive transfer of electrons down only one of the two parallel cofactor branches. In contrast to the RC core polypeptides (psaA and psaB) of photosystem I (PSI), where electron transfer occurs down both parallel redox-active cofactor branches, there is greater protein-cofactor asymmetry between the PSII RC core polypeptides (D1 and D2). We have focused on the identification of protein-cofactor relationships that determine the branch along which primary charge separation occurs (P680+/pheophytin-(Pheo)). We have previously shown that mutagenesis of the strong hydrogen-bonding residue, D1-E130, to less polar residues (D1-E130Q,H,L) shifted the midpoint potential of the PheoD1/PheoD1- couple to more negative values, reducing the quantum yield of primary charge separation. We did not observe, however, electron transfer down the inactive branch in D1-E130 mutants. The protein residue corresponding to D1-E130 on the inactive branch is D2-Q129 which presumably has a reduced hydrogen-bonding interaction with PheoD2 relative to the D1-E130 residue with PheoD1. Analysis of the recent 2.9 Å cyanobacterial PSII crystal structure indicated, however, that the D2-Q129 residue was too distant from the PheoD2 headgroup to serve as a possible hydrogen bond donor and directly impact its midpoint potential as well as potentially determine the directionality of electron transfer. Our objective was to characterize the function of this highly conserved inactive branch residue by replacing it with a nonconservative leucine or a conservative histidine residue. Measurements of Chl fluorescence decay kinetics and thermoluminescence studies indicate that the mutagenesis of D2-Q129 decreases the redox gap between QA and QB due to a lowering of the redox potential of QB. The

  12. Transition Metal Donor-Peptide-Acceptor Complexes: From Intramolecular Electron Transfer Reactions to the Study of Reactive Intermediates

    Isied, Stephan S.


    The trans-polyproline (PII) oligomers (Figure 1) are unusually rigid peptide structures which have been extensively studied by our group for peptide mediated intramolecular electron transfer (ET) at long distances. We have previously studied ET across a series of metal ion donor (D) acceptor (A) oligoproline peptides with different distances, driving forces and reorganizational energies. The majority of these experiments involve generating the ET intermediate using pulse radiolysis methods, although more recently photochemical methods are also used. Results of these studies showed that ET across peptides can vary by more than twelve orders of magnitude. Using ruthenium bipyridine donors, ET reaction rate constants across several proline residues (n = 4 - 9) occurred in the millisecond (ms) to {micro}s timescale, thus limiting the proline peptide conformational motions to only minor changes (far smaller than the large changes that occur on the ms to sec timescale, such as trans to cis proline isomerization). The present report describes our large data base of experimental results for D-peptide-A complexes in terms of a model where the involvement of both superexchange and hopping (hole and electron) mechanisms account for the long range ET rate constants observed. Our data shows that the change from superexchange to hopping mechanisms occurs at different distances depending on the type of D and A and their interactions with the peptides. Our model is also consistent with generalized models for superexchange and hopping which have been put forward by a number of theoretical groups to account for long range ET phenomena.

  13. Nucleophilic phosphine-catalyzed intramolecular Michael reactions of N-allylic substituted α-amino nitriles: construction of functionalized pyrrolidine rings via 5-endo-trig cyclizations.

    En, Da; Zou, Gong-Feng; Guo, Yuan; Liao, Wei-Wei


    Pyrrolidine rings are common moieties for pharmaceutical candidates and natural compounds, and the construction of these skeletons has received much attention. α-Amino nitriles are versatile intermediates in synthetic chemistry and have been widely used in the generation of multiple polyfunctional structures. Herein, a novel nucleophilic phosphine-catalyzed intramolecular Michael reaction of N-allylic substituted α-amino nitriles has been developed for the efficient construction of functionalized 2,4-disubstituted pyrrolidines (N-heterocyclic α-amino nitriles) via 5-endo-trig cyclization. Furthermore, the one-pot sequence of the synthesis of pyrrolidine and the subsequent transformations of the functionalized products have also been demonstrated.

  14. Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

    Chittaranjan Bhanja


    Full Text Available Enantioselective organocatalysis has become a field of central importance within asymmetric chemical synthesis and appears to be efficient approach toward the construction of complex chiral molecules from simple achiral materials in one-pot transformations under mild conditions with high stereocontrol. This review addresses the most significant synthetic methods reported on chiral-amine-catalyzed tandem Michael conjugate addition of heteroatom-centered nucleophiles to α,β-unsaturated compounds followed by cyclization reactions for the enantioselective construction of functionalized chiral chromenes, thiochromenes and 1,2-dihydroquinolines in optically enriched forms found in a myriad of bioactive natural products and synthetic compounds.

  15. Chemometric resolution of NIR spectra data of a model aza-Michael reaction with a combination of local rank exploratory analysis and multivariate curve resolution-alternating least squares (MCR-ALS) method.

    del Río, Vanessa; Callao, M Pilar; Larrechi, M Soledad; Montero de Espinosa, Lucas; Ronda, J Carles; Cádiz, Virginia


    The aza-Michael reaction, a variation of the Michael reaction in which an amine acts as the nucleophile, permits the synthesis of sophisticated macromolecular structures with potential use in many applications such as drug delivery systems, high performance composites and coatings. The aza-Michael product can be affected by a retro-Mannich-type fragmentation. A way of determining the reactions that are taking place and evaluate the quantitative evolution of the chemical species involved in the reactions is presented. The aza-Michael reaction between a modified fatty acid ester with alpha,beta-unsaturated ketone groups (enone containing methyl oleate (eno-MO)) and aniline (1:1) was studied isothermally at 95 degrees C and monitored in situ by near-infrared spectroscopy (NIR). The number of reactions involved in the system was determined analyzing the rank matrix of NIR spectra data recorded during the reaction. Singular value decomposition (SVD) and evolving factor analysis (EFA) adapted to analyze full rank augmented data matrices have been used. In the experimental conditions, we found that the resulting aza-Michael adduct undergoes a retro-Mannich-type fragmentation, but the final products of this reaction were present in negligible amounts. This was confirmed by recording the (1)H NMR spectra of the final product. Applying multivariate curve resolution-alternating least squares (MCR-ALS) to the NIR spectra data obtained during the reaction, it has been possible to obtain the concentration values of the species involved in the aza-Michael reaction. The performance of the model was evaluated by two parameters: ALS lack of fit (lof=1.31%) and explained variance (R(2)=99.92%). Also, the recovered spectra were compared with the experimentally recorded spectra for the reagents (aniline and eno-MO) and the correlation coefficients (r) were 0.9997 for the aniline and 0.9578 for the eno-MO.

  16. X-Ray absorption in homogeneous catalysis research: the iron-catalyzed Michael addition reaction by XAS, RIXS and multi-dimensional spectroscopy.

    Bauer, Matthias; Gastl, Christoph


    A survey over X-ray absorption methods in homogeneous catalysis research is given with the example of the iron-catalyzed Michael addition reaction. A thorough investigation of the catalytic cycle was possible by combination of conventional X-ray absorption spectroscopy (XAS), resonant inelastic X-ray scattering (RIXS) and multi-dimensional spectroscopy. The catalytically active compound formed in the first step of the Michael reaction of methyl vinyl ketone with 2-oxocyclopentanecarboxylate (1) could be elucidated in situ by RIXS spectroscopy, and the reduced catalytic activity of FeCl(3) x 6 H(2)O (2) compared to Fe(ClO(4))(3) x 9 H(2)O (3) could be further explained by the formation of a [Fe(III)Cl(4)(-)](3)[Fe(III)(1-H)(2)(H(2)O)(2)(+)][H(+)](2) complex. Chloride was identified as catalyst poison with a combined XAS-UV/vis study, which revealed that Cl(-) binds quantitatively to the available iron centers that are deactivated by formation of [FeCl(4)(-)]. Operando studies in the course of the reaction of methyl vinyl ketone with 1 by combined XAS-Raman spectroscopy allowed the exclusion of changes in the oxidation state and the octahedral geometry at the iron site; a reaction order of two with respect to methyl vinyl ketone and a rate constant of k = 1.413 min(-2) were determined by analysis of the C=C and C=O vibration band. Finally, a dedicated experimental set-up for three-dimensional spectroscopic studies (XAS, UV/vis and Raman) of homogeneous catalytic reactions under laboratory conditions, which emerged from the discussed investigations, is presented.

  17. Multifunctional Electrochemical Platforms Based on the Michael Addition/Schiff Base Reaction of Polydopamine Modified Reduced Graphene Oxide: Construction and Application.

    Huang, Na; Zhang, Si; Yang, Liuqing; Liu, Meiling; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo


    In this paper, a new strategy for the construction of multifunctional electrochemical detection platforms based on the Michael addition/Schiff base reaction of polydopamine modified reduced graphene oxide was first proposed. Inspired by the mussel adhesion proteins, 3,4-dihydroxyphenylalanine (DA) was selected as a reducing agent to simultaneously reduce graphene oxide and self-polymerize to obtain the polydopamine-reduced graphene oxide (PDA-rGO). The PDA-rGO was then functionalized with thiols and amines by the reaction of thiol/amino groups with quinine groups of PDA-rGO via the Michael addition/Schiff base reaction. Several typical compounds containing thiol and/or amino groups such as 1-[(4-amino)phenylethynyl] ferrocene (Fc-NH2), cysteine (cys), and glucose oxidase (GOx) were selected as the model molecules to anchor on the surface of PDA-rGO using the strategy for construction of multifunctional electrochemical platforms. The experiments revealed that the composite grafted with ferrocene derivative shows excellent catalysis activity toward many electroactive molecules and could be used for individual or simultaneous detection of dopamine hydrochloride (DA) and uric acid (UA), or hydroquinone (HQ) and catechol (CC), while, after grafting of cysteine on PDA-rGO, simultaneous discrimination detection of Pb(2+) and Cd(2+) was realized on the composite modified electrode. In addition, direct electron transfer of GOx can be observed when GOx-PDA-rGO was immobilized on glassy carbon electrode (GCE). When glucose was added into the system, the modified electrode showed excellent electric current response toward glucose. These results inferred that the proposed multifunctional electrochemical platforms could be simply, conveniently, and effectively regulated through changing the anchored recognition or reaction groups. This study would provide a versatile method to design more detection or biosensing platforms through a chemical reaction strategy in the future.

  18. Direct targeted glycation of the free sulfhydryl group of cysteine residue (Cys-34) of BSA. Mapping of the glycation sites of the anti-tumor Thomsen-Friedenreich neoglycoconjugate vaccine prepared by Michael addition reaction.

    Demian, Wael L L; Kottari, Naresh; Shiao, Tze Chieh; Randell, Edward; Roy, René; Banoub, Joseph H


    We present in this manuscript the characterization of the exact glycation sites of the Thomsen-Friedenreich antigen-BSA vaccine (TF antigen:BSA) prepared using a Michael addition reaction between the saccharide antigen as an electrophilic acceptor and the nucleophilic thiol and L-Lysine ε-amino groups of BSA using different ligation conditions. Matrix laser desorption ionization time-of-flight mass spectrometry of the neoglycoconjugates prepared with TF antigen:protein ratios of 2:1 and 8:1, allowed to observe, respectively, the protonated molecules for each neoglycoconjugates: [M + H](+) at m/z 67,599 and 70,905. The measurements of these molecular weights allowed us to confirm exactly the carbohydrate:protein ratios of these two synthetic vaccines. These were found to be closely formed by a TF antigen:BSA ratios of 2:1 and 8:1, respectively. Trypsin digestion and liquid chromatography coupled with electrospray ionization mass spectrometry allowed us to identify the series of released glycopeptide and peptide fragments. De novo sequencing affected by low-energy collision dissociation tandem mass spectrometry was then employed to unravel the precise glycation sites of these neoglycoconjugate vaccines. Finally, we identified, respectively, three diagnostic and characteristic glycated peptides for the synthetic glycoconjugate possessing a TF antigen:BSA ratio 2:1, whereas we have identified for the synthetic glycoconjugate having a TF:BSA ratio 8:1 a series of 14 glycated peptides. The net increase in the occupancy sites of these neoglycoconjugates was caused by the large number of glycoforms produced during the chemical ligation of the synthetic carbohydrate antigen onto the protein carrier. Copyright © 2014 John Wiley & Sons, Ltd.

  19. The pseudo-Michael reaction of 1-aryl-4,5-dihydro-1H-imidazol-2-amines with ethyl ethoxymethylenecyanoacetate.

    Kaczor, Agnieszka A; Kijkowska-Murak, Urszula; Pihlaja, Kalevi; Sinkkonen, Jari; Wysocki, Waldemar; Karczmarzyk, Zbigniew; Matosiuk, Dariusz

    The pseudo-Michael reaction of 1-aryl-4,5-dihydro-1H-imidazol-2-amines with ethyl 2-cyano-3-methoxyprop-2-enoate (ethyl ethoxymethylenecyanoacetate) is investigated. At -10 °C reaction takes place on the exocyclic nitrogen atom, giving exclusively ethyl esters of 2-cyano-3-[(1-phenyl-4,5-dihydro-1H-imidazol-2-yl)amino]prop-2-enoic acid. The formation of isomeric enamines which may be a theoretical product of the reaction on N3 ring nitrogen atom is not observed. The N6 enamines, heated in boiling acetic acid, yield cyclic 1-aryl-5-oxo-2,3-dihydroimidazo[1,2-a]pyrimidine-6-carbonitriles. Heating of the enamines to the temperature of 120-140 °C without a solvent makes it possible to obtain a mixture of 1-aryl-5-oxo-2,3-dihydroimidazo[1,2-a]pyrimidine-6-carbonitriles and ethyl 1-aryl-5-imino-2,3-dihydroimidazo[1,2-a]pyrimidine-6-carboxylates. The reaction of the respective hydrobromides of 1-aryl-4,5-dihydro-1H-imidazol-2-amines with ethyl ethoxymethylenecyanoacetate in the presence of triethylamine gives selectively 1-aryl-5-oxo-1,2,3,5-dihydroimidazo[1,2-a]pyrimidine-6-carbonitriles.

  20. Excited states in electron-transfer reaction products : ultrafast relaxation dynamics of an isolated acceptor radical anion.

    D. A. Horke; Roberts, G.M.; Verlet, J. R. R.


    The spectroscopy and ultrafast relaxation dynamics of excited states of the radical anion of a representative charge-transfer acceptor molecule, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, have been studied in the gas phase using time-resolved photoelectron spectroscopy. The photoelectron spectra reveal that at least two anion excited states are bound. Time-resolved studies show that both excited states are very short-lived and internally convert to the anion ground state, with the ...


    Microwave-assisted reaction of 2'-hydroxychalcones in the presence of DBU resulted in the formation of hitherto unknown dimers by conjugate addition of the intermediate cyclic ketone to the starting enone.

  2. Organocatalytic Asymmetric Michael Addition of 4-Hydroxycoumarin to β,γ-Unsaturated α-Keto Esters

    Suh, Chang Won; Han, Tae Hyun; Kim, Dae Young [Soonchunhyang Univ., Asan (Korea, Republic of)


    In conclusion, we have developed organocatalytic enantioselective conjugate addition reaction of 4-hydroxycoumarin (1) to β,γ-unsaturated α-keto esters 2 to afford biologically valuable warfarin derivatives 3. The process is efficiently catalyzed by a binaphthyl-modified thiourea organocatalyst. The coumarin core is present as a characteristic structural motif in a large number of natural products and biologically active molecules.1 Particularly, many of these naturally occurring 4-hydroxycoumarin and their synthetic analogues are important precursors for the synthesis of natural products and pharmaceuticals. Enantioselective organocatalytic conjugate addition of 4-hydroxycoumarin to α,β-unsaturated ketones is a straightforward method to access warfarin which is an effective anticoagulants. Although a number of reactions of α,β-unsaturated ketones as Michael acceptors have been reported, the corresponding β,γ-unsaturated α-keto esters have received relatively little attention as Michael acceptors. Recently, several groups have reported the asymmetric Michael addition of 4-hydroxycoumarin to β,γ-unsaturated α-keto esters catalyzed by Cu(II)-bisoxazoline, N,N'-dioxide-Ni(II) complexes, thiourea catalysts. Although several efficient methods have been achieved by these systems, an effective method for the synthesis of warfarin analogues is still a challenge.

  3. Kinetic study on Michael-type reactions of β-nitrostyrenes with cyclic secondary amines in acetonitrile: transition-state structures and reaction mechanism deduced from negative enthalpy of activation and analyses of LFERs.

    Um, Ik-Hwan; Kang, Ji-Sun; Park, Jong-Yoon


    A kinetic study is reported for the Michael-type reactions of X-substituted β-nitrostyrenes (1a-j) with a series of cyclic secondary amines in MeCN. The plots of pseudo-first-order rate constant k(obsd) vs [amine] curve upward, indicating that the reactions proceed through catalyzed and uncatalyzed routes. The dissection of k(obsd) into Kk2 and Kk3 (i.e., the rate constants for the uncatalyzed and catalyzed routes, respectively) revealed that Kk3 is much larger than Kk2, implying that the reactions proceed mainly through the catalyzed route when [amine] > 0.01 M. Strikingly, the reactivity of β-nitrostyrene (1g) toward piperidine decreases as the reaction temperature increases. Consequently, a negative enthalpy of activation is obtained, indicating that the reaction proceeds through a relatively stable intermediate. The Brønsted-type plots for the reactions of 1g are linear with β(nuc) = 0.51 and 0.61, and the Hammett plots for the reactions of 1a-j are also linear with ρX = 0.84 and 2.10 for the uncatalyzed and catalyzed routes, respectively. The reactions are concluded to proceed through six-membered cyclic transition states for both the catalyzed and uncatalyzed routes. The effects of the substituent X on reactivity and factors influencing β(nuc) and ρX obtained in this study are discussed.

  4. Chiral ionic liquid/ESI-MS methodology as an efficient tool for the study of transformations of supported organocatalysts: deactivation pathways of Jørgensen-Hayashi-type catalysts in asymmetric Michael reactions.

    Maltsev, Oleg V; Chizhov, Alexander O; Zlotin, Sergei G


    The deactivation pathways of Jørgensen-Hayashi-type organocatalysts modified with an ionic liquid fragment in asymmetric Michael reactions of α,β-enals with C- (nitromethane, dimethylmalonate) or N-nucleophiles (N-carbobenzyloxyhydroxylamine) that involved an iminium-ion formation step were studied for the first time by the electrospray ionization mass spectrometry (ESI-MS). "Parasitic" side reactions and undesirable cation intermediates that poisoned the catalysts were identified in accordance with their m/z values as well as their relation to the reported mechanisms of Michael reactions in the presence of O-TMS-α,α-diarylprolinol (TMS=trimethylsilyl) derivatives. The proposed approach may be useful for the study of transformations of other types of organocatalysts modified with ionic groups in various organocatalytic reactions and for the development of novel robust catalysts and processes that would be suitable for large-scale industrial applications.

  5. Enantioselective Michael reaction catalyzed by well-defined chiral ru amido complexes: isolation and characterization of the catalyst intermediate, ru malonato complex having a metal-carbon bond.

    Watanabe, Masahito; Murata, Kunihiko; Ikariya, Takao


    Chiral Ru amido complexes promote asymmetric Michael addition of malonates to cyclic enones, leading to Michael adducts with excellent ee's, in which the chiral Ru amido complexes react with malonates to give isolable catalyst intermediates, chiral Ru malonato complexes bearing a metal bound C-nucleophile.

  6. Molecular Characterization of Thiols in Fossil Fuels by Michael Addition Reaction Derivatization and Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry.

    Wang, Meng; Zhao, Suoqi; Liu, Xuxia; Shi, Quan


    Thiols widely occur in sediments and fossil fuels. However, the molecular composition of these compounds is unclear due to the lack of appropriate analytical methods. In this work, a characterization method for thiols in fossil fuels was developed on the basis of Michael addition reaction derivatization followed by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). Model thiol compound studies showed that thiols were selectively reacted with phenylvinylsulfone and transformed to sulfones with greater than 98% conversions. This method was applied to a coker naphtha, light and heavy gas oils, and crude oils from various geological sources. The results showed that long alkyl chain thiols are readily present in petroleum, which have up to 30 carbon atoms. Large DBE dispersity of thiols indicates that naphthenic and aromatic thiols are also present in the petroleum. This method is capable of detecting thiol compounds in the part per million range by weight. This method allows characterization of thiols in a complex hydrocarbon matrix, which is complementary to the comprehensive analysis of sulfur compounds in fossil fuels.

  7. Donor/Acceptor-Stabilized 1-Silaketene: Reversible [2+2] Cycloaddition with Pyridine and Evolution by an Olefin Metathesis Reaction.

    Reyes, Morelia Lopez; Troadec, Thibault; Rodriguez, Ricardo; Baceiredo, Antoine; Saffon-Merceron, Nathalie; Branchadell, Vicenç; Kato, Tsuyoshi


    The reaction of silacyclopropylidene 1 with benzaldehyde generates a 1-silaketene complex 2 by a formal atomic silicon insertion into the C=O bond of the aldehyde. The highly reactive 1-silaketene 2 undergoes a reversible [2+2] cycloaddition with pyridine to give sila-β-lactam 3. Of particular interest, in the presence of 4-dimethylaminopyridine (DMAP), 1-silaketene complex 2 evolves through an intramolecular olefin metathesis reaction, generating a new 1-silaketene complex 8 and cis-stilbene. Theoretical studies suggest that the reaction proceeds through the formation of a transient silacyclobutanone, a four-membered-ring intermediate, similar to that proposed by Chauvin and co-workers for the transition-metal-based olefin metathesis.

  8. Reactions of the cumyloxyl and benzyloxyl radicals with strong hydrogen bond acceptors. Large enhancements in hydrogen abstraction reactivity determined by substrate/radical hydrogen bonding.

    Salamone, Michela; DiLabio, Gino A; Bietti, Massimo


    A kinetic study on hydrogen abstraction from strong hydrogen bond acceptors such as DMSO, HMPA, and tributylphosphine oxide (TBPO) by the cumyloxyl (CumO(•)) and benzyloxyl (BnO(•)) radicals was carried out in acetonitrile. The reactions with CumO(•) were described in terms of a direct hydrogen abstraction mechanism, in line with the kinetic deuterium isotope effects, k(H)/k(D), of 2.0 and 3.1 measured for reaction of this radical with DMSO/DMSO-d(6) and HMPA/HMPA-d(18). Very large increases in reactivity were observed on going from CumO(•) to BnO(•), as evidenced by k(H)(BnO(•))/k(H)(CumO(•)) ratios of 86, 4.8 × 10(3), and 1.6 × 10(4) for the reactions with HMPA, TBPO, and DMSO, respectively. The k(H)/k(D) of 0.91 and 1.0 measured for the reactions of BnO(•) with DMSO/DMSO-d(6) and HMPA/HMPA-d(18), together with the k(H)(BnO(•))/k(H)(CumO(•)) ratios, were explained on the basis of the formation of a hydrogen-bonded prereaction complex between the benzyloxyl α-C-H and the oxygen atom of the substrates followed by hydrogen abstraction. This is supported by theoretical calculations that show the formation of relatively strong prereaction complexes. These observations confirm that in alkoxyl radical reactions specific hydrogen bond interactions can dramatically influence the hydrogen abstraction reactivity, pointing toward the important role played by structural and electronic effects.

  9. Professor Michael Levitt

    Gemma-Louise Davies


    Full Text Available Professor Michael Levitt (Stanford University, USA won the 2013 Nobel Prize in Chemistry for the development of multiscale models for complex chemical systems—computational tools which can calculate the course of chemical reactions. Professor Levitt was born in Pretoria, South Africa; he came to the UK on a summer vacation aged 16, where he decided to stay and study for his A‑levels. His interest in the physics of living systems drove him to study biophysics at King’s College London, before securing a PhD position at the Laboratory of Molecular Biology in Cambridge. In the interim year between his degree and beginning his PhD, Professor Levitt worked at the Weizmann Institute of Science in Israel, where he met his future wife. They married later that year and moved to Cambridge, where their three children were born. After completing his PhD, he spent time working in Israel, Cambridge, the Salk Institute and Stanford (both California. Since 1986, he has split his time between Israel and California. Outside of science, he is a keen hiker and he is well-known to have attended the eclectic ‘Burning Man’ Festival in California.[1]Professor Levitt visited the University of Warwick to speak at the Computational Molecular Science Annual Conference in March 2015. In this interview, Dr Gemma-Louise Davies, an Institute of Advanced Study Global Research Fellow, spoke to Professor Levitt about the importance of Interdisciplinarity in his field, role models in Academia, and his plans for the future.Image: Professor Michael Levitt (left with Dr Scott Habershon (right, organiser of the 2015 Computational Molecular Science Annual Conference during his visit to the University of Warwick in March 2015.[1] ‘Burning Man’ is a unique annual festival dedicated to community, art, music, self-expression and self-reliance. Tens of thousands of people flock to this temporary metropolis built in the Californian desert.

  10. Recent advances in the synthesis of nitrogen heterocycles via radical cascade reactions using isonitriles as radical acceptors.

    Zhang, Bo; Studer, Armido


    Nitrogen heterocycles belong to a highly important class of compounds which are found in various natural products, biologically active structures, and medicinally relevant compounds. Therefore, there is continuing interest in the development of novel synthetic methods for the construction of nitrogen containing heterocycles. Recently, radical insertion reactions into isonitriles have emerged as an efficient and powerful strategy for the construction of nitrogen heterocycles, such as phenanthridines, indoles, quinolines, quinoxalines, and isoquinolines. This review highlights recent advances in this fast growing research area and also includes important pioneering studies in this area.

  11. [Synthesis of 11-[(2-pyridyl)amino]- and 11-[(9-anthracenylcarbonyl)amino]undecyl phosphate and investigation of their acceptor properties in the enzymic reaction catalyzed by galactosylphosphotransferases from Salmonella].

    Danilov, L L; Balagurova, N M; Vinnikova, A N; Utkina, N S; Torgov, V I; Kalinchuk, N A; Druzhinina, T N; Veselovsky, V V


    11-[(2-Pyridyl)amino]undecyl phosphate and 11-[(9-anthracenylcarbonyl)amino]undecyl phosphate were chemically synthesized. The abiliy of these new fluorescent derivatives of undecyl phosphate to serve as acceptor substrate of galactosyl phosphate residue in the enzymic reaction catalyzed by galactosylphosphotransferase from Salmonella anatum or Salmonella newport membrane preparation was demonstrated.

  12. One-Pot Synthesis of 2-Acylindole-3-acetylketones via Domino Aza-alkylation/Michael Reaction Using o-Aminophenyl α,β-Unsaturated Ketones Followed by Desulfonative Dehydrogenation

    Kim, A Reum; Yu, Mi Rim; Sim, Jong Tack; Kim, Sung Gon [Kyonggi Univ., Suwon (Korea, Republic of)


    The development of novel and practical synthetic methods with a minimum number of operations for the construction of bioactive structurally complex compounds is a major challenge in synthetic organic chemistry. Recently, we reported an efficient method for the stereoselective synthesis of 2,3-disubstituted indoline derivatives; cis-2,3-disubstituted indolines were obtained by the aza-alkylation/Michael cascade reaction of 2-(tosylamino)phenyl α,β-unsaturated ketones with α-bromoacetophenones in good yields and with excellent diastereoselectivities (Scheme 2, Eq. (1)). Among the available synthetic strategies, domino or cascade reactions have received wide acceptance as highly efficient and powerful methods for the synthesis of molecules with a high structural complexity. An efficient synthesis of 2,3-disubstituted indoles was developed by the domino aza-alkylation/intramolecular Michael reaction of 2-(tosylamino)phenyl α,β-unsaturated ketones with α-bromoacetophenones, followed by desulfonative dehydrogenation with DBU. The reaction afforded structurally diverse and highly functionalized 2,3-disubstituted indoles in moderate to excellent yields (up to 99%). The synthesis of 2,3-disubstituted indoles without desulfonation through DDQ-induced oxidative dehydrogenation was also achieved.

  13. The first peripherally masked thiol dendrimers: a facile and highly efficient functionalization strategy of polyester dendrimers via one-pot xanthate deprotection/thiol-acrylate Michael addition reactions.

    Auty, Sam E R; Andrén, Oliver; Malkoch, Michael; Rannard, Steven P


    Introducing multiple reactive functional groups at the periphery of dendrimer materials presents considerable challenges if the functionality is able to self-react. An efficient and facile approach to introducing masked thiols at the surface of polyester dendrimers is presented. One-pot, deprotection/thiol-acrylate Michael addition from the xanthate-functional dendritic substrates (generation zero to two) has been achieved for the first time, with high efficiency demonstrated using three acrylates of varying chemistry and avoiding disulfide formation.

  14. Organometallic enantiomeric scaffolding. Sequential semipinacol/1,5-"Michael-like" reactions as a strategic approach to bridgehead-quaternary center aza[3.3.1]bicyclics: application to the total synthesis of (-)-adaline.

    Coombs, Thomas C; Zhang, Yongqiang; Garnier-Amblard, Ethel C; Liebeskind, Lanny S


    A nontraditional approach to the enantiocontrolled construction of quaternary center-bearing heteroatom-bridged bicyclo[3.3.1]nonanes (homotropanes) is reported that is based on organometallic enantiomeric scaffolding. This strategy takes advantage of the unique reactivity profiles of TpMo(CO)(2)(5-oxo-eta(3)-pyranyl) and TpMo(CO)(2)(5-oxo-eta(3)-pyridinyl) scaffolds, and features a molybdenum-mediated semipinacol/1,5-"Michael-like" reaction sequence to establish the quaternary center and synthesize the bridged bicyclic structure. An asymmetric total synthesis of (-)-adaline highlights this methodology.

  15. Copper (0) nanoparticles onto silica: A stable and facile catalyst for one-pot synthesis of 2,2'-arylmethylene bis (3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) via cascade Knoevenagel/ Michael reaction



    Solid supported copper (0) nanoparticles were prepared by physical adsorption of copper (0)nanoparticles (synthesized through bottom-up approach) on the solid supports such as silica, HAP, cellulose andbasic alumina. Studies comparing these supported catalysts were done with the synthesis of arylmethylene-bis-(3-hydroxy-2-cyclohexene-1-one) via the cascade Knoevenagel/Michael reaction. The highly efficient catalystwas characterized by spectroscopic techniques like XPS, TGA, EDX, SEM, TEM and AAS. The biologicalimportance of arylmethylene-bis-(3-hydroxy-2-cyclohexene-1-one) enforced us to synthesize these compoundscatalytically using solid supported copper (0) nanopartcles.

  16. Organocatalytic cascade aza-Michael/hemiacetal reaction between disubstituted hydrazines and α,β-unsaturated aldehydes: Highly diastereo- and enantioselective synthesis of pyrazolidine derivatives

    Zhi-Cong Geng


    Full Text Available The catalytic synthesis of nitrogen-containing heterocycles is of great importance to medicinal and synthetic chemists, and also a challenge for modern chemical methodology. In this paper, we report the synthesis of pyrazolidine derivatives through a domino aza-Michael/hemiacetal sequence with chiral or achiral secondary amines as organocatalysts. Thus, a series of achiral pyrazolidine derivatives were obtained with good yields (up to 90% and high diastereoselectivities (>20:1 with pyrrolidine as an organocatalyst, and enantioenriched pyrazolidines are also achieved with good results (up to 86% yield, >10/1 regioselectivity, >20:1 dr, 99% ee in the presence of (S-diphenylprolinol trimethylsilyl ether catalyst.

  17. Rational Design of an Ultrasensitive and Highly Selective Chemodosimeter by a Dual Quenching Mechanism for Cysteine Based on a Facile Michael-Transcyclization Cascade Reaction.

    Li, Xiangmin; Zheng, Yongjun; Tong, Hongjuan; Qian, Rui; Zhou, Lin; Liu, Guixia; Tang, Yun; Li, Hao; Lou, Kaiyan; Wang, Wei


    Differentiation of biologically important thiols, such as cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) is still a challenging task. Herein, we present a novel fluorescent chemodosimeter capable of selectively detecting Cys over other biothiols including Hcy and GSH and other amino acids by a facile thiol-Michael addition/transcyclization rearrangement cascade click process. The unique transcyclization step is critical for the selectivity as a result of the kinetically favorable formation of a six-membered ring with the Cys Michael adduct. Moreover, the probe adopts a distinctive dual quenching mechanism-photoinduced electron transfer (PET) and photoinduced intramolecular charge transfer (ICT) to deliver a drastic turn-on fluorescence response only at the Cys-selective transcylization step. The judicious selection of strong electron-withdrawing naphthalimide fluorophore with maleimide group enhances the electrophilicity and thus reactivity for the cascade process leading to fast detection and ultrasensitivity with a detection limit of 2.0 nm (S/N=3). The probe has demonstrated its practical utility potential in Cys imaging in live cells.

  18. Pentanidium-catalyzed enantioselective phase-transfer conjugate addition reactions

    Ma, Ting


    A new chiral entity, pentanidium, has been shown to be an excellent chiral phase-transfer catalyst. The enantioselective Michael addition reactions of tert-butyl glycinate-benzophenone Schiff base with various α,β- unsaturated acceptors provide adducts with high enantioselectivities. A successful gram-scale experiment at a low catalyst loading of 0.05 mol % indicates the potential for practical applications of this methodology. Phosphoglycine ester analogues can also be utilized as the Michael donor, affording enantioenriched α-aminophosphonic acid derivatives and phosphonic analogues of (S)-proline. © 2011 American Chemical Society.


    Serge Cipko


    Full Text Available This paper examines the reaction of the Ukrainian community in Canada at the Ukrainian famine of 1932–1933 in particular highlights the activities member of parliament, a Ukrainian-born Michael Luchkovich which 5 February 1934 gave a speech in federal parliament, reporting on the famine in the USSR and the related this protest the Ukrainian diaspora.

  20. Following Michael Faraday's Footprints

    Galeano, Javier


    Last fall I had the good fortune of receiving financial support to shoot a documentary about Michael Faraday. I took the opportunity to learn more about this great experimentalist and to visit the highlights of places in his life. In this paper, I would like to share a list and description of some of the most remarkable places in London suitable…

  1. Michael Faraday's Bicentenary.

    Williams, L. Pearce; And Others


    Six articles discuss the work of Michael Faraday, a chemist whose work revolutionized physics and led directly to both classical field and relativity theory. The scientist as a young man, the electromagnetic experiments of Faraday, his search for the gravelectric effect, his work on optical glass, his laboratory notebooks, and his creative use of…

  2. New Stetter reactions catalyzed by thiamine diphosphate dependent MenD from E. coli.

    Beigi, Maryam; Waltzer, Simon; Zarei, Mostafa; Müller, Michael


    The intermolecular asymmetric Stetter reaction is a rarely found biocatalysts transformation. MenD, the second enzyme of the menaquinone biosynthetic pathway, catalyzes as a physiological reaction a Stetter-like addition of α-ketoglutarate to isochorismate. The substrate range of MenD for similar 1,4-additions is highly restricted. All other thiamine diphosphate dependent enzymes known to act as stetterases are members of the PigD enzyme subfamily, which accept aliphatic and aromatic α,β-unsaturated ketones and thioesters as Michael acceptor substrates. Here, we describe the unexpected activity of MenD with short-chain α,β-unsaturated acids and derivatives as substrates in Stetter reactions. MenD possesses a characteristic substrate range with respect to Michael acceptor substrates which is distinctly different from the classical stetterases. This provides biocatalytic access to new types of products which are not related to the products currently accessible by thiamine diphosphate dependent enzyme catalysis.

  3. Michael Faraday, media man.

    Fara, Patricia


    Michael Faraday was an enthusiastic portrait collector, and he welcomed the invention of photography not only as a possible means of recording observations accurately, but also as a method for advertising science and its practitioners. This article (which is part of the Science in the Industrial Revolution series) shows that like many eminent scientists, Faraday took advantage of the burgeoning Victorian media industry by posing in various roles.

  4. Michael Learns to Rock



    夜幕降临.空气中传来北欧的声音,来自丹麦的四人流行乐队Michael Learns to Rock(迈克学摇滚)正把探情款款的歌声带到上海的咖啡厅和酒吧。北欧一直活跃着一批世界顶级的乐队.从丹麦的A-Ha到Aqua,从瑞典的ABBA到Roxette和Ace of Base,从挪威的Se

  5. Michael Frayn visits CERN


    Award-winning playwright and novelist Michael Frayn gave a guest lecture in the main auditorium at CERN on Friday 15 March about his new book The Human Touch: Our Part in the Creation of the Universe. The lecture focused on cosmology and philosophy and the limitations that language places on our ability to understand the creation of a universe in which we seem to play such a small part. In addition to his novels and plays, which include Copenhagen, a play about the 1941 meeting between German physicist Werner Heisenberg and Danish physicist Niels Bohr, Frayn has translated several works from Russian, including plays by Chekhov and Tolstoy.

  6. Synthesis of pyrazole containing α-amino acids via a highly regioselective condensation/aza-Michael reaction of β-aryl α,β-unsaturated ketones

    Gilfillan, Lynne; Artschwager, Raik; Harkiss, Alexander H.; Liskamp, Rob M J; Sutherland, Andrew


    A synthetic approach for the preparation of a new class of highly conjugated unnatural α-amino acids bearing a 5-arylpyrazole side-chain has been developed. Horner-Wadsworth-Emmons reaction of an aspartic acid derived β-keto phosphonate ester with a range of aromatic aldehydes gave β-aryl α,β-unsatu

  7. Discovery-Oriented Approach To Organic Synthesis: Tandem Aldol Condensation-Michael Addition Reactions. Identifying Diastereotopic Hydrogens in an Achiral Molecule by NMR Spectroscopy

    Wachter-Jurcsak, Nanette; Reddin, Kendra


    We have found a beautiful example of anisochrony of diastereotopic acyclic methylene hydrogens in a symmetric diketone, synthesized by techniques traditionally performed in an introductory organic laboratory course. Synthesis of the diketone is high-yielding and easy to carry out, and the products can be directly isolated with a good degree of purity with no need of further manipulation. The reaction can be accomplished in a single laboratory session.

  8. Triphenylphosphine-Catalyzed Michael Addition of Alcohols to Acrylic Compounds

    LIU, Hai-Ling; JIANG, Huan-Feng; WANG, Yu-Gang


    A facile triphenylphosphine-catalyzed Michael addition of alcohols to acrylic compounds was described. The reaction was carried out in open air at refluxing temperature in the presence of 10 mol% PPh3. Michael addition of saturated and unsaturated alcohols to acrylonitrile or acrylates has been examined. The reaction gaveβ-alkoxy derivatives with isolated yields of 5%-79%. PPh3 is cheaper and more stable than those trialkylphosphines previously used for the similar reactions, and the products can be easily separated from the reaction mixture via distillation.

  9. Enantioselective Michael Addition of Water

    Chen, B.S.; Resch, V.; Otten, L.G.; Hanefeld, U.


    The enantioselective Michael addition using water as both nucleophile and solvent has to date proved beyond the ability of synthetic chemists. Herein, the direct, enantioselective Michael addition of water in water to prepare important β-hydroxy carbonyl compounds using whole cells of Rhodococcus st

  10. An overview of electron acceptors in microbial fuel cells

    Ucar, Deniz; Zhang, Yifeng; Angelidaki, Irini


    as an electron acceptor due to its high oxidation potential and ready availability. Recent studies, however, have begun to assess the use of different electron acceptors because of the (1) diversity of redox potential, (2) needs of alternative and more efficient cathode reaction, and (3) expanding of MFC based...

  11. Interview with Michael Gazzaniga.

    Gazzaniga, Michael


    Widely considered the father of the field of cognitive neuroscience, Professor Michael S. Gazzaniga is one of the world's premier neuroscientists. He founded the Center for Neuroscience at the University of California, Davis; the Center for Cognitive Neuroscience at Dartmouth College; the Cognitive Neuroscience Institute; Journal of Cognitive Neuroscience; and the Cognitive Neuroscience Society. He is currently the director of the Sage Center for the Study of the Mind at the University of California, Santa Barbara. Born on December 12, 1939 in Los Angeles and educated at Dartmouth College, he received his Ph.D. in psychobiology at the California Institute of Technology under the tutelage of Roger Sperry. As a graduate student, Professor Gazzaniga initiated the first lateralized testing of human split-brain patients, leading to a fundamental shift in our understanding of functional lateralization in the brain and how the cerebral hemispheres communicate with one another. His many scholarly publications and pioneering work during the last 50 years have produced significant contributions to our understanding of how the brain enables the mind. His landmark 1995 book for MIT Press, The Cognitive Neurosciences, now in its fourth edition, is recognized as the sourcebook for the field. He has also published many books accessible to a lay audience, including Mind Matters, Nature's Mind, and The Ethical Brain.

  12. Theoretical study on the asymmetric Michael addition of cyclohexanone with trans-beta-nitrostyrene catalyzed by a pyrrolidine-type chiral ionic liquid.

