The role of the degree of polymerization in the chiroptical properties of dynamic asymmetric poly(diphenylacetylene)s

Abstract

Non-symmetric poly(diphenylacetylene)s (PDPAs) show a strong relationship between the size of the macromolecules and their electronic circular dichroism (ECD) spectra. Thus, polymers and oligomers of PDPAs with the same screw...

Conformational Kinetics in Chiral Poly(diphenylacetylene)s: A Dynamic P/M Memory Effect

“…In these studies, the polymer adopts a preferred helical sense after thermal annealing at high temperature (e.g. 80 °C during 24 h) in a specific solvent [48–53] . One of these PDPAs, poly‐( L )‐ 1 , a dissymmetric chiral poly(diphenylacetylene) that bears the benzamide of ( L )‐alanine methyl ester at one of the aryl rings of the diphenylacetylene was reported by our group [48] .…”

“…80 °C during 24 h) in a specific solvent. [48][49][50][51][52][53] One of these PDPAs, poly-(L)-1, a dissymmetric chiral poly(diphenylacetylene) that bears the benzamide of (L)alanine methyl ester at one of the aryl rings of the diphenylacetylene was reported by our group. [48] This polymer was prepared according to the protocol reported by Tang and co-workers.…”

“…This family of helical polymers has attracted the attention of the scientific community lately due to the properties associated with the PDPA backbone, such as chemical, photochemical, and thermal stabilities, combined with their intrinsic optical and chiroptical properties–CD, fluorescence emission, CPL−, which make PDPAs promising materials. Originally, these materials were considered as static, although recently it was found possible to modulate the elongation or helical sense of chiral PDPAs demonstrating the dynamic properties of these polymers [44–50] …”

“…Originally, these materials were considered as static, although recently it was found possible to modulate the elongation or helical sense of chiral PDPAs demonstrating the dynamic properties of these polymers. [44][45][46][47][48][49][50]…”

Stimuli-responsive synthetic helical polymers

“…Freire performed also solvent-dependent studies on PDPAs functionalized with chiral amino acids as pendants, 147,392,393 obtaining syn / anti conformational equilibria similar to those obtained for PPAs, although the activation energy to promote helix inversion is very high providing the polymers a memory effect. Also, the same group studied how the aromatic substitution in chiral PPAs ( i.e.…”