EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2010
Huaqiang Zhang
Abstract Carbazole-based donor,acceptor compounds with tunable HOMO,LUMO gaps were synthesized by Suzuki and Sonogashira cross-coupling reactions. Their optical and electrochemical properties were fully characterized. The results show that materials with different emission colors ranging from blue to green to orange could be obtained. The experimental results were also supported by theoretical calculations. [source]

A New Donor,Acceptor,Donor Polyfluorene Copolymer with Balanced Electron and Hole Mobility,

ADVANCED FUNCTIONAL MATERIALS, Issue 18 2007
A. Gadisa
Abstract A new alternating polyfluorene copolymer poly[2,7-(9,9-dioctylfluoren)- alt -5,5-(5,,8,-di-2-thienyl-(2,,3,-bis-(3,,-octyloxyphenyl)-quinoxaline))] (APFO-15), which has electron donor,acceptor,donor units in between the fluorene units, is synthesized and characterized. This polymer has a strong absorption and emission in the visible range of the solar spectrum. Its electroluminescence and photoluminescence emissions extend from about 560 to 900 nm. Moreover, solar cells with efficiencies in excess of 3.5,% have been realized from blends of APFO-15 and an electron acceptor molecule, a methanofullerene [6,6]-phenyl-C61 -butyric acid methyl ester (PCBM). It has also been observed that electron and hole transport is balanced both in the pure polymer phase and in polymer/PCBM bulk heterojunction films, which makes this material quite attractive for applications in opto-electronic devices. [source]

Hydrogen Bonding of Fluorinated Saccharides in Solution: F Acting as H-Bond Acceptor in a Bifurcated H-Bond of 4-Fluorinated Levoglucosans,

HELVETICA CHIMICA ACTA, Issue 10 2007
Bruno Bernet
Abstract 4-Fluorinated levoglucosans were synthesised to test if OH,,,F H-bonds are feasible even when the O,,,F distance is increased. The fluorinated 1,6-anhydro- , - D -glucopyranoses were synthesised from 1,6,:,3,4-dianhydro- , - D -galactopyranose (8). Treatment of 8 with KHF2 and KF gave 43% of 4-deoxy-4-fluorolevoglucosan (9), which was transformed into the 3- O -protected derivatives 13 by silylation and 15 by silylation, acetylation, and desilylation. 4-Deoxy-4-methyllevoglucosan (19) and 4-deoxylevoglucosan (21) were prepared as reference compounds that can only form a bivalent H-bond from HOC(2) to OC(5). They were synthesised from the iPr3Si-protected derivative of 8. Intramolecular bifurcated H-bonds from HOC(2) to FC(4) and OC(5) of the 4-fluorinated levoglucosans in CDCl3 solution are evidenced by the 1H-NMR scalar couplings h1J(F,OH) and 3J(H,OH). The OH,,,F H-bond over an O,,,F distance of ca. 3.0,Å is thus formed in apolar solvents, at least when favoured by the simultaneous formation of an OH,,,O H-bond. [source]

Effect of Donor, Acceptor, and Donor,Acceptor Codoping on the Electrical Properties of Ba0.6Sr0.4TiO3 Thin Films for Tunable Device Applications

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2009
Yuanyuan Zhang
We have investigated the effects of donor, acceptor, and donor,acceptor codoping on both the dielectric properties and the leakage current behavior of Ba0.6Sr0.4TiO3 thin films prepared by the metalorganic solution deposition technique. La and Co were selected as donor and acceptor dopants, respectively. The electrical properties depend strongly on the type of dopants. Compared with others, codoped BST films have a much lower loss tangent, higher figure of merit, and lower leakage current. The electronic conduction mechanisms of the three types of dopants are reported. [source]

Effect of the Liquid-Phase Characteristic on the Microstructures and Dielectric Properties of Donor- (Niobium) and Acceptor- (Magnesium) Doped Barium Titanate