    Sun, Hui; Zhang, Dongju; Zhang, Changqiao; Liu, Chengbu


    The Michael addition of cyclohexanone with trans-beta-nitrostyrene catalyzed by a chiral ionic liquid (CIL) pyrrolidine-imidazolium bromide, which represents a prototype of CIL-promoted asymmetric syntheses, has been investigated by performing density functional theory calculations. We show the details of the mechanism and energetics, the influence of the acid additive on the reactivity, and the functional role of the CIL in the asymmetric addition. It is found that the reaction proceeds via two stages, i.e., the initial enamine formation, where the imine complex is first created and then isomerizes into the enamine intermediate, and the subsequent Michael addition involving a three-step mechanism. The calculations show that the presence of the acid additive changes the imine formation mechanism and lowers the reaction barrier, as well as, more importantly, makes the reaction become highly thermodynamically favored. It is also suggested that both the anion and cation of the CIL synergically facilitate the reaction, which act as the proton acceptor in the imine-enamine tautomerism and the stabilizer of the negative charge in the C-C bond formation process, respectively. The present theoretical study rationalizes the early experimental findings well and provides aid to some extent for the rational design of efficient CIL catalysts.

  13. The role of deep acceptor centers in the oxidation of acceptor-doped wide-band-gap perovskites ABO3

    Putilov, L. P.; Tsidilkovski, V. I.


    The impact of deep acceptor centers on defect thermodynamics and oxidation of wide-band-gap acceptor-doped perovskites without mixed-valence cations is studied. These deep centers are formed by the acceptor-bound small hole polarons whose stabilization energy can be high enough (significantly higher than the hole-acceptor Coulomb interaction energy). It is shown that the oxidation enthalpy ΔHox of oxide is determined by the energy εA of acceptor-bound states along with the formation energy EV of oxygen vacancies. The oxidation reaction is demonstrated to be either endothermic or exothermic, and the regions of εA and EV values corresponding to the positive or negative ΔHox are determined. The contribution of acceptor-bound holes to the defect thermodynamics strongly depends on the acceptor states depth εA: it becomes negligible at εA less than a certain value (at which the acceptor levels are still deep). With increasing εA, the concentration of acceptor-bound small hole polarons can reach the values comparable to the dopant content. The results are illustrated with the acceptor-doped BaZrO3 as an example. It is shown that the experimental data on the bulk hole conductivity of barium zirconate can be described both in the band transport model and in the model of hopping small polarons localized on oxygen ions away from the acceptor centers. Depending on the εA magnitude, the oxidation reaction can be either endothermic or exothermic for both mobility mechanisms.

  14. An active and selective heterogeneous catalytic system for Michael addition

    Hoda Keipour; Mohammad A. Khalilzadeh; Abolfazl Hosseini; Afsaneh Pilevar; Daryoush Zareyee


    Potassium fluoride doped natural zeolite was found to be an efficient and selective solid base catalyst for 1,4-Michael addition.The catalyst is easily prepared and the workup procedure simplified by simple filtration.All products were obtained in high yields as well as short reaction times.

  15. Q&A: Michael Honey

    Helicher, Karl


    The mid-1960s saw civil rights victories in Congress during Lyndon B. Johnson's presidency. In "Going Down Jericho Road," Michael Honey wrote how Martin Luther King Jr.'s final focus showed that the struggle for black and working class parity continued. The 1968 Memphis sanitation workers strike was a gritty struggle won in the streets by a host…

  16. Michael Beitz: Objects of Communication

    Hoefferle, Mary


    For this Instructional Resource, the author interviewed contemporary sculptor Michael Beitz, who uses art to explore the role of designed objects in human communication and emotional experience. This column was written in response to calls for using Enduring Understandings/Big Ideas (National Coalition for Core Arts Standards, 2013; Stewart &…

  17. Enhanced Olefin Cross Metathesis Reactions: The Copper Iodide Effect

    Voigtritter, Karl; Ghorai, Subir


    Copper iodide has been shown to be an effective co-catalyst for the olefin cross metathesis reaction. In particular, it has both a catalyst stabilizing effect due to iodide ion, as well as copper(I)-based phosphine-scavenging properties that apply to use of the Grubbs-2 catalyst. A variety of Michael acceptors and olefinic partners can be cross-coupled under mild conditions in refluxing diethyl ether that avoid chlorinated solvents. This effect has also been applied to chemistry in water at room temperature using the new surfactant TPGS-750-M. PMID:21528868

  18. Asymmetric Stetter reactions catalyzed by thiamine diphosphate-dependent enzymes.

    Kasparyan, Elena; Richter, Michael; Dresen, Carola; Walter, Lydia S; Fuchs, Georg; Leeper, Finian J; Wacker, Tobias; Andrade, Susana L A; Kolter, Geraldine; Pohl, Martina; Müller, Michael


    The intermolecular asymmetric Stetter reaction is an almost unexplored transformation for biocatalysts. Previously reported thiamine diphosphate (ThDP)-dependent PigD from Serratia marcescens is the first enzyme identified to catalyze the Stetter reaction of α,β-unsaturated ketones (Michael acceptor substrates) and α-keto acids. PigD is involved in the biosynthesis of the potent cytotoxic agent prodigiosin. Here, we describe the investigation of two new ThDP-dependent enzymes, SeAAS from Saccharopolyspora erythraea and HapD from Hahella chejuensis. Both show a high degree of homology to the amino acid sequence of PigD (39 and 51 %, respectively). The new enzymes were heterologously overproduced in Escherichia coli, and the yield of soluble protein was enhanced by co-expression of the chaperone genes groEL/ES. SeAAS and HapD catalyze intermolecular Stetter reactions in vitro with high enantioselectivity. The enzymes possess a characteristic substrate range with respect to Michael acceptor substrates. This provides support for a new type of ThDP-dependent enzymatic activity, which is abundant in various species and not restricted to prodigiosin biosynthesis in different strains. Moreover, PigD, SeAAS, and HapD are also able to catalyze asymmetric carbon-carbon bond formation reactions of aldehydes and α-keto acids, resulting in 2-hydroxy ketones.

  19. Michael J. Fox: Spurring Research on Parkinson's

    ... please turn JavaScript on. Feature: Parkinson's Disease Michael J. Fox: Spurring Research on Parkinson's Past Issues / Winter 2014 Table of Contents Michael J. Fox and his wife, actress Tracy Pollan, founded ...

  20. Michael Faraday vs. the Spiritualists

    Hirshfeld, Alan


    In the 1850s, renowned physicist Michael Faraday launched a public campaign against pseudoscience and spiritualism, which were rampant in England at the time. Faraday objected especially to claims that electrical or magnetic forces were responsible for paranormal phenomena, such as table-spinning and communication with the dead. Using scientific methods, Faraday unmasked the deceptions of spiritualists, clairvoyants and mediums and also laid bare the credulity of a public ill-educated in science. Despite his efforts, Victorian society's fascination with the paranormal swelled. Faraday's debacle anticipates current controversies about public science education and the interface between science and religion. This episode is one of many described in the new biography, The Electric Life of Michael Faraday (Walker & Co.), which chronicles Faraday's discoveries and his unlikely rise from poverty to the pinnacle of the English science establishment.

  1. Michael Niegl (1985-2009)


    Our friend and colleague Michael Niegl died in a tragic accident in the first hours of the new year. Michael was a Master’s student in Microsystems Engineering at the University of Applied Sciences Wiener Neustadt. He was responsible for the development of the ATLAS Beam Conditions Monitor (BCM) ROD FPGA firmware, which acquires the data from the BCM detector modules and provides online monitoring of the LHC beams within the ATLAS experiment. He spent several months at CERN to carry out beam tests on the BCM detectors and received his Bachelor of Science with first class honours for his thesis: Concept and Implementation of an FPGA-based Data Recorder and Processor for the ATLAS Beam Conditions Monitor. Michael spent six months at CERN last year to finish the development and commissioning of the ROD firmware for the first beam. He worked the entire night of 10 September to fine tune the system for the first beam. It was a joy to ...

  2. Michael De Sousa (1989 - 2012)


    We are deeply saddened to announce the death of Mr Michael De Sousa on 13 May 2012. Mr De Sousa, who was born on 02.09.1989, was working as an apprentice in the TE Department and had been at CERN since 24.08.2009. The Director-General has sent a message of condolence to his family on behalf of the CERN personnel. Social Affairs Human Resources Department     It is with great emotion and deep sadness that we learn of the tragic loss of our colleague and friend Michael De Sousa. Michael was a hard working colleague, cordial and considerate. Within a few months, he marked his presence by the implementation of the instrumentation benches for gas permeation measurement in polymers, and the calibration of high technology gas analyzers, necessary for vacuum technology. His last contribution will enable us to measure pressures in the extreme high vacuum range for the ELENA project.  With the continuation of this activity, his memory will remain. His accomplishments will remain...

  3. Chiral Aminophosphines as Catalysts for Enantioselective Double-Michael Indoline Syntheses

    Ohyun Kwon


    Full Text Available The bisphosphine-catalyzed double-Michael addition of dinucleophiles to electron-deficient acetylenes is an efficient process for the synthesis of many nitrogen-containing heterocycles. Because the resulting heterocycles contain at least one stereogenic center, this double-Michael reaction would be even more useful if an asymmetric variant of the reaction were to be developed. Aminophosphines can also facilitate the double-Michael reaction and chiral amines are more readily available in Nature and synthetically; therefore, in this study we prepared several new chiral aminophosphines. When employed in the asymmetric double-Michael reaction between ortho-tosylamidophenyl malonate and 3-butyn-2-one, the chiral aminophosphines produced indolines in excellent yields with moderate asymmetric induction.

  4. [The synthesis of P1-[11-(anthracen-9-ylmethoxy)undecyl]-P2(2-Acetamido-2-deoxy-α-D-glucopyranosyl) diphosphate and the study of its acceptor properties in the enzymic reaction catalyzed by D-rhamnosyltransferase from Pseudomonas aeruginosa].

    Vinnikova, A N; Torgov, V I; Utkina, N S; Veselovsky, V V; Druzhinina, T N; Wang, S; Brockhausen; Danilov, L L


    P1-[11-(Anthracen-9-ylmethoxy)undecyl]-P2-(2-acetamido-2-deoxy-α-D-glucopyranosyl) diphosphate, a fluorescent derivative of undecyl diphosphate 2-acetamido-2-deoxyglucose, was chemically synthesized. The ability of the compound to serve as acceptor substrate of D-rhamnose residue in the enzymatic reaction catalyzed by D-rhamnosyltransferase from Pseudomonas aeruginosa PAO1 was demonstrated.

  5. [Synthesis and acceptor properties of 11-[(9'-anthracenyl)methoxy]undecyl phosphate and P1-{11-[(9'-anthracenyl)methoxy]undecyl}-P2-(alpha-D-galactopyranosyl) diphosphate in the enzymic reactions catalyzed by galactosylphosphotransferase and mannosyltransferase from Salmonella newport].

    Vinnikova, A N; Utkina, N S; Danilov, L L; Torgov, V I; Druzhinina, T N; Veselovskiĭ, V V


    Fluorescent 11-[(9'-anthracenyl)methoxy]undecyl phosphate and P1-{11-[(9'-anthracenyl)methoxy]undecyl}-P2-(alpha-D-galactopyranosyl) diphosphate were chemically synthesized for the first time. The ability of the first compound to serve as substrate-acceptor ofgalactosyl phosphate residue and the second compound of mannosyl residue in enzymic reactions catalyzed by galactosylphosphotransferase and mannosyltransferase from Salmonella newport membrane preparation was demonstrated.

  6. Steady-state FTIR spectra of the photoreduction of QA and QB in Rhodobacter sphaeroides reaction centers provide evidence against the presence of a proposed transient electron acceptor X between the two quinones.

    Breton, Jacques


    In the reaction center (RC) of the photosynthetic bacterium Rhodobacter sphaeroides, two ubiquinone molecules, QA and QB, play a pivotal role in the conversion of light energy into chemical free energy by coupling electron transfer to proton uptake. In native RCs, the transfer of an electron from QA to QB takes place in the time range of 5-200 micros. On the basis of time-resolved FTIR step-scan measurements in native RCs, a new and unconventional mechanism has been proposed in which QB- formation precedes QA- oxidation [Remy, A., and Gerwert, K. (2003) Nat. Struct. Biol. 10, 637-644]. The IR signature of the proposed transient intermediary electron acceptor (denoted X) operating between QA and QB has been recently measured by the rapid-scan technique in the DN(L210) mutant RCs, in which the QA to QB electron transfer is slowed 8-fold compared to that in native RCs. This IR signature has been reported as a difference spectrum involving states X+, X, QA, and QA- [Hermes, S., et al. (2006) Biochemistry 45, 13741-13749]. Here, we report the steady-state FTIR difference spectra of the photoreduction of either QA or QB measured in both native and DN(L210) mutant RCs in the presence of potassium ferrocyanide. In these spectra, the CN stretching marker modes of ferrocyanide and ferricyanide allow the extent of the redox reactions to be quantitatively compared and are used for a precise normalization of the QA-/QA and QB-/QB difference spectra. The calculated QA- QB/QA QB- double-difference spectrum in DN(L210) mutant RCs is closely equivalent to the reported QA- X+/QA X spectrum in the rapid-scan measurement. We therefore conclude that species X+ and X are spectrally indistinguishable from QB and QB-, respectively. Further comparison of the QA- QB/QA QB- double-difference spectra in native and DN(L210) RCs also allows the possibility that QB- formation precedes QA- reoxidation to be ruled out for native RCs.

  7. L-prolinol as a highly enantioselective catalyst for Michael addition of cyclohexanone to nitroolefins.

    Chua, Pei Juan; Tan, Bin; Zeng, Xiaofei; Zhong, Guofu


    Though many chiral amines such as l-proline and its derivatives have proven to be versatile catalysts in many reactions, L-prolinol was seldom used as organocatalyst for reactions. Herein, we report the first L-prolinol catalyzed asymmetric Michael addition of cyclohexanone to nitroolefins in the presence of benzoic acid to afford Michael adducts with high diastereoselectivities (87:13->99:1) and enantioselectivities (82-96%).

  8. The 1974 National Acceptors Survey.

    Laing, J; Phillips, J; Zablan, Z; Llorente, R; Cabigon, J


    The 1974 National Acceptors Survey in the Philippines studied 4 methods of contraception: pill, IUD, rhythm, and condom. After 1 year, 72% of IUD acceptors had an IUD in place but only 29% of condom acceptors were still using condoms. Pills and rhythm were equally effective in terms of continuation and pregnancy rates. Continuation rates were higher among acceptors at postpartum clinics than at other clnics, higher among urban respondents than rural, and higher among older respondents. Those with more children had higher continuation rates, whereas those who wanted more children had lower continuation rates. Continuation rates also increased 1) as the duration of marriage lengthened; 2) with a later age at marriage; 3) with higher educational attainment; 4) among income-contributing respondents with higher incomes; 5) among previous contraceptive users; and 6) when physicians provided the services rather than nonmedical personnel, including medical screenings. Clinic attendance, husband's occupation, whether or not there was payment, and husband's support are other factors that seemed to affect continuation rates. Contraceptive effectiveness values were higher among pill and IUD acceptors. The percentage of reduction in fertility following acceptance of a method was 74% for IUDs and 27% for condoms. Fertility reduction was great among acceptors at postpartum clinics, acceptors in central visayas, and the highly educated. Future births averted ranged, for every 100 acceptors, 208 with the IUD, 32 with the condom, and 1 each pill and rhythm. Factors affecting method selection were administrative, beliefs, and preferences. The most common complaint about provision of clinical services was that the staff should spend more time in home visits (86%).

  9. Video interview with Michael Dell

    CERN Bulletin


    Michael Dell, founder and presently Chairman of the Board of Directors and Chief Executive Office of the DELL computer company visited CERN on Tuesday 26th January 2010. The Bulletin and the Video productions team had the opportunity to meet him. The video interview is transcribed for your convenience.   Michael S. Dell with CERN Director-General Rolf Heuer. What motivated you to come and visit CERN? I obviously heard about the great science and research has going on here, and DELL is very pleased to be a partner and providing a lot of the computers to analyse the data and I really wanted to see for myself in person, some of the great science that is going on here. What is your view on fundamental research in IT, and in general? I think if you look at the field of science in the last hundred years, we have been able to solve a lot of problems, but there are still lots of unsolved problems and unsolved mysteries. And it is only through basic fundamental research that we will address these probl...

  10. An Overview of Electron Acceptors in Microbial Fuel Cells.

    Ucar, Deniz; Zhang, Yifeng; Angelidaki, Irini


    Microbial fuel cells (MFC) have recently received increasing attention due to their promising potential in sustainable wastewater treatment and contaminant removal. In general, contaminants can be removed either as an electron donor via microbial catalyzed oxidization at the anode or removed at the cathode as electron acceptors through reduction. Some contaminants can also function as electron mediators at the anode or cathode. While previous studies have done a thorough assessment of electron donors, cathodic electron acceptors and mediators have not been as well described. Oxygen is widely used as an electron acceptor due to its high oxidation potential and ready availability. Recent studies, however, have begun to assess the use of different electron acceptors because of the (1) diversity of redox potential, (2) needs of alternative and more efficient cathode reaction, and (3) expanding of MFC based technologies in different areas. The aim of this review was to evaluate the performance and applicability of various electron acceptors and mediators used in MFCs. This review also evaluated the corresponding performance, advantages and disadvantages, and future potential applications of select electron acceptors (e.g., nitrate, iron, copper, perchlorate) and mediators.

  11. Acceptors in ZnO

    Mccluskey, Matthew D.; Corolewski, Caleb; Lv, Jinpeng; Tarun, Marianne C.; Teklemichael, Samuel T.; Walter, Eric D.; Norton, M. G.; Harrison, Kale W.; Ha, Su Y.


    Zinc oxide (ZnO) has potential for a range of applications in the area of optoelectronics. The quest for p-type ZnO has focused much attention on acceptors. In this paper, Cu, N, and Li acceptor impurities are discussed. Experimental evidence shows that these point defects have acceptor levels 3.2, 1.5, and 0.8 eV above the valence-band maximum, respectively. The levels are deep because the ZnO valence band is quite low compared to conventional, non-oxide semiconductors. Using MoO2 contacts, the electrical resistivity of ZnO:Li was measured and showed behavior consistent with bulk hole conduction for temperatures above 400 K. A photoluminescence peak in ZnO nanocrystals has been attributed to an acceptor, which may involve a zinc vacancy. High field (W-band) electron paramagnetic resonance measurements on the nanocrystals revealed an axial center with g = 2.0033 and g = 2.0075, along with an isotropic center at g = 2.0053.

  12. Acceptors in ZnO

    McCluskey, Matthew D., E-mail:; Corolewski, Caleb D.; Lv, Jinpeng; Tarun, Marianne C.; Teklemichael, Samuel T. [Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164-2814 (United States); Walter, Eric D. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Norton, M. Grant; Harrison, Kale W. [School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164-2920 (United States); Ha, Su [Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99164-6515 (United States)


    Zinc oxide (ZnO) has potential for a range of applications in the area of optoelectronics. The quest for p-type ZnO has focused much attention on acceptors. In this paper, Cu, N, and Li acceptor impurities are discussed. Experimental evidence indicates these point defects have acceptor levels 3.2, 1.4, and 0.8 eV above the valence-band maximum, respectively. The levels are deep because the ZnO valence band is quite low compared to conventional, non-oxide semiconductors. Using MoO{sub 2} contacts, the electrical resistivity of ZnO:Li was measured and showed behavior consistent with bulk hole conduction for temperatures above 400 K. A photoluminescence peak in ZnO nanocrystals is attributed to an acceptor, which may involve a Zn vacancy. High field (W-band) electron paramagnetic resonance measurements on the nanocrystals revealed an axial center with g{sub ⊥} = 2.0015 and g{sub //} = 2.0056, along with an isotropic center at g = 2.0035.

  13. Excitation energy transfer in donor-bridge-acceptor systems.

    Albinsson, Bo; Mårtensson, Jerker


    This perspective will focus on the mechanistic aspects of singlet and triplet excitation energy transfer. Well defined donor-bridge-acceptor systems specifically designed for investigating the distance and energy gap dependencies of the energy transfer reactions are discussed along with some recent developments in computational modeling of the electronic coupling.

  14. Role of bicarbonate at the acceptor side of photosystem II

    Rensen, van J.J.S.


    Besides being the substrate for the carboxylation reaction of photosynthesis, CO2 (bicarbonate) is required for the activity of Photosystem II (water plastoquinone oxido-reductase). It plays a role on the electron donor side as well as the electron acceptor side. In this contribution, attention will

  15. Poly(trifluoromethyl)azulenes: structures and acceptor properties.

    Clikeman, Tyler T; Bukovsky, Eric V; Kuvychko, Igor V; San, Long K; Deng, Shihu H M; Wang, Xue-Bin; Chen, Yu-Sheng; Strauss, Steven H; Boltalina, Olga V


    Six new poly(trifluoromethyl)azulenes prepared in a single high-temperature reaction exhibit strong electron accepting properties in the gas phase and in solution and demonstrate the propensity to form regular π-stacked columns in donor-acceptor crystals when mixed with pyrene as a donor.

  16. Synthesis and X-ray crystal structure of the first tetrathiafulvalene-based acceptor-donor-acceptor sandwich

    Simonsen, Klaus B.; Thorup, Niels; Cava, Michael P.


    The synthesis and characterization of a bis-macrocyclic A-D-A sandwich produced in a simple one-pot reaction is reported. Only one acceptor unit participates in charge-transfer interactions with the TTF unit in the solid state....


    CAO Weixiao; ZHANG Peng; FENG Xinde


    Photoinduced charge transfer polymerization of styrene(St) with electron acceptor as initiator was investigated. In case of fumaronitrile (FN) or maleic anhydride (MA) as initiator the polymerization takes place regularly, whereas the tetrachloro-1, 4-benzenequinone (TCQ), 2, 3-dichloro-5, 6-dicyano-1, 4-benzenequinone (DDQ) . or tetracyano ethylene (TCNE) as initiator the polymerization proceeds reluctantly only after the photoaddition reaction. A mechanism was proposed that free radicals would be formed following the charge and proton transfer in the exciplex formed between St and electron acceptors.

  18. Effect of the addition of a fused donor-acceptor ligand on a Ru(II) complex: synthesis, characterization, and photoinduced electron transfer reactions of [Ru(TTF-dppz)2(Aqphen)]2+.

    Dupont, Nathalie; Ran, Ying-Fen; Jia, Hong-Peng; Grilj, Jakob; Ding, Jie; Liu, Shi-Xia; Decurtins, Silvio; Hauser, Andreas


    The synthesis and the photophysical properties of the complex [Ru(TTF-dppz)(2)(Aqphen)](2+) (TTF = tetrathiafulvalene, dppz = dipyrido-[3,2-a:2',3'-c]phenazine, Aqphen = anthraquinone fused to phenanthroline via a pyrazine bridge) are described. In this molecular triad excitation into the metal-ligand charge transfer bands results in the creation of a long-lived charge separated state with TTF acting as electron donor and anthraquinone as terminal acceptor. The lifetime of the charge-separated state is 400 ns in dichloromethane at room temperature. A mechanism for the charge separation involving an intermediate charge-separated state is proposed based on transient absorption spectroscopy.

  19. An efficient catalyst-free synthesis of novel chromeno[4,3-b]quinolones through Michael initiated ring closure (MIRC) reaction with in situ generated 3-(arylmethylene)chroman-2,4-diones



    A catalyst-free multicomponent reaction capable of affording a wide range of eighteen novel chromeno[4,3-b]quinolone derivatives (6a–6r) via one-pot two-step domino protocol, in ethylene glycol is reported. Catalyst-free conditions along with green solvent system make the process eco-friendly as well aseconomical. High yields of the products were obtained in short reaction times by forming three new bonds and one stereocenter in a single operation. The salient features of the present protocol are short reaction times, eco-friendly solvents, high yields and easy work-up procedure.

  20. A Metal-Ligand Cooperative Pathway for Intermolecular Oxa-Michael Additions to Unsaturated Nitriles

    Perdriau, Sebastien; Zijlstra, Douwe S.; Heeres, Hero J.; de Vries, Johannes G.; Otten, Edwin


    An unprecedented catalytic pathway for oxa-Michael addition reactions of alcohols to unsaturated nitriles has been revealed using a PNN pincer ruthenium catalyst with a dearomatized pyridine backbone. The isolation of a catalytically competent Ru-dieneamido complex from the reaction between the Ru

  1. Asymmetric Synthesis of Substituted Thiolanes through Domino Thia-Michael-Henry Dynamic Covalent Systemic Resolution using Lipase Catalysis.

    Zhang, Yan; Vongvilai, Pornrapee; Sakulsombat, Morakot; Fischer, Andreas; Ramström, Olof


    Dynamic systems based on consecutive thia-Michael and Henry reactions were generated and transformed using lipase-catalyzed asymmetric transformation. Substituted thiolane structures with three contiguous stereocenters were resolved in the process in high yields and high enantiomeric excesses.

  2. Antitumor Activity of Components from Isondon rubescens (Hemsley) H. Hara and Their Acetyl Derivatives Predicted by Michael Addition Reaction%迈克尔加成反应预测冬凌草活性成分及其乙酰化产物抗肿瘤活性

    刘建群; 高俊博


    为了快速、简便地评价冬凌草(Isodon rubescens(Hemsley) H. Hara)活性成分的抗肿瘤活性,以冬凌草活性成分冬凌草甲素和冬凌草乙素及其乙酰化产物与对硝基苯甲酰乙酸乙酯( ENBA)进行迈克尔加成反应,以反应动力学得出迈克尔加成反应的反应活性,首次以反应活性预测了对冬凌草甲素(1)、冬凌草乙素(2)、1,14-二乙酰基冬凌草甲素(1a)和1,6-二乙酰基冬凌草乙素(2a)4个对映-贝壳杉烯的抗肿瘤活性。结果表明:4种活性成分的迈克尔加成反应均符合二级动力学方程,反应活性1>1a>2>2a,根据阿伦尼乌斯公式,测得冬凌草甲素活化能(Ea)为(38.7±5.8) kJ/mol,冬凌草乙素Ea 为(46.8±7.1) kJ/mol。采用1 H NMR和13 C NMR等波谱技术鉴定冬凌草甲素与ENBA经迈克尔加成反应得到的新化合物为1α,6β,7β,14β-四羟基-7α,20-环氧-17-(2-(3-(4-硝基苯基))-3-氧-丙酸乙酯)-对映贝壳杉烷-15-酮,命名为nitrobenoridonin (1b)。4个对映-贝壳杉烯具有较强的体外抗肿瘤活性,经测定它们的抗肿瘤活性大小依次为1>1a>2>2a,与其迈克尔加成反应活性排序一致,表明迈克尔加成反应活性与抗肿瘤活性之间存在较好的相关性,可以通过测定迈克尔加成反应活性预测对映-贝壳杉烯的抗肿瘤活性。%The kinetics of the Michael addition reaction among four ent-kaurenes, i. e. oridonin ( 1 ) and ponicidin (2) from Isodon rubescens (Hemsley) H. Hara,1,14-diacetyl oridonin (1a),1,6-diacetyl ponicidin (2a) and ethyl 4-nitrobenzoylacetate ( ENBA) was investigated for the first time in order to conveniently predict their antitumor activity. Stoichiometric analysis indicated that the reaction between these ent-kaurenes and ENBA followed second order kinetics. The descending order of reaction rates of the four ent-kaurenes was clearly showed as 1,1a, 2 and 2a. According to the Arrhenius equation,the activation energy of the overall reaction between

  3. Development of imide- and imidazole-containing electron acceptors for use in donor-acceptor conjugated compounds and polymers

    Li, Duo

    Conjugated organic compounds and polymers have attracted significant attention due to their potential application in electronic devices as semiconducting materials, such as organic solar cells (OSCs). In order to tune band gaps, donor-acceptor (D-A) structure is widely used, which has been proved to be one of the most effective strategies. This thesis consists of three parts: 1) design, syntheses and characterization of new weak acceptors based on imides and the systematic study of the structure-property relationship; (2) introduction of weak and strong acceptors in one polymer to achieve a broad coverage of light absorption and improve the power conversion efficiency (PCE); (3) modification of benzothiadiazole (BT) acceptor in order to increase the electron withdrawing ability. Imide-based electron acceptors, 4-(5-bromothiophen-2-y1)-2-(2-ethylhexyl)-9- phenyl- 1H-benzo[f]isoindole-1,3(2H)-dione (BIDO-1) and 4,9-bis(5-bromothiophen-2-yl)-2-(2-ethylhexyl)-benzo[f]isoindole-1,3-dione (BIDO-2), were designed and synthesized. In this design, naphthalene is selected as its main core to maintain a planar structure, and thienyl groups are able to facilitate the bromination reaction and lower the band gap. BIDO-1 and BIDO-2 were successfully coupled with different donors by both Suzuki cross-coupling and Stille cross-coupling reactions. Based on the energy levels and band gaps of the BIDO-containing compounds and polymers, BIDO-1 and BIDO-2 are proved to be weak electron acceptors. Pyromellitic diimide (PMDI) was also studied and found to be a stronger electron acceptor than BIDO . In order to obtain broad absorption coverage, both weak acceptor ( BIDO-2) and strong acceptor diketopyrrolopyrrole (DPP) were introduced in the same polymer. The resulting polymers show two absorption bands at 400 and 600 nm and two emission peaks at 500 and 680 nm. The band gaps of the polymers are around 1.6 eV, which is ideal for OSC application. The PCE of 1.17% was achieved. Finally

  4. Michael Wood’s Yangzhou Dream

    Yuan; Dan


    <正>Mr.Michael Wood is a wellknown British historian and documentary maker who has produced more than a hundred documentaries on various national histories and cultures exemplified by The Story of India.They enjoy wide popularity in more than 150 countries.I met him in February when he took his fi lm crew to Yangzhou to shoot The Story of China documentary for the British Broadcasting Corporation(BBC).It was a snowy day,cold and wet,but Michael said happily that the

  5. Ytterbium triflate catalyzed Michael additions of beta-ketoesters in water

    Keller, E; Feringa, BL


    Michael addition of various beta-ketoesters towards enones and alpha,beta-unsaturated aldehydes resulted in a quantitative conversion to the corresponding 1,4-adducts by performing the reactions in water in the presence of ytterbium triflate as a water-tolerant Lewis acid.

  6. Highly efficient ytterbium triflate catalyzed Michael additions of alpha-nitroesters in water

    Keller, E; Feringa, B.L.

    Michael additions of alpha-nitroesters with enones and alpha,beta-unsaturated aldehydes result in quantitative conversions to the corresponding 1,4-adducts by performing the reactions in water in the presence of ytterbium triflate as water-tolerant Lewis acid.




    Addition of the Schiff bases derived from reaction of glycine alkyl esters with benzophenoneimine to alpha,beta-unsaturated ketones, followed by hydrogenation of the addition products, leads to 5- or 3,5-substituted prolines. Hydrolysis of the Michael adducts rather than hydrogenation allows




    Addition of the Schiff bases derived from reaction of glycine alkyl esters with benzophenoneimine to alpha,beta-unsaturated ketones, followed by hydrogenation of the addition products, leads to 5- or 3,5-substituted prolines. Hydrolysis of the Michael adducts rather than hydrogenation allows synthes

  9. Highly efficient ytterbium triflate catalyzed Michael additions of alpha-nitroesters in water

    Keller, E; Feringa, B.L.


    Michael additions of alpha-nitroesters with enones and alpha,beta-unsaturated aldehydes result in quantitative conversions to the corresponding 1,4-adducts by performing the reactions in water in the presence of ytterbium triflate as water-tolerant Lewis acid.

  10. Michael Hauskeller: Sex and the Posthuman Condition

    Miller, Lantz Eugene


    This new book from Michael Hauskeller explores the currently marketed or projected sex/love products that exhibit some trait of so-called “posthumanistic” theory or design. These products are so designated because of their intention to fuse high technologies, including robotics and computing, with

  11. Michael Hauskeller: Sex and the Posthuman Condition

    Miller, Lantz Flemming


    This new book from Michael Hauskeller explores the currently marketed or projected sex/love products that exhibit some trait of so-called “posthumanistic” theory or design. These products are so designated because of their intention to fuse high technologies, including robotics and computing, with t

  12. Reframing Michael Scott: Exploring Inappropriate Workplace Communication

    Schaefer, Zachary A.


    Individuals who work in professional settings interact with others who may exhibit a variety of cultural beliefs and decision-making approaches. Page (2007) argues that cognitive diversity (i.e., how people approach and attempt to solve problems) is a vital asset in effective organizations. Michael Scott, who portrays the inept main character on…

  13. Comments on Michael (1993): Establishing Operations

    Moore, J.


    The present comments concern Michael's concept of motivative variables, and the implications of that concept for our understanding of the nature of reinforcement as well as the extinction of responses maintained through positive and negative reinforcement. We note that both extinction and altering motivative variables decrease responding, but…

  14. Reflections: Michael Watts interviewed by Murat Arsel

    M. Arsel (Murat)


    textabstractMichael Watts is ‘Class of 1963’ Chair in Undergraduate Studies and Chancellor’s Professor of Geography at the University of California, Berkeley. Born and raised in rural southwest England, Watts studied at University College London and completed his PhD in 1979 at the University of Mic

  15. Anaerobic electron acceptor chemotaxis in Shewanella putrefaciens

    Nealson, K. H.; Moser, D. P.; Saffarini, D. A.


    Shewanella putrefaciens MR-1 can grow either aerobically or anaerobically at the expense of many different electron acceptors and is often found in abundance at redox interfaces in nature. Such redox interfaces are often characterized by very strong gradients of electron acceptors resulting from rapid microbial metabolism. The coincidence of S. putrefaciens abundance with environmental gradients prompted an examination of the ability of MR-1 to sense and respond to electron acceptor gradients in the laboratory. In these experiments, taxis to the majority of the electron acceptors that S. putrefaciens utilizes for anaerobic growth was seen. All anaerobic electron acceptor taxis was eliminated by the presence of oxygen, nitrate, nitrite, elemental sulfur, or dimethyl sulfoxide, even though taxis to the latter was very weak and nitrate and nitrite respiration was normal in the presence of dimethyl sulfoxide. Studies with respiratory mutants of MR-1 revealed that several electron acceptors that could not be used for anaerobic growth nevertheless elicited normal anaerobic taxis. Mutant M56, which was unable to respire nitrite, showed normal taxis to nitrite, as well as the inhibition of taxis to other electron acceptors by nitrite. These results indicate that electron acceptor taxis in S. putrefaciens does not conform to the paradigm established for Escherichia coli and several other bacteria. Carbon chemo-taxis was also unusual in this organism: of all carbon compounds tested, the only positive response observed was to formate under anaerobic conditions.

  16. L-Proline Catalyzed Michael Additions of Thiophenols to α,β-Unsaturated Compounds, Particularly α-Enones, in the Ionic Liquid [bmim]PF6

    Stefan Toma


    Full Text Available L-Proline catalyzed additions of 13 different thiols to 11 different α-enoneMichael acceptors in [bmim] PF6 are reported. Reasonable to high yields of the reactionproducts were isolated in most cases.

  17. Principles of Chemistry (by Michael Munowitz)

    Kovac, Reviewed By Jeffrey


    At a time when almost all general chemistry textbooks seem to have become commodities designed by marketing departments to offend no one, it is refreshing to find a book with a unique perspective. Michael Munowitz has written what I can only describe as a delightful chemistry book, full of conceptual insight, that uses a novel and interesting pedagogic strategy. This is a book that has much to recommend it. This is the best-written general chemistry book I have ever read. An editor with whom I have worked recently remarked that he felt his job was to help authors make their writing sing. Well, the writing in Principles of Chemistry sings with the full, rich harmonies and creative inventiveness of the King's Singers or Chanticleer. Here is the first sentence of the introduction: "Central to any understanding of the physical world is one discovery of paramount importance, a truth disarmingly simple yet profound in its implications: matter is not continuous." This is prose to be savored and celebrated. Principles of Chemistry has a distinct perspective on chemistry: the perspective of the physical chemist. The focus is on simplicity, what is common about molecules and reactions; begin with the microscopic and build bridges to the macroscopic. The author's perspective is clear from the organization of the book. After three rather broad introductory chapters, there are four chapters that develop the quantum mechanical theory of atoms and molecules, including a strong treatment of molecular orbital theory. Unlike many books, Principles of Chemistry presents the molecular orbital approach first and introduces valence bond theory later only as an approximation for dealing with more complicated molecules. The usual chapters on descriptive inorganic chemistry are absent (though there is an excellent chapter on organic and biological molecules and reactions as well as one on transition metal complexes). Instead, descriptive chemistry is integrated into the development of

  18. [4 + 2] Annulation of Donor-Acceptor Cyclopropanes with Acetylenes Using 1,2-Zwitterionic Reactivity.

    Novikov, Roman A; Tarasova, Anna V; Denisov, Dmitry A; Borisov, Denis D; Korolev, Victor A; Timofeev, Vladimir P; Tomilov, Yury V


    A new process for the [4 + 2] annulation of donor-acceptor cyclopropanes with acetylenes under the effect of anhydrous GaCl3 using 1,2-zwitterion reactivity was elaborated. The reaction opens access to substituted dihydronaphthalenes, naphthalenes, and other fused carbocycles. The direction of the reaction can be efficiently controlled by temperature.

  19. Michael Haneke film Euroopa parim / M. T.

    M. T.


    IX PÖFFil linastuv Michael Haneke film "Varjatud" ("Cache") võitis laupäeval mitu Euroopa Filmiakadeemia auhinda, selhulgas parima filmi, parima lavastaja, parima meesnäitleja (Daniel Auteuil) ja FIPRESCI auhinna. Parim naisnäitleja - Julia Jentsch ("Sophie Scholli viimased päevad"), operaator - Franz Lustig ("Don't Come Knocking"), stsenaarium - Hany Abu-Assad, Bero Beyer ("Kohe paradiisi")

  20. STS-86 Pilot Michael Bloomfield suits up


    STS-86 Pilot Michael J. Bloomfield relaxes for a moment while donning his launch and entry suit with the assistance of a suit technician in the Operations and Checkout Building. This will be Bloomfields first spaceflight. He and the six other crew members will depart shortly for Launch Pad 39A, where the Space Shuttle Atlantis awaits liftoff on a 10-day mission slated to be the seventh docking of the Space Shuttle with the Russian Space Station Mir.

  1. Comments on Michael (1993): Establishing Operations

    Moore, J


    The present comments concern Michael's concept of motivative variables, and the implications of that concept for our understanding of the nature of reinforcement as well as the extinction of responses maintained through positive and negative reinforcement. We note that both extinction and altering motivative variables decrease responding, but they do so differently. The former does so by discontinuing the response-reinforcer relation. The latter does so by altering the motivation to respond. ...

  2. Michael Haneke film Euroopa parim / M. T.

    M. T.


    IX PÖFFil linastuv Michael Haneke film "Varjatud" ("Cache") võitis laupäeval mitu Euroopa Filmiakadeemia auhinda, selhulgas parima filmi, parima lavastaja, parima meesnäitleja (Daniel Auteuil) ja FIPRESCI auhinna. Parim naisnäitleja - Julia Jentsch ("Sophie Scholli viimased päevad"), operaator - Franz Lustig ("Don't Come Knocking"), stsenaarium - Hany Abu-Assad, Bero Beyer ("Kohe paradiisi")

  3. [Lacrimators as acceptors for NADH].

    Wallenfels, K; Ertel, W; Höckendorf, A; Rieser, J; Uberschär, K H


    Lachrymators of varied structure are reduced either by hydrogen addition or halogen substitution using NADH model compounds as donors. Similar compounds without lachrymatory activity were reduced either very slowly or not at all. CS (o-Chlorobenzalmalonitril) is reduced by NADH, the reaction being catalyzed by an enzyme present in erythrocytes. Thus the lachrymatory action follows a general scheme for the activity of sensory transduction. This scheme consists of a reception in the nerve cell membrane and a fast or simultaneous chemical transformation in an enzymic reaction.

  4. Obituary: Michael James Ledlow, 1964-2004

    Puxley, Philip John; Grashuis, Randon M.


    Michael James Ledlow died on 5 June 2004 from a large, unsuspected brain tumor. Since 2000 he had been on the scientific staff of the Gemini Observatory in La Serena, Chile, initially as a Science Fellow and then as a tenure-track astronomer. Michael was born in Bartlesville, Oklahoma on 1 October 1964 to Jerry and Sharon Ledlow. He obtained his Bachelor Degree in astrophysics at the University of Oklahoma in 1987 and attended the University of New Mexico for his graduate work, obtaining his PhD while studying Galaxy Clusters under Frazer Owen in 1994. From 1995-1997 Michael held a postdoctoral position with Jack Burns at New Mexico State University where he used various astronomical facilities including the VLA and Apache Point Observatory to study distant galaxies. From 1998-2000 Michael rejoined the Physics and Astronomy Department at the University of New Mexico where he was a visiting professor until he moved on to Gemini. At the Gemini Observatory, Mike shared in the excitement, hard work and many long days and nights associated with bringing on-line a major new astronomical facility and its instrumentation. Following its commissioning he assisted visiting observers, supported and took data for many more remote users via the queue system, and for each he showed the same care and attention to detail evident in his own research to ensure that all got the best possible data. His research concentrated on the radio and optical properties of galaxy clusters, especially rich Abell clusters such as A2125, on luminous radio galaxies, including the detection of a powerful double radio source in the "wrong sort of galaxy," the spiral system 0313-192, and on EROs (extremely red objects), dusty galaxies barely detectable at optical wavelengths. Michael thoroughly enjoyed living in Chile and enthusiastically immersed himself in the culture of his surroundings. He and his family were actively involved with the International English Spanish Association in La Serena. He had a

  5. Highly E-Selective and Enantioselective Michael Addition to Electron-Deficient Internal Alkynes Under Chiral Iminophosphorane Catalysis.

