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Modular Synthetic Approach (modular + synthetic_approach)
Selected AbstractsA Modular Synthetic Approach to Conjugated Pentacene Di-, Tri-, and Tetramers,ANGEWANDTE CHEMIE, Issue 35 2010Dan Lehnherr Achtung, Bandlücke! Di-, tri- und tetramere Pentacene können aus einem vielfältig einsetzbaren Baustein durch Hay-Homokupplungen und auch durch Cadiot-Chodkiewicz-Kreuzkupplungen synthetisiert werden. Durch diese modulare Herangehensweise können Löslichkeit, Stabilität und HOMO-LUMO-Bandlücke der Verbindungen in Abhängigkeit von ihrer Länge bewertet werden. Im iBu3Si-substituierten Pentacen-Dimer treten weit reichende dreidimensionale ,-Überlappungen auf (siehe Bild; n=2). [source] Highly Efficient and Versatile Phosphine-Phosphoramidite Ligands for Asymmetric HydrogenationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2009Matthias Eggenstein Abstract A set of novel phosphine-phosphoramidite ligands possessing two elements of chirality have been prepared through a modular synthetic approach. The ligands (11bS)- N -[2-(diphenylphosphino)phenyl]- N -[(S)-1-phenylethyl]dinaphtho[2,1- d:1,,2,- f][1,3,2]dioxaphosphepin-4-amine [(Sa,Sc)- 1a] and (11bR)- N -[2-(diphenylphosphino)phenyl]- N -[(S)-1-(1-naphthyl)ethyl]dinaphtho[2,1- d:1,,2,- f][1,3,2]dioxaphosphepin-4-amine [(Sa,Sc)- 1b] are unique in providing enantioselectivities ,96% ee and ,94% ee, respectively, in mechanistically distinct hydrogenations of CC, CN and CO double bonds in combination with three different transition metals (rhodium, iridium, and ruthenium, respectively). Particularly remarkable are the enantiomeric excesses up to 97% achieved in the iridium-catalyzed hydrogenation of 2-substituted quinolines, where (11bS)- N -[2-(diphenylphosphino)phenyl]- N -[(S)-1-(naphthalen-1-yl)ethyl]-8,9,10,11, 12,13,14,15-octahydrodinaphtho[2,1- d:1,,2,- f][1,3,2]dioxaphosphepin-4-amine [(Sa,Sc)- 2] proved to be the most selective ligand. Substantially lower ees were obtained with the mismatched diastereomer (Ra,Sc)- 1b and with the N -phenyl-substituted ligand 1c, missing a second element of chirality. [source] Triaminotriazines,photophysical investigations of a porphyrin-appended triazine receptor with a naphthalene diimide guest,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 8-9 2006Kenneth P. Ghiggino Abstract A modular synthetic approach to preparing a family of triaminotriazine receptors bearing porphyrin chromophores is described. The porphyrin-appended triaminotriazines are prepared in a stepwise manner employing either cyanuric chloride or fluoride and 5-(4,-aminophenyl)-10,15,20-triphenylporphyrin in the first step. Reaction of the porphyrintriazine with excess 1-pentylamine leads to a triazine core programmed for three-point hydrogen bonding. Addition of a complementary naphthalene diimide yields a supramolecular donor,acceptor dyad. Photophysical studies in CH2Cl2 solvent show efficient quenching of porphyrin fluorescence within the dyad, consistent with an electron transfer process. Copyright © 2006 John Wiley & Sons, Ltd. [source] Tailored composite polymer,metal nanoparticles by miniemulsion polymerization and thiol-ene functionalizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2010Kim Y. van Berkel Abstract A simple and modular synthetic approach, based on miniemulsion polymerization, has been developed for the fabrication of composite polymer,metal nanoparticle materials. The procedure produces well-defined composite structures consisting of gold, silver, or MnFe2O4 nanoparticles (,10 nm in diameter) encapsulated within larger spherical nanoparticles of poly(divinylbenzene) (,100 nm in diameter). This methodology readily permits the incorporation of multiple metal domains into a single polymeric particle, while still preserving the useful optical and magnetic properties of the metal nanoparticles. The morphology of the composite particles is retained upon increasing the inorganic content and also upon redispersion in organic solvents. Finally, the ability to tailor the surface chemistry of the composite nanoparticles and incorporate steric stabilizing groups using simple thiol-ene chemistry is demonstrated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1594,1606, 2010 [source] | ||||||||||