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2003
Seok-Hyun Yoon
Changes in the microstructure and dielectric properties with the variation of the donor/acceptor ratio in BaTiO3 ceramics were investigated. In donor-rich specimens, a liquid that appeared during sintering did not penetrate into grain boundaries. However, in the acceptor-rich specimens, the grains were separated by a liquid film during sintering. The much higher mobility of the liquid film than that of the grain boundaries was suggested to cause extensive grain growth in acceptor-rich BaTiO3. The macroscopic homogenization of dopants because of grain growth in acceptor-rich specimens resulted in changes in the dielectric properties. [source]

Composite Worm-Like Aggregates Formed from a Pair of Block-Copolymers Containing Hydrogen-Bonding Donor and Acceptor

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 2 2007
De'an Xiong
Abstract Worm-like aggregates with a PAA/P4VP complex core and a PEG/PNIPAM mixed shell were prepared in ethanol by the comicellization of poly(ethylene glycol)- block -poly(acrylic acid) (PEG- b -PAA) and poly(N -isopropylacrylamide)- block -poly(4-vinylpyridine) (PNIPAM- b -P4VP) through hydrogen-bonding. The formed aggregates were studied by dynamic light scattering, static light scattering, 1H NMR, and transmission electron microscopy. The length of worm-like aggregates could be adjusted by changing the weight ratio of W(PNIPAM- b -P4VP)/W(PEG- b -PAA). When the ratio changed from 20 to 150%, the length changed from about 100 nm to several microns, and the diameter stayed almost unchanged at about 15 nm. [source]

A Water Soluble Donor,Acceptor [2]Catenane that Can Switch between a Coplanar and a Gemini-Sign Conformation,

ANGEWANDTE CHEMIE, Issue 31 2010
Yu Au-Yeung
Im Zeichen des Zwillings: Ein Donor-Akzeptor-[2]Catenan mit schaltbarer Konformation wurde aus einer dynamischen kombinatorischen Bibliothek erhalten. In einer der Konformationen wurde eine neuartige Anordnung der ,-Einheiten beobachtet, die an das astrologische Zeichen für Zwillinge erinnert (rechts). Das Catenan kann durch thermische und chemische Stimuli oder durch Änderung der Hydrophobie seiner Umgebung zwischen der parallelen und der nichtparallelen Konformation geschaltet werden. [source]

A Resonance Energy Transfer Immunoassay Based on a Thiol-Reactive Ruthenium Donor Dye and a Longwave-Emitting Acceptor

CHEMBIOCHEM, Issue 1 2007
Jochen Weh
Abstract A novel immunoassay is described that applies a thiol-reactive ruthenium metal,ligand complex as the donor dye in a luminescence energy transfer (LET) detection scheme. Unlike amine-reactive labels, the LET with a thiol label allows improved specificity and better reproducibility of labelling positions on proteins, because the number of reactive thiol groups of proteins is distinctly smaller. This helps to reduce the risk of over-labelling and self-quenching of the fluorophore. The synthesis of the thiol label was significantly improved, resulting in almost quantitative yields of pure product. The absorption and emission maxima of the ruthenium donor dye are at 460 nm and 600 nm, respectively, and a Stokes' shift of 140 nm warrants distinct separation of excitation and emission wavelengths even in turbid samples. A cyanine dye with an absorption maximum at 642 nm was chosen as the acceptor label because it has good overlap with the emission spectrum of the donor label. The emission of the acceptor peaks at 660 nm, thus further increasing the Stokes' shift (to an overall 200 nm). The quantification of anti-HSA with the LET immunoassay is possible with this new approach at concentrations as low as 220 pmol,L,1. [source]

Highly Selective Coupling of Alkenes and Aldehydes Catalyzed by [Ni(NHC){P(OPh)3}]: Synergy Between a Strong , Donor and a Strong , Acceptor.

CHEMINFORM, Issue 20 2007
Chun-Yu Ho
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Infrared Spectroscopy of Water Cluster Anions, (H2O)n=3-24 - in the HOH Bending Region: Persistence of the Double H-Bond Acceptor (AA) Water Molecule in the Excess Electron Binding Site of the Class I Isomers.