    Uraguchi, Daisuke; Yamada, Kohei; Ooi, Takashi


    A highly E-selective and enantioselective conjugate addition of 2-benzyloxythiazol-5(4H)-ones to β-substituted alkynyl N-acyl pyrazoles is achieved under the catalysis of a P-spiro chiral iminophosphorane. Simultaneous control of the newly generated central chirality and olefin geometry is possible with a wide array of the alkynyl Michael acceptors possessing different aromatic and aliphatic β-substituents, as well as the various α-amino acid-derived thiazolone nucleophiles. This protocol provides access to structurally diverse, optically active α-amino acids bearing a geometrically defined trisubstituted olefinic component at the α-position.

  6. Ruthenium(II) coordination chemistry of a fused donor-acceptor ligand: synthesis, characterization, and photoinduced electron-transfer reactions of [{Ru(bpy)2}(n)(TTF-ppb)](PF6)(2n) (n = 1, 2).

    Goze, Christine; Dupont, Nathalie; Beitler, Elvira; Leiggener, Claudia; Jia, Hongpeng; Monbaron, Philippe; Liu, Shi-Xia; Neels, Antonia; Hauser, Andreas; Decurtins, Silvio


    A pi-extended, redox-active bridging ligand 4',5'-bis(propylthio)tetrathiafulvenyl[i]dipyrido[2,3-a:3',2'-c]phenazine (L) was prepared via direct Schiff-base condensation of the corresponding diamine-tetrathiafulvalene (TTF) precursor with 4,7-phenanthroline-5,6-dione. Reactions of L with [Ru(bpy)(2)Cl(2)] afforded its stable mono- and dinuclear ruthenium(II) complexes 1 and 2. They have been fully characterized, and their photophysical and electrochemical properties are reported together with those of [Ru(bpy)(2)(ppb)](2+) and [Ru(bpy)(2)(mu-ppb)Ru(bpy)(2)](4+) (ppb = dipyrido[2,3-a:3',2'-c]phenazine) for comparison. In all cases, the first excited state corresponds to an intramolecular TTF --> ppb charge-transfer state. Both ruthenium(II) complexes show two strong and well-separated metal-to-ligand charge-transfer (MLCT) absorption bands, whereas the (3)MLCT luminescence is strongly quenched via electron transfer from the TTF subunit. Clearly, the transient absorption spectra illustrate the role of the TTF fragment as an electron donor, which induces a triplet intraligand charge-transfer state ((3)ILCT) with lifetimes of approximately 200 and 50 ns for mono- and dinuclear ruthenium(II) complexes, respectively.

  7. A conversation with Michael Freeman, MD.

    Freeman, M


    The Institute for Behavioral Healthcare, a nonprofit organization that serves as an informational resource on issues surrounding the delivery of Behavioral Health Care Services, has been directed by Dr. Michael Freeman since its inception in 1988. In this crucial, unstable period in health care, membership in the Institute and attendance at its sponsored meetings has increased dramatically. Recently, Medical Interface talked with Dr. Freeman about topics of interest to the behavioral health care industry, ranging from any willing provider laws to the benefit itself.

  8. Anne Michaels e le ferite del linguaggio

    Oriana Palusci


    Fugitive Pieces is analysed taking into consideration its polyphonic structure, the manifold motives and threads that weave together an intricate pattern, based on historical events and personal stories. Thanks to her use of scientific language from the realm of geology, paleobotany and geography, Michaels excavates time and space, past and present, in order to find a language to unveil the atrocities of Nazism against Jews, to preserve and evoke the memories of the survivors, but at the same time lead to a possible reconciliation with the past.

  9. Richard Michael Suzman (1942-2015).

    Kahneman, Daniel


    Presents an obituary for Richard Michael Suzman, who died on April 16, 2015. Suzman was trained as a sociologist and anthropologist, but he was attracted to the approaches of demography and economics. He came to know a great deal about diverse fields of science, including health, physiology, psychology, genetics, and economics. He was a scientific leader who was on a quest to develop new transdisciplinary fields and to mobilize the best scientists to work in them. Suzman's passion for transdisciplinary science was fully expressed in his greatest achievement: the famous Health and Retirement Survey (HRS), which he initiated in 1988 and continued to guide and inspire. (PsycINFO Database Record

  10. Michael Roitmann : Kalandus ei ole Eestile ilmselt prioriteetne valdkond / Michael Roitmann ; interv. Marko Saaret

    Roitmann, Michael


    Ilmunud ka: Delovõje Vedomosti 3. dets. lk. 9. Euroopa Komisjoni kalandusdirektoraadi koordinaator Euroopa Liidu laienemise küsimuses Michael Roitmann juhib tähelepanu Eesti kalanduse suurematele probleemidele ning prognoosib EL-iga liitumise mõju Eesti kalandussektori arengule

  11. Michael Roitmann : Kalandus ei ole Eestile ilmselt prioriteetne valdkond / Michael Roitmann ; interv. Marko Saaret

    Roitmann, Michael


    Ilmunud ka: Delovõje Vedomosti 3. dets. lk. 9. Euroopa Komisjoni kalandusdirektoraadi koordinaator Euroopa Liidu laienemise küsimuses Michael Roitmann juhib tähelepanu Eesti kalanduse suurematele probleemidele ning prognoosib EL-iga liitumise mõju Eesti kalandussektori arengule

  12. Novel Ionic Liquid with Both Lewis and Brønsted Acid Sites for Michael Addition

    Runpu Shen


    Full Text Available Ionic liquid with both Lewis and Brønsted acid sites has been synthesized and its catalytic activities for Michael addition were carefully studied. The novel ionic liquid was stable to water and could be used in aqueous solution. The molar ratio of the Lewis and Brønsted acid sites could be adjusted to match different reactions. The results showed that the novel ionic liquid was very efficient for Michael addition with good to excellent yields within several min. Operational simplicity, high stability to water and air, small amount used, low cost of the catalyst used, high yields, chemoselectivity, applicability to large-scale reactions and reusability are the key features of this methodology, which indicated that this novel ionic liquid also holds great potential for environmentally friendly processes.

  13. N-1 regioselective Michael-type addition of 5-substituted uracils to (2-hydroxyethyl acrylate

    Walczak Krzysztof Z


    Full Text Available Abstract N-1 regioselective Michael-type addition of 5-substituted uracils to (2-hydroxyethyl acrylate is presented. The reactions were performed in polar aprotic solvents and with avoidance of polymerization of acrylic substrate. The obtained adducts may serve as versatile substrates for further functionalization, e.g. into (3-uracil-1-ylpropanoic acids or transformations, with participation of hydroxyl group, into ester-conjugated acyclic nucleosides.

  14. New hits as phase II enzymes inducers from a focused library with heteroatom–heteroatom and Michael-acceptor motives

    Cabrera, Mauricio; de Ovalle, Stefani; Bollati-Fogolín, Mariela; Nascimento, Fabiana; Corbelini, Patrícia; Janarelli, Fernanda; Kawano, Daniel; Eifler-Lima, Vera Lucia; González, Mercedes; Cerecetto, Hugo


    The increased activity of phase-II-detoxification enzymes, such as quinone reductase (QR) and glutation S-transferase (GST), correlates with protection against chemically induced carcinogenesis. Herein we studied 11 different chemotypes, pyrazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiazole, 1,3,4-oxathiazole, thienyl hydrazone, α,β-unsaturated-oxime, α,β-unsaturated-N-oxide, coumarin and α,β-unsaturated-carbonyl, as phase-II enzymes inducers in order to identify new pharmacophores with chemopreventive activity. Fifty-four compounds were analyzed on wild-type mouse-hepatoma Hepa-1c1c7 and on the aryl-hydrocarbon-nuclear-translocator (Arnt)-defective mutant BpRc1 cells. New monofunctional inducers of QR and GST were identified, the 1,2,5-oxadiazol-2-oxide (3), the 1,2,4-triazine-4-oxides (23) and (32) and the tetrahydropyrimidinones (28) and (49). It was confirmed that Nrf2 nuclear translocation is the operative molecular mechanism that allows compound (3) to exert protective effects via expression of downstream phase-II enzymes. PMID:28031894

  15. donor-acceptor reactions: good bye to the laboratory jargon


    or sodium hydrogen sulfate cannot be regarded as ampholytes – pure water ... The principle of "giving and taking" is well-known in every-day life – less known is the ... So caustic soda or sodium hydroxide solution are called substances, but ...

  16. Syntheses of donor-acceptor-functionalized dihydroazulenes

    Broman, Søren Lindbæk; Jevric, Martyn; Bond, Andrew


    The dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch has been of interest for use in molecular electronics and advanced materials. The switching between the two isomers has previously been found to depend strongly on the presence of donor and acceptor groups. The fine-tuning of opt...

  17. Double Acceptor Interaction in Semimagnetic Quantum Dot

    A. Merwyn Jasper D. Reuben


    Full Text Available The effect of geometry of the semimagnetic Quantum Dot on the Interaction energy of a double acceptor is computed in the effective mass approximation using the variational principle. A peak is observed at the lower dot sizes as a magnetic field is increased which is attributed to the reduction in confinement.

  18. Electron Donor Acceptor Interactions. Final Progress Report



    The Gordon Research Conference (GRC) on Electron Donor Acceptor Interactions was held at Salve Regina University, Newport, Rhode Island, 8/11-16/02. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  19. Organic Materials in the Undergraduate Laboratory: Microscale Synthesis and Investigation of a Donor-Acceptor Molecule

    Pappenfus, Ted M.; Schliep, Karl B.; Dissanayake, Anudaththa; Ludden, Trevor; Nieto-Ortega, Belen; Lopez Navarrete, Juan T.; Ruiz Delgado, M. Carmen; Casado, Juan


    A series of experiments for undergraduate courses (e.g., organic, physical) have been developed in the area of small molecule organic materials. These experiments focus on understanding the electronic and redox properties of a donor-acceptor molecule that is prepared in a convenient one-step microscale reaction. The resulting intensely colored…

  20. Michael Maier--nine newly discovered letters.

    Lenke, Nils; Roudet, Nicolas; Tilton, Hereward


    The authors provide a transcription, translation, and evaluation of nine newly discovered letters from the alchemist Michael Maier (1568-1622) to Gebhardt Johann von Alvensleben (1576-1631), a noble landholder in the vicinity of Magdeburg. Stemming from the final year of his life, this correspondence casts new light on Maier's biography, detailing his efforts to secure patronage amid the financial crisis of the early Thirty Years' War. While his ill-fated quest to perfect potable gold continued to form the central focus of his patronage suits, Maier also offered his services in several arts that he had condemned in his printed works, namely astrology and "supernatural" magic. Remarks concerning his previously unknown acquaintance with Heinrich Khunrath call for a re-evaluation of Maier's negotiation of the discursive boundaries between Lutheran orthodoxy and Paracelsianism. The letters also reveal Maier's substantial contribution to a work previously ascribed solely to the English alchemist Francis Anthony.

  1. STS-97 Crew Interviews: Michael J. Bloomfield


    Live footage of a preflight interview with Pilot Michael J. Bloomfield is shown. The interview addresses many different questions including why Bloomfield became interested in the space program, the events and people that influence him and ultimately led to his interest, and his vigorous training in the astronaut program. Other interesting information that this one-on-one interview discusses are the main goals of the STS-97 mission, its scheduled docking with the new International Space Station (ISS), and its delivery of the first set of U.S.-provided solar arrays, batteries, and radiators. Bloomfield briefly discusses his responsibilities during the much-anticipated docking as well as during the scheduled space-walks.

  2. Asymmetric synthesis of cyclopentanes bearing four contiguous stereocenters via an NHC-catalyzed Michael/Michael/esterification domino reaction† †Electronic supplementary information (ESI) available: Experimental procedures and characterization date (NMR, IR, MS, HPLC). CCDC 1437686. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5cc09581f Click here for additional data file. Click here for additional data file.

    Shu, Tao; Ni, Qijian; Song, Xiaoxiao; Zhao, Kun; Wu, Tianyu; Puttreddy, Rakesh; Rissanen, Kari


    An NHC-catalyzed Michael/Michael/esterification domino reaction via homoenolate/enolate intermediates for the asymmetric synthesis of tetrasubstituted cyclopentanes bearing four contiguous stereocenters is described. A variety of α,β-unsaturated aldehydes and 2-nitroallylic acetates react well with good domino yields and high stereoselectivities. PMID:26750327

  3. Book Review: Invitation to Topological Robotics by Michael Farber

    Raussen, Martin


    Book Review: Invitaton to Topological Robotics by Michael Farber. Zurich Lectures in Advanced Mathematics, European Mathematical Society (2008), ISBN 978-3-03719-054-8......Book Review: Invitaton to Topological Robotics by Michael Farber. Zurich Lectures in Advanced Mathematics, European Mathematical Society (2008), ISBN 978-3-03719-054-8...

  4. Interview with Michael Apple: The Biography of a Public Intellectual

    Peters, Michael A.


    Michael W. Apple is the John Bascom Professor of Curriculum and Instruction and Educational Policy Studies in the Departments of Curriculum and Instruction (CI) and Educational Policy Studies (EPS) at the University of Wisconsin-Madison School of Education where he has taught since 1970. Michael Apple is one of the foremost educational theorists…

  5. Michael J. Meaney: Award for Distinguished Scientific Contributions

    American Psychologist, 2012


    Presents Michael J. Meaney as one of the winners of the American Psychological Association's Award for Distinguished Scientific Contributions (2012). Michael J. Meaney has taken the phenomenon of "handling" of newborn rats and opened a new area of investigation that has given new meaning to epigenetics via his work demonstrating transgenerational…

  6. Michael Young and the Curriculum Field in South Africa

    Hoadley, Ursula


    The paper addresses the question of what we should make of Michael Young's recent work with respect to curriculum theory by considering the particular case of South African curriculum reform. The paper thus traces two trajectories: the evolution of Michael Young's ideas over time and South African curriculum reform in the post-apartheid period.…

  7. An Interview with Sir Michael Marmot



    Full Text Available In August of 2008 the WHO Commission on the Social Determinants of Health concluded its work with the publication of a report entitled: “Closing the gap in a generation: Health equity through action on the social determinants of health.” The Commission’s chair, Sir Michael Marmot, was kind enough to answer our questions about the Commission’s recommendations. This interview was conducted by email in May of this year. Social Medicine: We congratulate the Com-mission on its excellent work in bringing attention to the social determinants of health and the Commission’s call for health equity. We appreciated the Commission’s recognition that: “Social Justice is a matter of life and death.” We were also happy that the Commission included representatives of civil society in their work. This was an important affirmation of democratic values. When thinking about health inequalities people often use the analogue of the ladder to show how the gradient of worsening health outcomes affects all people in society except (presumably those at the very top. Thinking about the ladder leads us to pose the following question: Is making the ladder shorter (i.e. reducing inequalities the only approach to inequalities or is it possible to imagine making the ladder disappear entirely? Sir Michael Marmot: All societies have hier-archies. It is not conceivable, therefore, to have a society with no ladder. The conceptual framework of the Commission on Social Determinants of Health leads us to think of at least two (linked ways to address the relation between position on the ladder and health: act at the societal level to reduce social inequalities, and break the link between position in the social hierarchy and health. The first argues for reducing the slope of the social gradient. To see this, suppose, just for a moment, that the ladder were defined on the basis of years of education. People who had three years or fewer had life expectancy of 50 years

  8. Porphyrin Donor and Tunable Push-Pull Acceptor Conjugates-Experimental Investigation of Marcus Theory.

    Reekie, Tristan A; Sekita, Michael; Urner, Lorenz M; Bauroth, Stefan; Ruhlmann, Laurent; Gisselbrecht, Jean-Paul; Boudon, Corinne; Trapp, Nils; Clark, Timothy; Guldi, Dirk M; Diederich, François


    We report on a series of electron donor-acceptor conjugates incorporating a Zn(II) -porphyrin-based electron donor and a variety of non-conjugated rigid linkers connecting to push-pull chromophores as electron acceptors. The electron acceptors comprize multicyanobutadienes or extended tetracyanoquinodimethane analogues with first reduction potentials ranging from -1.67 to -0.23 V vs. Fc(+) /Fc in CH2 Cl2 , which are accessible through a final-step cycloaddition-retroelectrocyclization (CA-RE) reaction. Characterization of the conjugates includes electrochemistry, spectroelectrochemistry, DFT calculations, and photophysical measurements in a range of solvents. The collected data allows for the construction of multiple Marcus curves that consider electron-acceptor strength, linker length, and solvent, with data points extending well into the inverted region. The enhancement of electron-vibration couplings, resulting from the rigid spacers and, in particular, multicyano-groups in the conformationally highly fixed push-pull acceptor chromophores affects the charge-recombination kinetics in the inverted region drastically. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Ionic liquid-supported (ILS) (S)-pyrrolidine sulfonamide, a recyclable organocatalyst for the highly enantioselective Michael addition to nitroolefins.

    Ni, Bukuo; Zhang, Qianying; Dhungana, Kritanjali; Headley, Allan D


    A new class of ionic liquid supported (ILS) (S)-pyrrolidine sulfonamide organocatalyst has been developed and shown to be a very effective catalyst for the asymmetric Michael addition reactions of ketones and aldehyde to nitroolefins with high enantio- and diastereoselectivities. This ILS organocatalyst is also easily recycled and could be reused at least five times without significant loss of its ability to affect the outcome of the asymmetric reactions.

  10. Race, punishment, and the Michael Vick experience.

    Piquero, Alex R; Piquero, Nicole Leeper; Gertz, Marc; Baker, Thomas; Batton, Jason; Barnes, J C


    Objective. The relationship between race and crime has been contentious, focusing primarily on offending and incarceration patterns among minorities. There has been some limited work on public perceptions of criminal punishment, and findings show that while minorities believe in the role and rule of law, they simultaneously perceive the justice system as acting in a biased and/or unfair manner. Two limitations have stalled this literature. First, research has focused mainly on criminal punishments to the neglect of noncriminal punishments. Second, most studies have not examined whether race remains salient after considering other demographic variables or discrimination and legitimacy attitudes.Methods. Using data from 400 adults, we examine how race affects perceptions of criminal punishment and subsequent reinstatement into the National Football League in the case of Michael Vick, a star professional quarterback who pled guilty to charges of operating an illegal dog-fighting ring.Results. Findings show that whites are more likely to view Vick's punishment as too soft and that he should not be reinstated, while nonwhites had the opposite views. Race remained significant after controlling for other variables believed to be related to punishment perceptions.Conclusion. Attitudes toward both criminal punishment and NFL reinstatement vary across race such that there exists important divides in how individuals perceive the system meting out punishment and subsequently reintegrating offenders back into society. These results underscore that white and nonwhites perceive the law and its administration differently.

  11. Obituary: Michael John Klein, 1940-2005

    Gulkis, Samuel


    Michael John Klein died on 14 May 2005 at home in South Pasadena, California. The cause of death was tongue cancer that metastasized to the lungs. He was a non-smoker. Mike was a passionate radio astronomer, a trusted astronomical observer, an educator and a family man. Mike was born on 19 January 1940 in Ames, Iowa, the son of Florence Marie (Graf) and Fred Michael Klein. His mother was a homemaker, and his father was a banker. Mike had two older sisters, Lois Jean (Klein) Flauher and Marilyn June (Klein) Griffin. In 1962, Mike married his high school sweetheart Barbara Dahlberg, who survives him along with their three children, Kristin Marie (Klein) Shields, Michael John Klein Jr., Timothy Joel Klein, and six grandchildren. Mike developed a love for astronomy early in his life, and credited an early morning, newspaper-delivery route that he had at age twelve, which took him outside well before sunrise. He told family members that as he walked along his route, he stared into the sky and wondered what everything was. He studied sky charts, located stars, and began to understand how the planets shifted their positions relative to the stars each day. Another big influence in Mike's life was his brother in-law, Jim Griffin. Jim helped Mike understand that his passion for science did not have to remain a hobby, but could and should become a career. Jim's encouragement led Mike to attend Iowa State University in Ames, where he earned a BS in electrical engineering in 1962. Mike then started graduate school in electrical engineering at Michigan State, but after one semester transferred to the University of Michigan, Ann Arbor, where he earned an MS (1966) and PhD (1968) in astronomy. His doctoral dissertation, under the direction of Professor Fred Haddock, was based on extensive observations of the planets and examined the physical and thermal properties of planetary atmospheres and surfaces. Mike was awarded a Resident Research Associate position at JPL by the National

  12. Lipase-mediated conversion of vegetable oils into biodiesel using ethyl acetate as acyl acceptor

    Modi, M.K.; Reddy, J.R.C.; Rao, B.V.S.K.; Prasad, R.B.N. [Indian Institute of Chemical Technology, Hyderabad (India). Division of Lipid Science and Technology


    Ethyl acetate was explored as an acyl acceptor for immobilized lipase-catalyzed preparation of biodiesel from the crude oils of Jatropha curcas (jatropha), Pongamia pinnata (karanj) and Helianthus annus (sunflower). The optimum reaction conditions for interesterification of the oils with ethyl acetate were 10% of Novozym-435 (immobilized Candida antarctica lipase B) based on oil weight, ethyl acetate to oil molar ratio of 11:1 and the reaction period of 12 h at 50 {sup o}C. The maximum yield of ethyl esters was 91.3%, 90% and 92.7% with crude jatropha, karanj and sunflower oils, respectively under the above optimum conditions. Reusability of the lipase over repeated cycles interesterification and ethanolysis was also investigated under standard reaction conditions. The relative activity of lipase could be well maintained over twelve repeated cycles with ethyl acetate while it reached to zero by 6th cycle when ethanol was used as an acyl acceptor. (author)

  13. Organocatalytic, enantioselective synthesis of benzoxaboroles via Wittig/oxa-Michael reaction Cascade of α-formyl boronic acids† †Electronic supplementary information (ESI) available. CCDC 1487136. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6sc04522g Click here for additional data file. Click here for additional data file.

    Hazra, Gurupada; Maity, Sanjay; Bhowmick, Sudipto


    An unprecedented enantioselective synthesis of 3-substituted benzoxaboroles has been developed. An in situ generated ortho-boronic acid containing chalcone provides the chiral benzoxaboroles via an asymmetric oxa-Michael addition of hydroxyl group attached to the boronic acid triggered by the cinchona alkaloid based chiral amino-squaramide catalysts. In general, good yields with good to excellent enantioselectivities (up to 99%) were obtained. The resulting benzoxaboroles were converted to the corresponding chiral β-hydroxy ketones without affecting the enantioselectivity. PMID:28451370

  14. Asymmetric Sequential Aza-Diels-Alder and O-Michael Addition: Efficient Construction of Chiral Hydropyrano[2,3-b]pyridines%Asymmetric Sequential Aza-Diels-Alder and O-Michael Addition: Efficient Construction of Chiral Hydropyrano[2,3-b]pyridines

    尹祥; 圊清清; 董琳; 陈应春


    An asymmetric aza-Diels-Alder and O-Michael addition sequence has been developed to construct chiral hy- dropyrano[2,3-b]pyridine derivatives with good yields and excellent stereoselectivity, by starting with N-Ts-l-aza- 1,3-butadienes and aliphatic aldehydes tethered to an α,β-unsaturated ketone motif. A tandem O-Michael addition reaction was completed via acid catalysis.

  15. Conjugated donor-acceptor-acceptor (D-A-A) molecule for organic nonvolatile resistor memory.

    Dong, Lei; Li, Guangwu; Yu, An-Dih; Bo, Zhishan; Liu, Cheng-Liang; Chen, Wen-Chang


    A new donor-acceptor-acceptor (D-A-A) type of conjugated molecule, N-(4-(N',N'-diphenyl)phenylamine)-4-(4'-(2,2-dicyanovinyl)phenyl) naphthalene-1,8-dicarboxylic monoimide (TPA-NI-DCN), consisting of triphenylamine (TPA) donors and naphthalimide (NI)/dicyanovinylene (DCN) acceptors was synthesized and characterized. In conjunction with previously reported D-A based materials, the additional DCN moiety attached as end group in the D-A-A configuration can result in a stable charge transfer (CT) and charge-separated state to maintain the ON state current. The vacuum-deposited TPA-NI-DCN device fabricated as an active memory layer was demonstrated to exhibit write-once-read-many (WORM) switching characteristics of organic nonvolatile memory due to the strong polarity of the TPA-NI-DCN moiety. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Meet EPA Scientist Michael Nye, Ph.D.

    Michael Nye, Ph.D., is a social scientist who studies natural risk, socio-demographic change and sustainable behavior. Prior to joining EPA, he worked for the UK Environment Agency in flood risk management and emergency preparedness

  17. Nitrosonium (NO+) catalyzed Michael addition of indoles to unsaturated enones

    Guai Li Wu; Long Min Wu


    An efficient Michael addition of indoles to unsaturated enones, such as chalcones and β-nitrostyrenes, was achieved in thepresence of a catalytic amount of nitrosoninm tetrafluoroborate in ethyl ether.

  18. Immigration and Social Systems : Collected Essays of Michael Bommes


    Michael Bommes (hoogleraar Sociologie en Migratieonderzoek) was een van de meest briljante en originele geleerden in zijn vakgebied. Deze postume bundel bevat een selectie van zijn belangrijkste werk over immigratie en de verzorgingsstaat, de integratie van immigranten, discriminatie, illegale

  19. A metal-ligand cooperative pathway for intermolecular oxa-Michael additions to unsaturated nitriles.

    Perdriau, Sébastien; Zijlstra, Douwe S; Heeres, Hero J; de Vries, Johannes G; Otten, Edwin


    An unprecedented catalytic pathway for oxa-Michael addition reactions of alcohols to unsaturated nitriles has been revealed using a PNN pincer ruthenium catalyst with a dearomatized pyridine backbone. The isolation of a catalytically competent Ru-dieneamido complex from the reaction between the Ru catalyst and pentenenitrile in combination with DFT calculations supports a mechanism in which activation of the nitrile through metal-ligand cooperativity is a key step. The nitrile-derived Ru-N moiety is sufficiently Brønsted basic to activate the alcohol and initiate conjugate addition of the alkoxide to the α,β-unsaturated fragment. This reaction proceeds in a concerted manner and involves a six-membered transition state. These features allow the reaction to proceed at ambient temperature in the absence of external base. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Binomial distribution-based quantitative measurement of multiple-acceptors fluorescence resonance energy transfer by partially photobleaching acceptor

    Zhang, Lili; Yu, Huaina; Zhang, Jianwei; Chen, Tongsheng


    We report that binomial distribution depending on acceptor photobleaching degree can be used to characterize the proportions of various kinds of FRET (Fluorescence Resonance Energy Transfer) constructs resulted from partial acceptor photobleaching of multiple-acceptors FRET system. On this basis, we set up a rigorous quantitation theory for multiple-acceptors FRET construct named as Mb-PbFRET which is not affected by the imaging conditions and fluorophore properties. We experimentally validate Mb-PbFRET with FRET constructs consisted of one donor and two or three acceptors inside living cells on confocal and wide-field microscopes.

  1. Michael Polanyi: Science as Personal Knowledge and Social Practice.

    Nye, Mary Jo


    Tacit knowing: 2016 marked the 125th anniversary of the birth of the physical chemist Michael Polanyi, as well as the 40th of his death. This essay discusses his philosophy of science-in particular, his most significant work in this area, Personal Knowledge-from the perspective of his personal biography, as well as its lasting influence on the social sciences. In the photograph: Michael Polanyi at the Fritz Haber Institute in 1968.

  2. Anomalous surplus energy transfer observed with multiple FRET acceptors.

    Srinagesh V Koushik

    Full Text Available BACKGROUND: Förster resonance energy transfer (FRET is a mechanism where energy is transferred from an excited donor fluorophore to adjacent chromophores via non-radiative dipole-dipole interactions. FRET theory primarily considers the interactions of a single donor-acceptor pair. Unfortunately, it is rarely known if only a single acceptor is present in a molecular complex. Thus, the use of FRET as a tool for measuring protein-protein interactions inside living cells requires an understanding of how FRET changes with multiple acceptors. When multiple FRET acceptors are present it is assumed that a quantum of energy is either released from the donor, or transferred in toto to only one of the acceptors present. The rate of energy transfer between the donor and a specific acceptor (k(D-->A can be measured in the absence of other acceptors, and these individual FRET transfer rates can be used to predict the ensemble FRET efficiency using a simple kinetic model where the sum of all FRET transfer rates is divided by the sum of all radiative and non-radiative transfer rates. METHODOLOGY/PRINCIPAL FINDINGS: The generality of this approach was tested by measuring the ensemble FRET efficiency in two constructs, each containing a single fluorescent-protein donor (Cerulean and either two or three FRET acceptors (Venus. FRET transfer rates between individual donor-acceptor pairs within these constructs were calculated from FRET efficiencies measured after systematically introducing point mutations to eliminate all other acceptors. We find that the amount of energy transfer observed in constructs having multiple acceptors is significantly greater than the FRET efficiency predicted from the sum of the individual donor to acceptor transfer rates. CONCLUSIONS/SIGNIFICANCE: We conclude that either an additional energy transfer pathway exists when multiple acceptors are present, or that a theoretical assumption on which the kinetic model prediction is based is

  3. Entrevista al profesor D. Michael Walker. - Interview with Professor D. Michael Walker.

    Caravaca Guerrero, Consuelo Isabel


    Full Text Available Entrevistar a un investigador de la talla de D. Michael Walker supone hablar de un investigador reconocido a nivel nacional e internacional, uno de los mayores expertos en evolución humana de nuestros días. Nació en Colchester (Inglaterra en 1941 y tiene doble nacionalidad: británica y australiana. Actualmente es profesor emérito de la Universidad de Murcia en el Departamento de Zoología y Antropología Física de la Facultad de Biología. Pero su currículum no acaba aquí, Michael realizó tres carreras, Fisiología Animal, Medicina, y Arqueología Prehistórica, en la Universidad de Oxford. Es Doctor por esta universidad, gracias a su tesis leída sobre Paleoantropología y Prehistoria de las cuencas de los ríos Segura y Vinalopó. Nuestro entrevistado, también fue elegido Académico (Fellow –F.S.A.- en 1988 de la Society of Antiquaries of Londono SAL. Fundada en 1707, la SAL es la equivalente británica de la española Real Academia de la Historia. Es Fellow también del Real Instituto Antropológico de la Gran Bretaña (Royal Anthropological Institute of Great Britain y socio emérito de la Asociación Americana de Antropólogos Físicos (American Association of Physical Anthropologists.

  4. Evaluation of deoxygenated oligosaccharide acceptor analogs as specific inhibitors of glycosyltransferases.

    Hindsgaul, O; Kaur, K J; Srivastava, G; Blaszczyk-Thurin, M; Crawley, S C; Heerze, L D; Palcic, M M


    The glycosyltransferases controlling the biosynthesis of cell-surface complex carbohydrates transfer glycosyl residues from sugar nucleotides to specific hydroxyl groups of acceptor oligosaccharides. These enzymes represent prime targets for the design of glycosylation inhibitors with the potential to specifically alter the structures of cell-surface glycoconjugates. With the aim of producing such inhibitors, synthetic oligosaccharide substrates were prepared for eight different glycosyltransferases. The enzymes investigated were: A, alpha(1----2, porcine submaxillary gland); B, alpha(1----3/4, Lewis); C, alpha(1----4, mung bean); D, alpha(1----3, Lex)-fucosyltransferases; E, beta(1----4)-galactosyltransferase; F, beta(1----6)-N-acetylglucosaminyltransferase V; G, beta(1----6)-mucin-N-acetylglucosaminyltransferase ("core-2" transferase); and H, alpha(2----3)-sialyltransferase from rat liver. These enzymes all transfer sugar residues from their respective sugar nucleotides (GDP-Fuc, UDP-Gal, UDP-GlcNAc, and CMP-sialic acid) with inversion of configuration at their anomeric centers. The Km values for their synthetic oligosaccharide acceptors were in the range of 0.036-1.3 mM. For each of these eight enzymes, acceptor analogs were next prepared where the hydroxyl group undergoing glycosylation was chemically removed and replaced by hydrogen. The resulting deoxygenated acceptor analogs can no longer be substrates for the corresponding glycosyltransferases and, if still bound by the enzymes, should act as competitive inhibitors. In only four of the eight cases examined (enzymes A, C, F, and G) did the deoxygenated acceptor analogs inhibit their target enzymes, and their Ki values (all competitive) remained in the general range of the corresponding acceptor Km values. No inhibition was observed for the remaining four enzymes even at high concentrations of deoxygenated acceptor analog. For these latter enzymes it is suggested that the reactive acceptor hydroxyl groups are

  5. Positronium Inhibition and Quenching by Organic Electron Acceptors and Charge Transfer Complexes

    Jansen, P.; Eldrup, Morten Mostgaard; Jensen, Bror Skytte;


    the inhibition intensifies and the quenching almost vanishes. The reaction constants between ortho-Ps and the acceptors were determinded to be: 1.5 × 1010 M−1 s−1 for SO2 in dioxane 3.7 × 1010 M−1 s−1 for SO2 in n-heptane, 3.4 × 1010 M−1 s−1 for tetracyanoquinodimethane in tetrahydrofurane and 1.6 × 1010 M−1 s−1...

  6. Guest Foreword from Michael Thomas CMG QC

    Michael Thomas


    precedents and thought in a unique legal market in which ideas drawn from Islamic law, civil law and common law can intermingle and blend. It is not surprising therefore to see that this new publication will be dedicated to the subject of international law, both public and private. Its laudable aim is to promote legal discourse around the world, and to promote a wider international understanding of contemporary legal issues for the common benefit. As an open access, bilingual journal, addressing topics concerning any jurisdiction, I hope it will reach a wide audience, and fulfil its aim of promoting understanding between different cultures. I am sure that the journal will not only benefit Qatar’s legal community by advancing academic and practice-based legal discussion. I am also confident that it will stimulate thought in the global legal community at large. May I wish it every success and a long life. Michael Thomas CMG QC

  7. Quantum computing with acceptor spins in silicon.

    Salfi, Joe; Tong, Mengyang; Rogge, Sven; Culcer, Dimitrie


    The states of a boron acceptor near a Si/SiO2 interface, which bind two low-energy Kramers pairs, have exceptional properties for encoding quantum information and, with the aid of strain, both heavy hole and light hole-based spin qubits can be designed. Whereas a light-hole spin qubit was introduced recently (arXiv:1508.04259), here we present analytical and numerical results proving that a heavy-hole spin qubit can be reliably initialised, rotated and entangled by electrical means alone. This is due to strong Rashba-like spin-orbit interaction terms enabled by the interface inversion asymmetry. Single qubit rotations rely on electric-dipole spin resonance (EDSR), which is strongly enhanced by interface-induced spin-orbit terms. Entanglement can be accomplished by Coulomb exchange, coupling to a resonator, or spin-orbit induced dipole-dipole interactions. By analysing the qubit sensitivity to charge noise, we demonstrate that interface-induced spin-orbit terms are responsible for sweet spots in the dephasing time [Formula: see text] as a function of the top gate electric field, which are close to maxima in the EDSR strength, where the EDSR gate has high fidelity. We show that both qubits can be described using the same starting Hamiltonian, and by comparing their properties we show that the complex interplay of bulk and interface-induced spin-orbit terms allows a high degree of electrical control and makes acceptors potential candidates for scalable quantum computation in Si.

  8. Asymmetric Synthesis of Highly Functionalized Tetrahydropyrans via a One-Pot Organocatalytic Michael/Henry/Ketalization Sequence

    Hahn, Robert; Raabe, Gerhard; Enders, Dieter


    A diastereo- and enantioselective Michael/Henry/ketalization sequence to functionalized tetrahydropyrans is described. The multicomponent cascade reaction uses acetylacetone or β-keto esters, β-nitrostyrenes, and alkynyl aldehydes as substrates affording tetrahydropyrans with five contiguous stereocenters. Employing a bifunctional quinine-based squaramide organocatalyst, the title compounds are obtained in moderate to good yields (27–80%), excellent enantiomeric excesses (93–99% ee), and high diastereomeric ratios (dr > 20:1) after one crystallization. PMID:24971998

  9. Highly enantioselective Michael addition of cyclohexanone to nitroolefins catalyzed by pyrrolidine-based bifunctional benzoylthiourea in water.

    Wang, Zhen-Yu; Ban, Shu-Rong; Yang, Meng-Chen; Li, Qing-Shan


    Organocatalysis and aqueous reactions are identified as the focus of the greening of chemistry. Combining these two strategies effectively remains an interesting challenge in organic synthesis. Herein, we used pyrrolidine-based benzoylthiourea 1c to catalyze the asymmetric Michael addition of cyclohexanone to various nitroolefins in water to afford the corresponding compounds in moderate to good yields, and with excellent diastereoselectivities (up to >99:1 dr) and enantioselectivities (up to 99% ee).

  10. Obituary: Michael John Seaton, 1923-2007

    Pradhan, Anil; Nahar, Sultana


    Professor Michael John Seaton, hailed as the "Father of Atomic Astrophysics," passed away on May 29, 2007. He was one of the few Honorary Fellows of both the American Astronomical Society and the American Physical Society, so honored for his monumental contributions to both physics and astronomy. Mike Seaton was born on January 16, 1923 in Bristol, England. He attended Wallington County High School. But his leftist political activities, even at that stage, led to his expulsion, though he was eventually allowed to matriculate. He enlisted in the Royal Air Force as a navigator during the Second World War, and flew many dangerous missions. His legendary concentration and precision are reflected in the following anecdote. Once after a bombing mission his aircraft was lost in fog over the Alps. Seaton calculated the position and coordinates in flight to guide the aircraft. When the fog lifted, the crew found themselves flying perilously close to the mountains, but made it safely back. His associates often said, "A Seaton calculation is carried out as if his life depended on it." After the War he was admitted to University College London (UCL) as an undergraduate. Thereafter, he spent all of his professional career at UCL. Seaton received his Batchelor's degree in 1948, and his Ph.D. in 1951. His tenure at UCL coincided with the golden age of atomic astrophysics, for he was largely responsible for it. Seaton was elected Fellow of the Royal Society in 1967, and as President of the Royal Astronomical Society (RAS) in 1978. He was the recipient of an Honorary Doctorate from the Observatoire de Paris, an Honorary D.Sc. from the Queen's University of Belfast, the Gold Medal for Astronomy by the RAS, the Guthrie Medal by the Institute of Physics, the Royal Society Hughes award for lifetime work by the RAS, and several other prestigious awards. Nevertheless, as Alex Dalgarno recently remarked, Seaton was not part of the establishment because he chose not to be. Though rooted in

  11. Photoinduced Intramolecular Charge Transfer in Donor-acceptor Dyad and Donor-bridge-acceptor Triad

    Yong Ding; Yuan-zuo Li; Feng-cai Ma


    The ground and excited state properties of the [60]fullerene,diphenylbenzothiadiazole-triphenylamine (PBTDP-TPA) dyad and fullerene-diphenylbenzothiadiazole-triphenylamine (fullerene-PBTDP-TPA) triad were investigated theoretically using density functional theory with B3LYP functional and 3-21G basis set and time-dependent density functional theory with B3LYP functional and STO-3G basis set as well as 2D and 3D real space analysis methods.The 2D site representation reveals the electron-hole coherence on exci- tation.The 3D transition density shows the orientation and strength of the transition dipole moment,and the 3D charge difference density gives the orientation and result of the intramolecular charge transfer.Also, photoinduced intermolecular charge transfer (ICT) in PBTDP-TPA-fullerene triad are identified with 2D and 3D representations,which reveals the mechanisms of ICT in donor-bridge-acceptor triad on excitation. Besides that we also found that the direct superexchange ICT from donor to acceptor (tunneling through the bridge) strongly promotes the ICT in the donor-bridge-acceptor triad.

  12. Alkyl Radicals as Hydrogen Bond Acceptors: Computational Evidence

    Hammerum, Steen


    , and gives rise to pronounced shifts of IR stretching frequencies and to increased absorption intensities. The hydrogen bond acceptor properties of alkyl radicals equal those of many conventional acceptors, e.g., the bond length changes and IR red-shifts suggest that tert-butyl radicals are slightly better...

  13. Charge recombination versus charge separation in donor-bridge-acceptor systems.

    Wiberg, Joanna; Guo, Lijun; Pettersson, Karin; Nilsson, Daniel; Ljungdahl, Thomas; Mårtensson, Jerker; Albinsson, Bo


    Optimizing the ratio of the rates for charge separation (CS) over charge recombination (CR) is crucial to create long-lived charge-separated states. Mastering the factors that govern the electron transfer (ET) rates is essential when trying to achieve molecular-scale electronics, artificial photosynthesis, and also for the further development of solar cells. Much work has been put into the question of how the donor-acceptor distances and donor-bridge energy gaps affect the electronic coupling, V(DA), and thus the rates of ET. We present here a unique comparison on how these factors differently influence the rates for CS and CR in a porphyrin-based donor-bridge-acceptor model system. Our system contains three series, each of which focuses on a separate charge-transfer rate-determining factor, the donor-acceptor distance, the donor-bridge energy gap, and last, the influence of the electron acceptor on the rate for charge transfer. In these three series both CS and CR are governed by superexchange interactions which make a CR/CS comparative study ideal. We show here that the exponential distance dependence increases slightly for CR compared to that for CS as a result of the increased tunneling barrier height for this reaction, in accordance with the McConnell superexchange model. We also show that the dependence on the tunneling barrier height is different for CS and CR. This difference is highly dependent on the electron acceptor and thus cannot solely be explained by the differences in the frontier orbitals of the electron donor in these porphyrin systems.

