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Fréchet-type Poly (fréchet-type + poly)

Distribution by Scientific Domains

Chemistry	75%

Selected Abstracts

Synthesis of Carrier-Transporting Dendrimers with Perylenebis(dicarboximide)s as a Luminescent Core

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2006
Jianfeng Pan
Abstract Well-defined, modular dendrimers enable processing techniques and electronic properties to be tuned independently. Moreover, the dendritic topology can isolate the core chromophore, thus reducing or eliminating strong intermolecular interactions. This paper presents the synthesis of three series of flexible, dendron-functionalized dendrimers as red-light-emitting materials by a convergent approach: (1) carbazole (CZ) or oxadiazole (OXZ) terminated imide-type dendrimers, (2) cascade energy-transferring imide-type dendrimers, and (3) CZ-terminated perylene bay-type dendrimers. They all consist of the luminescent core of perylenebis(dicarboximide)s with specific functional groups of CZ or OXZ at the periphery and are constructed from flexible Fréchet-type poly(aryl ether) dendrons. The chemical structures of the dendrons and dendrimers were determined by standard spectroscopic techniques including 1H and 13C NMR spectroscopy and low/high-resolution mass spectrometry (ESI or MALDI-TOF). The dendrimers are designed on the basis of the following considerations: (1) dendron functionalization to incorporate CZ or OXZ units to realize the carrier-injection adjustment, (2) tuning or improving solubility, functionality, glass-transition temperature (Tg) with well-defined dendrons, and (3) avoiding luminescence quenching with the help of high site-isolation of dendrons to enhance core luminescence. DSC results indicate that the incorporation of Fréchet-type poly(aryl ether) dendrons can improve the amorphous properties and increase Tg. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Fluorocarbon End-functionalized Polymers from Poly(arylether) Dendritic Initiators

MACROMOLECULAR SYMPOSIA, Issue 1 2005
A. Pillay Narrainen
Abstract Fréchet-type poly(arylether) first and second generation (G1 and G2 respectively) dendrons were prepared from 1-(bromomethyl)-3,5-bis(trifluoromethyl)benzene. The latter and the brominated versions of the two dendrons were successfully employed in the copper mediated living radical polymerization (LRP) of styrene-d8 giving polymers of predictable molecular weights and narrow polydispersities. Contact angle measurements and ion beam analysis were used to explore the adsorption of these materials to the air-polymer surface in blended films with unfunctionalized hydrogenous polystyrene. Although contact angle analysis indicated only modest changes in the hydrophobicity and lipophobicity of the surface, ion beam analysis clearly showed the formation of an excess layer of dendron functionalized polymer at the exposed surface that increased with increasing fluorine content. [source]

Synthesis of Dendritic BINAP Ligands and Their Applications in Asymmetric Hydrogenation

CHINESE JOURNAL OF CHEMISTRY, Issue 11 2002
Guo-Jun Deng
Abstract A new type of chiral dendritic ligands with 2,2,-bis(diphenylphosphino)-1,1,-binaphthyl (BINAP) located at the focal point of the dendrimer has been synthesized through the condensation reaction of 5-amino BINAP and Fréchet-type poly (aryl ether) dendrons with carboxyl groups as the linker in high reaction yields, respectively. The ruthenium complexes of these dendritic ligands were found to be very efficient catalysts in asymmetric hydrogenation of 2-phenylacryclic acids as well as facile catalyst recycling. [source]