CHEMINFORM, Issue 35 2006
Joseph R. Roscioli
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Heterocyclic Nonlinear Optical Chromophores Composed of Phenothiazine or Carbazole Donor and 2-Cyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran Acceptor

CHEMINFORM, Issue 23 2005
Min Ju Cho
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Stereospecific Deoxygenation of Phosphine Oxides with Retention of Configuration Using Triphenylphosphine or Triethyl Phosphite as an Oxygen Acceptor.

CHEMINFORM, Issue 12 2005
Hai-Chen Wu
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Effect of the Michael Acceptor in the Asymmetric Intramolecular Stetter Reaction.

CHEMINFORM, Issue 7 2004
Mark S. Kerr
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Interferon Alfa-2b or Not 2b?

DERMATOLOGIC SURGERY, Issue 1 2007
Significant Differences Exist in the Decision-Making Process between Melanoma Patients Who Accept or Decline High-Dose Adjuvant Interferon Alfa-2b Treatment
BACKGROUND Patients with thick (Breslow >4 mm) primary melanoma and/or regional nodal metastasis have a high risk of tumor recurrence. High-dose adjuvant interferon (IFN) alfa-2b offers ,10% improvement in relapse-free survival and overall survival with significant toxicity. OBJECTIVE The objective was to determine which prognostic factors and patient characteristics are significant in the decision to undergo IFN therapy. METHODS Of 781 patients who underwent sentinel lymph node (SLN) biopsy, 135 of 781 (17.3%) had positive SLN or thick melanomas and were informed of a ,50% risk of recurrence/disease-related mortality and offered IFN. Telephone surveys delineated reasons behind patients' decisions to accept IFN. RESULTS Acceptors, 60 of 135 (45%), decided to take IFN alfa-2b whereas 75 of 135 (55%) declined. Being female (OR, 2.4; 95% CI, 1.17,5.03; p=.017) and positive SLN status (OR, 2.2; 95% CI, 1.01,4.97; p=.048) were strongly associated with patients who chose IFN. Acceptors of IFN were younger, more influenced by physicians, and less affected by depression and side effect profile (p<.05 for all). Decliners were more concerned by strained relationships with family and social life (p<.05). CONCLUSIONS Gender and positive SLN were predictive of high-risk melanoma patients' acceptance of IFN treatment. Physician insight into melanoma patients' therapeutic decision-making process can guide patients through this difficult disease. [source]

N -Allylideneamines Derived from Acrolein: Synthesis and Use as Acceptors of Two Nucleophiles

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2009
Isao Mizota
Abstract Two practical methods have been developed for the preparation of N -allylideneamines 1b,c. One involves the isomerization of propargylamines and the other the dehydration of acrolein. N -Allylideneamines 1b,c thus prepared were used as efficient substrates for 1,4- and 1,2-double nucleophilic addition reactions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

1,8-Bis(dialkylamino)-4,5-dinitronaphthalenes and 4,5-Bis(dimethylamino)naphthalene-1,8-dicarbaldehyde as "Push,Pull" Proton Sponges: When and Why Formyl Groups Become Stronger ,-Electron Acceptors than Nitro Groups

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2009
Valery A. Ozeryanskii
Abstract Single-crystal X-ray studies of four representatives of "push,pull" proton sponges, namely 1,8-bis(dimethylamino)-, 1,8-bis(diethylamino)-, 1,8-bis(dipropylamino)-4,5-dinitronaphthalenes and 4,5-bis(dimethylamino)naphthalene-1,8-dicarbaldehyde have been performed at low and ambient temperatures. The most interesting and unexpected result is that the formyl groups in the peri -dialdehyde display stronger ,-acceptor effects than the nitro groups. This phenomenon is ascribed to smaller steric demands of the CHO groups, their lower electrostatic repulsion, and specific packing forces. The naphthalene cores of all but one of the molecules are markedly twisted (21,26°) while that of the diethylamino derivative is not (<5°), providing different and somewhat unpredictable ways of resonance stabilization and steric relaxation. The through-conjugation in the above compounds is also discussed for gas and solution phases on the basis of theoretical calculations, UV/Vis and 1H NMR spectra.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Synthesis of Novel Bifunctional Michael Acceptors