  14. Acceptor impurity activation in III-nitride light emitting diodes

    Römer, Friedhard, E-mail:; Witzigmann, Bernd, E-mail: [Department of Electrical Engineering, University of Kassel, 34121 Kassel (Germany)


    In this work, the role of the acceptor doping and the acceptor activation and its impact on the internal quantum efficiency (IQE) of a Gallium Nitride (GaN) based multi-quantum well light emitting diode is studied by microscopic simulation. Acceptor impurities in GaN are subject to a high activation energy which depends on the presence of proximate dopant atoms and the electric field. A combined model for the dopant ionization and activation barrier reduction has been developed and implemented in a semiconductor carrier transport simulator. By model calculations, we demonstrate the impact of the acceptor activation mechanisms on the decay of the IQE at high current densities, which is known as the efficiency droop. A major contributor to the droop is the electron leakage which is largely affected by the acceptor doping.

  15. Synthesis of new pyrrolidine-based organocatalysts and study of their use in the asymmetric Michael addition of aldehydes to nitroolefins

    Alejandro Castán


    Full Text Available New pyrrolidine-based organocatalysts with a bulky substituent at C2 were synthesized from chiral imines derived from (R-glyceraldehyde acetonide by diastereoselective allylation followed by a sequential hydrozirconation/iodination reaction. The new compounds were found to be effective organocatalysts for the Michael addition of aldehydes to nitroolefins and enantioselectivities up to 85% ee were achieved.

  16. Direct Asymmetric Michael Additions of Ketones to Nitroolefins and Chalcones Catalyzed by a Chiral C2-Symmetric Pyrrolidine-based Tetraamine

    马世俊; 吴璐璐; 刘明; 王永梅


    C2-Symmetric pyrrolidine-based tetraamine, available from commercially starting materials, showed good cata- lytic activity for asymmetric Michael additions of ketones to nitroalkenes especially to chalcones. The reactions proceeded to give the corresponding products in good yields and in a highly selective manner.

  17. Michael hydratase alcohol dehydrogenase or just alcohol dehydrogenase?

    Resch, V.A.; Jin, J.; Chen, B.S.; Hanefeld, U.


    The Michael hydratase – alcohol dehydrogenase (MhyADH) from Alicycliphilus denitrificans was previously identified as a bi-functional enzyme performing a hydration of α,β-unsaturated ketones and subsequent oxidation of the formed alcohols. The investigations of the bi-functionality were based on a

  18. Michael Moore kaevati kohtusse pettuse eest / Mari Rebane

    Rebane, Mari


    Dokumentaalfilm "9/11 Fahrenheiti" ("Fahrenheit 9/11") : režissöör Michael Moore : USA 2004. Iraagi sõja invaliidistunud veteran andis režissööri kohtusse teda kujutavate flmikaadrite loata ja tenentsliku kasutamise pärast

  19. Reading Michael Apple--The Sociological Imagination at Work

    Ball, Stephen J.


    This article discusses Michael Apple's contribution to the sociology of education and education policy analysis and the politics of education. It focuses on ways of "reading" Apple as an intellectual and an activist and looks at the trajectory of his work over a long and illustrious career.

  20. Eesti luksushotellide ristiisa / Michael Stenner ; interv. Malle Koido

    Stenner, Michael


    Eesti tipphotelle 1997. aastast juhtinud sakslane, praegu hotellide Kolm Õde ja Telegraaf juht räägib Eesti ja Saksamaa erinevustest, Eesti hotelliärist, teeninduskultuurist ja personalist. Lisa: Kes on Michael Stenner ning kuidas ta Eestisse sattus? Ilmunud ka: Linnaleht : Pärnu, 23. veebr. 2007, lk. 5-6

  1. Tweeting Prayers and Communicating Grief over Michael Jackson Online

    Sanderson, Jimmy; Cheong, Pauline Hope


    Death and bereavement are human experiences that new media helps facilitate alongside creating new social grief practices that occur online. This study investigated how people's postings and tweets facilitated the communication of grief after pop music icon Michael Jackson died. Drawing on past grief research, religion, and new media studies, a…

  2. Genres and Genre Theory: A Response to Michael Rosen

    Christie, Frances


    This paper responds to Michael Rosen's blog entries, "How Genre Theory Saved the World", arguing that genre theory in the tradition of systemic functional linguistics (SFL) has made an important contribution to language and literacy pedagogy. It emerged in the Australian context in about 1980 and was initially developed in response to…

  3. Michael Moore kaevati kohtusse pettuse eest / Mari Rebane

    Rebane, Mari


    Dokumentaalfilm "9/11 Fahrenheiti" ("Fahrenheit 9/11") : režissöör Michael Moore : USA 2004. Iraagi sõja invaliidistunud veteran andis režissööri kohtusse teda kujutavate flmikaadrite loata ja tenentsliku kasutamise pärast

  4. SuchThatCast Episode 6: Michael Boylan

    Soraker, Johnny


    Michael Boylan is the John J. McDonnell jr chair in Ethics, and professor and chair of the philosophy department at Marymount University in Arlington, Virginia. In addition to being a poet and novelist, he has written more than 100 published articles and 25 books primarily in ethics, social and

  5. The correspondence of Michael Faraday, v.4 1849-1855

    James, F


    This volume includes 70% of previously unpublished letters of Michael Farday spanning half of the 1850s and most of 1860. Topics include Faraday's work on regelation, the transmission of light through gold and his appointment by Emperor Napoleon III to be a Commander of the Legion of Honour.

  6. Correspondence of Michael Faraday, v.5 1855-1860

    Faraday, Michael


    This volume includes 70% of previously unpublished letters of Michael Farday spanning half of the 1850s and most of 1860. Topics include Faraday's work on regelation, the transmission of light through gold and his appointment by Emperor Napoleon III to be a Commander of the Legion of Honour.

  7. Professor Porter ja tema viis konkurentsitegurit / Michael E Porter

    Porter, Michael E


    Maailmas tuntud juhtimisguru Michael Porter viie konkurentsijõu teooriast ja selle rakendatavusest erinevates valdkondades. Lisad: Erinevused valdkondade kasumlikkuses; 5 määravat konkurentsijõudu; Investeeritud kapitali keskmine tasuvus; Mõnede USA tegevusvaldkondade kasumlikkus; Valdkonnaanalüüs praktikas; Valdkonna määratlemine; Valdkonnaanalüüsi sammud

  8. Michael Young's "The Rise of the Meritocracy": A Philosophical Critique

    Allen, Ansgar


    This paper examines Michael Young's 1958 dystopia, "The Rise of the Meritocracy". In this book, the word "meritocracy" was coined and used in a pejorative sense. Today, however, meritocracy represents a positive ideal against which we measure the justice of our institutions. This paper argues that, when read in the twenty-first century, Young's…

  9. Educational Implications of Michael Fishbane's "Sacred Attunement: A Jewish Theology"

    Marom, Daniel


    This article posits Michael Fishbane's Judaic scholarship as a prime resource for Jewish education. The link between the two fields can be made through a translation of the theological underpinnings of Fishbane's insights into Judaism to educational purposes and practices. Initial work with Jewish educators on establishing this link encouraged…

  10. Fooling LC: Michael Crichton and "Eaters of the Dead."

    Lonergan, David


    Chronicles the variety of means with which the novelist Michael Crichton has attempted to give his works the appearance of nonfiction. Specific and successful techniques utilized in "Eaters of the Dead" are noted, and the resulting erroneous classifications by the Library of Congress and subsequent catalogers are discussed. (Author)

  11. Berliinis võidutses Michael Haneke / Jüri Laulik

    Laulik, Jüri, 1959-


    IX PÖFFil linastuv Michael Haneke film "Varjatud" ("Cache") võitis laupäeval mitu Euroopa Filmiakadeemia auhinda, sealhulgas parima filmi, parima lavastaja ja parima meesnäitleja (Daniel Auteuil) auhinna. Parima naisnäitleja tiitli pälvis Julia Jentsch ("Sophie Scholli viimased päevad"). Elutööpreemia sai sir Sean Connery

  12. "No More Excuses": Michael M. Crow on Analytics

    Crow, Michael M.


    Michael M. Crow became the 16th president of Arizona State University in July 2002, with the goal of transforming ASU into what he calls a "New American University"--an institution combining the highest levels of academic excellence, inclusiveness to a broad demographic, and maximum societal impact. His view included increasing graduate…

  13. A Good Time: A Conversation with C. Michael Nelson

    Zabel, Robert; Kaff, Marilyn; Teagarden, Jim


    C. Michael Nelson began his special education career as a teacher of adolescents with learning and behavior disorders. He has worked as a child psychologist and as a professor with the Department of Special Education and Rehabilitation Counseling at the University of Kentucky. He coordinated the graduate Personnel Preparation Program for Teachers…

  14. Michael hydratase alcohol dehydrogenase or just alcohol dehydrogenase?

    Resch, V.A.; Jin, J.; Chen, B.S.; Hanefeld, U.


    The Michael hydratase – alcohol dehydrogenase (MhyADH) from Alicycliphilus denitrificans was previously identified as a bi-functional enzyme performing a hydration of α,β-unsaturated ketones and subsequent oxidation of the formed alcohols. The investigations of the bi-functionality were based on a s

  15. SuchThatCast Episode 6: Michael Boylan

    Søraker, J.H.


    Michael Boylan is the John J. McDonnell jr chair in Ethics, and professor and chair of the philosophy department at Marymount University in Arlington, Virginia. In addition to being a poet and novelist, he has written more than 100 published articles and 25 books primarily in ethics, social and poli

  16. Professor Porter ja tema viis konkurentsitegurit / Michael E Porter

    Porter, Michael E


    Maailmas tuntud juhtimisguru Michael Porter viie konkurentsijõu teooriast ja selle rakendatavusest erinevates valdkondades. Lisad: Erinevused valdkondade kasumlikkuses; 5 määravat konkurentsijõudu; Investeeritud kapitali keskmine tasuvus; Mõnede USA tegevusvaldkondade kasumlikkus; Valdkonnaanalüüs praktikas; Valdkonna määratlemine; Valdkonnaanalüüsi sammud

  17. Tweeting Prayers and Communicating Grief over Michael Jackson Online

    Sanderson, Jimmy; Cheong, Pauline Hope


    Death and bereavement are human experiences that new media helps facilitate alongside creating new social grief practices that occur online. This study investigated how people's postings and tweets facilitated the communication of grief after pop music icon Michael Jackson died. Drawing on past grief research, religion, and new media studies, a…

  18. Immigration and Social Systems : Collected Essays of Michael Bommes


    Popular science Michael Bommes (hoogleraar Sociologie en Migratieonderzoek) was een van de meest briljante en originele geleerden in zijn vakgebied. Deze postume bundel bevat een selectie van zijn belangrijkste werk over immigratie en de verzorgingsstaat, de integratie van immigranten, discriminatie, illegale migratie, migrantennetwerken en migratiebeleidsonderzoek. Deze bundel laat zien hoe Bommes' inzichten en deskundigheid een fundamentele bijdrage hebben geleverd aan immigratiestudies....

  19. Utility of Certain Π Acceptors for Spectrophotometric Determination of Sildenafil Citrate

    Nora H. Al-Shaalan


    Full Text Available Sildenafil citrate was determined through charge transfer complexes (CTC formation with three electron acceptor reagents. The methods involve the reaction of Sildenafil citrate as n-donor with either Chloranil (tetrachloro 1,4-benzoquinone, tetracyanoethylene (TCNE or 7,7,8,8-tetracyanoquinodimethane (TCNQ as n-acceptors, to give a stable and highly colored radical anion. The colored products were quantified spectrophotometrically. The condition ranges adhering to Beer's law are 0.05-3.00 mg/ml. The molar ratios of the reactants were ascertained. The different parameters were carefully studied and optimized. Statistical analysis of the results revealed equal precision and accuracy to the results of the reported method. The methods were applied for determination of sildenafil citrate in pure form and in Viagra tablets.

  20. Intramolecular Charge-Transfer Interaction of Donor-Acceptor-Donor Arrays Based on Anthracene Bisimide.

    Iwanaga, Tetsuo; Ogawa, Marina; Yamauchi, Tomokazu; Toyota, Shinji


    We designed anthracene bisimide (ABI) derivatives having two triphenylamine (TPA) groups as donor units at the 9,10-positions to form a novel π-conjugated donor-acceptor system. These compounds and their analogues with ethynylene linkers were synthesized by Suzuki-Miyaura and Sonogashira coupling reactions, respectively. In UV-vis spectra, the linker-free derivatives showed broad absorption bands arising from intramolecular charge-transfer interactions. Introducing ethynylene linkers resulted in a considerable red shift of the absorption bands. In fluorescence spectra, the ethynylene derivatives showed intense emission bands at 600-650 nm. Their photophysical and electrochemical properties were compared with those of the corresponding mono TPA derivatives on the basis of theoretical calculations and cyclic voltammetry to evaluate the intramolecular electronic interactions between the donor and acceptor units.

  1. Michael additions of thiocompounds to {alpha}, {beta}-unsaturated carbonyl compounds in aqueous media: stereoselectivity with unambiguous characterization by NMR

    Almeida, Queli Aparecida Rodrigues de; Pereira, Maria Luiza de Oliveira; Coelho, Ricardo Bezerra; Kaiser, Carlos Roland; Jones Junior, Joel; Silva, Flavia Martins da [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica. Dept. de Quimica Organica]. E-mail:; Carvalho, Erika Martins de [Instituto de Tecnologia em Farmacos (Far-Manguinhos), Rio de Janeiro, RJ (Brazil)


    The reactions of crotonaldehyde (8) with thiophenol (2) and benzalacetone (10) with ethane-1,2- dithiol (11) yield Michael addition products. The reactions of thiophenol (2) with (R)-carvone (13) and (S)-perillaldehyde (15) lead to (2S,3R,5S)-5-isopropenyl-2-methyl-3-(phenylthio)cyclohexanone (14) and (1R,2R,4S)-4-isopropenyl-2-(phenylthio)cyclohexanecarbaldehyde (16), respectively. An unambiguous elucidation of the stereochemistry of 14 and 16 by NMR is also presented. (author)

  2. Michael Pärt ئ suure muusika taustajõud / Michael Pärt ; interv. Siim Nestor

    Pärt, Michael


    Arvo Pärdi pojast Michael Pärdist. Tema tööst "music editor"-ina - helimonteerijana, tööst muusika produktsiooni, salvestamise ja muusika kirjutamise abijõuna. Koostööst maailmas tuntud muusikutega

  3. Michael Pärt ئ suure muusika taustajõud / Michael Pärt ; interv. Siim Nestor

    Pärt, Michael


    Arvo Pärdi pojast Michael Pärdist. Tema tööst "music editor"-ina - helimonteerijana, tööst muusika produktsiooni, salvestamise ja muusika kirjutamise abijõuna. Koostööst maailmas tuntud muusikutega

  4. Alteration of cartilage glycosaminoglycan protein acceptor by somatomedin and cortisol.

    Kilgore, B S; McNatt, M L; Meador, S; Lee, J A; Hughes, E R; Elders, M J


    The effect of somatomedin and cortisol on embryonic chick cartilage in vitro indicates that somatomedin stimulates 35SO4 uptake while cortisol decreases it with no effect on glycosaminoglycan turnover. Xylosyltransferase activity is increased in crude fractions of somatomedin-treated cartilage but decreased in cortisol-treated cartilage. By using a Smith-degraded proteoglycan as an exogenous acceptor, xylosyltransferase activities from both treatments were equivalent, suggesting that the enzyme was not rate limiting. The results of xylosyltransferase assays conducted by mixing enzyme and endogenous acceptor from control, cortisol-treated and somatomedin-treated cartilage, suggest both effects to be at the level of the acceptor protein.

  5. Donor–Acceptor Oligorotaxanes Made to Order

    Basu, Subhadeep [Northwestern Univ., Evanston, IL (United States); Coskun, Ali [Northwestern Univ., Evanston, IL (United States); Friedman, Douglas C. [Northwestern Univ., Evanston, IL (United States); Olson, Mark A. [Northwestern Univ., Evanston, IL (United States); Benitez, Diego [California Institute of Technology (Caltech), Pasadena, CA (United States); Tkatchouk, Ekaterina [California Institute of Technology (Caltech), Pasadena, CA (United States); Barin, Gokhan [Northwestern Univ., Evanston, IL (United States); Yang, Jeffrey [Northwestern Univ., Evanston, IL (United States); Fahrenbach, Albert C. [Northwestern Univ., Evanston, IL (United States); Goddard, William A. [California Institute of Technology (Caltech), Pasadena, CA (United States); Stoddart, J. Fraser [Northwestern Univ., Evanston, IL (United States)


    Five donor–acceptor oligorotaxanes made up of dumbbells composed of tetraethylene glycol chains, interspersed with three and five 1,5-dioxynaphthalene units, and terminated by 2,6-diisopropylphenoxy stoppers, have been prepared by the threading of discrete numbers of cyclobis(paraquat-p-phenylene) rings, followed by a kinetically controlled stoppering protocol that relies on click chemistry. The well-known copper(I)-catalyzed alkyne–azide cycloaddition between azide functions placed at the ends of the polyether chains and alkyne-bearing stopper precursors was employed during the final kinetically controlled template-directed synthesis of the five oligorotaxanes, which were characterized subsequently by ¹H NMR spectroscopy at low temperature (233 K) in deuterated acetonitrile. The secondary structures, as well as the conformations, of the five oligorotaxanes were unraveled by spectroscopic comparison with the dumbbell and ring components. By focusing attention on the changes in chemical shifts of some key probe protons, obtained from a wide range of low-temperature spectra, a picture emerges of a high degree of folding within the thread protons of the dumbbells of four of the five oligorotaxanes—the fifth oligorotaxane represents a control compound in effect—brought about by a combination of C[BOND]H···O and π–π stacking interactions between the π-electron-deficient bipyridinium units in the rings and the π-electron-rich 1,5-dioxynaphthalene units and polyether chains in the dumbbells. The secondary structures of a foldamer-like nature have received further support from a solid-state superstructure of a related [3]pseudorotaxane and density functional calculations performed thereon.

  6. Synthesis of donor-acceptor alkynylcyclopropanes by diastereoselective cyclopropanation of electron-deficient alkenes with alkoxyalkynyl Fischer carbene complexes.

    Barluenga, José; Fernández-Rodríguez, Manuel A; García-García, Patricia; Aguilar, Enrique; Merino, Isabel


    The reaction of electron-deficient alkenes with alkoxyalkynyl Fischer carbene complexes (FCCs) represents a straightforward route to a new type of captodative (donor-acceptor) alkynylcyclopropanes, which have been prepared in moderate to high yields and in a diastereoselective manner. Some studies regarding the employment of additives to facilitate the recovery of the metal moiety after the reaction are also described. Finally, the first example of a cyclopropanation reaction through employing Fischer carbene complexes under microwave irradiation is presented; this method proved to be an advantageous alternative to the thermal reaction.

  7. Aza-Michael Addition of Isatin and Phthalimide to Symmetrical Fumaric Esters in Ionic Liquid Media

    IMANZADEH Gholam Hassan; MOLLAEI TAVANA Mahdieh; ZAMANLOO Mohammad Reza; MANSOORI Yagoub


    Highly efficient aza-Michael additions of isatin and phthalimide to symmetrical fumaric esters in ionic liquid media to produce the corresponding Michael adducts in excellent yields are described which were performed at 100 ℃ for 1-5 h. The results show that these aza-Michael additions are not effective with fumaric esters containing sterically hindered alkoxy groups.

  8. Tribute to Professor Anthony J. McMichael

    Ashwin Swaminathan


    Full Text Available Emeritus Professor A. J. “Tony” McMichael (1942–2014 was an internationally renowned and pioneering Australian academic and advocate in epidemiology, who was passionate about understanding the influences of the environment on human health. In an illustrious career spanning more than four decades, he made significant contributions to the scientific community and policy discourse—including ground-breaking research related to the health of children. McMichael was a prolific academic writer with over 300 peer-reviewed papers; 160 book chapters and two sole-authored books. However, his outstanding talent was for integrating complex and seemingly unrelated strands from the environmental and health sciences into a cohesive narrative—and highlighting its relevance to lay persons, scientists and governments alike. He was instrumental in validating this nascent field of research and inspiring many others to follow his lead.

  9. Tribute to Professor Anthony J. McMichael.

    Swaminathan, Ashwin; Lucas, Robyn M; Harley, David


    Emeritus Professor A. J. "Tony" McMichael (1942-2014) was an internationally renowned and pioneering Australian academic and advocate in epidemiology, who was passionate about understanding the influences of the environment on human health. In an illustrious career spanning more than four decades, he made significant contributions to the scientific community and policy discourse-including ground-breaking research related to the health of children. McMichael was a prolific academic writer with over 300 peer-reviewed papers; 160 book chapters and two sole-authored books. However, his outstanding talent was for integrating complex and seemingly unrelated strands from the environmental and health sciences into a cohesive narrative-and highlighting its relevance to lay persons, scientists and governments alike. He was instrumental in validating this nascent field of research and inspiring many others to follow his lead.

  10. Pengaruh Tipografi pada Era Massimo Vignelli terhadap Tipografi Michael Bierut

    Irwan Harnoko


    Full Text Available Massimo Vignelli is a senior graphic designer lived in New York, as a vocal modernism against postmodernism. His statement firmly opposing post-modernism in several occasions: interview in Helvetica the movie, type radio, talk show, and some articles in Looking Closer or AIGA Journal. Graphic design works of Massimo Vignelli reflected his characteristic, which is firmly choosing typeface. Typefaces of Vignelly are around 5 typefaces: Bodoni, Helvetica, Times Roman, Century, and Futura. The article uses formal analysis method. The writers collected materials about Michael Bierut, Massimo VIgnelli and Tibor Kalman from books and websites. The writers compare the typeface opinion of Massimo Vignelli (modernism designer, Michael Bierut designer (transition era designer from modernism to post-modernism, and Tibor Kalman (a designer in A Century of Graphic Design, as the influence of Bieruts betrayal over Vignelli.

  11. Pengaruh Tipografi pada Era Massimo Vignelli terhadap Tipografi Michael Bierut

    Irwan Harnoko


    Full Text Available Massimo Vignelli is a senior graphic designer lived in New York, as a vocal modernism against post-modernism. His statement firmly opposing post-modernism in several occasions: interview in Helvetica the movie, typeradio, talkshow, and some articles in Looking Closer or AIGA Journal. Graphic design works of Massimo Vignelli reflected his characteristic, which is firmly choosing typeface. Typefaces of Vignelly are around 5 typefaces: Bodoni, Helvetica, Times Roman, Century, and Futura. The article uses formal analysis method. The writers collected materials about Michael Bierut, Massimo VIgnelli and Tibor Kalman from books and websites. The writers compare the typeface opinion of Massimo Vignelli (modernism designer, Michael Bierut designer (transition era designer from modernism to post-modernism, and Tibor Kalman (a designer in A Century of Graphic Design, as the influencer of Bierut’s betrayal over Vignelli. 

  12. Copper Toxicity Affects Photosystem II Electron Transport at the Secondary Quinone Acceptor, QB1

    Mohanty, Narendranath; Vass, Imre; Demeter, Sándor


    The nature of Cu2+ inhibition of photosystem II (PSII) photochemistry in pea (Pisum sativum L.) thylakoids was investigated monitoring Hill activity and light emission properties of photosystem II. In Cu2+-inhibited thylakoids, diphenyl carbazide addition does not relieve the loss of Hill activity. The maximum yield of fluorescence induction restored by hydroxylamine in Tris-inactivated thylakoids is markedly reduced by Cu2+. This suggests that Cu2+ does not act on the donor side of PSII but on the reaction center of PSII or on components beyond. Thermoluminescence and delayed luminescence studies show that charge recombination between the positively charged intermediate in water oxidation cycle (S2) and negatively charged primary quinone acceptor of pSII (QA−) is largely unaffected by Cu2+. The S2QB− charge recombination, however, is drastically inhibited which parallels the loss of Hill activity. This indicates that Cu2+ inhibits photosystem II photochemistry primarily affecting the function of the secondary quinone electron acceptor, QB. We suggest that Cu2+ does not block electron flow between the primary and secondary quinone acceptor but modifies the QB site in such a way that it becomes unsuitable for further photosystem II photochemistry. PMID:16666731

  13. C-H-Activated Direct Arylation of Strong Benzothiadiazole and Quinoxaline-Based Electron Acceptors.

    Zhang, Junxiang; Parker, Timothy C; Chen, Wayne; Williams, LaRita; Khrustalev, Victor N; Jucov, Evgheni V; Barlow, Stephen; Timofeeva, Tatiana V; Marder, Seth R


    Electron acceptors are important components of π-conjugated materials, but the strong electron-withdrawing properties of the required synthetic intermediates often make them poor substrates in synthetic schemes designed around conventional organometallic cross-coupling. Here, strong benzodiimine-based acceptors, including 5,6-difluoro[2,1,3]benzothiadiazole, 5,6-dicyano[2,1,3]benzothiadiazole, 5,6-dicyanobenzo[d][1,2,3]triazole, 6,7-dicyanoquinoxaline, and 6,7-dinitroquinoxaline, are shown to undergo facile palladium-catalyzed C-H direct arylation with a variety of bromoarenes in moderate to high yields. The electrochemical characteristics of di-2-thienyl derivatives synthesized using this methodology are compared and suggest that, in an electron-transfer sense, 5,6-dicyano[2,1,3]benzothiadiazole is a comparably strong acceptor to benzo[1,2-c:4,5-c']bis[1,2,5]thiadiazole. The synthetic results suggest that high electron-withdrawing ability, which has traditionally limited reaction yields and structural variety in organic electronic materials, may be advantageous when employing C-H activated direct arylation in certain circumstances.

  14. Euroopa parimaks filmiks sai Michael Haneke "Valge lint" / Andres Laasik

    Laasik, Andres, 1960-2016


    Euroopa Filmiakadeemia auhindadest: parima filmiauhinna sai Saksamaal Bochumis toimunud tseremoonial Michael Haneke "Valge lint", mille eest Haneke sai ka parima režissööri ja stsenaristi auhinna. Parimaks meesnäitlejaks pärjati Tahar Rahim ("Un Prophete"), parimaks naisnäitlejaks Kate Winslet ("The Reader"), publikupreemia sai Danny Boyle'i "Rentslimiljonär. Ka teistest võitjatest

  15. The cinema of Michael Bay : an aesthetic of excess

    Bennett, Bruce


    The hyper-kinetic action films of Michael Bay have come to exemplify the commercial, technical and aesthetic transformations of contemporary blockbuster cinema during a period in which the dynamic, disorienting effects of media convergence are reconfiguring viewing practices and remodelling cinematic institutions. However, despite their commercial success and cultural visibility, these films remain more or less absent from academic criticism of late twentieth and early twenty-first century gl...

  16. Analysis of the black crust on Saint Michael's Church

    Popister, I.; Zeman, A.


    The goal of the present study is to characterize the black crust on the main stone used at Saint Michael's Church in Cluj-Napoca, Romania. The gases in the atmosphere, along with natural and artificial pollutants can cause damage the integrity of the stone when it comes in contact with the stone's chemistry. In order to explain the mechanism of stone decay due to black crust it is necessary to know what "weathering" means, so it must be seen as a complex process that consists of: type of material, the environment in which the material is located, and the amount of time required for the process to take place. Each material has particular properties, due to its composition and genesis. When it comes in contact with the acidity of the "acid rain" (caused by sulphur, nitrogen oxides and carbon dioxide), the rain penetrates into the pore structure, corroding it and "allowing" the atmospheric particles to penetrate the stone. St. Michael's Church is one of the oldest Gothic architectural monuments in Cluj, Romania, being built predominantly from Cenozoic (Upper Eocene) limestone, locally known as the Cluj Limestone. The main quarry was in Baciu, near Cluj. The samples that were collected from the Saint Michael's Church were characterized by means of: optical microscope, Scattering Electronic Microscope, thin sections, EDS The samples that were collected from the Saint Michael's Church went through a series of tests: optical microscope, Scattering Electronic Microscope, thin sections, EDX, and cross-section. The optical microscope analysis of the thin sections revealed that the black crust layer is approximately 0.01mm, and in the sample there are perfectly shaped ooides, which is characteristic to this type of limestone. The SEM analysis shows a resedimentation layer on the surface of the black crust, which occurred probably due to the effect of acid rain. Further information regarding the results of the test will be presented on the poster.

  17. Euroopa parimaks filmiks sai Michael Haneke "Valge lint" / Andres Laasik

    Laasik, Andres, 1960-2016


    Euroopa Filmiakadeemia auhindadest: parima filmiauhinna sai Saksamaal Bochumis toimunud tseremoonial Michael Haneke "Valge lint", mille eest Haneke sai ka parima režissööri ja stsenaristi auhinna. Parimaks meesnäitlejaks pärjati Tahar Rahim ("Un Prophete"), parimaks naisnäitlejaks Kate Winslet ("The Reader"), publikupreemia sai Danny Boyle'i "Rentslimiljonär. Ka teistest võitjatest

  18. Development of Polymer Acceptors for Organic Photovoltaic Cells

    Yujeong Kim


    Full Text Available This review provides a current status report of the various n-type polymer acceptors for use as active materials in organic photovoltaic cells (OPVs. The polymer acceptors are divided into four categories. The first section of this review focuses on rylene diimide-based polymers, including perylene diimide, naphthalene diimide, and dithienocoronene diimide-based polymers. The high electron mobility and good stability of rylene diimides make them suitable for use as polymer acceptors in OPVs. The second section deals with fluorene and benzothiadiazole-based polymers such as poly(9,9’-dioctylfluorene-co-benzothiadiazole, and the ensuing section focuses on the cyano-substituted polymer acceptors. Cyano-poly(phenylenevinylene and poly(3-cyano-4-hexylthiophene have been used as acceptors in OPVs and exhibit high electron affinity arising from the electron-withdrawing cyano groups in the vinylene group of poly(phenylenevinylene or the thiophene ring of polythiophene. Lastly, a number of other electron-deficient groups such as thiazole, diketopyrrolopyrrole, and oxadiazole have also been introduced onto polymer backbones to induce n-type characteristics in the polymer. Since the first report on all-polymer solar cells in 1995, the best power conversion efficiency obtained with these devices to date has been 3.45%. The overall trend in the development of n-type polymer acceptors is presented in this review.

  19. Fullerene-bisadduct acceptors for polymer solar cells.

    Li, Yongfang


    Polymer solar cells (PSCs) have drawn great attention in recent years for their simple device structure, light weight, and low-cost fabrication in comparison with inorganic semiconductor solar cells. However, the power-conversion efficiency (PCE) of PSCs needs to be increased for their future application. The key issue for improving the PCE of PSCs is the design and synthesis of high-efficiency conjugated polymer donors and fullerene acceptors for the photovoltaic materials. For the acceptor materials, several fullerene-bisadduct acceptors with high LUMO energy levels have demonstrated excellent photovoltaic performance in PSCs with P3HT as a donor. In this Focus Review, recent progress in high-efficiency fullerene-bisadduct acceptors is discussed, including the bisadduct of PCBM, indene-C60 bisadduct (ICBA), indene-C70 bisadduct (IC70BA), DMPCBA, NCBA, and bisTOQC. The LUMO levels and photovoltaic performance of these bisadduct acceptors with P3HT as a donor are summarized and compared. In addition, the applications of an ICBA acceptor in new device structures and with other conjugated polymer donors than P3HT are also introduced and discussed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. New eco-friendly animal bone meal catalysts for preparation of chalcones and aza-Michael adducts

    Riadi Yassine


    Full Text Available Abstract Two efficient reactions were successfully carried out using Animal Bone Meal (ABM and potassium fluoride or sodium nitrate doped ABMs as new heterogeneous catalysts under very mild conditions. After preparation and characterization of the catalysts, we first report their use in a simple and convenient synthesis of various chalcones by Claisen–Schmidt condensation and then in an aza-Michael addition involving several synthesized chalcones with aromatic amines. All the reactions were carried out at room temperature in methanol; the chalcone synthesis was also achieved in water environment under microwave irradiation. Doping ABM enhances the rate and yield at each reaction. Catalytic activities are discussed and the ability to re-use the ABM is demonstrated. Results For Claisen–Schmidt the use of ABM alone, yields never exceeded 17%. In each entry, KF/ABM and NaNO3/ABM (79-97% gave higher yields than using ABM alone under thermic condition. Also the reaction proceeded under microwave irradiation in good yields (72-94% for KF/ABM and 81-97% for NaNO3/ABM and high purity. For aza-Michael addition the use of ABM doped with KF or NaNO3 increased the catalytic activity remarkably. The very high yields could be noted (84-95% for KF/ABM and 81-94% for NaNO3/ABM. Conclusion The present method is an efficient and selective procedure for the synthesis of chalcones an aza-Michael adducts. The ABM and doped ABMs are a new, inexpensive and attractive solid supports which can contribute to the development of catalytic processes and reduced environmental problems.

  1. A highly selective fluorescent probe based on Michael addition for fast detection of hydrogen sulfide

    Gao, Baozhen; Cui, Lixia; Pan, Yong; Xue, Minjie; Zhu, Boyu; Zhang, Guomei; Zhang, Caihong; Shuang, Shaomin; Dong, Chuan


    A new 4-hydroxy-1,8-naphthalimide-based compound (probe 1) has been designed and synthesized. The colorimetric and fluorescent properties of probe 1 towards hydrogen sulfide (H2S) were investigated in detail. The results show that the probe 1 could selectively and sensitively recognize H2S rather than other reactive sulfur species. The reaction mechanism of this probe is an intramolecular cyclization caused by the Michael addition of H2S to give 4-hydroxy-1,8-naphthalimide. The intramolecular charge transfer of 4-hydroxy-1,8-naphthalimide is significant. Probe 1 quickly responded to H2S and showed a 75-fold fluorescence enhancement in 5 min. Moreover, probe 1 could detect H2S quantitatively with a detection limit as low as 0.23 μM.

  2. Near infrared organic light-emitting diodes based on acceptor-donor-acceptor (ADA) using novel conjugated isatin Schiff bases

    Taghi Sharbati, Mohammad, E-mail: [Department of Electrical and Electronics Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of); Soltani Rad, Mohammad Navid, E-mail: [Department of Chemistry, Shiraz University of Technology, Shiraz 71555-313 (Iran, Islamic Republic of); Behrouz, Somayeh [Department of Chemistry, Shiraz University of Technology, Shiraz 71555-313 (Iran, Islamic Republic of); Gharavi, Alireza [Photonics Lab, Department of Electrical and Computer Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of); Emami, Farzin [Department of Electrical and Electronics Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of)


    Fabrications of a single layer organic light emitting diodes (OLEDs) based on two conjugated acceptor-donor-acceptor (ADA) isatin Schiff bases are described. The electroluminescent spectra of these materials range from 630 to 700 nm and their band gaps were measured between 1.97 and 1.77 eV. The measured maximum external quantum efficiencies (EQE) for fabricated OLEDs are 0.0515% and 0.054% for two acceptor-donor-acceptor chromophores. The Commission International De L'Eclairage (CIE) (1931) coordinates of these two compounds were attained and found to be (0.4077, 0.4128) and (0.4411, 0.4126) for two used acceptor-donor-acceptor chromophores. The measured I-V curves demonstrated the apparent diode behavior of two ADA chromophores. The turn-on voltages in these OLEDs are directly dependent on the thickness. These results have demonstrated that ADA isatin Schiff bases could be considered as promising electroluminescence-emitting materials for fabrication of OLEDs.

  3. Tailoring the optoelectronic properties of donor-acceptor-donor type {pi}-conjugated polymers via incorporating different electron-acceptor moieties

    Tarkuc, Simge [Department of Chemistry, Middle East Technical University, 06531, Ankara (Turkey); Opto-Electronic Materials, DelftChemTech, Delft University of Technology, Julianalaan 136, 2628 BL Delft (Netherlands); Udum, Yasemin Arslan [Institute of Science and Technology, Department of Advanced Technologies, Gazi University, 06570 Ankara (Turkey); Toppare, Levent, E-mail: [Department of Chemistry, Middle East Technical University, 06531, Ankara (Turkey); Department of Biotechnology, Middle East Technical University, 06531 Ankara (Turkey); Department of Polymer Science and Technology, Middle East Technical University, 06531 Ankara (Turkey)


    Syntheses of donor-acceptor-donor type of {pi}-conjugated monomers were performed to examine the effect of the acceptor units' strength on the electrochemical and optoelectrochemical properties of the resulting monomer and polymer. Palladium catalyzed Stille cross-coupling reaction of an organotin reagent with an organic electrophile was used for the synthesis of target monomers, 5,8-bis(4-hexylthiophen-2-yl)-2-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl) -3-(2,3-dihydrobenzo[b][1,4]dioxin-7-yl)quinoxaline (DBQHT) and 10,13-bis(4-hexylthiophen-2-yl)dibenzo[a,c]phenazine (PHEHT). The presence of the strong electron-donating ethylenedioxy groups on pendant phenyl rings increased electron density on DBQHT, thus the oxidation potential of DBQHT shifts to a lower value than that of PHEHT. The {pi}-{pi}* absorption maximum of PPHEHT was about 40 nm red-shifted compare to that of PDBQHT, which can be attributed to the increase of the effective conjugation and coplanarity of PPHEHT relative to PDBQHT via using phenanthrene fused quinoxaline unit as the acceptor. The electronic band gap of polymer, defined as the onset of the {pi}-{pi}* transition, is found to be 1.65 eV for PPHEHT and 1.82 eV for PDBQHT. Both polymer films showed multi-color electrochromism. PDBQHT can be switched between a red neutral state and a green oxidized state with two intermediate states; purple and brown. PPHEHT also shows multicolored electrochromic behavior with three distinct states: a blue neutral state, a gray intermediate state, and a green oxidized state.

  4. Electron Transfer Reactions: Generalized Spin-Boson Approach

    Merkli, Marco


    We introduce a mathematically rigorous analysis of a generalized spin-boson system for the treatment of a donor-acceptor (reactant-product) quantum system coupled to a thermal quantum noise. The donor/acceptor probability dynamics describes transport reactions in chemical processes in presence of a noisy environment -- such as the electron transfer in a photosynthetic reaction center. Besides being rigorous, our analysis has the advantages over previous ones that (1) we include a general, non energy-conserving system-environment interaction, and that (2) we allow for the donor or acceptor to consist of multiple energy levels lying closely together. We establish explicit expressions for the rates and the efficiency (final donor-acceptor population difference) of the reaction. In particular, we show that the rate increases for a multi-level acceptor, but the efficiency does not.

  5. Designer Metallic Acceptor-Containing Halogen Bonding: General Strategies.

    Zhang, Xinxing; Bowen, Kit H


    Being electrostatic interactions in nature, hydrogen bonding (HB) and halogen bonding (XB) are considered to be two parallel worlds. In principle, all the applications that HB has could also be applied to XB. However, there has been no report on a metallic XB acceptor but metal anions have been observed to be good HB acceptors. This missing mosaic piece of XB is because common metal anions are reactive for XB donors. In view of this, we propose two strategies for designing metallic acceptor-containing XB using ab initio calculations. The first one is to utilize a metal cluster anion with a high electron detachment energy, such as the superatom, Al13- as the XB acceptor. The second strategy is to design a ligand passivated/protected metal core while it still can maintain the negative charge; several exotic clusters, such as PtH5-, PtZnH5- and PtMgH5-, are utilized as examples. Based on these two strategies, we anticipate that more metallic acceptor-containing XB will be discovered.

  6. Creation of Superheterojunction Polymers via Direct Polycondensation: Segregated and Bicontinuous Donor-Acceptor π-Columnar Arrays in Covalent Organic Frameworks for Long-Lived Charge Separation.

    Jin, Shangbin; Supur, Mustafa; Addicoat, Matthew; Furukawa, Ko; Chen, Long; Nakamura, Toshikazu; Fukuzumi, Shunichi; Irle, Stephan; Jiang, Donglin


    By developing metallophthalocyanines and diimides as electron-donating and -accepting building blocks, herein, we report the construction of new electron donor-acceptor covalent organic frameworks (COFs) with periodically ordered electron donor and acceptor π-columnar arrays via direct polycondensation reactions. X-ray diffraction measurements in conjunction with structural simulations resolved that the resulting frameworks consist of metallophthalocyanine and diimide columns, which are ordered in a segregated yet bicontinuous manner to form built-in periodic π-arrays. In the frameworks, each metallophthalocyanine donor and diimide acceptor units are exactly linked and interfaced, leading to the generation of superheterojunctions-a new type of heterojunction machinery, for photoinduced electron transfer and charge separation. We show that this polycondensation method is widely applicable to various metallophthalocyanines and diimides as demonstrated by the combination of copper, nickel, and zinc phthalocyanine donors with pyrommellitic diimide, naphthalene diimide, and perylene diimide acceptors. By using time-resolved transient absorption spectroscopy and electron spin resonance, we demonstrated that the COFs enable long-lived charge separation, whereas the metal species, the class of acceptors, and the local geometry between donor and acceptor units play roles in determining the photochemical dynamics. The results provide insights into photoelectric COFs and demonstrate their enormous potential for charge separation and photoenergy conversions.

