Synthesis and chiroptical properties of a helical poly(phenylacetylene) bearing optically active pyrene pendants

Fluorescent molecular spring that visualizes the extension and contraction motions of a double-stranded helicate bearing terminal pyrene units triggered by release and binding of alkali metal ions

A unique springlike motion of a fluorescent pyrene-terminated double-stranded helicate is visualized by the catch and release of alkali metal ions.

Synthesis and helical structures of poly(ω-alkynamide)s having chiral side chains: effect of solvent on their screw-sense inversion

New ω-alkynamides, (S)-HC≡CCH2CONHCH2CH(CH3)CH2CH3 (1) and (S)-HC≡CCH2CH2CONHCH(CH3)CH2CH2CH2CH2CH3 (2) were synthesized and polymerized with a rhodium catalyst in CHCl3 to obtain cis-stereoregular poly(ω-alkynamide)s (poly(1) and poly(2)). Polarimetric, CD, and IR spectroscopic studies revealed that in solution the polymers adopted predominantly one-handed helical structures stabilized by intramolecular hydrogen bonds between the pendent amide groups. This behavior was similar to that of the corresponding poly(N-alkynylamide) counterparts (poly(3) and poly(4)) reported previously, whereas the helical senses were opposite to each other. The helical structures of the poly(ω-alkynamide)s were stable upon heating similar to those of the poly(N-alkynylamide)s, but the solvent response was completely different. An increase in MeOH content in CHCl3/MeOH resulted in inversion of the predominant screw-sense for poly(1) and poly(2). Conversely, poly(3) was transformed into a random coil, and poly(4) maintained the predominant screw-sense irrespective of MeOH content. The solvent dependence of predominant screw-sense for poly(1) and poly(2) was reasonably explained by molecular orbital studies using the conductor-like screening model (COSMO).

Synthesis of Functional Disubstituted Polyacetylenes Bearing Highly Polar Functionalities via Activated Ester Strategy

We demonstrate a facile synthetic route to functional disubstituted polyacetylenes bearing highly polar groups based on polymer reactions. A pentafluorophenyl (PFP) ester-containing diphenylacetylene was designed and polymerized to obtain PFP activated ester-functionalized disubstituted polyacetylene (P1). P1 was used as a parent polymer to further react separately with diverse amines, giving rise to a series of functional disubstituted polyacetylenes with a chiral moiety and hydroxyl and carboxyl groups in high yields under mild condition. Spectral characterization data indicated that the polymers' structures were well consistent with the expected results. The helicity and emission property of polymers were also studied.