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2004
Laura Mediavilla Urbaneja
Abstract The conjugated dienones 1a, 1c,e, and 1g were synthesized by aldol reaction of cyclohex-2-enones 3 with aldehydes or ketones and subsequent elimination. Whereas the acetone adducts could be converted into the desired products 1a/g by treatment with CeCl3·7H2O/NaI, the dienones 1c,e were obtained by Appel bromination and dehydrobromination with triethylamine. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Hybrid Microstructures: One-Dimensional Microwires Formed by the Co-Assembly of Complementary Aromatic Donors and Acceptors (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2009
Mater.
A complementary donor-acceptor pair of truxene derivatives, Tr3 and its oxidized counterpart TrO3, are presented by Pei et al. on page 1746, and used to build a foundation for the investigation of aromatic donor,acceptor interaction. Two-component one-dimensional microstructures are realized by a simple solution process reliant on this interaction. Such a hybrid material opens new possibilities in the future design of multicomponent organic nano- and microstructures. [source]

One-Dimensional Microwires Formed by the Co-Assembly of Complementary Aromatic Donors and Acceptors

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2009
Jie-Yu Wang
Abstract A truxene derivative (Tr3) with a C3 symmetric conjugated plane is synthesized; this derivative is a perfect match, in both size and structure, with its oxidized counterpart, the truxenone derivative (TrO3), a new electron acceptor that was recently reported. The complementary pair, Tr3 and TrO3, sets a good platform for the investigation of aromatic donor,acceptor interactions. Detailed 1H NMR experiments, photoluminescence spectroscopy, as well as differential scanning calorimetry are performed to investigate the interaction between Tr3 and TrO3, from solution to mesophase. One-dimensional microbelts readily formed from a 1:1 mixture of Tr3 and TrO3. Scanning electron microscopy, powder X-ray diffraction, as well as fluorescence microscopy are performed to elucidate their co-assembly structure in the solid state. Moreover, modulation of the co-assembly structure is easily realized by changing the concentration or mixing ratio. The present system opens the possibility of forming 1D heterostructures via electron donor,acceptor interaction, and its potential application as P,N junction and photowaveguide materials in optoelectronic devices. [source]

Cationic Polymerization of 2-Vinylthiophene by Chloroarylmethanes as Surface Initiators on Silica and Consecutive Hydride Abstraction by Acceptors

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 12 2004
Susanne Höhne
Abstract Summary: 2-Vinylthiophene (2-VT) has been cationically polymerized using chloroarylmethane derivatives as the surface polymerization initiator on silica. By applying this procedure a soluble fraction of poly(vinylthiophene) (PVT) and PVT/silica composites can be simultaneously synthesized. The mass balance of the products (soluble fraction and hybrid particle fraction) depends significantly on temperature and 2-VT/silica ratio. The hydride abstraction reaction of PVT both in solution and immobilized on silica particle surface has been studied using 2,3-dichloro-5,6-dicyano-1,4-quinone (DDQ), tetrachloro-1,4-quinone (chloranile,=,ClA) and triphenylmethylium as reagents. The transformation process of PVT towards conjugated polymers has been studied with UV-vis spectroscopy and ESR spectroscopy. Cyclic voltammetry shows that chloranil is complexated with the formed polymer. Radical formation increases with increasing degree of conversion. The soluble fraction of the conjugated PVT sections formed is capable of reacting with each other as evidenced by GPC data. Structure of PVT/silica and resulting hybrid materials have been investigated by solid state 13C {1H} CP MAS NMR-spectroscopy showing a reaction of methine and methylene hydrogen atoms after treatment with DDQ or chloranil as hydride acceptors. For all poly-(2-vinylthiophene)/hydride acceptor systems studied, chloranil has been found to be the best reagent for the transformation of PVT towards conjugated polymers. Transformation of PVT in poly(2-ethinylthiophene) (PET) and PVT-PET copolymers. [source]

Quantitative Structure,Activity Relationship Studies for the Binding Affinities of Imidazobenzodiazepines for the ,6 Benzodiazepine Receptor Isoform Utilizing Optimized Blockwise Variable Combination by Particle Swarm Optimization for Partial Least Squares Modeling