  7. Michael Marinov memorial volume multiple facets of quantization and supersymmetry

    Vainshtein, A I


    This book is dedicated to the memory of Michael Marinov, the theorist who, together with Felix Berezin, introduced the classical description of spin by anticommuting Grassmann variables. It contains original papers and reviews by physicists and mathematicians written specifically for the book. These articles reflect the current status and recent developments in the areas of Marinov's research: quantum tunneling, quantization of constrained systems, supersymmetry, and others. The personal recollections included portray the human face of M Marinov, a person of great knowledge and integrity.

  8. Michael Kohlhaas or the Germans and Their Law

    Heike Jung


    Full Text Available Asked to pick a single representative ‘German’ piece for a discourse on ‘Law and Literature’ one almost inevitably ends up with Kleist’s tale Michael Kohlhaas. It seems to be the literary incarnation of the German stance vis-à-vis the law. It is all about horses; it could just as well be about dogs. Kohlhaas fights a devastating battle, using legal means and outright violence, even warfare, for their recovery in good shape. Victorious eventually with his legal actions, he is happy to trade in his own life for this victory, thus giving an extreme example for the nice line between being in the right and pursuing this position with disproportionate rigour. Of course, the interpretations of Michael Kohlhaas (which, in its complete version, dates of 1810 have varied from epoch to epoch as well as from reader to reader. It is not possible to rehearse the bulk of ‘Kohlhaas literature’. In comparing legal cultures, it might be of interest to look into the question why such a somber story on the law forms part and will continue to form part of the German cultural heritage. Si se tiene que elegir un único representante “alemán” para una ponencia sobre “derecho y literatura”, es inevitable optar por la obra de Kleist, Michael Kohlhaas. Parece la encarnación literaria de la posición alemana hacia el derecho. El libro trata de caballos; también podría tratar sobre perros. Kohlhaas libra una batalla devastadora usando medios legales y la violencia pura y dura, incluso la guerra, para que se recuperen en buena forma. Finalmente resulta ganador mediante acciones legales, está contento de dedicar su propia vida para conseguir esta victoria, dando así un ejemplo extremo de la línea que existe entre tener la razón y seguir esta posición con un rigor desproporcionado. Por supuesto, las interpretaciones de Michael Kohlhaas (publicado en 1810 han variado de una época a otra, y de un lector a otro. No es posible revisar el grueso de

  9. Hechter Michael, Horne Christine (Dir., Theories of Social Order

    Yves Laberge


    Full Text Available Cette anthologie méconnue examine le concept fondamental de l’ordre social en 34 textes tantôt anciens (de Tocqueville, Marx, Engels, Simmel ou relativement récents (le chapitre 19 comparant les groupes humains aux fourmis date de 2007. Ici, l’ordre social est compris de diverses manières ; Michael Hechter et Christine Horne rappellent d’emblée que « sans ordre social, il ne peut y avoir ni agriculture, ni industrie, ni commerce, ni investissement, ni développement économique, ni justice, n...

  10. Estratégia competitiva: Michael Porter 30 anos depois

    Manuel Portugal Ferreira; Fernando A. Ribeiro Serra; Marcelo Lopes Carneiro; Aline Botelho Schneider


    Os estudos de estratégia têm sido muito influenciados pelos trabalhos de Michael Porter, em todas as suas fases, como as cinco forças, as estratégias genéricas, a cadeia de valor e as vantagens competitivas das nações. Neste artigo, analisou-se a influência de Porter nos trabalhos brasileiros em estratégia, a partir dos trabalhos selecionados e apresentados no EnANPAD. No levantamento para a análise dos artigos, considerando 10 anos de EnANPAD (1997-2006), foram selecionados 46 artigos. A ide...

  11. The Correspondence of Michael Faraday Pt 6 1860-1867

    Frank, James


    Michael Faraday (1791-1867) was one of the most important men of science in nineteenth century Britain. His discoveries of electro-magnetic rotations (1821) and electro-magnetic induction (1831) laid the foundations of the modern electrical industry. His discovery of the magneto-optical effect and diamagnetism (1845) led him to formulate the field theory of electro-magnetism, which forms one of the cornerstones of modern physics.These and a whole host of other fundamental discoveries in physics and chemistry, together with his lecturing at the Royal Institution, his work for the state (includi

  12. Improving Photoconductance of Fluorinated Donors with Fluorinated Acceptors

    Garner, Logan E.; Larson, Bryon; Oosterhout, Stefan; Owczarczyk, Zbyslaw; Olson, Dana C.; Kopidakis, Nikos; Boltalina, Olga V.; Strauss, Steven H.; Braunecker, Wade A.


    This work investigates the influence of fluorination of both donor and acceptor materials on the generation of free charge carriers in small molecule donor/fullerene acceptor BHJ OPV active layers. A fluorinated and non-fluorinated small molecule analogue were synthesized and their optoelectronic properties characterized. The intrinsic photoconductance of blends of these small molecule donors was investigated using time-resolved microwave conductivity. Blends of the two donor molecules with a traditional non-fluorinated fullerene (PC70BM) as well as a fluorinated fullerene (C60(CF3)2-1) were investigated using 5% and 50% fullerene loading. We demonstrate for the first time that photoconductance in a 50:50 donor:acceptor BHJ blend using a fluorinated fullerene can actually be improved relative to a traditional non-fluorinated fullerene by fluorinating the donor molecule as well.

  13. Hyperpolarizability studies of some nonconjugated twin donor–acceptor molecules

    Elizabeth Chirackal Varkey; Krishnapillai Sreekumar


    Extensive theoretical calculation on the effects of spacer length enhancement on the second-order NLO properties of twin donor acceptor molecules having two amide units bridged by the CH2 spacers was performed. The role of such aliphatic bridges on the Donor–Acceptor groups was computed by ZINDO/CV quantum chemical formalism. The odd-even effects were observed in twin donor acceptor systems (with two aliphatic units) linked by an alkyl spacer of varying length from = 1 to = 12. The system considered for the present study was ,'-alkane-(1, ) diyl bis-4-hydroxy hexanamides. For an odd number of CH2 spacers, the value was an order of magnitude higher than that for the even number of CH2 spacers. The origin for such oscillation is attributed to the similar oscillations in the dipole moment difference between the ground state and the dipole allowed state and to some extent on the variation in the oscillator strength.

  14. An overview of molecular acceptors for organic solar cells

    Hudhomme Piétrick


    Full Text Available Organic solar cells (OSCs have gained serious attention during the last decade and are now considered as one of the future photovoltaic technologies for low-cost power production. The first dream of attaining 10% of power coefficient efficiency has now become a reality thanks to the development of new materials and an impressive work achieved to understand, control and optimize structure and morphology of the device. But most of the effort devoted to the development of new materials concerned the optimization of the donor material, with less attention for acceptors which to date remain dominated by fullerenes and their derivatives. This short review presents the progress in the use of non-fullerene small molecules and fullerene-based acceptors with the aim of evaluating the challenge for the next generation of acceptors in organic photovoltaics.

  15. Removal of CO from CO-contaminated hydrogen gas by carbon-supported rhodium porphyrins using water-soluble electron acceptors

    Yamazaki, Shin-ichi; Siroma, Zyun; Asahi, Masafumi; Ioroi, Tsutomu


    Carbon-supported Rh porphyrins catalyze the oxidation of carbon monoxide by water-soluble electron acceptors. The rate of this reaction is plotted as a function of the redox potential of the electron acceptor. The rate increases with an increase in the redox potential until it reaches a plateau. This profile can be explained in terms of the electrocatalytic CO oxidation activity of the Rh porphyrin. The removal of CO from CO(2%)/H2 by a solution containing a carbon-supported Rh porphyrin and an electron acceptor is examined. The complete conversion of CO to CO2 is achieved with only a slight amount of Rh porphyrins. Rh porphyrin on carbon black gives higher conversion than that dissolved in solution. This reaction can be used not only to remove CO in anode gas of stationary polymer electrolyte fuel cells but also to regenerate a reductant in indirect CO fuel cell systems.

  16. En recuerdo de Michael Heyd (1943-2014

    Peset, José Luis


    Full Text Available In homage to Professor Michael Heyd, in this paper are presented some of the main influences of his book “Be sober and reasonable” (1995 on several studies about Robert Burton and his classical book The Anatomy of Melancholy. Mainly, the relations between medicine and religious thought are briefly followed, looking for confluences between North and South Europe. The influence of “enthusiasm” and “melancholy” in the history of European thought was always an important interest in the life and teaching of this very intelligent researcher of cultural history.En homenaje al Profesor Michael Heyd, se muestran en este artículo algunas de las influencias principales de su libro “Be sober and reasonable” (1995 en algunos estudios sobre el clásico libro de Robert Burton The Anatomy of Melancholy. En especial, se siguen brevemente las relaciones entre la medicina y el pensamiento religioso, buscando confluencias entre el norte y el sur de Europa. La influencia de “entusiasmo” y “melancolía” en la historia del pensamiento europeo fue siempre un importante interés en la vida y la enseñanza de este muy inteligente investigador en historia cultural.

  17. BUS 320 Assignment 2: Case Study: Michael Dell—The Man Behind Dell



    BUS 320 Assignment 2: Case Study: Michael Dell—The Man Behind Dell   Click Link Below To Buy: Or Visit   Assignment 2: Case Study: Michael Dell—The Man Behind Dell Presentation (Change Management) Michael Dell began building and selling computers from his dorm room at age 19. He dropped out of the University of Texas when his sales hit $60 million and has nev...

  18. A facile synthesis of 1,2,3-triazolyl indole hybrids via SbCl3-catalysed Michael addition of indoles to 1,2,3-triazolyl chalcones

    Poovan Shanmugavelan; Murugan Sathishkumar; Sangaraiah Nagarajan; Alagusundaram Ponnuswamy


    An efficient, facile and environmentally benign synthesis of a library of 1,2,3-triazolyl chalcone hybrids (3a-u) has been accomplished by grinding the reactants at room temperature in excellent yields in very short reaction time. Subsequently, SbCl3 catalysed Michael addition of indoles to the chalcones afford 1,2,3-triazolyl indole hybrids (5a-l) in excellent yields.

  19. Stereoselective amine-thiourea-catalysed sulfa-Michael/nitroaldol cascade approach to 3,4,5-substituted tetrahydrothiophenes bearing a quaternary stereocenter

    Sara Meninno


    Full Text Available An investigation on the stereoselective cascade sulfa-Michael/aldol reaction of nitroalkenes and commercially available 1,4-dithiane-2,5-diol to 3,4,5-substituted tetrahydrothiophenes, bearing a quaternary stereocenter, is presented. A secondary amine thiourea derived from (R,R-1,2-diphenylethylamine was found to be the most effective catalyst when using trans-β-methyl-β-nitrostyrenes affording the heterocyclic products in good yields and moderate stereoselectivities.

  20. N-Heterocyclic Carbene Catalyzed [4+2] Annulation of Enals via a Double Vinylogous Michael Addition: Asymmetric Synthesis of 3,5-Diaryl Cyclohexenones.

    Chen, Xiang-Yu; Liu, Qiang; Chauhan, Pankaj; Li, Sun; Peuronen, Anssi; Rissanen, Kari; Jafari, Ehsan; Enders, Dieter


    A strategy for the N-heterocyclic carbene (NHC) catalyzed asymmetric synthesis of 3,5-diaryl substituted cyclohexenones has been developed via oxidative [4+2] annulation of enals and alkenylisoxazoles. It is the first example of using NHC organocatalysis in a double vinylogous Michael type reaction, a challenging but highly desirable topic. This unprecedented protocol affords good yields as well as high to excellent diastereo- and enantioselectivities. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. A Stereoselective Route to Tetrahydrobenzoxazepines and Tetrahydrobenzodiazepines via Ring-Opening and Aza-Michael Addition of Activated Aziridines with 2-Hydroxyphenyl and 2-Aminophenyl Acrylates.

    Shahi, Chandan Kumar; Bhattacharyya, Aditya; Nanaji, Yerramsetti; Ghorai, Manas K


    A simple and efficient synthetic route to 2,3,4,5-tetrahydrobenzoxazepines and -benzodiazepines bearing easily functionalizable appendages has been developed by ring-opening of activated aziridines with 2-hydroxyphenyl acrylates and 2-aminophenyl acrylate, respectively, and subsequent intramolecular C-N bond formation through palladium-catalyzed aza-Michael reaction. The straightforward synthetic approach delivers the desired molecular scaffolds in high yields (up to 82%) with excellent stereoselectivity (ee up to 94%).

  2. Acceptors in II-IV Semiconductors - Incorporation and Complex Formation


    A strong effort is currently devoted to the investigation of defects and the electrical activation of dopant atoms in II-VI semiconductors. In particular, the knowledge about the behaviour of acceptors, prerequisite for the fabrication of p-type semiconductors, is rather limited. The perturbed $\\,{\\gamma\\gamma}$ -angular correlation technique (PAC) and the photoluminescence spectroscopy (PL) using the radioactive isotopes $^{77}\\!$Br and $^{111}\\!$Ag will be applied for investigating the behaviour of acceptor dopant atoms and their interactions with defects in II-VI semiconductors. The main topic will be the identification of the technical conditions for the incorporation of electrically active acceptors in the II-VI semiconductors ~ZnS, ZnSe, ZnTe, CdS, CdSe, and CdTe with particular emphasis on the compounds~ CdTe, ZnSe, and ZnTe. The investigations will be supplemented by first exploratory PL experiments with the group V acceptors $^{71}\\!$As and $^{121}\\!$Sb. With help of the probe $^{111}\\!$Ag, the pos...

  3. Fluorescence Resonance Energy Transfer Using Spiropyran and Diarylethene Photochromic Acceptors

    E. A. Jares-Erijman


    Full Text Available We describe the preparation and photophysical characterization of two model compounds designed to test a new approach for the quantitative determination of Fluorescence Resonance Energy Transfer (FRET in biological systems. The method enables modulation of FRET by exploiting the unique reversible spectral properties of photochromic diarylethenes and spiropyrans to create switchable energy acceptors.

  4. Covalent non-fused tetrathiafulvalene-acceptor systems.

    Pop, Flavia; Avarvari, Narcis


    Covalent donor-acceptor (D-A) systems have significantly contributed to the development of many organic materials and to molecular electronics. Tetrathiafulvalene (TTF) represents one of the most widely studied donor precursors and has been incorporated into the structure of many D-A derivatives with the objective of obtaining redox control and modulation of the intramolecular charge transfer (ICT), in order to address switchable emissive systems and to take advantage of its propensity to form regular stacks in the solid state. In this review, we focus on the main families of non-fused TTF-acceptors, which are classified according to the nature of the acceptor: nitrogen-containing heterocycles, BODIPY, perylenes and electron poor unsaturated hydrocarbons, as well as radical acceptors. We describe herein the most representative members of each family with a brief mention of their synthesis and a special focus on their D-A characteristics. Special attention is given to ICT and its modulation, fluorescence quenching and switching, photoconductivity, bistability and spin distribution by discussing and comparing spectroscopic and electrochemical features, photophysical properties, solid-state properties and theoretical calculations.

  5. Anaerobic methanotrophy in tidal wetland: Effects of electron acceptors

    Lin, Li-Hung; Yu, Zih-Huei; Wang, Pei-Ling


    Wetlands have been considered to represent the largest natural source of methane emission, contributing substantially to intensify greenhouse effect. Despite in situ methanogenesis fueled by organic degradation, methanotrophy also plays a vital role in controlling the exact quantity of methane release across the air-sediment interface. As wetlands constantly experience various disturbances of anthropogenic activities, biological burrowing, tidal inundation, and plant development, rapid elemental turnover would enable various electron acceptors available for anaerobic methanotrophy. The effects of electron acceptors on stimulating anaerobic methanotrophy and the population compositions involved in carbon transformation in wetland sediments are poorly explored. In this study, sediments recovered from tidally influenced, mangrove covered wetland in northern Taiwan were incubated under the static conditions to investigate whether anaerobic methanotrophy could be stimulated by the presence of individual electron acceptors. Our results demonstrated that anaerobic methanotrophy was clearly stimulated in incubations amended with no electron acceptor, sulfate, or Fe-oxyhydroxide. No apparent methane consumption was observed in incubations with nitrate, citrate, fumarate or Mn-oxides. Anaerobic methanotrophy in incubations with no exogenous electron acceptor appears to proceed at the greatest rates, being sequentially followed by incubations with sulfate and Fe-oxyhydroxide. The presence of basal salt solution stimulated methane oxidation by a factor of 2 to 3. In addition to the direct impact of electron acceptor and basal salts, incubations with sediments retrieved from low tide period yielded a lower rate of methane oxidation than from high tide period. Overall, this study demonstrates that anaerobic methanotrophy in wetland sediments could proceed under various treatments of electron acceptors. Low sulfate content is not a critical factor in inhibiting methane

  6. Optical and electrical properties of zinc oxide thin films with low resistivity via Li-N dual-acceptor doping

    Zhang Daoli, E-mail: [Department of Electronic Science and Technology, Huazhong University of Science and Technology, No. 1037 Luoyu Road, Hongshan District, Wuhan City, Hubei Province 430074 (China); Wuhan National Laboratory for Optoelectronics, 1037 Luoyu Road, Hongshan District, Wuhan City, Hubei Province 430074 (China); Zhang Jianbing [Department of Electronic Science and Technology, Huazhong University of Science and Technology, No. 1037 Luoyu Road, Hongshan District, Wuhan City, Hubei Province 430074 (China); Wuhan National Laboratory for Optoelectronics, 1037 Luoyu Road, Hongshan District, Wuhan City, Hubei Province 430074 (China); Guo Zhe [Department of Electronic Science and Technology, Huazhong University of Science and Technology, No. 1037 Luoyu Road, Hongshan District, Wuhan City, Hubei Province 430074 (China); Miao Xiangshui [Department of Electronic Science and Technology, Huazhong University of Science and Technology, No. 1037 Luoyu Road, Hongshan District, Wuhan City, Hubei Province 430074 (China); Wuhan National Laboratory for Optoelectronics, 1037 Luoyu Road, Hongshan District, Wuhan City, Hubei Province 430074 (China)


    Highlights: > Zinc oxide films have been deposited on glass substrates by Li-N dual-acceptor doping method via a modified SILAR method. > The resistivity of ZnO film was found to be 1.04 {Omega} cm with a Hall mobility of 0.749 cm{sup 2} V{sup -1} s{sup -1}, carrier concentration of 8.02 x 1018 cm{sup -3}, and transmittance of about 80% in visible range showing good crystallinity with prior c-axis orientation. > A shallow acceptor level of 91 meV is identified from free-to-neutral-acceptor transitions. > Another deep level of 255 meV was ascribed to Li{sub Zn}-Li{sub i} complex. - Abstract: Zinc oxide thin films with low resistivity have been deposited on glass substrates by Li-N dual-acceptor doping method via a modified successive ionic layer adsorption and reaction process. The thin films were systematically characterized via scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction, ultraviolet-visible spectrophotometry and fluorescence spectrophotometry. The resistivity of zinc oxide film was found to be 1.04 {Omega} cm with a Hall mobility of 0.749 cm{sup 2} V{sup -1} s{sup -1} and carrier concentration of 8.02 x 10{sup 18} cm{sup -3}. The Li-N dual-acceptor doped zinc oxide films showed good crystallinity with prior c-axis orientation, and high transmittance of about 80% in visible range. Moreover, the effects of Li doping level and other parameters on crystallinity, electrical and ultraviolet emission of zinc oxide films were investigated.

  7. Design, synthesis and study of supramolecular donor-acceptor systems mimicking natural photosynthesis processes

    Bikram, Chandra

    This dissertation investigates the chemical ingenuity into the development of various photoactive supramolecular donor -- acceptor systems to produce clean and carbon free energy for the next generation. The process is inspired by the principles learned from nature's approach where the solar energy is converted into the chemical energy through the natural photosynthesis process. Owing to the importance and complexity of natural photosynthesis process, we have designed ideal donor-acceptor systems to investigate their light energy harvesting properties. This process involves two major steps: the first step is the absorption of light energy by antenna or donor systems to promote them to an excited electronic state. The second step involves, the transfer of excitation energy to the reaction center, which triggers an electron transfer process within the system. Based on this principle, the research is focused into the development of artificial photosynthesis systems to investigate dynamics of photo induced energy and electron transfer events. The derivatives of Porphyrins, Phthalocyanines, BODIPY, and SubPhthalocyanines etc have been widely used as the primary building blocks for designing photoactive and electroactive ensembles in this area because of their excellent and unique photophysical and photochemical properties. Meanwhile, the fullerene, mainly its readily available version C60 is typically used as an electron acceptor component because of its unique redox potential, symmetrical shape and low reorganization energy appropriate for improved charge separation behavior. The primary research motivation of the study is to achieve fast charge separation and slow charge recombination of the system by stabilizing the radical ion pairs which are formed from photo excitation, for maximum utility of solar energy. Besides Fullerene C60, this dissertation has also investigated the potential application of carbon nanomaterials (Carbon nanotubes and graphene) as primary

  8. Research Progress in the Environmentally-Friendly Michael Addition%环境友好型Michael加成的研究进展

    李志峰; 侯海亮; 应安国; 许松林


    Michael加成反应是有机合成领域一类非常重要的反应。随着人们环保意识的增强和对绿色化学研究的深入,环境友好型Michael加成取得了诸多成功。综述了近5年来离子液体、酶催化、负载固相催化、聚乙二醇(PEG)等参与的Michael 加成反应的研究进展。着重分析了反应体系的高效性、催化剂可能的催化反应机理以及催化剂的循环使用性,并以此对环境友好型Michael加成的发展做出了展望。%Michael addition is one kind of important reaction in the organic field. With the enhancement of environmental awareness and the depth of green chemistry research, environmentally-friendly Michael addition has made many successes. The research progress over the past 5 years in the Michael addition involving ionic liquids, enzyme catalysis, solid phase sup-ported catalysis and polyethylene glycol (PEG) is reviewed. This paper is consisted of six parts, focusing on the efficiency of the reaction system, the probable catalytic mechanism and the recycle of the catalyst. In the first part, a brief introduction is given. Then the Michael addition used the ionic liquid as catalyst or/and solvent is elaborated. In this part, acidic ionic liquid, basic ionic liquids and chiral ionic liquid are described, respectively. As a mild catalyst, enzymes are described in the third part. The solid phase supported catalysis has been used in many reaction without exception to Michael addition. So, in the fourth part, the catalysts of polymer supported, silica-supported and superparamagnetic nano supported are stated. Following, the successful use of polyethylene glycol (PEG) as a green solvent is presented. Finally, the conclusion, the existing problems of these green technologies and the prospect are summarized.

  9. Profiles in medical courage: Michael Wilkins and the Willowbrook School

    Robbins RA


    Full Text Available No abstract available. Article truncated at 150 words. “Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has. "- Margaret Mead With this article we begin an intermittent series on physicians who displayed courage in trying to help their patients. Although there are many examples, hopefully what will be illustrated are examples of the lesser known doctors who identified problems and stood up to address them. Few remember the controversy surrounding the now closed Willowbrook School and Dr. Michael Wilkins’ involvement. However, Wilkins’ courage in advocating for change not only resulted in substantial improvement in conditions at the school but also led to the Civil Rights of Institutionalized Persons Act (CRIPA of 1980.Wilkins was originally from Kansas City and graduated from the University of Missouri School of Medicine in 1967 (1. He left Missouri to do his pediatric internship and complete his military obligation…

  10. Michael Longley’s Father: Memory, Mourning and History

    Barry Sloan


    Full Text Available Michael Longley’s father has been a recurring presence in the poet’s work from his earliest to his most recent collection. This paper examines the exceptional strength of that bond reflected in the varied and changing ways in which the poet has responded to it – memorizing and mourning his loss; discovering through his father’s First World War stories a means of memorialising loss of life in contemporary conflicts and a way of facing the history of the twentieth century; confronting his own ageing and sense of mortality; and marking the specific, but also representative, generational history of his family. Close readings of key poems are offered to highlight Longley’s skills in meeting his own exacting standards of aesthetic propriety and moral and social responsibility for writers of elegy in order to avoid either exploitation of tragedy and loss, or facile gestures of consolation.

  11. Michael Tenzer, ed., Analytical Studies in World Music



    Pour Michael Tenzer, professeur de musique à l’Université de Colombie britannique et spécialiste (analyste et interprète) de musique pour gamelan, la réunion des textes proposés dans cet ouvrage a deux objectifs : construire une théorie de la musique dans le monde qui s’émancipe des oppositions entre musiques « classiques » et « populaires », « occidentales » et « non occidentales », c’est-à-dire jeter les bases d’une théorie générale de la musique et, pour ce faire, montrer que l’analyse mus...

  12. A Study of Postmodern Narrative in Michael Cunningham's The Hours

    Hajar Abbasi Narinabad


    Full Text Available This project aims at providing a detailed analysis of the major features of the theory of postmodern narrative and at going through the novel The Hours by the American writer Michael Cunningham concentrating on some postmodern narrative techniques. To do so, the researcher goes through the theories set forth by some postmodern theoreticians like Roland Barthes, Jacque Derrida, Jean-François Lyotard and Julia Kristeva to investigate the postmodern narrative techniques and elements used in the novel. The researcher first examines the theories and then critically applies them on the novel. The article goes through the most eminent elements of postmodern narrative including intertextuality, stream of consciousness style, fragmentation and representation respectively which are delicately utilized in The Hours. The article concludes by recommending a few directions for the further research.

  13. Importance of the nature of α-substituents in pyrrolidine organocatalysts in asymmetric Michael additions.

    Patil, Mahendra P; Sharma, Akhilesh K; Sunoj, Raghavan B


    The fundamental factors contributing toward the stereoselectivity in organocatalyzed asymmetric Michael reaction between aldehydes (propanal and 3-phenyl propanal) and methyl vinyl ketone (MVK) are established by using density functional theory methods. Three of the most commonly employed α-substituted pyrrolidine organocatalysts are examined. Several key stereochemical modes of addition between (i) a model enamine or (ii) pyrrolidine enamines derived from aldehydes and secondary amine to MVK are examined. Among these possibilities, the addition of (E)-enamine to cis-MVK is found to have a lower activation barrier. The stereochemical outcome of the reaction is reported on the basis of the relative energies between pertinent diastereomeric transition states. Moderate selectivity is predicted for the reaction involving pyrrolidine catalysts I and II, which carry relatively less bulky α-substituents dimethylmethoxymethyl and diphenylmethyl, respectively. On the other hand, high selectivity is computed in the case of catalyst III having a sufficiently large α-substituent (diarylmethoxymethyl or diphenylprolinol methyl ether). The enantiomeric excess in the case of 3-phenyl propanal is found to be much higher as compared to that with unsubstituted propanal, suggesting potential for improvement in stereoselectivity by substrate modifications. The computed enantiomeric excess is found to be in reasonable agreement with the reported experimental stereoselectivities. A detailed investigation on the geometries of the crucial transition states reveals that apart from steric interactions between the α-substituent and MVK, various other factors such as orbital interactions and weak stabilizing hydrogen-bonding interactions play a vital role in stereoselectivity. The results serve to establish the importance of cumulative effects of various stabilizing and destabilizing interactions at the transition state as responsible for the stereochemical outcome of the reaction. The

  14. Asymmetric synthesis of functionalized cyclohexanes bearing five stereocenters via a one-pot organocatalytic Michael-Michael-1,2-addition sequence.

    Chauhan, Pankaj; Urbanietz, Gregor; Raabe, Gerhard; Enders, Dieter


    A highly stereoselective one-pot procedure involving an enantioselective Michael addition promoted by low loading of an amino-squaramide catalyst followed by an achiral base catalyzed domino Michael-Knoevenagel-type 1,2-addition sequence provides efficient access to fully substituted cyclohexanes bearing five contiguous stereogenic centers in good yields (68-86%) and excellent stereoselectivities (>30 : 1 dr and 96-99% ee).

  15. Dynamic Solvent Effect on Ultrafast Charge Recombination Kinetics in Excited Donor-Acceptor Complexes.

    Mikhailova, Tatyana V; Mikhailova, Valentina A; Ivanov, Anatoly I


    Manifestation of the dynamic solvent effect (DSE) on the charge recombination (CR) kinetics of photoexcited donor-acceptor complexes in polar solvents has been investigated within the framework of the multichannel stochastic model. The model takes into account the reorganization of both the solvent and a number of intramolecular high-frequency vibration modes as well as their relaxation. The non-Markovian solvent dynamics is described in terms of two relaxation modes. The similarities and differences inherent to ultrafast charge transfer reactions occurring in the nonequilibrium and thermal regimes have been identified. The most important differences are as follows: (1) the DSE is strong in the area of weak exergonicity and is weak in the area of strong exergonicity for thermal reactions, whereas for the nonequilibrium reactions, the regions of strong and weak DSEs are reversed; (2) an increase in the electronic coupling value results in a decrease in the magnitude of DSE for nonequilibrium electron transfer and in its increase for the thermal reactions; and (3) the two-staged regime most clearly manifests if the reorganization energy of the relaxation modes noticeably exceeds the CR free-energy gap. With an increase in electronic coupling, the kinetics approaches the exponential regime because in the limit of strong electronic coupling, the reaction includes only single, nonequilibrium, stage.

  16. Estratégia competitiva: Michael Porter 30 anos depois

    Manuel Portugal Ferreira


    Full Text Available Os estudos de estratégia têm sido muito influenciados pelos trabalhos de Michael Porter, em todas as suas fases, como as cinco forças, as estratégias genéricas, a cadeia de valor e as vantagens competitivas das nações. Neste artigo, analisou-se a influência de Porter nos trabalhos brasileiros em estratégia, a partir dos trabalhos selecionados e apresentados no EnANPAD. No levantamento para a análise dos artigos, considerando 10 anos de EnANPAD (1997-2006, foram selecionados 46 artigos. A identificação e seleção dos artigos envolveram os seguintes critérios: busca complementar por palavra-chave Porter na base de dados do EnANPAD; avaliação dos títulos e resumos dos artigos apresentados na área de estratégia entre 1997 e 2006, bem como na íntegra quando necessário. Procedeu-se também à análise das referências utilizadas nos artigos e o posicionamento dos autores em relação às tipologias de Porter. Como resultado, verificou-se que Michael Porter é um autor com grande influência nas pesquisas acadêmicas de estratégia. Seus estudos mais utilizados são os da análise da indústria e das estratégias genéricas, e também se verificou que a maioria dos estudos analisados é favorável aos seus conceitos, mesmo existindo pesquisas contrárias.

  17. 75 FR 22436 - Michael Williams-Control Exemption-St. Maries River Railroad, Inc.


    ... Surface Transportation Board Michael Williams-Control Exemption-St. Maries River Railroad, Inc. Michael Williams (applicant),\\1\\ a noncarrier, has filed a verified notice of exemption to acquire control of St... from STMA's parent, Potlatch Land & Lumber, LLC, by Williams Group, Inc. (WG).\\2\\ Applicant...

  18. A Response to Michael Newman's "Calling Transformative Learning into Question: Some Mutinous Thoughts"

    Cranton, Patricia; Kasl, Elizabeth


    This article presents the authors' response to Michael Newman's "Calling Transformative Learning into Question: Some Mutinous Thoughts". The authors begin by noting their appreciation of Michael Newman's challenge to transformative learning theory. In their response, the authors review and comment on the fatal flaws presented by Newman and then…

  19. Markets, Marx, Modernity and Mathematics Education: A Response to Michael Apple.

    Gates, Peter

    This paper is a response to Michael Apple's paper, "What Postmodernists Forget: Cultural Capital and Official Knowledge." The paper advocates Michael's identification of the current dangers and processes of the growth of new right ideologies in the development of subjectivity, society, and education. The differences in success in the education…

  20. Organocatalytic Enantioselective Henry Reactions

    Raquel P. Herrera


    Full Text Available A large number of interesting organocatalytic enantioselective protocols have been explored and successfully applied in the last decade. Among them, the Henry (nitroaldol reaction represents a powerful carbon-carbon bond-forming procedure for the preparation of valuable synthetic intermediates, such as enantioenriched nitro alcohols, which can be further transformed in a number of important nitrogen and oxygen-containing compounds. This area of research is still in expansion and a more complex version of this useful process has recently emerged, the domino Michael/Henry protocol, affording highly functionalized cycles with multiple stereogenic centers.

  1. Lipase-catalyzed biodiesel production with methyl acetate as acyl acceptor

    Huang Ying; Yan Yunjun [School of Life Science and Technology, Huazhong Univ. of Science and Technology, Wuhan (China)


    Biodiesel is an alternative diesel fuel made from renewable biological resources. During the process of biodiesel production, lipase-catalyzed transesterification is a crucial step. However, current techniques using methanol as acyl acceptor have lower enzymatic activity; this limits the application of such techniques in large-scale biodiesel production. Furthermore, the lipid feedstock of currently available techniques is limited. In this paper, the technique of lipase-catalyzed transesterification of five different oils for biodiesel production with methyl acetate as acyl acceptor was investigated, and the transesterification reaction conditions were optimized. The operation stability of lipase under the obtained optimal conditions was further examined. The results showed that under optimal transesterification conditions, both plant oils and animal fats led to high yields of methyl ester: cotton-seed oil, 98%; rape-seed oil, 95%; soybean oil, 91%; tea-seed oil, 92%; and lard, 95%. Crude and refined cotton-seed oil or lard made no significant difference in yields of methyl ester. No loss of enzymatic activity was detected for lipase after being repeatedly used for 40 cycles (ca. 800 h), which indicates that the operational stability of lipase was fairly good under these conditions. Our results suggest that cotton-seed oil, rape-seed oil and lard might substitute soybean oil as suitable lipid feedstock for biodiesel production. Our results also show that our technique is fit for various lipid feedstocks both from plants and animals, and presents a very promising way for the large-scale biodiesel production. (orig.)

  2. Lipase-catalyzed biodiesel synthesis with different acyl acceptors

    Ognjanović Nevena D.


    Full Text Available Biodiesel is an alternative fuel for diesel engine that is environmentally acceptable. Conventionally, biodiesel is produced by transesterification of triglycerides and short alcohols in the presence of an acid or an alkaline catalyst. There are several problems associated with this kind of production that can be resolved by using lipase as the biocatalyst. The aim of the present work was to investigate novel acyl acceptors for biodiesel production. 2-Propanol and n-butanol have a less negative effect on lipase stability, and they also improve low temperature properties of the fuel. However, excess alcohol leads to inactivation of the enzyme, and glycerol, a major byproduct, can block the immobilized enzyme, resulting in low enzymatic activity. This problem was solved by using methyl acetate as acyl acceptor. Triacetylglycerol is produced instead of glycerol, and it has no negative effect on the activity of the lipase.

  3. An organic donor/acceptor lateral superlattice at the nanoscale.

    Otero, Roberto; Ecija, David; Fernandez, Gustavo; Gallego, José María; Sanchez, Luis; Martín, Nazario; Miranda, Rodolfo


    A precise control of the nanometer-scale morphology in systems containing mixtures of donor/acceptor molecules is a key factor to improve the efficiency of organic photovoltaic devices. Here we report on a scanning tunneling microscopy study of the first stages of growth of 2-[9-(1,3-dithiol-2-ylidene)anthracen-10(9H)-ylidene]-1,3-dithiole, as electron donor, and phenyl-C61-butyric acid methyl ester, as electron acceptor, on a Au(111) substrate under ultrahigh vacuum conditions. Due to differences in bonding strength with the substrate and different interactions with the Au(111) herringbone surface reconstruction, mixed thin films spontaneously segregate into a lateral superlattice of interdigitated nanoscale stripes with a characteristic width of about 10-20 nm, a morphology that has been predicted to optimize the efficiency of organic solar cells.

  4. Electron Acceptor Materials Engineering in Colloidal Quantum Dot Solar Cells

    Liu, Huan


    Lead sulfide colloidal quantum dot (CQD) solar cells with a solar power conversion efficiency of 5.6% are reported. The result is achieved through careful optimization of the titanium dioxide electrode that serves as the electron acceptor. Metal-ion-doped sol-gel-derived titanium dioxide electrodes produce a tunable-bandedge, well-passivated materials platform for CQD solar cell optimization. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Selection of electron acceptors and strategies for in situ bioremediation

    Norris, R.D. [Eckenfelder, Inc., Nashville, TN (United States)


    The most critical aspect of designing in situ bioremediation systems is, typically, the selection and method of delivery of the electron acceptor. Nitrate, sulfate, and several forms of oxygen can be introduced, depending on the contaminants and the site conditions. Oxygen can be added as air, pure oxygen, hydrogen peroxide, or an oxygen release compound. Simplistic cost calculations can illustrate the advantages of some methods over others, providing technical requirements can be met.

  6. Current advances in fused tetrathiafulvalene donor-acceptor systems.

    Bergkamp, Jesse J; Decurtins, Silvio; Liu, Shi-Xia


    Electron donor (D) and acceptor (A) systems have been studied extensively. Among them, fused D-A systems have attracted much attention during the past decades. Herein, we will present the evolution of tetrathiafulvalene (TTF) fused D-A systems and their potential applications in areas such as solar cells, OFETs, molecular wires and optoelectronics just to name a few. The synthesis and electrochemical, photophysical and intrinsic properties of fused D-A systems will be described as well.

  7. 2012 Gordon Research Conference, Electron donor-acceptor interactions, August 5-10 2012

    McCusker, James [Michigan State Univ., East Lansing, MI (United States)


    The upcoming incarnation of the Gordon Research Conference on Electron Donor Acceptor Interactions will feature sessions on classic topics including proton-coupled electron transfer, dye-sensitized solar cells, and biological electron transfer, as well as emerging areas such as quantum coherence effects in donor-acceptor interactions, spintronics, and the application of donor-acceptor interactions in chemical synthesis.

  8. Structural basis for non-genuine phenolic acceptor substrate specificity of Streptomyces roseochromogenes prenyltransferase CloQ from the ABBA/PT-barrel superfamily

    Araya-Cloutier, Carla; Martens, Bianca; Schaftenaar, Gijs; Leipoldt, Franziska; Gruppen, Harry


    Acceptor substrate specificity of Streptomyces roseochromogenes prenyltransferase SrCloQ was investigated using different non-genuine phenolic compounds. RP-UHPLC-UV-MSn was used for the tentative annotation and quantification of the prenylated products. Flavonoids, isoflavonoids and stilbenoids with different types of substitution were prenylated by SrCloQ, although with less efficiency than the genuine substrate 4-hydroxyphenylpyruvate. The isoflavan equol, followed by the flavone 7,4’-dihydroxyflavone, were the best non-genuine acceptor substrates. B-ring C-prenylation was in general preferred over A-ring C-prenylation (ratio 5:1). Docking studies of non-genuine acceptor substrates with the B-ring oriented towards the donor substrate dimethylallyl pyrophosphate, showed that the carbonyl group of the C-ring was able to make stabilizing interactions with the residue Arg160, which might determine the preference observed for B-ring prenylation. No reaction products were formed when the acceptor substrate had no phenolic hydroxyl groups. This preference can be explained by the essential hydrogen bond needed between a phenolic hydroxyl group and the residue Glu281. Acceptor substrates with an additional hydroxyl group at the C3’ position (B-ring), were mainly O3’-prenylated (> 80% of the reaction products). This can be explained by the proximity of the C3’ hydroxyl group to the donor substrate at the catalytic site. Flavones were preferred over isoflavones by SrCloQ. Docking studies suggested that the orientation of the B-ring and of the phenolic hydroxyl group at position C7 (A-ring) of flavones towards the residue Tyr233 plays an important role in this observed preference. Finally, the insights obtained on acceptor substrate specificity and regioselectivity for SrCloQ were extended to other prenyltransferases from the CloQ/NhpB family. PMID:28355308

  9. Donor-Acceptor Block Copolymers: Synthesis and Solar Cell Applications

    Kazuhiro Nakabayashi


    Full Text Available Fullerene derivatives have been widely used for conventional acceptor materials in organic photovoltaics (OPVs because of their high electron mobility. However, there are also considerable drawbacks for use in OPVs, such as negligible light absorption in the visible-near-IR regions, less compatibility with donor polymeric materials and high cost for synthesis and purification. Therefore, the investigation of non-fullerene acceptor materials that can potentially replace fullerene derivatives in OPVs is increasingly necessary, which gives rise to the possibility of fabricating all-polymer (polymer/polymer solar cells that can deliver higher performance and that are potentially cheaper than fullerene-based OPVs. Recently, considerable attention has been paid to donor-acceptor (D-A block copolymers, because of their promising applications as fullerene alternative materials in all-polymer solar cells. However, the synthesis of D-A block copolymers is still a challenge, and therefore, the establishment of an efficient synthetic method is now essential. This review highlights the recent advances in D-A block copolymers synthesis and their applications in all-polymer solar cells.

