Boc-D-alanine

Optically active helical substituted (co)polyacetylenes containing pendent pyrene groups are prepared and then noncovalently immobilized on graphene via π-π interactions. The resulting graphene composite is characterized by XRD, FTIR, Raman, circular dichroism, UV-vis absorption, TEM, TGA, and fluorescent spectroscopy techniques. The helical polyacetylene endows graphene with the desired optical activity. Also interestingly, the dispersibility of the functionalized graphene in tetrahydrofuran is remarkably improved due to the presence of the helical polymer chains. The present methodology opens new opportunities and serves as a versatile platform toward preparing novel graphene-based materials.

Suspension polymerization has been extensively utilized with vinyl monomers to prepare vinyl-polymer microparticles (μm size; denoted MPs) with a variety of morphologies and significant applications. However, suspension polymerization of acetylenic monomers has remained a big challenge. This communication reports the first methodology for performing suspension polymerizations of acetylenic monomers, from which optically active microparticles (OAMPs) are constructed exclusively from helical substituted polyacetylenes. Chiral monomer (M1) and achiral monomer (M2) separately underwent suspension polymerization at room temperature in aqueous media in the presence of Rh-based catalyst with poly(vinyl alcohol) as a stabilizer, providing MPs (200~700 mm) in high yield (>80%). The obtained OAMPs, both crosslinked and non-crosslinked, were characterized by SEM, polarimetry, circular dichroism, and UV-vis spectroscopy. The chiral substituted polyacetylene chains constituting the MPs were found to adopt helices of predominantly one-handed screw sense, affording the particles with pronounced optical activity. The MPs derived from achiral M2 exhibited optical inactivity. The present study opens up new opportunities for preparing novel (non-)crosslinked microparticles derived from acetylenic monomers.

This communication reports the first integration of two significant concepts, "macromolecular helicity-derived chirality," and "magneticity" in one single microsphere entity. The novel chiral magnetic composite microspheres consisted of magnetic Fe(3)O(4) nanoparticles and optically active helical substituted polyacetylene. Therefore, they exhibited both remarkable optical activity and magneticity. The microspheres adsorbed (R)-(+)-1-phenylethylamine much more quickly than the other enantiomer, demonstrating the potential applications of the chiral magnetic composite microspheres in chiral recognition and chiral resolution.