Study Spiral Heat Of Main Chain Conformation Of Polyphenylacetylene With Double Hydroxyl

Polyacetylene prepared by rhodium catalyst,such as [Rh(nbd)Cl]2, is a typical dynamic helical polymer, and its main-chain conformation can be cis-transoidal or cis-cisoidal depending on the monomer structure and the environment.In this study, we report that a thermotropic chiral induction system consisting of a chiral amine and a polyacetylene prepared from an achiral phenylacetylene having two hydroxyl groups shows a tunable critical one-handed spiralization temperature (COST) in nonpolar solvents such as toluene, hexane. The conformation of poly(1) in the system of poly(1)/chiral phenylethyl amine/toluene could be induced into one-handed helix along with transformation of main chain conformation from cis-transoidal to cis-cisoidal by heating the system to a temperature higher than the COST. The COST can be adjusted by changing the chiral amine concentration in the system, and the higher concentration affords the higher COST. This unique thermotropic chiral induction phenomenon may be caused by the difference in strength of H-bonds of -OH/-NH2 and -OH/-OH at different temperature. In addition, the induced one-handed helical clarity of the polyacetylene can be self-stabilized by intramolecular H-bonds after precipitating the polyacetylene in methanol to remove the chiral amine, i.e. the induced one-handed helical chirality of the polyacetylene can be perfectly saved in solid state.