  10. Fullerene derivatives as electron acceptors for organic photovoltaic cells.

    Mi, Dongbo; Kim, Ji-Hoon; Kim, Hee Un; Xu, Fei; Hwang, Do-Hoon


    Energy is currently one of the most important problems humankind faces. Depletion of traditional energy sources such as coal and oil results in the need to develop new ways to create, transport, and store electricity. In this regard, the sun, which can be considered as a giant nuclear fusion reactor, represents the most powerful source of energy available in our solar system. For photovoltaic cells to gain widespread acceptance as a source of clean and renewable energy, the cost per watt of solar energy must be decreased. Organic photovoltaic cells, developed in the past two decades, have potential as alternatives to traditional inorganic semiconductor photovoltaic cells, which suffer from high environmental pollution and energy consumption during production. Organic photovoltaic cells are composed of a blended film of a conjugated-polymer donor and a soluble fullerene-derivative acceptor sandwiched between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-coated indium tin oxide positive electrode and a low-work-function metal negative electrode. Considerable research efforts aim at designing and synthesizing novel fullerene derivatives as electron acceptors with up-raised lowest unoccupied molecular orbital energy, better light-harvesting properties, higher electron mobility, and better miscibility with the polymer donor for improving the power conversion efficiency of the organic photovoltaic cells. In this paper, we systematically review novel fullerene acceptors synthesized through chemical modification for enhancing the photovoltaic performance by increasing open-circuit voltage, short-circuit current, and fill factor, which determine the performance of organic photovoltaic cells.

  11. Income-generating activities for family planning acceptors.


    The Income Generating Activities program for Family Planning Acceptors was introduced in Indonesia in 1979. Capital input by the Indonesian National Family Planning Coordination Board and the UN Fund for Population Activities was used to set up small businesses by family planning acceptors. In 2 years, when the businesses become self-sufficient, the loans are repaid, and the money is used to set up new family planning acceptors in business. The program strengthens family planning acceptance, improves the status of women, and enhances community self-reliance. The increase in household income generated by the program raises the standards of child nutrition, encourages reliance on the survival of children, and decreases the value of large families. Approximately 18,000 Family Planning-Income Generating Activities groups are now functioning all over Indonesia, with financial assistance from the central and local governments, the World Bank, the US Agency for International Development, the UN Population Fund, the Government of the Netherlands, and the Government of Australia through the Association of South East Asian Nations.

  12. Virtual screening of electron acceptor materials for organic photovoltaic applications

    Halls, Mathew D.; Djurovich, Peter J.; Giesen, David J.; Goldberg, Alexander; Sommer, Jonathan; McAnally, Eric; Thompson, Mark E.


    Virtual screening involves the generation of structure libraries, automated analysis to predict properties related to application performance and subsequent screening to identify lead systems and estimate critical structure-property limits across a targeted chemical design space. This approach holds great promise for informing experimental discovery and development efforts for next-generation materials, such as organic semiconductors. In this work, the virtual screening approach is illustrated for nitrogen-substituted pentacene molecules to identify systems for development as electron acceptor materials for use in organic photovoltaic (OPV) devices. A structure library of tetra-azapentacenes (TAPs) was generated by substituting four nitrogens for CH at 12 sites on the pentacene molecular framework. Molecular properties (e.g. ELUMO, Eg and μ) were computed for each candidate structure using hybrid DFT at the B3LYP/6-311G** level of theory. The resulting TAPs library was then analyzed with respect to intrinsic properties associated with OPV acceptor performance. Marcus reorganization energies for charge transport for the most favorable TAP candidates were then calculated to further determine suitability as OPV electron acceptors. The synthesis, characterization and OPV device testing of TAP materials is underway, guided by these results.

  13. Design directed self-assembly of donor-acceptor polymers.

    Marszalek, Tomasz; Li, Mengmeng; Pisula, Wojciech


    Donor-acceptor polymers with an alternating array of donor and acceptor moieties have gained particular attention during recent years as active components of organic electronics. By implementation of suitable subunits within the conjugated backbone, these polymers can be made either electron-deficient or -rich. Additionally, their band gap and light absorption can be precisely tuned for improved light-harvesting in solar cells. On the other hand, the polymer design can also be modified to encode the desired supramolecular self-assembly in the solid-state that is essential for an unhindered transport of charge carriers. This review focuses on three major factors playing a role in the assembly of donor-acceptor polymers on surfaces which are (1) nature, geometry and substitution position of solubilizing alkyl side chains, (2) shape of the conjugated polymer defined by the backbone curvature, and (3) molecular weight which determines the conjugation length of the polymer. These factors adjust the fine balance between attractive and repulsive forces and ensure a close polymer packing important for an efficient charge hopping between neighboring chains. On the microscopic scale, an appropriate domain formation with a low density of structural defects in the solution deposited thin film is crucial for the charge transport. The charge carrier transport through such thin films is characterized by field-effect transistors as basic electronic elements.

  14. Asymmetric Synthesis of Functionalized Tricyclic Chromanes via an Organocatalytic Triple Domino Reaction.

    Kumar, Mukesh; Chauhan, Pankaj; Valkonen, Arto; Rissanen, Kari; Enders, Dieter


    A highly stereoselective triple domino reaction for the synthesis of functionalized tricyclic chromane scaffolds has been developed. A secondary amine-catalyzed domino Michael/Michael/aldol condensation reaction between aliphatic aldehydes, nitro-chromenes, and α,β-unsaturated aldehydes leads to the formation of synthetically important tricyclic chromanes bearing four contiguous stereogenic centers including a tetrasubstituted carbon in good yields (20-66%) and excellent stereoselectivities (>20:1 dr and >99% ee).

  15. Spectral, thermal and kinetic studies of charge-transfer complexes formed between the highly effective antibiotic drug metronidazole and two types of acceptors: σ- and π-acceptors.

    Refat, Moamen S; Saad, Hosam A; Adam, Abdel Majid A


    Understanding the interaction between drugs and small inorganic or organic molecules is critical in being able to interpret the drug-receptor interactions and acting mechanism of these drugs. A combined solution and solid state study was performed to describe the complexation chemistry of drug metronidazole (MZ) which has a broad-spectrum antibacterial activity with two types of acceptors. The acceptors include, σ-acceptor (i.e., iodine) and π-acceptors (i.e., dichlorodicyanobenzoquinone (DDQ), chloranil (CHL) and picric acid (PA)). The molecular structure, spectroscopic characteristics, the binding modes as well as the thermal stability were deduced from IR, UV-vis, (1)H NMR and thermal studies. The binding ratio of complexation (MZ: acceptor) was determined to be 1:2 for the iodine acceptor and 1:1 for the DDQ, CHL or PA acceptor, according to the CHN elemental analyses and spectrophotometric titrations. It has been found that the complexation with CHL and PA acceptors increases the values of enthalpy and entropy, while the complexation with DDQ and iodine acceptors decreases the values of these parameters compared with the free MZ donor.

  16. Shape-Tunable Charge Carrier Dynamics at the Interfaces between Perovskite Nanocrystals and Molecular Acceptors

    Ahmed, Ghada H.


    Hybrid organic/inorganic perovskites have recently emerged as an important class of materials and have exhibited remarkable performance in photovoltaics. To further improve their device efficiency, an insightful understanding of the interfacial charge transfer (CT) process is required. Here, we report the first direct experimental observation of the tremendous effect that the shape of perovskite nanocrystals (NCs) has on interfacial CT in the presence of a molecular acceptor. A dramatic change in CT dynamics at the interfaces of three different NC shapes, spheres, platelets, and cubes, is recorded. Our results clearly demonstrate that the mechanism of CT is significantly affected by the NC shape. More importantly, the results demonstrate that complexation on the NC surface acts as an additional driving force not only to tune the CT dynamics but also to control the reaction mechanism at the interface. This observation opens a new venue for further developing perovskite NCs-based applications.

  17. Charge Carrier Dynamics at Silver Nanocluster-Molecular Acceptor Interfaces

    Almansaf, Abdulkhaleq


    A fundamental understanding of interfacial charge transfer at donor-acceptor interfaces is very crucial as it is considered among the most important dynamical processes for optimizing performance in many light harvesting systems, including photovoltaics and photo-catalysis. In general, the photo-generated singlet excitons in photoactive materials exhibit very short lifetimes because of their dipole-allowed spin radiative decay and short diffusion lengths. In contrast, the radiative decay of triplet excitons is dipole forbidden; therefore, their lifetimes are considerably longer. The discussion in this thesis primarily focuses on the relevant parameters that are involved in charge separation (CS), charge transfer (CT), intersystem crossing (ISC) rate, triplet state lifetime, and carrier recombination (CR) at silver nanocluster (NCs) molecular-acceptors interfaces. A combination of steady-state and femto- and nanosecond broadband transient absorption spectroscopies were used to investigate the charge carrier dynamics in various donor-acceptor systems. Additionally, this thesis was prolonged to investigate some important factors that influence the charge carrier dynamics in Ag29 silver NCs donor-acceptor systems, such as the metal doping and chemical structure of the nanocluster and molecular acceptors. Interestingly, clear correlations between the steady-state measurements and timeresolved spectroscopy results are found. In the first study, we have investigated the interfacial charge transfer dynamics in positively charged meso units of 5, 10, 15, 20-tetra (1- methyl-4-pyridino)-porphyrin tetra (p-toluene sulfonate) (TMPyP) and neutral charged 5, 10, 15, 20-tetra (4-pyridyl)-porphyrin (TPyP), with negatively charged undoped and gold (Au)- doped silver Ag29 NCs. Moreover, this study showed the impact of Au doping on the charge carrier dynamics of the system. In the second study, we have investigated the interfacial charge transfer dynamics in [Pt2 Ag23 Cl7 (PPh3

  18. Ultrafast Photoinduced Electron Transfer in Bimolecular Donor-Acceptor Systems

    Alsulami, Qana A.


    The efficiency of photoconversion systems, such as organic photovoltaic (OPV) cells, is largely controlled by a series of fundamental photophysical processes occurring at the interface before carrier collection. A profound understanding of ultrafast interfacial charge transfer (CT), charge separation (CS), and charge recombination (CR) is the key determinant to improving the overall performances of photovoltaic devices. The discussion in this dissertation primarily focuses on the relevant parameters that are involved in photon absorption, exciton separation, carrier transport, carrier recombination and carrier collection in organic photovoltaic devices. A combination of steady-state and femtosecond broadband transient spectroscopies was used to investigate the photoinduced charge carrier dynamics in various donor-acceptor systems. Furthermore, this study was extended to investigate some important factors that influence charge transfer in donor-acceptor systems, such as the morphology, energy band alignment, electronic properties and chemical structure. Interestingly, clear correlations among the steady-state measurements, time-resolved spectroscopy results, grain alignment of the electron transporting layer (ETL), carrier mobility, and device performance are found. In this thesis, we explored the significant impacts of ultrafast charge separation and charge recombination at donor/acceptor (D/A) interfaces on the performance of a conjugated polymer PTB7-Th device with three fullerene acceptors: PC71BM, PC61BM and IC60BA. Time-resolved laser spectroscopy and high-resolution electron microscopy can illustrate the basis for fabricating solar cell devices with improved performances. In addition, we studied the effects of the incorporation of heavy metals into π-conjugated chromophores on electron transfer by monitoring the triplet state lifetime of the oligomer using transient absorption spectroscopy, as understanding the mechanisms controlling intersystem crossing and

  19. Quantitative First-Principles Kinetic Modeling of the Aza-Michael Addition to Acrylates in Polar Aprotic Solvents.

    Desmet, Gilles B; D'hooge, Dagmar R; Omurtag, Pinar Sinem; Espeel, Pieter; Marin, Guy B; Du Prez, Filip E; Reyniers, Marie-Françoise


    This work presents a detailed computational study and kinetic analysis of the aza-Michael addition of primary and secondary amines to acrylates in an aprotic solvent. Accurate rate coefficients for all elementary steps in the various competing mechanisms are calculated using an ONIOM-based approach in which the full system is calculated with M06-2X/6-311+G(d,p) and the core system with CBS-QB3 corrected for solvation using COSMO-RS. Diffusional contributions are taken into account using the coupled encounter pair model with diffusion coefficients calculated based on molecular dynamics simulations. The calculated thermodynamic and kinetic parameters for all forward and reverse elementary reactions are fed to a microkinetic model giving excellent agreement with experimental data obtained using GC analysis. Rate analysis reveals that for primary and secondary amines, the aza-Michael addition to ethyl acrylate occurs preferentially according to a 1,2-addition mechanism, consisting of the pseudoequilibrated formation of a zwitterion followed by a rate controlling amine assisted proton transfer toward the singly substituted product. The alternative 1,4-addition becomes competitive if substituents are present on the amine or double bond of the acrylate. Primary amines react faster than secondary amines due to increased solvation of the zwitterionic intermediate and less sterically hindered proton transfer.

  20. The effect of intramolecular donor–acceptor moieties with donor–π-bridge–acceptor structure on the solar photovoltaic performance

    T. L. Wang


    Full Text Available A series of intramolecular donor–acceptor polymers containing different contents of (E-1-(2-ethylhexyl-6,9-dioctyl-2-(2-(thiophen-3-ylvinyl-1H-phenanthro[9,10-d]imidazole (thiophene-DOPI moiety and 4,4-diethylhexylcyclopenta[ 2,1-b:3,4-b']dithiophene (CPDT unit was synthesized via Grignard metathesis (GRIM polymerization. The synthesized random copolymers and homopolymer of thiophene-DOPI contain the donor–π-bridge–acceptor conjugated structure to tune the absorption spectra and energy levels of the resultant polymers. UV-vis spectra of the three polymer films exhibit panchromatic absorptions ranging from 300 to 1100 nm and low band gaps from 1.38 to 1.51 eV. It is found that more thiophene-DOPI moieties result in the decrease of band gap and lower the highest occupied molecular orbital (HOMO and lowest unoccupied molecular orbital (LUMO values of polymers. Photovoltaic performance results indicate that if the content of the intramolecular donor–acceptor moiety is high enough, the copolymer structure may be better than homopolymer due to more light-harvesting afforded by both monomer units.

  1. 77 FR 30047 - Notice of Opportunity for Public Comment on Surplus Property Release at Michael J Smith Field...


    ... Michael J Smith Field, Beaufort, NC AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice... approximately 7.5 acres of airport property, located at the Michael J Smith Field, be used for aeronautical... Authority to release approximately 7.5 acres of airport property at the Michael J Smith Field. The...

  2. 75 FR 62635 - Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program...


    ... AFFAIRS Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program... needed to determine patients' satisfaction with services provided by or through the Michael E. DeBakey.... Title: Patient Satisfaction Survey Michael E. DeBakey Home Care Program, VA Form 10-0476. OMB...

  3. Recognition of Gene Acceptor Site Based on Multi-objective Optimization

    Jing ZHAO; Yue-Min ZHU; Pei-Ming SONG; Qing FANG; Jian-Hua LUO


    A new method for predicting the gene acceptor site based on multi-objective optimization is introduced in this paper. The models for the acceptor, branch and distance between acceptor site and branch site were constructed according to the characteristics of the sequences from the exon-intron database and using common biological knowledge. The acceptor function, branch function and distance function were defined respectively, and the multi-objective optimization model was constructed to recognize the splice site. The test results show that the algorithm used in this study performs better than the SplicePredictor,which is one of the leading acceptor site detectors.

  4. Dynamics of iron-acceptor-pair formation in co-doped silicon

    Bartel, T.; Gibaja, F.; Graf, O.; Gross, D.; Kaes, M.; Heuer, M.; Kirscht, F. [Calisolar GmbH, Magnusstrasse 11, 12489 Berlin (Germany); Möller, C. [CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Str. 14, 99099 Erfurt (Germany); TU Ilmenau, Institut für Physik, Weimarer Str. 32, 98693 Ilmenau (Germany); Lauer, K. [CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Str. 14, 99099 Erfurt (Germany)


    The pairing dynamics of interstitial iron and dopants in silicon co-doped with phosphorous and several acceptor types are presented. The classical picture of iron-acceptor pairing dynamics is expanded to include the thermalization of iron between different dopants. The thermalization is quantitatively described using Boltzmann statistics and different iron-acceptor binding energies. The proper understanding of the pairing dynamics of iron in co-doped silicon will provide additional information on the electronic properties of iron-acceptor pairs and may become an analytical method to quantify and differentiate acceptors in co-doped silicon.

  5. A Musical Italy: Michael W. Balfe’s Italian Experiences

    Basil Walsh


    Full Text Available The Dublin-born musician, Michael W. Balfe, was a singer, composerand conductor whose brilliant musical career was heavily influenced byformative experiences in Italy. In 1825, Balfe, interested in broadeninghis musical studies first went to Paris where he was introduced to thegreat composers, Luigi Cherubini and Gioachino Rossini, who took apersonal interest in him and his musical talents. On the advice of Rossinihe spent the next few years in Italy studying singing with the famousRossini singer, Filippo Galli, and taking music composition lessonsfrom Ferdinando Paer, in Rome. Later in Milan he studied harmonyand counterpoint with Vincenzo Federici. By 1831, when he was only23 years old, his first three operas had been produced in Palermo, Pavia,and Milan. He returned to London in August 1835, participatingwith the great Lablache, Tamburini, Rubini and Grisi in a concert inVauxhall Gardens. In 1834 he made his debut at La Scala, Milan, singingopposite the renowned mezzo-soprano, Maria Malibran in Rossini’sOtello. He appeared again with Malibran in Venice early in 1835,singing once more in Rossini and Bellini operas. Balfe worked as a singerand composer throughout the Italian peninsula/states during the years,1825-1835 and this article will chart these experiences and demonstratehow the time he spent in Italy and the people he met, influenced hislife and later career as an important and popular European composer.

  6. El fetiche etnográfico de Michael Taussig

    Matthew Carlin


    Full Text Available El antropólogo Michael Taussig ha producido una gran cantidad de trabajo etnográfico sobre América Latina en el que toma por objeto la universalidad de la cultura burguesa y en el que, al reorientar la mirada del etnógrafo hacia los elementos embriagantes y orgiásticos de la vida, atenúa las líneas que dividen ciencia y arte. En este ensayo tengo la intención de mostrar lo siguiente: 1 que sus etnografías sobre magia, violencia y el Es-tado, están enraizadas en su priorización del mundo fenomenológico y en una concepción materialista en deuda con la teoría estética alemana del si-glo XIX y con la antropología especulativa de Karl Marx y Walter Benjamin; 2 que su proyecto etnográfico no consiste en la eliminación de la ciencia del ámbito de la etnografía, sino en disminuir el papel de la explicación en favor de una forma de escritura que, como el arte, trabaja para refundar las imágenes del mundo.

  7. Michael Field’s “A Dance of Death”

    LeeAnne Richardson


    Full Text Available The 1912 poem "A Dance of Death" by Michael Field (pen name of Katherine Bradley and her niece Edith Cooper depicts Salome in an alternate version of the biblical story: this Salome dances on a frozen river, falls through the ice, and is decapitated on a jagged edge. Nonetheless, her beautiful head continues dancing over the frozen river. This poem is highly unusual, especially in the context of the other poems in the postconversion volume Poems of Adoration, because it questions, rather than submits to, authority. In re-writing a familiar Christian tale, as well as a familiar decadent theme, Field uses the poem to assert the supremacy of their artistic vision, which (despite their ardent Catholicism cannot be subject to any law outside themselves. Like the continually dancing head of Salome, which continues to create beauty even after nature (and perhaps God has struck it down, the poet is subjugate only to her own law and creates without boundaries or restrictions on her art. Bradley and Cooper were acutely aware of their authorial persona (actively taking not only a masculine but also a singular poetic identity, and their mode of reconciling the apparent contradictions of this identity are mirrored in their presentation of Salome in a "Dance of Death."

  8. Subjetividade e defesa na obra de Michael Balint

    Renata Mello


    Full Text Available Currently we can observe the diffusion of the so-called tough patients in psychoanalytic clinic. These patients have proven resistant to the classic psychoanalysis technique, leading to the necessity of relying on their psychic dynamics, aiming at a broader understanding of what is at stake in these cases. It can be observed that the subjectivation process relates to a precocious traumatic experience that touches the relation of the individual with what is external to him. Because of the overwhelming intensity provoked by the trauma, elementary protection measures are mobilized in order to prevent a narcissistic collapse. The defense then becomes the preferred way through which psychism constitutes itself, which translates into a meaningful impoverishment of subjective life. In an attempt to understand this dynamic and propose a direction for the psychic treatment, we will resort to Michael Balint¿s ideas about primary object relations, as his thinking offers important elements for a renewal of the understanding of both the analytical practice and the very psychic dynamic we currently see. In regards to Balint¿s ideas, we will hold on to his primary love theory and to the question of the modalities of defensive links - ocnophilia and philobatism - given the lack of loving of the primordial objects, ideas that can provide subsidies to deal with these tough patients.

  9. Noise-Assisted Quantum Electron Transfer in Multi-Level Donor-Acceptor System

    Gurvitz, Shmuel; Berman, Gennady P


    We analytically and numerically study noise-assisted quantum electron transfer (ET) in bio-complexes consisting of a single-level electron donor and an acceptor which is modeled by many electron energy levels. Interactions are included between the donor and the acceptor energy levels and with the protein environment, which is modeled by a diagonal classical noise acting on all donor and acceptor energy levels. Different regions of parameters characterizing (i) the number of the acceptor levels, (ii) the acceptor "band-width", and (iii) the amplitude of noise and its correlation time are considered. Under some conditions, we derive analytical expressions for the ET rate and efficiency, which reveal the coarse-grain features. We obtain equal occupation of all levels at large times, independently of the structure of the acceptor band. We discuss the multi-scale regime of the acceptor population, and the accompanying effect of quantum coherent oscillations, which are analogous to those observed in experiments on ...

  10. Acceptor and donor impurities in GaN nanocrystals

    Echeverría-Arrondo, C.; Pérez-Conde, J.; Bhattacharjee, A. K.


    We investigate acceptor and donor states in GaN nanocrystals doped with a single substitutional impurity. Quantum dots (QD's) of zinc-blende structure and spherical shape are considered with the radius ranging from 4.5 to 67.7 A. The size-dependent energy spectra are calculated within the sp3d5s* tight-binding model, which yields a good agreement with the confinement-induced blue shifts observed in undoped QD's. The computed binding energy is strongly enhanced with respect to the experimental...

  11. Eesti disain on kõva, ent see tuleb moondada ekspordiks / Michael Thomson ; interv. Urmas Oja

    Thomson, Michael


    Euroopa Disainiassotsiatsioonide Liidu presidendi ja Tallinnas toimunud festivali Disainiöö Eesti disainiauhinna Bruno žürii juhi Michael Thomsoni arvamus eesti disainist ning disainipoliitika vajalikkusest Eestis. Auhinnasaajate nimekiri

  12. Theory and practice in action: the contributions of Michael Perkins to clinical linguistics.

    Damico, Jack S; Lynch, Karen E


    This article reviews the scholarly contributions of Michael R. Perkins in the discipline of clinical linguistics and provides some indication of the reasons that he has been so successful. Three primary attributes were described through an analysis of his publications.

  13. Tõsine fotoelamus Dubrovnikus / Wade Goddard, Heidi Levine, Michael Robinson Chaver ; interv. Ahto Külvet

    Goddard, Wade


    Dubrovniku vanalinnas asub Sõjafotokeskus. Intervjuu keskuse asutaja, kanadalasest fotograafi Wade Goddardi ja kahe seal augustis avatud näitusel osalenud fotograafi Heidi Levine'i ja Michael Robinson Chavez'iga. Sõjafotograafi tööst

  14. Reports of the working groups / Eino Tamm, Sahlin Michael, Valve Kirsipuu...[jt.


    Töögruppide "EU enlargement and relevant institutional reforms" (juhatajad Eino Tamm, Michael Sahlin) ja "Maintaining of competitiveness of Estonia and other candidate countries" (juhatajad Valve Kirsipuu, Terry Calbom) tööst. Autor: Reformierakond

  15. Tõsine fotoelamus Dubrovnikus / Wade Goddard, Heidi Levine, Michael Robinson Chaver ; interv. Ahto Külvet

    Goddard, Wade


    Dubrovniku vanalinnas asub Sõjafotokeskus. Intervjuu keskuse asutaja, kanadalasest fotograafi Wade Goddardi ja kahe seal augustis avatud näitusel osalenud fotograafi Heidi Levine'i ja Michael Robinson Chavez'iga. Sõjafotograafi tööst

  16. High Blood Cholesterol Q&A Dr. Michael Lauer | NIH MedlinePlus the Magazine

    ... high cholesterol research. Dr. Michael Lauer and his wife, Dr. Robin Avery, agree on the health benefits ... trial of the drug methotrexate in high-risk patients with vascular disease. We have come to appreciate ...

  17. Dr. Michael DeBakey "is a magician of the heart…"

    ... of Baylor's new Michael E. DeBakey Library and Museum. In a lengthy Christmas Day interview that year ... blood circulation. — 1706 Raymond de Vieussens, a French anatomy professor, first describes the structure of the heart's ...

  18. Reports of the working groups / Eino Tamm, Sahlin Michael, Valve Kirsipuu...[jt.


    Töögruppide "EU enlargement and relevant institutional reforms" (juhatajad Eino Tamm, Michael Sahlin) ja "Maintaining of competitiveness of Estonia and other candidate countries" (juhatajad Valve Kirsipuu, Terry Calbom) tööst. Autor: Reformierakond

  19. A Conversation with his Honour Chief Judge Michael Rozenes AO County Court of Victoria

    Michael Rozenes


    Full Text Available VULJ Editors and invited students interviewed the Chief Judge of the County Court of Victoria, His Honour Michael Rozenes AO QC, on Tuesday 19 August 2014 at the College of Law & Justice, Victoria University.

  20. Stereoselective Michael Addition of Glycine Anions to Chiral Fischer Alkenylcarbene Complexes. Asymmetric Synthesis of beta-Substituted Glutamic Acids.

    Ezquerra, Jesús; Pedregal, Concepción; Merino, Isabel; Flórez, Josefa; Barluenga, José; García-Granda, Santiago; Llorca, María-Amparo


    The reaction of lithium enolates of achiral N-protected glycine esters with chiral alkoxyalkenylcarbene complexes of chromium provided the corresponding Michael adducts with either high anti or syn selectivity depending on the nature of the nitrogen protecting group, and high diastereofacial selectivity when carbene complexes containing the (-)-8-phenylmenthyloxy group were employed. Subsequent oxidation of the metal-carbene moiety followed by deprotection of the amine group and hydrolysis of both carboxylic esters afforded enantiomerically enriched 3-substituted glutamic acids of natural as well as unnatural stereochemistry. Alternatively, when the deprotection step was performed previously to the oxidation, cyclic aminocarbene complexes were formed, which finally led to optically active 3-substituted pyroglutamic acids.

  1. One-pot organocatalytic enantioselective Michael/Povarov domino strategy for the construction of spirooctahydroacridine-3,3'-oxindole scaffolds.

    Wu, Hao; Wang, Yong-Mei


    An asymmetric organocatalytic one-pot strategy for the construction of spirooctahydroacridine-3,3'-oxindole scaffolds has been successfully developed by means of a domino Michael/Povarov reaction sequence. The one-pot protocol affords the chiral spirocyclohexaneoxindoles bearing an octahydroacridine motif with five stereocenters in good to high yields (up to 89 % yield) with excellent to perfect diastereoselectivities (up to >20:1 d.r.) and enantioselectivities (up to >99 % ee). This highly efficient one-pot domino procedure will allow diversity-oriented syntheses of this intriguing class of compounds with potential biological activities. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Perylene-Diimide Based Donor-Acceptor-Donor Type Small-Molecule Acceptors for Solution-Processable Organic Solar Cells

    Ganesamoorthy, Ramasamy; Vijayaraghavan, Rajagopalan; Sakthivel, Pachagounder


    Development of nonfullerene acceptors plays an important role in the commercial availability of plastic solar cells. We report herein synthesis of bay-substituted donor-acceptor-donor (D-A-D)-type perylene diimide (PDI)-based small molecules (SM-1 to SM-4) by Suzuki coupling method and their use as acceptors in bulk heterojunction organic solar cells (BHJ-OSCs) with poly(3-hexylthiophene) (P3HT) polymer donor. We varied the number of electron-rich thiophene units and the solubilizing side chains and also evaluated the optical and electrochemical properties of the small molecules. The synthesized small molecules were confirmed by Fourier-transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and high-resolution mass spectroscopy (HR-MS). The small molecules showed extensive and strong absorption in the ultraviolet-visible (UV-Vis) region up to 750 nm, with bandgap (E_{{g}}^{{opt}} ) reduced below polymer donor showed maximum power conversion efficiency (PCE) of 0.19% with V oc of 0.30 V, J sc of 1.72 mA cm-2, and fill factor (FF) of 37%. The PCE decreased with the number of thiophene units. The PCE of SM-2 was lower than that of SM-1. This difference in PCE can be explained by the higher aggregation tendency of the bithiophene compared with the thiophene unit. Introduction of the solubilizing group in the bay position increased the aggregation property, leading to much lower PCE than for the small molecules without solubilizing group.

  3. A post-Byzantine creation: The archangel Michael triumphant and psychopomp

    Leontakianakou Irini


    Full Text Available This paper deals with a specific iconographic type of Archangel Michael: he is shown bearing a soul in the form of a swaddled infant, while subduing an old man who is wearing only a loincloth. Who is Michael subduing? Three possible answers are considered: 1 the figure can be identified with Satan the fallen angel who, like Michael, has an immaterial nature and is commonly considered as his enemy par excellence; 2 he can also be an anonymous sinner, whose soul is depicted in Michael's hand; 3 finally, one could identify him with Hades, the god of the Underworld and personification of death, because he is depicted as an old man, semi-nude with a pronounced musculature, as well as because of the assimilation of Michael to God. Rather than making a single choice, the author proposes a combined interpretation of the image, which allows for the integration of all the aspects of Michael's cult (military, triumph over Satan, psychopomp, archangel of the Last Judgment and unifies the past (the fall of Satan, the present (death of a sinner and the future (Last Judgment.

  4. Evolution of the acceptor side of photosystem I: ferredoxin, flavodoxin, and ferredoxin-NADP(+) oxidoreductase.

    Pierella Karlusich, Juan José; Carrillo, Néstor


    The development of oxygenic photosynthesis by primordial cyanobacteria ~2.7 billion years ago led to major changes in the components and organization of photosynthetic electron transport to cope with the challenges of an oxygen-enriched atmosphere. We review herein, following the seminal contributions as reported by Jaganathan et al. (Functional genomics and evolution of photosynthetic systems, vol 33, advances in photosynthesis and respiration, Springer, Dordrecht, 2012), how these changes affected carriers and enzymes at the acceptor side of photosystem I (PSI): the electron shuttle ferredoxin (Fd), its isofunctional counterpart flavodoxin (Fld), their redox partner ferredoxin-NADP(+) reductase (FNR), and the primary PSI acceptors F x and F A/F B. Protection of the [4Fe-4S] centers of these proteins from oxidative damage was achieved by strengthening binding between the F A/F B polypeptide and the reaction center core containing F x, therefore impairing O2 access to the clusters. Immobilization of F A/F B in the PSI complex led in turn to the recruitment of new soluble electron shuttles. This function was fulfilled by oxygen-insensitive [2Fe-2S] Fd, in which the reactive sulfide atoms of the cluster are shielded from solvent by the polypeptide backbone, and in some algae and cyanobacteria by Fld, which employs a flavin as prosthetic group and is tolerant to oxidants and iron limitation. Tight membrane binding of FNR allowed solid-state electron transfer from PSI bridged by Fd/Fld. Fine tuning of FNR catalytic mechanism led to formidable increases in turnover rates compared with FNRs acting in heterotrophic pathways, favoring Fd/Fld reduction instead of oxygen reduction.

  5. Polaronic contributions to oxidation and hole conductivity in acceptor-doped BaZrO3

    Lindman, Anders; Erhart, Paul; Wahnström, Göran


    Acceptor-doped perovskite oxides like BaZrO3 are showing great potential as materials for renewable energy technologies where hydrogen acts an energy carrier, such as solid oxide fuel cells and hydrogen separation membranes. While ionic transport in these materials has been investigated intensively, the electronic counterpart has received much less attention and further exploration in this field is required. Here, we use density functional theory (DFT) to study hole polarons and their impact on hole conductivity in Y-doped BaZrO3. Three different approaches have been used to remedy the self-interaction error of local and semilocal exchange-correlation functionals: DFT +U , pSIC-DFT, and hybrid functionals. Self-trapped holes are found to be energetically favorable by about -0.1 eV and the presence of yttrium results in further stabilization. Polaron migration is predicted to occur through intraoctahedral transfer and polaron rotational processes, which are associated with adiabatic barriers of about 0.1 eV. However, the rather small energies associated with polaron formation and migration suggest that the hole becomes delocalized and bandlike at elevated temperatures. These results together with an endothermic oxidation reaction [A. Lindman, P. Erhart, and G. Wahnström, Phys. Rev. B 91, 245114 (2015), 10.1103/PhysRevB.91.245114] yield a picture that is consistent with experimental data for the hole conductivity. The results we present here provide new insight into hole transport in acceptor-doped BaZrO3 and similar materials, which will be of value in the future development of sustainable technologies.

  6. Progress in ZnO Acceptor Doping: What Is the Best Strategy?

    Judith G. Reynolds


    Full Text Available This paper reviews the recent progress in acceptor doping of ZnO that has been achieved with a focus toward the optimum strategy. There are three main approaches for generating p-type ZnO: substitutional group IA elements on a zinc site, codoping of donors and acceptors, and substitution of group VA elements on an oxygen site. The relevant issues are whether there is sufficient incorporation of the appropriate dopant impurity species, does it reside on the appropriate lattice site, and lastly whether the acceptor ionization energy is sufficiently small to enable significant p-type conduction at room temperature. The potential of nitrogen doping and formation of the appropriate acceptor complexes is highlighted although theoretical calculations predict that nitrogen on an oxygen site is a deep acceptor. We show that an understanding of the growth and annealing steps to achieve the relevant acceptor defect complexes is crucial to meet requirements.

  7. The structure and bonding of iron-acceptor pairs in silicon

    Zhao, S.; Assali, L.V.C.; Kimerling, L.C. [Massachusetts Inst. of Technology, Cambridge, MA (United States)


    The highly mobile interstitial iron and Group III impurities (B, Al, Ga, In) form iron-acceptor pairs in silicon. Based on the migration kinetics and taking host silicon as a dielectric medium, we have simulated the pairing process in a static silicon lattice. Different from the conventional point charge ionic model, our phenomenological calculations include (1) a correction that takes into account valence electron cloud polarization which adds a short range, attractive interaction in the iron-acceptor pair bonding; and (2) silicon lattice relaxation due to the atomic size difference which causes a local strain field. Our model explains qualitatively (1) trends among the iron-acceptor pairs revealing an increase of the electronic state hole emission energy with increasing principal quantum number of acceptor and decreasing pair separation distance; and (2) the stable and metastable sites and configurational symmetries of the iron-acceptor pairs. The iron-acceptor pairing and bonding mechanism is also discussed.

  8. Pd(0)-catalyzed intramolecular α-arylation of sulfones: domino reactions in the synthesis of functionalized tetrahydroisoquinolines.

    Solé, Daniel; Pérez-Janer, Ferran; Mancuso, Raffaella


    A new strategy for the synthesis of tetrahydroisoquinolines based on the Pd(0)-catalyzed intramolecular α-arylation of sulfones is reported. The combination of this Pd-catalyzed reaction with intermolecular Michael and aza-Michael reactions allows the development of two- and three-step domino processes to synthesize diversely functionalized scaffolds from readily available starting materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Binding characteristics of homogeneous molecularly imprinted polymers for acyclovir using an (acceptor-donor-donor)-(donor-acceptor-acceptor) hydrogen-bond strategy, and analytical applications for serum samples.

    Wu, Suqin; Tan, Lei; Wang, Ganquan; Peng, Guiming; Kang, Chengcheng; Tang, Youwen


    This paper demonstrates a novel approach to assembling homogeneous molecularly imprinted polymers (MIPs) based on mimicking multiple hydrogen bonds between nucleotide bases by preparing acyclovir (ACV) as a template and using coatings grafted on silica supports. (1)H NMR studies confirmed the AAD-DDA (A for acceptor, D for donor) hydrogen-bond array between template and functional monomer, while the resultant monodisperse molecularly imprinted microspheres (MIMs) were evaluated using a binding experiment, high performance liquid chromatography (HPLC), and solid phase extraction. The Langmuir isothermal model and the Langmuir-Freundlich isothermal model suggest that ACV-MIMs have more homogeneous binding sites than MIPs prepared through normal imprinting. In contrast to previous MIP-HPLC columns, there were no apparent tailings for the ACV peaks, and ACV-MIMs had excellent specific binding properties with a Ka peak of 3.44 × 10(5)M(-1). A complete baseline separation is obtained for ACV and structurally similar compounds. This work also successfully used MIMs as a specific sorbent for capturing ACV from serum samples. The detection limit and mean recovery of ACV was 1.8 ng/mL(-1) and 95.6%, respectively, for molecularly imprinted solid phase extraction coupled with HPLC. To our knowledge, this was the first example of MIPs using AAD-DDA hydrogen bonds.

  10. Donor-Acceptor-Type Semiconducting Polymers Consisting of Benzothiadiazole Derivatives as Electron-Acceptor Units for Organic Photovoltaic Cells.

    Kim, Hee Su; Park, Jong Baek; Kim, Ji-Hoon; Hwang, Do-Hoon


    We synthesized two fused pentacyclic donor-acceptor structures, where the two different outer electron rich thiophene (DTPBT) and electron poor benzene (ICTh) moieties are covalently bonded to the central electron-deficient benzothiadiazole core by two nitrogen bridges. These new electron-acceptor DTPBT and ICTh building blocks were copolymerized with fluorene, as the electron donor group, via Suzuki coupling polymerization, to produce two new alternating copolymers, PFDTPBT and PFICTh, respectively. The average molecular weights of the synthesized polymers were determined by GPC. The number-average molecular weights of PFDTPBT and PFICTh were 19,000 (PDI = 2.5) and 20,000 (PDI = 4.0), respectively. The optical bandgap energies of the polymers were measured from their absorption onsets to be 2.15 and 2.55 eV, depending on the polymer structure. The HOMO energy levels of the polymers were determined, by measuring the oxidation onsets of the polymer films by cyclic voltammetry. The measured HOMO energy levels of PFDTPBT and PFICTh were -5.10 and -5.57 eV, respectively. When the polymers were blended with PC71BM, as the active layer for bulk-heterojunction photovoltaic devices, power conversion efficiencies were 2.08% and 0.34%, respectively, under AM 1.5 G (100 mW cm(-2)) conditions.

  11. Magnetic anisotropy of single Mn acceptors in GaAs in an external magnetic field

    Bozkurt, M Murat; Mahani, MR; Studer, P; Tang, J-M; Schofield, SR; Curson, NJ; Flatté, ME Michael; Silov, AY Andrei; Hirjibehedin, CF; Canali, CM; Koenraad, PM Paul


    We investigate the effect of an external magnetic field on the physical properties of the acceptor hole states associated with single Mn acceptors placed near the (110) surface of GaAs. Crosssectional scanning tunneling microscopy images of the acceptor local density of states (LDOS) show that the strongly anisotropic hole wavefunction is not significantly affected by a magnetic field up to 6 T. These experimental results are supported by theoretical calculations based on a tightbinding model...

  12. Enzymatic production of biodiesel from microalgal oil using ethyl acetate as an acyl acceptor.

    Alavijeh, Razieh Shafiee; Tabandeh, Fatemeh; Tavakoli, Omid; Karkhane, Aliasghar; Shariati, Parvin


    Microalgae have become an important source of biomass for biodiesel production. In enzymatic transesterification reaction, the enzyme activity is decreased in presence of alcohols. The use of different acyl acceptors such as methyl/ethyl acetate is suggested as an alternative and effective way to overcome this problem. In this study, ethyl acetate was used for the first time in the enzymatic production of biodiesel by using microalga, Chlorella vulgaris, as a triglyceride source. Enzymatic conversion of such fatty acids to biodiesel was catalyzed by Novozym 435 as an efficient immobilized lipase which is extensively used in biodiesel production. The best conversion yield of 66.71% was obtained at the ethyl acetate to oil molar ratio of 13:1 and Novozym 435 concentration of 40%, based on the amount of oil, and a time period of 72 h at 40℃. The results showed that ethyl acetate have no adverse effect on lipase activity and the biodiesel amount was not decreased even after seven transesterification cycles, so ethyl acetate has a great potential to be substituted for short-chain alcohols in transesterification reaction.

  13. Synthesis of Naphthalene-Based Push-Pull Molecules with a Heteroaromatic Electron Acceptor.

    Šarlah, David; Juranovič, Amadej; Kožar, Boris; Rejc, Luka; Golobič, Amalija; Petrič, Andrej


    Naphthalene derivatives bearing electron-accepting and electron-donating groups at the 2,6-positions belong to the family of D-π-A push-pull dyes. It has been found that these compounds, e.g., 2-(1-(6-((2-(fluoro)ethyl)(methyl)amino)naphthalen-2-yl)ethylidene)malononitrile (FDDNP), show not only interesting optical properties, such as solvatochromism, but they have the potential to label protein aggregates of different compositions formed in the brain of patients suffering from neurodegenerative diseases like Alzheimer's (AD). In continuation of our research we set our goal to find new FDDNP analogs, which would inherit optical and binding properties but hopefully show better specificity for tau protein aggregates, which are characteristic for neurodegeneration caused by repetitive mild trauma. In this work we report on the synthesis of new FDDNP analogs in which the acceptor group has been formally replaced with an aromatic five- or six-membered heterocycle. The heterocyclic moiety was annealed to the central naphthalene ring either by classical ring closure reactions or by modern transition metal-catalyzed coupling reactions. The chemical characterization, NMR spectra, and UV/vis properties of all new compounds are reported.

