Home  About us  Contact
 

Active Poly (active + poly)

Distribution by Scientific Domains
Polymers and Materials Science80%

Selected Abstracts

Control of Induced Chirality in Optically Active Poly(N-propargylcarbamate) Films by Solvent Vapor

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 15 2009
Toshiyuki Fukushima
Abstract Chiral polyethyne derivatives with lyotropic liquid-crystalline properties are found to be able to self-assemble, forming two chiral organizations with opposite handedness in solid thin films by selection of the casting solvent and its concentration. After the film preparation, chiral organization could also be induced by simple exposure to an appropriate organic solvent's vapor for several minutes without thermal treatment. Furthermore, irreversible inversion of the handedness of the chiral organization in the film could be achieved by exposure to solvent vapor. [source]

Helical Arrays of Pendant Fullerenes on Optically Active Poly(phenylacetylene)s

CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2005
Tatsuya Nishimura Dr.
Abstract Novel, optically active, stereoregular poly(phenylacetylene)s bearing the bulky fullerene as the pendant were synthesized by copolymerization of an achiral phenylacetylene bearing a [60]fullerene unit with optically active phenylacetylene components in the presence of a rhodium catalyst. The C60 -bound phenylacetylene was prepared by treatment of C60 with N -(4-ethynylbenzyl)glycine in a Prato reaction. The obtained copolymers exhibited induced circular dichroism (ICD) in solution both in the main-chain region and in the achiral fullerene chromophoric region, although their ICD intensities were highly dependent on the structures of the optically active phenylacetylenes and the solution temperature. These results indicate that the optically active copolymers form one-handed helical structures and that the pendant achiral fullerene groups are arranged in helical arrays with a predominant screw sense along the polymer backbone. The structures and morphology of the copolymers on solid substrates were also investigated by atomic force microscopy. [source]

Synthesis and chiroptical properties of optically active poly(ethynylcarbazole) derivatives: Substituent effect on the helix formation

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2007
Fumio Sanda
Abstract Novel chiral acetylene monomers containing carbazole, 2-ethynyl-9-[(S)-2-methylbutoxycarbonyl]carbazole (1), 3-ethynyl-9-[(S)-2-methylbutoxycarbonyl]carbazole (2), 2-ethynyl-9-[(S)-2-methylbutyl]carbazole (3), and 2-ethynyl-9-[(S)-4-methylhexyl]carbazole (4) were synthesized and polymerized with [(nbd)RhCl]2Et3N. The corresponding polyacetylenes with number-average molecular weights ranging from 68,700 to 310,000 were obtained in good yields. Poly(1) exhibited a large specific rotation and an intense Cotton effect in toluene, indicating that it formed a helix with predominantly one-handed screw sense, while the other three polymers showed no evidence for taking a helical structure. Poly(1) largely decreased the CD intensity upon heating from ,10 to 60 °C. Poly(1) showed a Cotton effect in film state in a manner similar to solution state. No chiral amplification was observed in the copolymerization of 1 with achiral 2-ethynyl-9- tert -butoxycarbonylcarbazole (5). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4450,4458, 2007 [source]

Macromolecular helicity inversion of poly(phenylacetylene) derivatives induced by various external stimuli

MACROMOLECULAR SYMPOSIA, Issue 1 2003
Katsuhiro Maeda
Abstract Unique macromolecular helicity inversion of stereoregular, optically active poly(phenylacetylene) derivatives induced by external achiral and chiral stimuli is briefly reviewed. Stereoregular, cis-transoidal poly(phenylacetylene)s bearing an optically active substituent, such as (1R,2S)-norephedrine (poly- 1) and , -cyclodextrin residues (poly- 2), show an induced circular dichroism (ICD) in the UV-visible region of the polymer backbone in solution due to a predominantly one-handed helical conformation of the polymers. However, poly- 1 undergoes a helix-helix transition upon complexation with chiral acids having an R configuration, and the complexes exhibit a dramatic change in the ICD of poly- 1. Poly- 2 also shows the inversion of macromolecular helicity responding to molecular and chiral recognition events that occurred at the remote cyclodextrin residues from the polymer backbone; the helicity inversion is accompanied by a visible color change. A similar helix-helix transition of poly((R)- or (S)-(4-((1-(1-naphthyl)ethyl)carbamoyl)phenyl)acetylene) is also briefly described. [source]

Microwave-assisted synthesis and characterization of heterocyclic, and optically active poly(amide-imide)s incorporating L -amino acids

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 12 2008
Abdol R. Hajipour
Abstract N,N,-Pyromelliticdiimido-di- L -alanine (1), N,N,-pyromelliticdiimido-di- L -phenylalanine (2), and N,N,-pyromelliticdiimido-di- L -leucine (3) were prepared from the reaction of pyromellitic dianhydride with corresponding L -amino acids in a mixture of glacial acetic acid and pyridine solution (3/2 ratio) under refluxing conditions. The microwave-assisted polycondensation of the corresponding diimide-diacyl chloride monomers (5,7) with 4-phenyl-2,6-bis(4-aminophenyl) pyridine (10) or 4-(p -methylthiophenyl)-2,6-bis(4-aminophenyl) pyridine (12) were carried out in a laboratory microwave oven. The resulting poly(amide-imide)s were obtained in quantitative yields, and they showed admirable inherent viscosities (0.12,0.55 dlg,1), were soluble in polar aprotic solvents, showed good thermal stability and high optical purity. The synthetic compounds were characterized by IR, MS, 1H NMR, and 13C NMR spectroscopy, elemental analysis, and specific rotation. Copyright © 2008 John Wiley & Sons, Ltd. [source]