Helical Conjugated Polymers:  Synthesis, Stability, and Chiroptical Properties of Poly(alkyl phenylpropiolate)s Bearing Stereogenic Pendants

Abstract

Chiral poly(alkyl phenylpropiolate)s −{(C6H5)CC[CO2(CH2)2OCOR*]} n − with R* =(S)-(+)-[1-(6-methoxy-2-naphthyl)ethyl (P1), (1R,2S,5R)-(−)-menthoxymethyl (P2), (S)-(+)-(α-acetoxy)benzyl (P3), and cholesteryloxy (P4) were synthesized, and their structures and properties were investigated. The monomers [C6H5C⋮CCO2(CH2)2OCOR*; 1 − 4] were prepared by esterifications of stereogenic acids 8 − 10 or chloroformate (11) with 3-hydroxyethyl phenylpropiolate (7) in high yields. Polymerizations of 1 − 4 were effected by MoCl5−Ph4Sn at 60 or 80 °C, and polymers with high molecular weights (M w up to ∼100 × 103) were obtained in moderate yields. The polymers were characterized by IR, NMR, TGA, UV, and CD analyses. All of the polymers are stable, losing little of their weights when heated to ≥300 °C and undergoing no chain scissions when annealed in air at ≥150 °C. The macromolecular chains take helical conformations with preferred handedness, and their helical chirality can be reversibly tuned by solvent or temperature to varying extents.

1,2,3-Triazole-Functionalized Polysulfone Synthesis through Microwave-Assisted Copper-Catalyzed Click Chemistry: A Highly Proton Conducting High Temperature Membrane

“…Similar impact of alkyl and phenyl substituents on the thermal stability of poly (alkylphenylpropiolate) has been reported. 61 Phosphoric acid doped 1,2,3-triazole functionalized polysulfone membranes…”

Chiral Amplification during Asymmetric‐Induced Copolymerization of Phenylacetylenes with Tight Cis‐Cisoidal Main Chains

“…Polyacetylene prepared by rhodium catalyst, such as [Rh(nbd)Cl] 2 (nbd: norbornadiene), is a typical dynamic helical polymer,7 its main‐chain conformation can be cis‐transoidal 11–18 or cis‐cisoidal 19–24 depending on the chemical structure of the monomer. The authors have developed two synthetic routes for one‐handed helical poly(substituted acetylene)s. The one is asymmetric‐induced polymerization (AIP) in which chiral‐substituted acetylenes are used as a monomer to afford dynamic helical cis‐transoidal polyacetylenes 25–27.…”

Synthesis, helicity, thermal stability, and low infrared emissivity of optically active polyacetylenes carrying tyrosine pendants

“…LPA and DPA exhibit high ½a As is known to all that a polymer chain with a helical conformation can exhibit very high optical activity. [9,19,37,51,52] Then, the high ½a 25 D values of LPA and DPA demonstrate that the large specific rotation difference between the monomer and the polymer may be result from the helical secondary structure. In other words, the polymer chains have been induced by the asymmetric forces of the chiral L-tyrosine and D-tyrosine pendants groups to take a helical conformation.…”

“…A polymer chain carrying chiral pendants can possibly show very high optical activity [9,19,51,52]; thus, the specific optical rotations of our polymers and those of their corresponding monomers were measured to study whether they are optically active. The specific optical rotations ½a 25 D of all the polymers and monomers are summarized in Table 2.…”

“…Meanwhile, optically active polymers have attracted great attention owing to the common advantages of any other macromolecules and their characteristic features such as ordered helical structure, multiple inter chain interaction, and adjustable optical parameter. [7][8][9][10] Consequently, their characteristic features provide the potential applications in electrical conductivity, asymmetric synthesis, molecular recognition, liquid crystalline materials for display, and infrared emissivity materials. [11][12][13][14][15] Among the majority of optically active polymers, polyacetylene is very interesting since it is a π-conjugated polymer which possesses a symmetric chain.…”