  14. Selective Michael-type addition of a D-glucuronic acid derivative in the synthesis of model substances for uronic acid containing polysaccharides


    Full Text Available A flexible protocol for the preparation of model substances for uronic acid containing polysaccharides is presented. We have synthesized a D-glucuronic acid derivative which is designed so that it easily can be conjugated with different structures and architectures by selective Michael-type addition. By successful coupling of the glucuronic acid derivative to polyethylene glycol with high degree of conversion, products were obtained that were easily characterized and which resembled polysaccharides in terms of solubility and purification methods that could be employed. The model substance can potentially be used to facilitate optimization of low-degree modification reactions of high molecular weight D-glucuronic acid containing polysaccharides.

  15. Amine donor and acceptor influence on the thermodynamics of ω-transaminase reactions

    Gundersen, Maria T.; Abu, Rohana; Schürmann, Martin


    In recent years biocatalytic transamination using ω-transaminase has become established as one of the most interesting routes to synthesize chiral amines with a high enantiomeric purity, especially in the pharmaceutical sector where the demand for such compounds is high. Nevertheless, one limitat...

  16. Positron Spur Reactions with Excess Electrons and Anions in Liquid Organic Mixtures of Electron Acceptors

    Lévay, B.; Mogensen, O. E.


    By means of the positron lifetime technique we have measured positronium (Ps) yields in mixtures of nonpolar liquids with various electron scavengers which bind the electron fairly weakly (1–2 eV) in stable anions. The results are discussed with reference to recent excess electron works, and new...... the minimum was shifted towards the lower concentrations, which might be explained by some overlap of the energy levels on CS2 and SF6. Antiinhibition effect of C6F6 and CS2 was studied in 0.05 M CCl4/hexane solutions. In the CS2 case first a small minimum appeared in the Ps yield versus CS2 concentration...

  17. Donor-acceptor pair recombination in gallium sulfide

    Aydinli, A.; Gasanly, N. M.; Gökşen, K.


    Low temperature photoluminescence of GaS single crystals shows three broad emission bands below 2.4 eV. Temperature and excitation light intensity dependencies of these bands reveal that all of them originate from close donor-acceptor pair recombination processes. Temperature dependence of the peak energies of two of these bands in the visible range follow, as expected, the band gap energy shift of GaS. However, the temperature dependence of the peak energy of the third band in the near infrared shows complex behavior by blueshifting at low temperatures followed by a redshift at intermediate temperatures and a second blueshift close to room temperature, which could only be explained via a configuration coordinate model. A simple model calculation indicates that the recombination centers are most likely located at the nearest neighbor lattice or interstitial sites.

  18. Quantum information processing using acceptors in silicon and phonon entanglement

    Clark, Susan; Reinke, Charles; McGuinness, Hayden; El-Kady, Ihab


    Quantum computing with large numbers of qubits remains challenging due to the decoherence and complexity that arise as more qubits are added to a system. Here I propose a new platform for semiconductor quantum computing which may be robust to common sources of decoherence and may not be difficult to fabricate repeatedly. This system consists of a hole bound to an acceptor in silicon which has been implanted in the center of a mechanical cavity (similar to a photonic crystal cavity) and connected to other cavities by a system of waveguides. I will outline a basic entangling gate and calculations showing the promise of this platform as the ideal qubit. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U. S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  19. Establishment of Plant Acceptor System for Hyperosmosis Transformation.


    Calli and adventitious buds induced from different explants such as young stems and leaves of tomato variety Moneymaker, and mature embryos and young spikelets of rice variety TP309 were used to establish hyperosmotic transformation system at various osmotica treatments.The results revealed that the calli induced from tomato young leaves and rice young spikelets were the ideal transfomation acceptor. The cells of calli were still vigorous when treated wity 0.75 mol/L hyperosmotic solution for 4 hours. The differentiation rates of calli varied from 7.5% to 93.3% in different media. The bud differentiation was apparently inhibited by hyperosmotic treatments. O.75mol/L sucrose hypertonic solution and O.2mol/L CaCl2 solution were favorable hyperosmoticum and hypoosmoticum respectively.

  20. Synthetic and DFT studies towards a unified approach to phlegmarine alkaloids: aza-Michael intramolecular processes leading to 5-oxodecahydroquinolines.

    Bradshaw, Ben; Luque-Corredera, Carlos; Saborit, Gisela; Cativiela, Carlos; Dorel, Ruth; Bo, Carles; Bonjoch, Josep


    A diastereoselective synthesis of cis-5-oxodecahydroquinolines is described in which three stereocenters are generated in a one-pot reaction. The reaction involves a lithium hydroxide-promoted Robinson annulation/intramolecular aza-Michael domino process from an achiral acyclic tosylamine-tethered β-keto ester. The development and scope of this reaction was facilitated through the use of DFT-based mechanistic studies, which enabled the observed diastereodivergent course of the azacyclization to be rationalized. The varying stereochemistry and stability of the resulting decahydroquinolines was found to depend on whether a β-keto ester or ketone were embedded in the substrates undergoing aminocyclization. This synthetic approach gave access not only to both diastereomeric cis-decahydroquinolines from the same precursor, but also to the corresponding trans isomers, through an epimerization processes of the corresponding N-unsubstituted cis-5-oxodecahydroquinolines. The described methodology provides advanced building-blocks with the three relative stereochemistries required for the total synthesis of phlegmarine alkaloids.

  1. Beyond fullerenes: design of nonfullerene acceptors for efficient organic photovoltaics.

    Li, Haiyan; Earmme, Taeshik; Ren, Guoqiang; Saeki, Akinori; Yoshikawa, Saya; Murari, Nishit M; Subramaniyan, Selvam; Crane, Matthew J; Seki, Shu; Jenekhe, Samson A


    New electron-acceptor materials are long sought to overcome the small photovoltage, high-cost, poor photochemical stability, and other limitations of fullerene-based organic photovoltaics. However, all known nonfullerene acceptors have so far shown inferior photovoltaic properties compared to fullerene benchmark [6,6]-phenyl-C60-butyric acid methyl ester (PC60BM), and there are as yet no established design principles for realizing improved materials. Herein we report a design strategy that has produced a novel multichromophoric, large size, nonplanar three-dimensional (3D) organic molecule, DBFI-T, whose π-conjugated framework occupies space comparable to an aggregate of 9 [C60]-fullerene molecules. Comparative studies of DBFI-T with its planar monomeric analogue (BFI-P2) and PC60BM in bulk heterojunction (BHJ) solar cells, by using a common thiazolothiazole-dithienosilole copolymer donor (PSEHTT), showed that DBFI-T has superior charge photogeneration and photovoltaic properties; PSEHTT:DBFI-T solar cells combined a high short-circuit current (10.14 mA/cm(2)) with a high open-circuit voltage (0.86 V) to give a power conversion efficiency of 5.0%. The external quantum efficiency spectrum of PSEHTT:DBFI-T devices had peaks of 60-65% in the 380-620 nm range, demonstrating that both hole transfer from photoexcited DBFI-T to PSEHTT and electron transfer from photoexcited PSEHTT to DBFI-T contribute substantially to charge photogeneration. The superior charge photogeneration and electron-accepting properties of DBFI-T were further confirmed by independent Xenon-flash time-resolved microwave conductivity measurements, which correctly predict the relative magnitudes of the conversion efficiencies of the BHJ solar cells: PSEHTT:DBFI-T > PSEHTT:PC60BM > PSEHTT:BFI-P2. The results demonstrate that the large size, multichromophoric, nonplanar 3D molecular design is a promising approach to more efficient organic photovoltaic materials.

  2. Ring opening of donor-acceptor cyclopropanes with the azide ion: a tool for construction of N-heterocycles.

    Ivanov, Konstantin L; Villemson, Elena V; Budynina, Ekaterina M; Ivanova, Olga A; Trushkov, Igor V; Melnikov, Mikhail Ya


    A general method for ring opening of various donor-acceptor cyclopropanes with the azide ion through an SN 2-like reaction has been developed. This highly regioselective and stereospecific process proceeds through nucleophilic attack on the more-substituted C2 atom of a cyclopropane with complete inversion of configuration at this center. Results of DFT calculations support the SN 2 mechanism and demonstrate good qualitative correlation between the relative experimental reactivity of cyclopropanes and the calculated energy barriers. The reaction provides a straightforward approach to a variety of polyfunctional azides in up to 91 % yield. The high synthetic utility of these azides and the possibilities of their involvement in diversity-oriented synthesis were demonstrated by the developed multipath strategy of their transformations into five-, six-, and seven-membered N-heterocycles, as well as complex annulated compounds, including natural products and medicines such as (-)-nicotine and atorvastatin.

  3. Self-assembly characteristics of a multipolar donor-acceptor-based bis-pyrene integrated molecular tweezer

    Deepak Asthana; Geeta Hundal; Pritam Mukhopadhyay


    A modular design of a molecular tweezer is presented that integrates a multipolar D--A [D: Donor, A: Acceptor] scaffold, 1-aminopyrene-based fluorophore units and L-alanine-based linkers. The synthesis of the molecule is based on two-fold aromatic nucleophilic reactions (ArSN) and coupling reactions of the acid and amino functionalities. This molecule crystallizes in a non-centrosymmteric (P21) space group.We present its rich self-assembly characteristics that involves an array of -stacking interactions. In addition, the molecular tweezer within its cleft forms H-bonding with two dimethylformamide molecules. Such multipolar D--A systems containing chiral and fluorophore units are potential candidatesfor a number of electronic and photonic applications.

  4. Contrasting performance of donor-acceptor copolymer pairs in ternary blend solar cells and two-acceptor copolymers in binary blend solar cells.

    Khlyabich, Petr P; Rudenko, Andrey E; Burkhart, Beate; Thompson, Barry C


    Here two contrasting approaches to polymer-fullerene solar cells are compared. In the first approach, two distinct semi-random donor-acceptor copolymers are blended with phenyl-C61-butyric acid methyl ester (PC61BM) to form ternary blend solar cells. The two poly(3-hexylthiophene)-based polymers contain either the acceptor thienopyrroledione (TPD) or diketopyrrolopyrrole (DPP). In the second approach, semi-random donor-acceptor copolymers containing both TPD and DPP acceptors in the same polymer backbone, termed two-acceptor polymers, are blended with PC61BM to give binary blend solar cells. The two approaches result in bulk heterojunction solar cells that have the same molecular active-layer components but differ in the manner in which these molecular components are mixed, either by physical mixing (ternary blend) or chemical "mixing" in the two-acceptor (binary blend) case. Optical properties and photon-to-electron conversion efficiencies of the binary and ternary blends were found to have similar features and were described as a linear combination of the individual components. At the same time, significant differences were observed in the open-circuit voltage (Voc) behaviors of binary and ternary blend solar cells. While in case of two-acceptor polymers, the Voc was found to be in the range of 0.495-0.552 V, ternary blend solar cells showed behavior inherent to organic alloy formation, displaying an intermediate, composition-dependent and tunable Voc in the range from 0.582 to 0.684 V, significantly exceeding the values achieved in the two-acceptor containing binary blend solar cells. Despite the differences between the physical and chemical mixing approaches, both pathways provided solar cells with similar power conversion efficiencies, highlighting the advantages of both pathways toward highly efficient organic solar cells.

  5. TiCl4-promoted Baylis-Hillman reaction: mechanistic rationale toward product distribution and stereoselectivity.

    Patel, Chandan; Sunoj, Raghavan B


    The mechanism of TiCl(4)-promoted Baylis-Hillman reaction between methyl vinyl ketone (MVK) and acetaldehyde, in the absence of any base, is studied using the mPW1K density functional theory. The study focuses on several mechanistic intricacies as well as selectivity issues at each step of the reaction. The minimum energy pathway for this reaction involves three major steps such as a chloride transfer resulting in a chloro-enolate, titanium-mediated aldol reaction, and elimination of HCl or HOTiCl(3). Both s-cis and s-trans conformers of MVK are considered along with various modes of chloride transfer involving different complexes between TiCl(4), aldehyde, and MVK. Chloride transfer is found to be kinetically more favored for s-cis-MVK than for s-trans-MVK. The diastereoselectivity in the next step, i.e., Ti-mediated aldol reaction between the enolate and aldehyde, is found to be dependent on the geometry of the enolate, wherein anti and syn BH products are predicted for Z and E enolates, respectively. An interesting secondary orbital interaction between the oxygen atoms of the enolate and aldehyde moieties in the transition states for the C-C bond formation is identified as one of the contributing factors toward the predicted diastereoselectivity in the formation of the alpha-chloromethyl aldol product (P2). It has earlier been reported that under different experimental conditions, any of the three products such as (i) a normal BH product (P1), (ii) 2-(chloromethyl)vinyl ketones (P3), and (iii) alpha-chloro methyl aldol could be generated (Scheme 1 ). The present study offers valuable insights toward rationalizing the observed product distribution as well as diastereoselectivity in TiCl(4)-promoted BH reaction under base-free conditions. The computed energetics indicate that when MVK is employed as the Michael acceptor, the formation of 2-(choromethyl)vinyl ketone is the preferred product rather than the corresponding normal BH product, consistent with the known

  6. Reactions of Vanadocene-Carbyls with Carbon Monoxide, Xylylisocyanide and Carbon Dioxide

    Nieman, J.; Teuben, J.H.


    Vanadocene-allyl Cp2V(η1-C3H5) (1a) reacts with strong π-acceptor substrate ligands such as carbon monoxide, carbon dioxide and isonitriles. No reactions are observed with poorer π-acceptor substrates such as alkynes and nitriles. Reaction of 1a with CO gives Cp[η4-C5H5(C3H5)]V(CO)2, showing that

  7. Organic Reaction Mechanisms in the Sixth Form Part 3: Reactions of Electron Pair Acceptors with Compounds Containing Multiple Bonds.

    Simpson, Peter


    The ideas behind electrophilic addition to alkenes, and electrophilic substitution in benzene derivatives are discussed. Teaching these concepts to secondary school students is stressed. Five main points useful at this age level are summarized. (Author/CW)

  8. Effect of Michael adduction on peptide preservation in natural waters.

    McKee, G A; Kobiela, M E; Hatcher, P G


    The reaction of peptides with chemicals already present in natural waters (such as polycyclic aromatic hydrocarbons) is one method that has been suggested to preserve peptides for the longer term. In this study we test whether the reaction of tetrapeptides with a model quinone can help stabilise the peptide in one polluted riverine system, Elizabeth River in Virginia, USA. We found that there is almost no difference in rate constants between the peptide and its quinone adduct (e.g. 6.62 versus 6.86 per day for AVFA and its respective adduct). However, when monitoring the removal of the adduct from natural water, we identified two new compounds that are formed as a result of its decomposition. Using tandem mass spectrometry we identified potential structures and mechanisms for the formation of these new compounds. These new compounds are more recalcitrant than their parent peptide-quinone adduct, since they remain in solution for 3-10 times longer. Based on our findings we postulate that the reaction of peptides with quinones can help preserve sections of the original peptide following an initial rearrangement of the original adduct, potentially explaining why seemingly labile peptides are observed in most natural waters.

  9. Analytical Study for the Charge-Transfer Complexes of Rosuvastatin Calcium with π-Acceptors

    Nourah Z. Alzoman


    Full Text Available Studies were carried out to investigate the charge-transfer (CT reaction of ROS-Ca, as a n-electron donor with various p-acceptors: tetracyanoethylene, p-chloranilic acid, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, 2,3,5,6-tetrabromo-1,4-benzoquinone, 1,3,5-trinitrobenzene, 2,3,5,6-tetrachloro-1,4-benzoquinone, 7,7,8,8-tetracyano-quinodimethane, and 2,4,7-trinitro-9-fluorenone. Different colored CT complexes were obtained. The reaction mechanism and site of interaction were determined by ultraviolet-visible spectrophotometric techniques and computational molecular modeling. The formation of the colored complexes was utilized in the development of simple, rapid and accurate spectrophotometric methods for the determination of ROS-Ca. Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.9984–0.9995 were found between the absorbances and the concentrations of ROS-Ca in the range of 2–200 mg mL−1. The limits of detection ranged from 0.41 to 12.24 mg mL−1. No interference could be observed from the additives commonly present in the tablets or from the drugs that are co-formulated with ROS-Ca in its combined formulations. The methods were successfully applied to the analysis of tablets with good accuracy and precision; the recovery percentages ranged from 99.54–100.46 ± 1.58–1.82%. The results were compared favorably with the reported method. The proposed methods are practical and valuable for routine application in quality control laboratories for determination of ROS-Ca in its bulk form and tablets.

  10. Life in the absence of oxygen: alterative electron acceptors for anaerobic microorganisms in a petroleum environment

    Balk, M.


    Anaerobic microorganisms derive energy by transferring electrons from an external source or donor to an external electron sink or terminal acceptor and often have the capacity to reduce 2 or more terminal electron acceptors. The well-known type of microbial respiration, in which oxygen serves as an

  11. Electric-field-induced ionization of acceptors in p-GaAs

    Dargys, A; Cesna, A; Zurauskiene, N


    Hole de-trapping dynamics out of shallow acceptors subjected to high pulsed electric fields is investigated in pure p-GaAs used in radiation detectors. The characteristic de-trapping times are found from current transients due to impact and tunnel ionization of the acceptors. The de-trapping times are presented as a function of electric field strength. (author)

  12. A combined study of mesomorphism, optical, and electronic properties of donor-acceptor columnar liquid crystals

    Eichhorn, S.H.; Shuai, C.; Ahmida, M.; Demenev, A.; Kayal, H.; Raad, F.S.; Kaafarani, B.R.; Patwardhan, S.; Grozema, F.C.; Siebbeles, L.D.A.; Taerum, T.; Perepichka, D.F.; Klenkler, R.


    Donor-acceptor structures have recently gained great popularity for the design of low band gap polymeric organic semiconductors. Presented here is a first systematic study of organic semiconductors based on columnar liquid crystals that consist of discotic and board-shaped donor-acceptor structures.

  13. Dichotomous Role of Exciting the Donor or the Acceptor on Charge Generation in Organic Solar Cells.

    Hendriks, Koen H; Wijpkema, Alexandra S G; van Franeker, Jacobus J; Wienk, Martijn M; Janssen, René A J


    In organic solar cells, photoexcitation of the donor or acceptor phase can result in different efficiencies for charge generation. We investigate this difference for four different 2-pyridyl diketopyrrolopyrrole (DPP) polymer-fullerene solar cells. By comparing the external quantum efficiency spectra of the polymer solar cells fabricated with either [60]PCBM or [70]PCBM fullerene derivatives as acceptor, the efficiency of charge generation via donor excitation and acceptor excitation can both be quantified. Surprisingly, we find that to make charge transfer efficient, the offset in energy between the HOMO levels of donor and acceptor that govern charge transfer after excitation of the acceptor must be larger by ∼0.3 eV than the offset between the corresponding two LUMO levels when the donor is excited. As a consequence, the driving force required for efficient charge generation is significantly higher for excitation of the acceptor than for excitation of the donor. By comparing charge generation for a total of 16 different DPP polymers, we confirm that the minimal driving force, expressed as the photon energy loss, differs by about 0.3 eV for exciting the donor and exciting the acceptor. Marcus theory may explain the dichotomous role of exciting the donor or the acceptor on charge generation in these solar cells.

  14. Multi-scale exciton and electron transfer in multi-level donor-acceptor systems

    Gurvitz, Shmuel; Nesterov, Alexander I.; Berman, Gennady P.


    We study theoretically the noise-assisted quantum exciton (electron) transfer (ET) in bio-complexes consisting of a single-level electron donor and an acceptor which has a complicated internal structure, and is modeled by many electron energy levels. Interactions are included between the donor and the acceptor energy levels and with the protein-solvent noisy environment. Different regions of parameters are considered, which characterize (i) the number of the acceptor levels, (ii) the acceptor ‘band-width’, and (iii) the amplitude of noise and its correlation time. Under some conditions, we derive analytical expressions for the ET rate and efficiency. We obtain equal occupation of all levels at large times, independent of the structure of the acceptor band and the noise parameters, but under the condition of non-degeneracy of the acceptor energy levels. We discuss the multi-scale dynamics of the acceptor population, and the accompanying effect of quantum coherent oscillations. We also demonstrate that for a large number of levels in the acceptor band, the efficiency of ET can be close to 100%, for both downhill and uphill transitions and for sharp and flat redox potentials.

  15. The CHINA CONNECTION: Michael Rossmann and his first encounter with me

    Jia-huai Wang


    @@ "We would have never belived it, if it were not told by Dorothy Hodgkin," Michael Rossmann of Purdue University said to me. He was referring to what the late Nobel laureate Dorothy Hodgkin announced in an international meeting about the achievements of Chinese scientists in determining the crystal structure of insulin in early 70's. This significant contribution occurred at the time when China was still deeply entangled in the chaos of the Cultural Revolution, while even in the international community there were less than a dozen protein structures solved by scientists (Michael included) from a handful of countries. Michael and I sat in his cozy dinning room. While enjoying a breakfast with his favorite applesauce,observing a wild rabbit sneaking underneath the bush in the garden, we had a long chat. That was dudng my first visit to his lab in West Lafayette in 1980.

  16. Donor-Acceptor Cyclopropanes as 1,2-Dipoles in GaCl3-Mediated [4 + 2]-Annulation with Alkenes: Easy Access to the Tetralin Skeleton.

    Novikov, Roman A; Tarasova, Anna V; Korolev, Victor A; Shulishov, Evgeny V; Timofeev, Vladimir P; Tomilov, Yury V


    A new process for (4 + 2)-annulation of donor-acceptor cyclopropanes (DACs) with unsaturated compounds in the presence of anhydrous GaCl3 has been developed. In this process, DACs act as sources of formal 1,2- and 1,4-dipoles to give polysubstituted tetralins in high yields and with high regio- and diastereoselectivity. Alkenes with both aryl and alkyl substituents at the double bond undergo this reaction equally readily. A most likely mechanism of the reaction has been proposed. It involves preliminary generation of a key 1,2-dipolar gallium complex and its subsequent participation in annulation with an alkene.

  17. Hexa-peri-hexabenzocoronene with Different Acceptor Units for Tuning Optoelectronic Properties.

    Keerthi, Ashok; Hou, Ian Cheng-Yi; Marszalek, Tomasz; Pisula, Wojciech; Baumgarten, Martin; Narita, Akimitsu


    Hexa-peri-hexabenzocoronene (HBC)-based donor-acceptor dyads were synthesized with three different acceptor units, through two pathways: 1) "pre-functionalization" of monobromo-substituted hexaphenylbenzene prior to the cyclodehydrogenation; and 2) "post-functionalization" of monobromo-substituted HBC after the cyclodehydrogenation. The HBC-acceptor dyads demonstrated varying degrees of intramolecular charge-transfer interactions, depending on the attached acceptor units, which allowed tuning of their photophysical and optoelectronic properties, including the energy gaps. The two synthetic pathways described here can be complementary and potentially be applied for the synthesis of nanographene-acceptor dyads with larger aromatic cores, including one-dimensionally extended graphene nanoribbons.

  18. Excitation energy transfer in partly ordered polymer films differing in donor and acceptor transition moments orientation

    Synak, A.; Bojarski, P.; Sadownik, M.; Kułak, L.; Gryczynski, I.; Grobelna, B.; Rangełowa-Jankowska, S.; Jankowski, D.; Kubicki, A.


    Based on spectroscopic measurements selected properties of nonradiative Förster energy transport are studied in uniaxially stretched polyvinyl alcohol thin films for three systems differing in donor and acceptor transition moments orientation relative to the axis of stretching. In particular, donor - acceptor emission anisotropy spectra yield completely different regularities for these systems in uniaxially stretched films, whereas they are similar in unstretched films. In particular it is shown that acceptor fluorescence can be either strongly polarized after nonradiative energy transfer in stretched films or depolarized depending on the angular distribution of acceptor transition moments in the matrix. Donor and acceptor emission anisotropy decays exhibit similar regularities to those of steady-state measurements. The obtained results are analyzed with the help of Monte Carlo simulations.

  19. The activation energy for Mg acceptor in the Ga-rich InGaN alloys

    Zhao, Chuan-Zhen; Wei, Tong; Chen, Li-Ying; Wang, Sha-Sha; Wang, Jun


    The activation energy for Mg acceptor in InxGa1-xN alloys is investigated. It is found that there are three factors to influence the activation energy for Mg acceptor. One is the stronger dependence of the VBM of InxGa1-xN depending on In content than that of the Mg acceptor energy level. The other is the concentration of Mg acceptors. Another is the extending of the valence band-tail states into the band gap. In addition, a model based on modifying the effective mass model is developed. It is found that the model can describe the activation energy for Mg acceptor in the Ga-rich InxGa1-xN alloys well after considering the influence of the valence band-tail states.

  20. Rise-Time of FRET-Acceptor Fluorescence Tracks Protein Folding

    Lindhoud, Simon; Westphal, Adrie H.; van Mierlo, Carlo P. M.; Visser, Antonie J. W. G.; Borst, Jan Willem


    Uniform labeling of proteins with fluorescent donor and acceptor dyes with an equimolar ratio is paramount for accurate determination of Förster resonance energy transfer (FRET) efficiencies. In practice, however, the labeled protein population contains donor-labeled molecules that have no corresponding acceptor. These FRET-inactive donors contaminate the donor fluorescence signal, which leads to underestimation of FRET efficiencies in conventional fluorescence intensity and lifetime-based FRET experiments. Such contamination is avoided if FRET efficiencies are extracted from the rise time of acceptor fluorescence upon donor excitation. The reciprocal value of the rise time of acceptor fluorescence is equal to the decay rate of the FRET-active donor fluorescence. Here, we have determined rise times of sensitized acceptor fluorescence to study the folding of double-labeled apoflavodoxin molecules and show that this approach tracks the characteristics of apoflavodoxinʼs complex folding pathway. PMID:25535076

  1. Unraveling high precision stereocontrol in a triple cascade organocatalytic reaction.

    Shinisha, C B; Sunoj, Raghavan B


    The mechanism and stereoselectivity in an organocatalyzed triple cascade reaction between an aldehyde, electron deficient olefin and an alpha,beta-unsaturated aldehyde are investigated for the first time using density functional theory. The factors responsible for high levels of observed stereoselectivity (Enders et al., Nature, 2006, 441, 861) towards the generation of cyclohexene carbaldehyde with four contiguous stereocentres are unravelled. The triple cascade reaction, comprising a Michael, Michael and aldol sequence as the key elementary reactions, is studied by identifying the corresponding transition states for the stereoselective C-C bond-formation. In the first Michael addition step between the enamine (derived from the chiral catalyst and propanal) and nitrostyrene, energetically the most preferred mode of addition is found to be between the si-face of (E)-anti-enamine on the si-face of nitrostyrene. The addition of the si-face of the nitroalkane anion on the re-face of the iminium ion (formed between the enal and the catalyst) is the lowest energy pathway for the second Michael addition step. The high level of asymmetric induction is rationalized with the help of relative activation barriers associated with the competitive diastereomeric pathways. Interesting weak interactions, along with the steric effects offered by the bulky alpha-substituent on the pyrrolidine ring, are identified as critical to the stereoselectivity in this triple cascade reaction. The predicted stereoselectivities using computed energetics are found to be in perfect harmony with the experimental stereoselectivities.

  2. Michael Goodsite gæsteprofessor på Thunderbird School of Global Management

    Pedersen, Jens Christian


    Professor Michael Goodsite er blevet udnævnt til "Visiting Professor of Global Processes and Senior Research Fellow in Climate Strategy" ved Thunderbird School of Global Management, som har verdens højst rangerede MBA uddannelse inden for international handel.......Professor Michael Goodsite er blevet udnævnt til "Visiting Professor of Global Processes and Senior Research Fellow in Climate Strategy" ved Thunderbird School of Global Management, som har verdens højst rangerede MBA uddannelse inden for international handel....

  3. Beyond the techno-thriller: Michael Crichton and societal issues in science and technology

    Stengler, E.


    Michael Crichton is primarily known for being an outstanding writer of techno-thrillers and co-creator of the genre. In this paper I suggest that his fictional works can and should be considered under the deeper and wider perspective of his concern for societal issues regarding science and technology with a profound consideration of their effects and on the life of people and the development of society.\\ud \\ud In fact this defining feature of his work is inclusive of numerous works by Michael...

  4. A new type of donor-acceptor cyclopropane reactivity: the generation of formal 1,2- and 1,4-dipoles.

    Novikov, Roman A; Tarasova, Anna V; Korolev, Victor A; Timofeev, Vladimir P; Tomilov, Yury V


    A new type of donor-acceptor cyclopropane reactivity has been discovered. On treatment with anhydrous GaCl3 , they react as sources of even-numbered 1,2- and 1,4-dipoles instead of the classical odd-numbered 1,3-dipoles due to migration of positive charge from the benzyl center. This type of reactivity has been demonstrated for new reactions, namely, cyclodimerizations of donor-acceptor cyclopropanes that occur as [2+2]-, [3+2]-, [4+2]-, [5+2], [4+3]-, and [5+4]-annulations. The [4+2]-annulation of 2-arylcyclopropane-1,1-dicarboxylates to give polysubstituted 2-aryltetralins has been developed in a preparative version that provides exceedingly high regio- and diastereoselectivity and high yields. The strategy for selective hetero-combination of donor-acceptor cyclopropanes was also been developed. The mechanisms of the discovered reactions involving the formation of a comparatively stable 1,2-ylide intermediate have been studied.

  5. Terahertz Stimulated Emission from Silicon Doped by Hydrogenlike Acceptors

    S. G. Pavlov


    Full Text Available Stimulated emission in the terahertz frequency range has been realized from boron acceptor centers in silicon. Population inversion is achieved at resonant optical excitation on the 1Γ_{8}^{+} → 1Γ_{7}^{−}, 1Γ_{6}^{−}, 4Γ_{8}^{−} intracenter transitions with a midinfrared free-electron laser. Lasing occurs on two intracenter transitions around 1.75 THz. The upper laser levels are the 1Γ_{7}^{−}, 1Γ_{6}^{−}, and 4Γ_{8}^{−} states, and the lower laser level for both emission lines is the 2Γ_{8}^{+} state. In contrast to n-type intracenter silicon lasers, boron-doped silicon lasers do not involve the excited states with the longest lifetimes. Instead, the absorption cross section for the pump radiation is the dominating factor. The four-level lasing scheme implies that the deepest even-parity boron state is the 2Γ_{8}^{+} state and not the 1Γ_{7}^{+} split-off ground state, as indicated by other experiments. This is confirmed by infrared absorption spectroscopy of Si:B.


    Jian-fei Qu; Jian Liu; Si-da Li; Zhi-yuan Xie; Yan-hou Geng


    Five novel donor-acceptor (D-A) conjugated cooligomers (F4B-hP,F5B-hP,F5B2[1,2]-hP,F5B2[1,3]-hP and F7B2[1,2]-hP) were synthesized.The absorption spectra of the cooligomers cover a wide range from 300 nm to 630 nm.The cooligomers could form films featured by alternating D-A lamellar nanostructures with the periods relative to the molecular lengths after thermal annealing or solvent vapor annealing.Single molecule solar cells were fabricated,and F5B-hP exhibited the best device performance.When the film of F5B-hP was thermally annealed,a power conversion efficiency (PCE) of 1.56% was realized.With solvent vapor annealing,the PCE could be further improved to 1.72% with a short-circuit current (Jsc) of 5.76 mA/cm2,an open-circuit voltage (VoC) of 0.87 V and a fill factor (FF) of 0.34.

  7. Serum cholesterol acceptor capacity in intrauterine growth restricted fetuses.

    Pecks, Ulrich; Rath, Werner; Bauerschlag, Dirk O; Maass, Nicolai; Orlikowsky, Thorsten; Mohaupt, Markus G; Escher, Geneviève


    Intrauterine growth restriction (IUGR) is an independent risk factor for the development of cardiovascular diseases later in life. The mechanisms whereby slowed intrauterine growth confers vascular risk are not clearly established. In general, a disturbed cholesterol efflux has been linked to atherosclerosis. The capacity of serum to accept cholesterol has been repeatedly evaluated in clinical studies by the use of macrophage-based cholesterol efflux assays and, if disturbed, precedes atherosclerotic diseases years before the clinical diagnosis. We now hypothesized that circulating cholesterol acceptors in IUGR sera specifically interfere with cholesterol transport mechanisms leading to diminished cholesterol efflux. RAW264.7 cells were used to determine efflux of [3H]-cholesterol in response to [umbilical cord serum (IUGR), n=20; controls (CTRL), n=20]. Cholesterol efflux was lower in IUGR as compared to controls [controls: mean 7.7% fractional [3H]-cholesterol efflux, standard deviation (SD)=0.98; IUGR: mean 6.3%, SD=0.79; P<0.0001]. Values strongly correlated to HDL (ρ=0.655, P<0.0001) and apoE (ρ=0.510, P=0.0008), and mildly to apoA1 (ρ=0.3926, P=0.0122) concentrations. Reduced cholesterol efflux in IUGR could account for the enhanced risk of developing cardiovascular diseases later in life.

  8. Analysis of nonlinear optical properties in donor–acceptor materials

    Day, Paul N. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); General Dynamics Information Technology, Inc., Dayton, Ohio 45431 (United States); Pachter, Ruth [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); Nguyen, Kiet A. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); UES, Inc., Dayton, Ohio 45432 (United States)


    Time-dependent density functional theory has been used to calculate nonlinear optical (NLO) properties, including the first and second hyperpolarizabilities as well as the two-photon absorption cross-section, for the donor-acceptor molecules p-nitroaniline and dimethylamino nitrostilbene, and for respective materials attached to a gold dimer. The CAMB3LYP, B3LYP, PBE0, and PBE exchange-correlation functionals all had fair but variable performance when compared to higher-level theory and to experiment. The CAMB3LYP functional had the best performance on these compounds of the functionals tested. However, our comprehensive analysis has shown that quantitative prediction of hyperpolarizabilities is still a challenge, hampered by inadequate functionals, basis sets, and solvation models, requiring further experimental characterization. Attachment of the Au{sub 2}S group to molecules already known for their relatively large NLO properties was found to further enhance the response. While our calculations show a modest enhancement for the first hyperpolarizability, the enhancement of the second hyperpolarizability is predicted to be more than an order of magnitude.

  9. Effects of Hydrogen on Acceptor Activation in Ternary Nitride Semiconductors

    Fioretti, Angela N. [National Renewable Energy Laboratory, Golden CO 80401 USA; Colorado School of Mines, Golden CO 80401 USA; Stokes, Adam [National Renewable Energy Laboratory, Golden CO 80401 USA; Colorado School of Mines, Golden CO 80401 USA; Young, Matthew R. [National Renewable Energy Laboratory, Golden CO 80401 USA; Gorman, Brian [Colorado School of Mines, Golden CO 80401 USA; Toberer, Eric S. [National Renewable Energy Laboratory, Golden CO 80401 USA; Colorado School of Mines, Golden CO 80401 USA; Tamboli, Adele C. [National Renewable Energy Laboratory, Golden CO 80401 USA; Colorado School of Mines, Golden CO 80401 USA; Zakutayev, Andriy [National Renewable Energy Laboratory, Golden CO 80401 USA


    Doping control is necessary to unlock the scientific and technological potential of many materials, including ternary II-IV-nitride semiconductors, which are closely related to binary GaN. In particular, ZnSnN2 has been reported to have degenerate doping density, despite bandgap energies that are well suited for solar energy conversion. Here, we show that annealing Zn-rich Zn1+xSn1-xN2 grown with added hydrogen reduces its free electron density by orders of magnitude, down to 4 x 1016 cm-3. This experimental observation can be explained by hydrogen passivation of acceptors in Zn1+xSn1-xN2 during growth, lowering the driving force for unintentional donor formation. These results indicate that the doping control principles used in GaN can be translated to ZnSnN2, suggesting that other strategies used in binary III-Vs can be applied to accelerate the technological development of ternary II-IV-N2 materials.

  10. Screening of recombinant glycosyltransferases reveals the broad acceptor specificity of stevia UGT-76G1.

    Dewitte, Griet; Walmagh, Maarten; Diricks, Margo; Lepak, Alexander; Gutmann, Alexander; Nidetzky, Bernd; Desmet, Tom


    UDP-glycosyltransferases (UGTs) are a promising class of biocatalysts that offer a sustainable alternative for chemical glycosylation of natural products. In this study, we aimed to characterize plant-derived UGTs from the GT-1 family with an emphasis on their acceptor promiscuity and their potential application in glycosylation processes. Recombinant expression in E. coli provided sufficient amounts of enzyme for the in-depth characterization of the salicylic acid UGT from Capsella rubella (UGT-SACr) and the stevia UGT from Stevia rebaudiana (UGT-76G1Sr). The latter was found to have a remarkably broad specificity with activities on a wide diversity of structures, from aliphatic and branched alcohols, over small phenolics to larger flavonoids, terpenoids and even higher glycoside compounds. As an example for its industrial potential, the glycosylation of curcumin was thoroughly evaluated. Under optimized conditions, 96% of curcumin was converted within 24h into the corresponding curcumin β-glycosides. In addition, the reaction was performed in a coupled system with sucrose synthase from Glycine max, to enable the cost-efficient (re)generation of UDP-Glc from sucrose as abundant and renewable resource.

  11. Phthalimide containing donor-acceptor polymers for effective dispersion of single-walled carbon nanotubes

    Baris Yilmaz


    Full Text Available Single-walled carbon nanotubes have been dispersed by novel phthalimide containing donor-acceptor type copolymers in organic media. Brominated phthalimide comonomer has been copolymerized with several electron rich structures using Suzuki and Stille coupling reactions. Carbon nanotube dispersion capability of the resultant polymers has been assessed by exploiting the non-covalent interaction of nanotube surface with the pi-system of conjugated backbone of polymers. Four polymers have been found to be good candidates for individually dispersing nanotubes in solution. In order to identify the dispersed nanotube species, 2D excitation-emission map and Raman spectroscopy have been performed. Molecular dynamics modelling has been utilized to reveal the binding energies of dispersants with the nanotube surface and the simulation results have been compared with the experimental findings. Both experimental and theoretical results imply the presence of a complex mechanism that governs the extent of dispersion capacity and selectivity of each conjugated polymeric dispersant in solubilizing carbon nanotubes.

  12. Utilization of toxic and vapors as alternate electron acceptors in biofilters

    Lee, B.D.; Apel, W.A.; Walton, M.R.


    Conceptually, biofilters are vapor phase bioreactors that rely on microorganisms in the bed medium to oxidize contaminants in off-gases flowing through the bed to less hazardous compounds. In the most studied and utilized systems reduced compounds such as fuel hydrocarbons are enzymatically oxidized to compounds such as carbon dioxide and water. In these types of reactions the microorganisms in the bed oxidize the contaminant and transfer the electrons to oxygen which is the terminal electron acceptor in the process. In essence the contaminant is the carbon and energy source for the microorganisms in the bed medium and through this catabolic process oxygen is reduced to water. An example of this oxidation process can be seen during the degradation of benzene and similar aromatic compounds. Aromatics are initially attacked by a dioxygenase enzyme which oxidizes the compounds to a labile dihydrodiole which is spontaneously converted to a catechol. The dihydroxylated aromatic rings is then opened by oxidative {open_quotes}ortho{close_quotes} or {open_quotes}meta{close_quotes} cleavage yielding cis, cis-muconic acid or 2-hydroxy-cis, cis-muconic semialdehyde, respectively. These organic compounds are further oxidized to carbon dioxide or are assimilated for cellular material. This paper describes the conversion of carbon tetrachloride using methanol as the primary carbon and energy source.

  13. EPR studies of the vitamin K 1 semiquinone radical anion. Comparison to the electron acceptor A 1 in green plant photosystem I

    Thurnauer, Marion C.; Brown, James W.; Gast, P.; Feezel, Laura L.

    Suggestions that the electron acceptor, A 1, in Photosystem I is a quinone have come from both optical and epr experiments. Vitamin K 1 (phylloquinone) is present in the PSI complex with a stoichiometry of two molecules per reaction center. In order to determine if A 1 can be identified with vitamin K 1, X-band and Q-band epr properties of the vitamin K 1 radical anion in frozen alcohol solutions are examined. The results are compared to the epr properties that have been observed for the reduced A 1 acceptor in vivo. The g-values obtained for the vitamin K 1 radical anion are consistent with identifying A 1 with vitamin K 1.

  14. Magneto-ionic phase control in a quasi-layered donor/acceptor metal-organic framework by means of a Li-ion battery system

    Taniguchi, Kouji; Narushima, Keisuke; Yamagishi, Kayo; Shito, Nanami; Kosaka, Wataru; Miyasaka, Hitoshi


    Electrical magnetism control is realized in a Li-ion battery system through a redox reaction involving ion migrations; “magneto-ionic control”. A quasi-layered metal-organic framework compound with a cross-linked π-conjugated/unconjugated one-dimensional chain motifs composed of electron-donor/acceptor units is developed as the cathode material. A change in magnetic phase from paramagnetic to ferrimagnetic is demonstrated by means of electron-filling control for the acceptor units via insertion of Li+-ions into pores in the material. The transition temperature is as high as that expected for highly π-conjugated layered systems, indicating an extension of π-conjugated exchange paths by rearranging coordination bonds in the first discharge process.

