2002/12/12 by Bing Shi Li, Kevin Ka Leung Cheuk, Liansheng Ling +4 · 1 citation
Chemistry · Materials Science · #Adduct #Amino acid #Chemistry #Hydrogen bond #Macromolecule #Methanol #Molecule #Organic chemistry #Phenylacetylene #Polydiacetylene-based materials and applications #Polymer #Polymer chemistry #Polymerization #Solvent #Supramolecular Self-Assembly in Materials #Synthesis and Properties of Aromatic Compounds #Valine
paper · doi:10.1021/ma0213091
openalex publication_date 2002/12/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22
In this work, we synthesized amino acid-containing poly(phenylacetylene)s and demonstrated the possibility of tuning their hierarchical structures by internal and external perturbations. A valine-acetylene adduct, 4-ethynylbenzoyl- l -valine methyl ester ( 5 ), was readily polymerized by [Rh(nbd)Cl] 2, and the resultant “polyester” ( 1 ) was selectively hydrolyzed by KOH to its “polyacid” congener, poly(4-ethynylbenzoyl- l -valine) ( 2 ). (Supra)molecular structures of the polymers were characterized by NMR, IR, UV, CD, and AFM techniques. The macromolecules took helical chain conformations in solutions. Their Cotton effects varied to different extents, when the polymer, solvent, and pH changed respectively from 1 to 2, from methanol to THF, and from neutral to basic. Upon evaporation of their methanol solutions, 1 and 2 self-assembled into micellar spheres and helical cables, respectively. Changing the solvent of 1 to THF changed its folding structure to helical cables, while increasing the pH of the methanol solution of 2 led to the formation of random threads. The denaturation from helical cables to random threads is probably caused by the cleavage of interstrand hydrogen bonds by base-mediated ionization of carboxyl groups of the valine pendants.