MOLECULAR INFORMATICS, Issue 1 2007
Leqian Hu
Abstract Binding affinities of a series of substituted imidazobenzodiazepines for the ,6 Benzodiazepine Receptor (BzR) isoform are investigated by the Optimized Blockwise Variable Combination (OBVC) by Particle Swarm Optimization (PSO) based on Partial Least Squares (PLS) modeling. The QSAR analysis result showed that MolRef, AlogP, MRCM**-3, Rotatable bonds (Rotlbonds), Hydrogen Bond Acceptors (Hbond acceptor), five Jurs descriptors, two Shadow indices descriptors and principal moment of inertia are the most important descriptors among all the investigated descriptors. One can change the molar refractivity, the polar interactions between molecules, the shape of the molecules, the principal moments of inertia about the principal axes of a molecule, the hydrophobic character of the molecule, the number of Rotlbonds and Hbond acceptors of the compounds to adjust the binding affinities of imidazobenzodiazepine for the ,6 BzR isoform. The Quantitative Structure,Activity Relationship (QSAR) analysis result was also compared with MLR, PLS, and hierarchical PLS algorithms. It has been demonstrated that OBVC by PSO for PLS modeling shows satisfactory performance in the QSAR analysis. [source]

Strain and Hückel Aromaticity: Driving Forces for a Promising New Generation of Electron Acceptors in Organic Electronics,

ANGEWANDTE CHEMIE, Issue 3 2010
G. Brunetti Dr.
Die Hauptmerkmale elektronenakzeptierender Materialien mit einem 9,9,-Bifluorenyliden-Gerüst sind verringerte Ringspannungen und ein Zugewinn an Aromatizität. Die Dimere (siehe Bild) zeigen eine Absorption nahe dem roten Spektralbereich (ca. 600,nm) sowie HOMO- (5.58,5.06,eV) und LUMO-Niveaus (3.37,3.09,eV), die die Materialien zusammen mit ihrer hohen Löslichkeit und thermischen Stabilität zu vielversprechenden Akzeptoren für Bulk-Heterojunction(BHJ)-Solarzellen machen. [source]

ChemInform Abstract: Enantioselective and Regiodivergent Copper-Catalyzed Conjugate Addition Trialkylaluminum Reagents to Extended Nitro-Michael Acceptors.

CHEMINFORM, Issue 41 2010
Matthieu Tissot
Abstract Regio- and enantioselective conjugate addition reaction of trimethyl aluminium (II) to nitroenynes (I) and nitrodienes (VI) is developed. [source]

ChemInform Abstract: Palladium(II)-Catalyzed Conjugate Phosphination of Electron-Deficient Acceptors.

CHEMINFORM, Issue 31 2009
Verena T. Trepohl
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: A Homogeneous, Recyclable Rhodium(I) Catalyst for the Hydroarylation of Michael Acceptors.

CHEMINFORM, Issue 26 2009
Ranjan Jana
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Intermolecular Asymmetric Reductive Aldol Reaction of Ketones as Acceptors Promoted by Chiral Rh(Phebox) Catalyst.

CHEMINFORM, Issue 35 2007
Takushi Shiomi
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Ab initio and AIM Theoretical Analysis of Hydrogen-Bond Radius of HD (D: F, Cl, Br, CN, HO, HS and CCH) Donors and Some Acceptors.

CHEMINFORM, Issue 7 2007
B. Raghavendra
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

,-Alkyl-,-allylation of Michael Acceptors Through the Palladium-Catalyzed Three-Component Coupling Between Allylic Substrates, Trialkylboranes, and Activated Olefins.

CHEMINFORM, Issue 32 2006
Nitin T. Patil
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Reactive Ketimino Radical Acceptors: Intermolecular Alkyl Radical Addition to Imines with a Phenolic Hydroxyl Group.

CHEMINFORM, Issue 29 2006
Hideto Miyabe
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Cyclohexenones as Michael Acceptors in the Staunton,Weinreb Annulation: A Simple Stannane Modification for the Synthesis of Polycyclic Systems.

CHEMINFORM, Issue 12 2006
Bryan Hill
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]