  15. Electronic, infrared, mass, 1H NMR spectral studies of the charge-transfer complexes of sulphonamide drugs with π-acceptors in acetonitrile

    Frag, Eman Y.; Mohamed, Gehad G.


    The rapid interaction between sulphonamides (sulphamethoxazole (SMZ), sulphaguanidine (SGD), sulphaquinoxaline sodium (SQX) and sulphadimidine sodium (SDD)) as n-electron donors with the 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid, p-CLA) as π-acceptors resulted in the formation of 1:1 charge-transfer complexes as the final products with the formula [(drug) (acceptor)]. The final products of the reactions have been isolated and characterized using FT-IR, 1H NMR, mass spectroscopy and elemental analyses as well as photometric measurements and thermogravimetric analysis (TG). The stoichiometry and apparent formation constants of the complexes formed were determined by applying the conventional spectrophotometric molar ratio method.

  16. Furan-based diketopyrrolopyrrole chromophores: Tuning the spectroscopic, electrochemical and aggregation-induced fluorescent properties with various intramolecular donor-acceptor spacers

    Tao, Tao; Chen, Liang; Cao, Hui; Chen, Min-Dong; Huang, Wei


    A family of furan-based diketopyrrolopyrrole chromophores, which comprise different donor or acceptor spacers, was synthesized by classic Suzuki-Miyaura reactions between dibrominated diketopyrrolopyrrole intermediate and five substituted aromatic boronic acids. They have the same π-extended unit and different pyridyl, thienyl and triarylamino tails with various intramolecular donor-acceptor spacers. Furthermore, absorption and emission spectral studies reveal that all dyes show extraordinarily large molar absorption coefficients (εmax = 22 400-120 000 L mol-1 cm-1) and high luminescence quantum yields (Φs = 27-88%). Moreover, the TGA studies indicate that the triarylamino-extended compounds have excellent thermal stabilities. A systematical investigation has been carried out, including energy gap correlation among optical, electrochemical and computational data. All the targeted chromophores exhibit potential applications in luminescent materials and optoelectronic devices.

  17. 78 FR 6851 - Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program...


    ... AFFAIRS Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program....'' SUPPLEMENTARY INFORMATION: Title: Patient Satisfaction Survey Michael E. DeBakey Home Care Program, VA Form 10.... Abstract: VA Form 10-0476 will be used to gather feedback from patients regarding their satisfaction...

  18. 77 FR 69550 - Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program...


    ... AFFAIRS Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program.... This notice solicits comments on information needed to determine patients' satisfaction with services... information technology. Title: Patient Satisfaction Survey Michael E. DeBakey Home Care Program, VA Form...

  19. 76 FR 624 - Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program...


    ... AFFAIRS Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program.... 2900-New (VA Form 10-0476).'' SUPPLEMENTARY INFORMATION: Title: Patient Satisfaction Survey Michael E... Review: New collection. Abstract: VA Form 10-0476 will be used to gather feedback from patients...

  20. Pyrrolidinyl-sulfamide derivatives as a new class of bifunctional organocatalysts for direct asymmetric Michael addition of cyclohexanone to nitroalkenes.

    Chen, Jia-Rong; Fu, Liang; Zou, You-Quan; Chang, Ning-Jie; Rong, Jian; Xiao, Wen-Jing


    A series of chiral pyrrolidinyl-sulfamide derivatives have been identified as efficient bifunctional organocatalysts for the direct Michael addition of cyclohexanone to a wide range of nitroalkenes. The desired Michael adducts were obtained in high chemical yields and excellent stereoselectivities (up to 99/1 dr and 95% ee).

  1. Analysis of Shewanella oneidensis Membrane Protein Expression in Response to Electron Acceptor Availability

    Giometti, Carol S.; Khare, Tripti; Verberkmoes, Nathan; O' Loughlin, Ed; Lindberg, Carl; Thompson, Melissa; Hettich, Robert


    Shewanella oneidensis MR-1, a gram negative metal-reducing bacterium, can utilize a large number of electron acceptors. In the natural environment, S. oneidensis utilizes insoluble metal oxides as well as soluble terminal electron acceptors. The purpose of this ERSP project is to identify differentially expressed proteins associated with the membranes of S. oneidensis MR-1 cells grown with different electron acceptors, including insoluble metal oxides. We hypothesize that through the use of surface labeling, subcellular fractionation, and a combination of proteome analysis tools, proteins involved in the reduction of different terminal electron acceptors will be elucidated. We are comparing the protein profiles from cells grown with the soluble electron acceptors oxygen and fumarate and with those from cells grown with the insoluble iron oxides goethite, ferrihydrite and lepidocrocite. Comparison of the cell surface proteins isolated from cells grown with oxygen or anaerobically with fumarate revealed an increase in the abundance of over 25 proteins in anaerobic cells, including agglutination protein and flagellin proteins along with the several hypothetical proteins. In addition, the surface protein composition of cells grown with the insoluble iron oxides varies considerably from the protein composition observed with either soluble electron acceptor as well as between the different insoluble acceptors.

  2. Synthesis and electrochemical studies of charge-transfer complexes of thiazolidine-2,4-dione with σ and π acceptors

    Singh, Prashant; Kumar, Pradeep; Katyal, Anju; Kalra, Rashmi; Dass, Sujata K.; Prakash, Satya; Chandra, Ramesh


    In the present work, we report the synthesis and characterization of novel charge-transfer complexes of thiazolidine-2,4-dione (TZD) with sigma acceptor (iodine) and pi acceptors (chloranil, dichlorodicyanoquinone, picric acid and duraquinone). We also evaluated their thermal and electrochemical properties and we conclude that these complexes are frequency dependent. Charge-transfer complex between thiazolidine-2,4-dione and iodine give best conductivity. In conclusion, complex with sigma acceptors are more conducting than with pi acceptors.

  3. Modeling microbial degradation of propylene glycol: electron acceptors and their related redox conditions

    Dathe, Annette; Fernandez, Perrine M.; Bloem, Esther; Meeussen, Johannes C. L.; French, Helen K.


    De-icing chemicals are applied in large amounts at airports during winter conditions to keep the runways and aircrafts ice-free. The commonly used propylene glycol (PG) is easily degradable by local microbial communities, but anoxic zones develop and soluble Fe+2 and Mn+2 ions can reach the groundwater. To enhance microbial induced remediation and reduce the release of iron and manganese, it was proposed to add NO3- together with PG. However, experiments conducted in the unsaturated zone at Gardermoen airport, Norway, revealed that manganese and iron were preferred over NO3- as electron acceptor [1]. The objectives of this study are to quantify mechanisms which control the order of reduction processes in an unsaturated sandy soil, and to test whether measured redox potentials can help to determine underlying biogeochemical reactions. We are modelling the microbial degradation of PG using Monod kinetics described for the chemical equilibrium tool ORCHESTRA [2], following an approach of [1]. The model is calibrated against gas measurements of CO2, NO2 and N2 released from batch experiments performed under controlled conditions. Fe+2 and Mn+2 were measured for the start and end of the experiment, as well as bulk resistivity, pH and electrical conductivity. With the calibrated model we are working towards a tool to quantify microbial induced redox reactions under different soil water saturations to account for seasonal water fluxes especially during snowmelt. [1] Schotanus, D., Meeussen, J.C.L., Lissner, H., van der Ploeg, M.J., Wehrer, M., Totsche, K.U., van der Zee, S.E.A.T.M., 2013. Transport and degradation of propylene glycol in the vadose zone: model development and sensitivity analysis. Environ Sci Pollut Res Int. [2] Meeussen, J.C.L., 2003. ORCHESTRA: An Object-Oriented Framework for Implementing Chemical Equilibrium Models. Environ. Sci. Technol. 37, 1175-1182.

  4. Michael Shaffer, 6th July 1936 to 23rd March 2009: A heartfelt tribute

    Mr. Michael Shaffer, Retired Pyraloidea Curator, at the Natural History Museum, London, England, passed away on March 23, 2009. He was an acknowledged world expert on Pyraloidea, a group of agriculturally important moths. He was curator of the largest Pyraloidea type collection in the world, and a...

  5. Michael Corleone's Destiny——From the perspective of interpersonal metafunction to analyze Godfather



    Godfather is Maria Puzo's famous long story. Maria Puzo presented us the unknown Italians-American's life with underworld background. Although many comments from different perspectives have been made, few studies are made. with Halliday's framework. This paper is an attempt to study the destiny of Michael Corleone from the perspective of interpersonal metafunction in systemic functional linguistis.

  6. Training and Mastery of Techniques in Wittgenstein's Later Philosophy: A Response to Michael Luntley

    Stickney, Jeff


    Responding to Michael Luntley's article, "Learning, Empowerment and Judgement," the author shows he cannot successfully make the following three moves: (1) dissolve the analytic distinction between learning by training and learning by reasoning, while advocating the latter; (2) diminish the role of training in Wittgenstein's philosophy, nor…

  7. Wolff-Michael Roth's passibility: at the limits of the constructivist metaphor: a book review

    Brendel, Michelle


    Wolff-Michael Roth deconstructs the preeminent role conceded to constructivism in Science Education and demonstrates how we learn and know through pain, suffering, love or passion. This review explores his book "Passibility: At the Limits of the Constructivist Metaphor" through the eyes of an outsider to the world of science education.

  8. European Management: an emerging competitive advantage of European nations : A reply to Michael Porter

    F.A.J. van den Bosch (Frans); A.A. van Prooijen


    textabstractThis article extends the debate begun in the June 1992 issue of EMJ when the authors first criticized Michael Porter's explanatory framework in his Competitive Advantage of Nations (1990), over the role of national culture on the competitive advantage of nations. In this paper, Frans van

  9. Little Mosie from the Margaree: A Biography of Moses Michael Coady.

    Welton, Michael R.

    This book examines the life of the Reverend Moses Michael Coady (1890-1959), a Roman Catholic priest who led the Antigonish Movement. During the Antigonish Movement, residents of the small maritime town of Antigonish, Nova Scotia, worked to achieve a nonviolent alternative to communism and fascism and to effect the social and economic…

  10. From Gouldner to Gramsci: The Making of Michael Apple's "Ideology and Curriculum"

    Gottesman, Isaac


    Michael Apple's "Ideology and Curriculum", published in 1979, helped initiate a broad turn in the field of education in the United States to Marxist thought as a lens through which to analyze the relationship between school and society. This classic text continues to inform scholarship in the field. While "Ideology" has…

  11. On the study of culture and mind: Interview with Prof. Michael Cole

    Glaveanu, Vlad Petre


    the two. And yet, as Professor Michael Cole and, more broadly, cultural psychologists would argue: there is no way of making sense of one if we disregard the other. Culture and mind constitute each other through action and communication and it is their intricate relationship that holds the key...

  12. European Management: an emerging competitive advantage of European nations : A reply to Michael Porter

    F.A.J. van den Bosch (Frans); A.A. van Prooijen


    textabstractThis article extends the debate begun in the June 1992 issue of EMJ when the authors first criticized Michael Porter's explanatory framework in his Competitive Advantage of Nations (1990), over the role of national culture on the competitive advantage of nations. In this paper, Frans van

  13. 78 FR 69661 - Michael Canales v. Edison International, EIX, Southern California Edison; Notice of Complaint


    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Michael Canales v. Edison International, EIX, Southern California Edison; Notice of Complaint Take notice that on November 11, 2013, pursuant to sections 205, 206, and 301 of the Federal Power Act (FPA), 16 U.S.C....

  14. Michael Eric Dyson: A Scholar and a Hip-Hop Preacher.

    Fletcher, Michael A.


    Introduces Michael Eric Dyson, an African American man who grew up in the ghetto and eventually received a PhD from Princeton University. Today, he is a professor at DePaul University, the author of a radically revisionist new biography of Martin Luther King, Jr., a lecturer and talk show guest, a Baptist preacher, and a self-styled hip-hop…

  15. How to move things around a hospital: transport logistics at St. Michael's.

    Yau, A; Zorn, R; McLaughlin, J


    Ongoing fiscal restraint challenges hospitals to focus their resources primarily on core services. Support services receive much less attention. This article describes the experience of Toronto's St. Michael's Hospital when it re-engineered its transport logistics by consolidating centralized support services into a logistics department and creating new roles and processes to enhance patient care.

  16. Moral Education and Education in Altruism: Two Replies to Michael Hand

    White, John


    This article is a critical discussion of two recent papers by Michael Hand on moral education. The first is his "Towards a Theory of Moral Education", published in the "Journal of Philosophy of Education" in 2014 (Volume 48, Issue 4). The second is a chapter called "Beyond Moral Education?" in an edited book of new…

  17. The power of virtual integration: an interview with Dell Computer's Michael Dell. Interview by Joan Magretta.

    Dell, M


    Michael Dell started his computer company in 1984 with a simple business insight. He could bypass the dealer channel through which personal computers were then being sold and sell directly to customers, building products to order. Dell's direct model eliminated the dealer's markup and the risks associated with carrying large inventories of finished goods. In this interview, Michael Dell provides a detailed description of how his company is pushing that business model one step further, toward what he calls virtual integration. Dell is using technology and information to blur the traditional boundaries in the value chain between suppliers, manufacturers, and customers. The individual pieces of Dell's strategy--customer focus, supplier partnerships, mass customization, just-in-time manufacturing--may be all be familiar. But Michael Dell's business insight into how to combine them is highly innovative. Direct relationships with customers create valuable information, which in turn allows the company to coordinate its entire value chain back through manufacturing to product design. Dell describes how his company has come to achieve this tight coordination without the "drag effect" of ownership. Dell reaps the advantages of being vertically integrated without incurring the costs, all the while achieving the focus, agility, and speed of a virtual organization. As envisioned by Michael Dell, virtual integration may well become a new organizational model for the information age.

  18. "Raising Standards" or Reducing Aspirations and Opportunities Still Further? Michael Gove and Examination Reforms

    Allen, Martin


    Well before the examinations grade crisis of 2012, Michael Gove had set out clear intentions for reforming public examinations. Though he claimed to be improving examinations and assessment by replicating practices that took place in high-performing countries and thus improving the ability of the UK economy to "compete", this…

  19. Noted astrophysicist Michael S. Turner to Head NSF'S mathematical and physical sciences directorate


    "The National Science Foundation has named celebrated astrophysicist Michael S. Turner of the University of Chicago as Assistant Director for Mathematical and Physical Sciences. He will head a $1 billion directorate that supports research in mathematics, physics, chemistry, materials and astronomy, as well as multidisciplinary programs and education" (1/2 page).

  20. Synthesis of bicyclic guanidines via cascade hydroamination/Michael additions of mono-N-acryloylpropargylguanidines.

    Kwon, Ki-Hyeok; Serrano, Catherine M; Koch, Michael; Barrows, Louis R; Looper, Ryan E


    A cascade silver(I)-catalyzed hydroamination/Michael addition sequence has been developed to deliver highly substituted bicyclic guanidines. This transformation gives rise to geometrically and constitutionally stable ene-guanidines and generates a remote stereocenter with moderate to high diastereoselectivity.

  1. Little Mosie from the Margaree: A Biography of Moses Michael Coady.

    Welton, Michael R.

    This book examines the life of the Reverend Moses Michael Coady (1890-1959), a Roman Catholic priest who led the Antigonish Movement. During the Antigonish Movement, residents of the small maritime town of Antigonish, Nova Scotia, worked to achieve a nonviolent alternative to communism and fascism and to effect the social and economic…

  2. Michael Pressley's Contributions to the History and Future of Strategies Research

    Harris, Karen R.; Alexander, Patricia; Graham, Steve


    The history of strategies research during the past quarter century has been a story of significant conceptualizations and reconceptualizations regarding the nature, development, and teaching of cognitive and metacognitive strategies. Theoretical models, empirical research, and discussions contributed by Michael Pressley have been central to…

  3. Outside in America: George Michael's music video, public sex and global pop culture

    Kooijman, J.


    Six months after his controversial arrest for ‘lewd conduct’ at a men’s public restroom in Beverly Hills, British pop star George Michael released the song and music video ‘Outside’ which can be seen as an explicit commentary on the controversy. In this article, I read the music video in three ways:

  4. Vice Premier Zeng Peiyan Meets with Michael Cohrs, CEO of Corporate & Investment Banking of Deutsche Bank


    <正>Invited by the CPAFFC, Michael Cohrs, Chief Executive Officer of the Corporate and Investment Banking of Deutsche Bank, visited Beijing from February 26 to 28, 2004. Vice Premier Zeng Peiyan of the State Council met with Cohrs and his party. Deutsche Bank AG, a global multipurpose bank

  5. Gender Relations and Sexual Harassment in the Workplace: Michael Crichton's "Disclosure" as a Teaching Tool.

    Comer, Debra R.; Cooper, Elizabeth A.


    Describes how to use Michael Crichton's novel "Disclosure" and the film based on it for class discussions of such issues as what constitutes sexual harassment, harassment of men, relationship between sexual harassment and power, organizational responses to harassment, and gender differences in career advancement tactics. (SK)

  6. Briti ekspert : euroliidus kaob Eestist tööpuudus / Michael Richardson ; interv. Airi Ilisson

    Richardson, Michael


    Eestis Suurbritannia tööreformi tutvustava töö- ja sotsiaalnõuniku sõnul on Suurbritannias peaaegu kadunud pikaajaline töötus noorte hulgas, vanematest inimestest on vaid üksikud tööta kauem kui aasta. Vt. samas: Kes on Michael Richardson?

  7. Michael Peters' Lyotardian Account of Postmodernism and Education: Some Epistemic Problems and Naturalistic Solutions

    Clark, John A.


    Postmodernism has established a significant hold in educational thought and some of the most important ideas are to be found in the writings of Michael Peters. This paper examines his postmodern stance and use of Lyotard's account of knowledge, and from a naturalist point of view raises a number of objections centred on science as a metanarrative,…

  8. Schools as "Poetry-Friendly Places": Michael Rosen on Poetry in the Curriculum

    Xerri, Daniel


    This article explores the views of children's poet Michael Rosen in relation to poetry in education. It is based on an interview in which Rosen not only discusses the significance of encouraging young people to engage with poetry at school but also analyzes a number of threats to poetry's place in the English curriculum. This article identifies…

  9. Training and Mastery of Techniques in Wittgenstein's Later Philosophy: A Response to Michael Luntley

    Stickney, Jeff


    Responding to Michael Luntley's article, "Learning, Empowerment and Judgement," the author shows he cannot successfully make the following three moves: (1) dissolve the analytic distinction between learning by training and learning by reasoning, while advocating the latter; (2) diminish the role of training in Wittgenstein's philosophy, nor…

  10. Subjectivity and Cultural Adjustment in Mathematics Education: A Response to Wolff-Michael Roth

    Brown, Tony


    In this volume, Wolff-Michael Roth provides a critical but partial reading of Tony Brown's book "Mathematics Education and Subjectivity". The reading contrasts Brown's approach with Roth's own conception of subjectivity as derived from the work of Vygotsky, in which Roth aims to "reunite" psychology and sociology. Brown's book, however, focuses on…

  11. Enzymatic carbon-carbon bond-forming Michael-type additions

    Geertsema, Edzard; Poelarends, Gerrit; Faber, Kurt; Fessner, Wolf-Dieter; Turner, Nicholas


    This chapter gives an overview of practical biocatalytic procedures for C-C bond-forming Michael(-type) additions suitable for organic synthesis purposes. Reported product yields, workup and isolation methods, stereoselectivity, and availability of the applied enzymes are assessed. All methodologies

  12. Kunstlik viljastamine - kas rahva püsimajäämise võti? / Michael Cook

    Cook, Michael


    Kunstlikust viljastamisest pole üksi abi - vaid siis, kui noored mehed ja naised pööravad selja tarbimiskultusele ja individualismile, hakkab sündimus tõusma taastootmisest kõrgemale, kirjutab BioEdge toimetaja Michael Cook

  13. The Educational Philosophies of Mordecai Kaplan and Michael Rosenak: Surprising Similarities and Illuminating Differences

    Schein, Jeffrey; Caplan, Eric


    The thoughts of Mordecai Kaplan and Michael Rosenak present surprising commonalities as well as illuminating differences. Similarities include the perception that Judaism and Jewish education are in crisis, the belief that Jewish peoplehood must include commitment to meaningful content, the need for teachers to teach from a position of…

  14. Michael Perelman: An ecological future in view of Marxist Economics (Ⅱ)

    Ren Xiaomei


    @@ Interviewee profile: Michael Perelman, currently professor of Economics Department of California State University, USA, American economist and economic historian with nearly 20 publications in the field of economics criticism, including Railroading Economics, Manufacturing Discontent, The Perverse Economy, and The Invention of Capitalism.

  15. Neuroscientific Investigator of High Mathematical Ability: An Interview with Michael W. O'Boyle

    Kalbfleisch, M. Layne


    This article presents an interview with Michael W. O'Boyle, a neuroscientific investigator of high mathematical ability. O'Boyle is a professor in the Department of Human Development and Family Studies, Texas Tech University, and Adjunct Professor of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center.…

  16. A tribute to Michael R. Raupach for contributions to aeolian fluid dynamics

    Since the early work of Bagnold in the 1940s, aeolian research has grown to become a major integral part of earth-system studies. Many individuals have contributed to this development, and Dr. Michael R. Raupach (MR2, 1950 – 2015) was one of the most outstanding. MR2 worked for about a decade (1985 ...

  17. What Work Do the Concepts of "Language" and "Literature" Do for Michael Rosenak?

    Levisohn, Jon A.


    Michael Rosenak uses the twin metaphors of "language" and "literature," borrowed from Oakeshott and Peters, to argue that the goal of education is initiation into a language. This goal transcends the study of literature in that language. It includes, as well, the development of the capacity both to critique literature and to…

  18. Book Review of "The Molecular Biology of Cancer" by Stella Pelengaris, Michael Khan (Editors

    Schmidt Christian


    Full Text Available Abstract Here, a review of "The Molecular Biology of Cancer" (Stella Pelengaris and Michael Khan [Editors] is given. The detailed description of the book is provided here: Pelengaris S, Khan M (Eds: The Molecular Biology of Cancer; Blackwell Publishing, Oxford (U.K.; 2006. 531 pages, 214 illustrations, ISBN 9-78140-511-814-9, £31.99.

  19. Outside in America: George Michael's music video, public sex and global pop culture

    Kooijman, J.


    Six months after his controversial arrest for ‘lewd conduct’ at a men’s public restroom in Beverly Hills, British pop star George Michael released the song and music video ‘Outside’ which can be seen as an explicit commentary on the controversy. In this article, I read the music video in three ways:

  20. Michael Faraday on the Learning of Science and Attitudes of Mind.

    Crawford, Elspeth


    Makes use of Michael Faraday's ideas on learning, focusing on his attitudes toward the unknowns of science and the development of an attitude that improves scientific decision making. This approach acknowledges that there is an inner struggle involved in facing unknowns. (DDR)

  1. An efficient green synthesis of dispirohydroquinolines via a diastereoselective one-pot eight-component reaction

    Sajjad Salahia; Malek Taher Maghsoodloua; Nourallah Hazeria; Mojtaba Lashkaria; Santiago Garcia-Granda; Laura Torre-Fernandez


    The one-pot eight-component reaction between Meldrum's acid, an aromatic aldehyde, and an aryl amine was achieved in the presence of citric acid catalyst. The corresponding dispirohydroquino-lines were obtained in good yields with excellent diastereoselectivity. This method is a combination of the Knoevenagel and Michael reactions.

  2. New Type of Donor-Acceptor Through-Space Conjugated Polymer

    Lin Lin


    Full Text Available We report the synthesis and properties of a novel through-space conjugated polymer with a [2.2]paracyclophane skeleton. The obtained polymer possessed donor (fluorene and acceptor (2,1,3-benzothiadiazole segments that were alternately π-stacked in proximity via the [2.2]paracyclophane moieties. The good overlap between the emission peak of the donor unit (fluorene and the CT band of the acceptor unit (2,1,3-benzothiadiazole caused fluorescence resonance energy transfer, and the visible green light emission from the acceptor unit was observed.

  3. Pyrimidone-based series of glucokinase activators with alternative donor-acceptor motif.

    Filipski, Kevin J; Guzman-Perez, Angel; Bian, Jianwei; Perreault, Christian; Aspnes, Gary E; Didiuk, Mary T; Dow, Robert L; Hank, Richard F; Jones, Christopher S; Maguire, Robert J; Tu, Meihua; Zeng, Dongxiang; Liu, Shenping; Knafels, John D; Litchfield, John; Atkinson, Karen; Derksen, David R; Bourbonais, Francis; Gajiwala, Ketan S; Hickey, Michael; Johnson, Theodore O; Humphries, Paul S; Pfefferkorn, Jeffrey A


    Glucokinase activators are a class of experimental agents under investigation as a therapy for Type 2 diabetes mellitus. An X-ray crystal structure of a modestly potent agent revealed the potential to substitute the common heterocyclic amide donor-acceptor motif for a pyridone moiety. We have successfully demonstrated that both pyridone and pyrimidone heterocycles can be used as a potent donor-acceptor substituent. Several sub-micromolar analogs that possess the desired partial activator profile were synthesized and characterized. Unfortunately, the most potent activators suffered from sub-optimal pharmacokinetic properties. Nonetheless, these donor-acceptor motifs may find utility in other glucokinase activator series or beyond.

  4. Optical spectroscopy of single beryllium acceptors in GaAs/AlGaAs quantum well

    Petrov, P. V.; Kokurin, I. A.; Klimko, G. V.; Ivanov, S. V.; Ivánov, Yu. L.; Koenraad, P. M.; Silov, A. Yu.; Averkiev, N. S.


    We carry out microphotoluminescence measurements of an acceptor-bound exciton (A0X ) recombination in the applied magnetic field with a single impurity resolution. In order to describe the obtained spectra we develop a theoretical model taking into account a quantum well (QW) confinement, an electron-hole and hole-hole exchange interaction. By means of fitting the measured data with the model we are able to study the fine structure of individual acceptors inside the QW. The good agreement between our experiments and the model indicates that we observe single acceptors in a pure two-dimensional environment whose states are unstrained in the QW plain.

  5. Solid state reactions of nitrogenous heterocyclic compounds (Ⅱ)——Solid state reactions of indole with carbonyl compounds

    李晓陆; 王永梅; 杜大明; 文忠; 熊国祥; 孟继本


    Solid state Michael addition reaction of indole with α,β-unsaturaled carbonyl compounds was carried out,by which a series of compounds containing three different heterocyclic groups binding to one carbon atom were obtained.In the presence of Lewis acid,indole could undergo the solid state condensation reaction with aromatic ketones and aldehydes or quinones.The solid state reaction showed higher selectivity and yield than solution reaction The structures of products were identified by IR,1H NMR,MS,elemental analysis and X-ray crystal analysis.The reaction mechanism was also proposed.

  6. Polymer-incarcerated gold-palladium nanoclusters with boron on carbon: a mild and efficient catalyst for the sequential aerobic oxidation-Michael addition of 1,3-dicarbonyl compounds to allylic alcohols.

    Yoo, Woo-Jin; Miyamura, Hiroyuki; Kobayashi, Shuū


    We have developed a polymer-incarcerated bimetallic Au-Pd nanocluster and boron as a catalyst for the sequential oxidation-addition reaction of 1,3-dicarbonyl compounds with allylic alcohols. The desired tandem reaction products were obtained in good to excellent yields under mild conditions with broad substrate scope. In the course of our studies, we discovered that the excess reducing agent, sodium borohydride, reacts with the polymer backbone to generate an immobilized tetravalent boron catalyst for the Michael reaction. In addition, we found bimetallic Au-Pd nanoclusters to be particularly effective for the aerobic oxidation of allylic alcohols under base- and water-free conditions. The ability to conduct the reaction under relatively neutral and anhydrous conditions proved to be key in maintaining good catalyst activity during recovery and reuse of the catalyst. Structural characterization (STEM, EDS, SEM, and N(2) absorption/desorption isotherm) of the newly prepared PI/CB-Au/Pd/B was performed and compared to PI/CB-Au/Pd. We found that while boron was important for the Michael addition reaction, it was found to alter the structural profile of the polymer-carbon black composite material to negatively affect the allylic oxidation reaction.

  7. Spectrophotometric and thermal studies on the charge--transfer complexes of 4-(aminomethyl) piperidine as donor with σ- and π-electron acceptors.

    Mostafa, Adel; El-Ghossein, Nada; Alqaradawi, Siham Y


    The spectroscopic characteristics of the solid charge-transfer molecular complexes (CT) formed in the reaction of the electron donor 4-(aminomethyl) piperidine (4AMP) with the σ-acceptor iodine and the π-acceptors 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TBCHD) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) have been studied in chloroform at 25°C. These were investigated through electronic, infrared spectra and thermal analysis as well as elemental analysis. The results show that the formed solid CT-complexes have the formulas [(4AMP)I](+)I3(-), [(4AMP)(DDQ)2] and [(4AMP)(TBCHD)] while in the case of 4AMP-TCNQ reaction, a short-lived CT complex is formed followed by rapid N-substitution by TCNQ forming the final reaction product 7,7,8-tricyano-8-aminomethylpiperidinylquinodimethane [TCAMPQDM] in full agreement with the known reaction stoichiometries in solution as well as the elemental measurements and the thermal analysis confirmed the structure of the obtained compounds. The formation constant kCT, molar extinction coefficient εCT, free energy change ΔG(0) and CT energy ECT have been calculated for the CT-complexes [(4AMP)I](+)I3(-), [(4AMP)(DDQ)2] and [(4AMP)(TBCHD)].

  8. Interface-induced heavy-hole/light-hole splitting of acceptors in silicon

    Mol, J. A. [Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH (United Kingdom); Salfi, J.; Simmons, M. Y.; Rogge, S., E-mail: [Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Rahman, R.; Hsueh, Y.; Klimeck, G. [Purdue University, West Lafayette, Indiana 47906 (United States); Miwa, J. A. [Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C (Denmark)


    The energy spectrum of spin-orbit coupled states of individual sub-surface boron acceptor dopants in silicon have been investigated using scanning tunneling spectroscopy at cryogenic temperatures. The spatially resolved tunnel spectra show two resonances, which we ascribe to the heavy- and light-hole Kramers doublets. This type of broken degeneracy has recently been argued to be advantageous for the lifetime of acceptor-based qubits [R. Ruskov and C. Tahan, Phys. Rev. B 88, 064308 (2013)]. The depth dependent energy splitting between the heavy- and light-hole Kramers doublets is consistent with tight binding calculations, and is in excess of 1 meV for all acceptors within the experimentally accessible depth range (<2 nm from the surface). These results will aid the development of tunable acceptor-based qubits in silicon with long coherence times and the possibility for electrical manipulation.

  9. Time-resolved spectroscopy of the fluorescence quenching of a donor — acceptor pair by halothane

    Sharma, A.; Draxler, S.; Lippitsch, M. E.


    Donor (anthracene) sensitized acceptor (perylene) fluorescence is quenched more efficiently by halothane than is intrinsic perylene fluorescence. The underlying process of dynamic fluorescence quenching is investigated by time-resolved fluorescence spectroscopy.

  10. Computational design of donor-bridge-acceptor systems exhibiting pronounced quantum interference effects.

    Gorczak, Natalie; Renaud, Nicolas; Galan, Elena; Eelkema, Rienk; Siebbeles, Laurens D A; Grozema, Ferdinand C


    Quantum interference is a well-known phenomenon that dictates charge transport properties of single molecule junctions. However, reports on quantum interference in donor-bridge-acceptor molecules are scarce. This might be due to the difficulties in meeting the conditions for the presence of quantum interference in a donor-bridge-acceptor system. The electronic coupling between the donor, bridge, and acceptor moieties must be weak in order to ensure localised initial and final states for charge transfer. Yet, it must be strong enough to allow all bridge orbitals to mediate charge transfer. We present the computational route to the design of a donor-bridge-acceptor molecule that features the right balance between these contradicting requirements and exhibits pronounced interference effects.

  11. A Novel Donor Acceptor Substituted Chiroptical Molecular Switch : Physical Properties and Photoisomerization Behavior

    Delden, R.A. van; Schoevaars, A.M.; Feringa, B.L.


    A novel donor acceptor substituted sterically overcrowded alkene was synthesized and characterized. Photoisomerization experiments it showed that this system could be converted with high efficiency towards a cis photostationary state and although the reverse isomerization towards the trans state was

  12. [Lipases in catalytic reactions of organic chemistry].

    Bezborodov, A M; Zagustina, N A


    Aspects of enzymatic catalysis in lipase-catalyzed reactions of organic synthesis are discussed in the review. The data on modern methods of protein engineering and enzyme modification allowing a broader range of used substrates are briefly summarized. The application of lipase in the preparation of pharmaceuticals and agrochemicals containing no inactive enantiomers and in the synthesis of secondary alcohol enantiomers and optically active amides is demonstrated. The subject of lipase involvement in the C-C bond formation in the Michael reaction is discussed. Data on the enzymatic synthesis of construction materials--polyesters, siloxanes, etc.--are presented. Examples demonstrating the application of lipase enzymatic catalysis in industry are given.

  13. Electron Donor-Acceptor Quenching and Photoinduced Electron Transfer for Coumarin Dyes.


    Mechanism of cousarin photodegradation . Ithe behavior of eoiuma dyes is water ad In aqueous detergent media,. and the effsects of medism aud, additives on...D-i36 345 ELECTRON DONOR-ACCEPTOR UENCHING AND PHOTOINDUCED i/i Ai ELECTRON TRANSFER FOR COUMARIN DYES (U) BOSTON UNIY MR DEPT OF CHEMISTRY G JONES...TYPE OF REPORT & PEIOD COVERED Electron Donor-acceptor Quenching and Photo- Technical, 1/1/82-10/31/82 induced Electron Transfer for Coumarin Dyes S

  14. Grain boundary defect chemistry of acceptor-doped titanates: Space charge layer width

    Vollman, M.; Waser, R. [Inst. fuer Werkstoffe der Elektrotechnik, Aachen (Germany)


    The grain boundary space charge depletion layers in acceptor-doped SrTiO{sub 3} ceramics were investigated by impedance spectroscopy in the time and frequency domain. Based on the layer and its dependence on the acceptor concentration, the temperature, and the oxygen partial pressure during annealing, a suggestion for a refined Schottky model is proposed. The local distribution of the donor type grain boundary states causing the depletion layer and the resulting band bending are discussed.

  15. Ternary Organic Solar Cells Based on Two Compatible Nonfullerene Acceptors with Power Conversion Efficiency >10.

    Liu, Tao; Guo, Yuan; Yi, Yuanping; Huo, Lijun; Xue, Xiaonan; Sun, Xiaobo; Fu, Huiting; Xiong, Wentao; Meng, Dong; Wang, Zhaohui; Liu, Feng; Russell, Thomas P; Sun, Yanming


    Two different nonfullerene acceptors and one copolymer are used to fabricate ternary organic solar cells (OSCs). The two acceptors show unique interactions that reduce crystallinity and form a homogeneous mixed phase in the blend film, leading to a high efficiency of ≈10.3%, the highest performance reported for nonfullerene ternary blends. This work provides a new approach to fabricate high-performance OSCs.

  16. Rise-time of FRET-acceptor fluorescence tracks protein folding

    Simon Lindhoud; Adrie H. Westphal; van Mierlo, Carlo P. M.; Visser, Antonie J. W. G.; Jan Willem Borst


    Uniform labeling of proteins with fluorescent donor and acceptor dyes with an equimolar ratio is paramount for accurate determination of Förster resonance energy transfer (FRET) efficiencies. In practice, however, the labeled protein population contains donor-labeled molecules that have no corresponding acceptor. These FRET-inactive donors contaminate the donor fluorescence signal, which leads to underestimation of FRET efficiencies in conventional fluorescence intensity and lifetime-based F...

  17. Beyond Fullerenes: Designing Alternative Molecular Electron Acceptors for Solution-Processable Bulk Heterojunction Organic Photovoltaics.

    Sauvé, Geneviève; Fernando, Roshan


    Organic photovoltaics (OPVs) are promising candidates for providing a low cost, widespread energy source by converting sunlight into electricity. Solution-processable active layers have predominantly consisted of a conjugated polymer donor blended with a fullerene derivative as the acceptor. Although fullerene derivatives have been the acceptor of choice, they have drawbacks such as weak visible light absorption and poor energy tuning that limit overall efficiencies. This has recently fueled new research to explore alternative acceptors that would overcome those limitations. During this exploration, one question arises: what are the important design principles for developing nonfullerene acceptors? It is generally accepted that acceptors should have high electron affinity, electron mobility, and absorption coefficient in the visible and near-IR region of the spectra. In this Perspective, we argue that alternative molecular acceptors, when blended with a conjugated polymer donor, should also have large nonplanar structures to promote nanoscale phase separation, charge separation and charge transport in blend films. Additionally, new material design should address the low dielectric constant of organic semiconductors that have so far limited their widespread application.

  18. The Effect of Acceptor and Donor Doping on Oxygen Vacancy Concentrations in Lead Zirconate Titanate (PZT

    Christoph Slouka


    Full Text Available The different properties of acceptor-doped (hard and donor-doped (soft lead zirconate titanate (PZT ceramics are often attributed to different amounts of oxygen vacancies introduced by the dopant. Acceptor doping is believed to cause high oxygen vacancy concentrations, while donors are expected to strongly suppress their amount. In this study, La3+ donor-doped, Fe3+ acceptor-doped and La3+/Fe3+-co-doped PZT samples were investigated by oxygen tracer exchange and electrochemical impedance spectroscopy in order to analyse the effect of doping on oxygen vacancy concentrations. Relative changes in the tracer diffusion coefficients for different doping and quantitative relations between defect concentrations allowed estimates of oxygen vacancy concentrations. Donor doping does not completely suppress the formation of oxygen vacancies; rather, it concentrates them in the grain boundary region. Acceptor doping enhances the amount of oxygen vacancies but estimates suggest that bulk concentrations are still in the ppm range, even for 1% acceptor doping. Trapped holes might thus considerably contribute to the charge balancing of the acceptor dopants. This could also be of relevance in understanding the properties of hard and soft PZT.

  19. The Effect of Acceptor and Donor Doping on Oxygen Vacancy Concentrations in Lead Zirconate Titanate (PZT)

    Slouka, Christoph; Kainz, Theresa; Navickas, Edvinas; Walch, Gregor; Hutter, Herbert; Reichmann, Klaus; Fleig, Jürgen


    The different properties of acceptor-doped (hard) and donor-doped (soft) lead zirconate titanate (PZT) ceramics are often attributed to different amounts of oxygen vacancies introduced by the dopant. Acceptor doping is believed to cause high oxygen vacancy concentrations, while donors are expected to strongly suppress their amount. In this study, La3+ donor-doped, Fe3+ acceptor-doped and La3+/Fe3+-co-doped PZT samples were investigated by oxygen tracer exchange and electrochemical impedance spectroscopy in order to analyse the effect of doping on oxygen vacancy concentrations. Relative changes in the tracer diffusion coefficients for different doping and quantitative relations between defect concentrations allowed estimates of oxygen vacancy concentrations. Donor doping does not completely suppress the formation of oxygen vacancies; rather, it concentrates them in the grain boundary region. Acceptor doping enhances the amount of oxygen vacancies but estimates suggest that bulk concentrations are still in the ppm range, even for 1% acceptor doping. Trapped holes might thus considerably contribute to the charge balancing of the acceptor dopants. This could also be of relevance in understanding the properties of hard and soft PZT. PMID:28774067

  20. Molecular helices as electron acceptors in high-performance bulk heterojunction solar cells.

    Zhong, Yu; Trinh, M Tuan; Chen, Rongsheng; Purdum, Geoffrey E; Khlyabich, Petr P; Sezen, Melda; Oh, Seokjoon; Zhu, Haiming; Fowler, Brandon; Zhang, Boyuan; Wang, Wei; Nam, Chang-Yong; Sfeir, Matthew Y; Black, Charles T; Steigerwald, Michael L; Loo, Yueh-Lin; Ng, Fay; Zhu, X-Y; Nuckolls, Colin


    Despite numerous organic semiconducting materials synthesized for organic photovoltaics in the past decade, fullerenes are widely used as electron acceptors in highly efficient bulk-heterojunction solar cells. None of the non-fullerene bulk heterojunction solar cells have achieved efficiencies as high as fullerene-based solar cells. Design principles for fullerene-free acceptors remain unclear in the field. Here we report examples of helical molecular semiconductors as electron acceptors that are on par with fullerene derivatives in efficient solar cells. We achieved an 8.3% power conversion efficiency in a solar cell, which is a record high for non-fullerene bulk heterojunctions. Femtosecond transient absorption spectroscopy revealed both electron and hole transfer processes at the donor-acceptor interfaces. Atomic force microscopy reveals a mesh-like network of acceptors with pores that are tens of nanometres in diameter for efficient exciton separation and charge transport. This study describes a new motif for designing highly efficient acceptors for organic solar cells.