Synthesis of Polymeric Topological Isomers through Electrostatic Self‐Assembly and Covalent Fixation with Star Telechelic Precursors

Abstract

Summary: A pair of macromolecular constitutional isomers having topologically distinctive, dicyclic constructions, that is, θ‐shaped and manacle‐shaped polymers, has been synthesized from a polymer self‐assembly, comprised of three‐armed star poly(tetrahydrofuran) [poly(THF)] having N‐phenylpyrrolidinium salt end groups carrying dicarboxylate counteranions (1S/2d). The presence of the two constitutional polymeric isomers was confirmed by means of a reversed‐phase liquid chromatography (RPC) technique. Moreover, size exclusion chromatography (SEC) showed that a major component possesses notably larger hydrodynamic volume than the others, and is assignable as a manacle‐shaped isomer while a minor component is assigned as a θ‐shaped isomer. The statistics of the covalent‐linking process of 1S/2d were consistent with the other experimental results.An “electrostatic self‐assembly and covalent fixation” process of a trifunctional star‐shaped precursor gives rise to θ‐shaped and manacle‐shaped polymers.imageAn “electrostatic self‐assembly and covalent fixation” process of a trifunctional star‐shaped precursor gives rise to θ‐shaped and manacle‐shaped polymers.

Cyclic polymers: Synthetic strategies and physical properties

“…[148][149][150][151][152][153][154][155][156][157][158][159][160][161][162][163][164] Characteristic for this approach is the combination of bifunctional polymer having positively charged electrophilic endgroups with the negatively charged ''b 2 '' or ''b 3 '' monomer typically the anion of a dicarboxylic or tricarboxylic acid. As illustrated in Schemes 41-43, the carboxylate anions react with the ammonium endgroups upon heating by formation of a covalend bond, namely an ester group.…”

“…However, the simultaneous preparation of manacle-and h-shaped poly THF should be outlined in Scheme 45. [160][161][162][163][164] Since the h-architecture is more compact than the manacle isomers, at least partial separation by gel chromatography (SEC) was feasible and allowed an unambiguous identification of both architectures. An interesting variation of this system was achieved by synthesizing manacle and h-shaped poly THFs having one or two C¼ ¼C double bonds in designated positions.…”

Topological polymer chemistry for designing multicyclic macromolecular architectures

“…[18][19][20] This synthesis was the first example of deliberately produced polymeric topological isomers or, more precisely, topologically distinct polymeric constitutional isomers. These polymeric topological isomers, as well as a pair of linear and ring polymers, were separated by reversed phase chromatography under critical and near-critical interaction conditions.…”

“…These polymeric topological isomers, as well as a pair of linear and ring polymers, were separated by reversed phase chromatography under critical and near-critical interaction conditions. [18][19][20][21][22] The chemical assignment of the polymeric topological isomers with either y or manacle construction has subsequently been performed by using polymers containing a cleavable olefinic group in a backbone segment (Scheme 3a). 23 Thus, a pair of y-and manacle-shaped polymeric isomers with a metathesis-cleavable olefinic unit at the specified position were synthesized by the ESA-CF process by using a linear precursor with an inner olefinic group at the center position.…”

“…18,19 The ESA-CF procedure was also applicable to an assembly composed of two starshaped trifunctional precursor units carrying three bifunctional carboxylate counteranion units (Scheme 10). 20 Alternatively, a pair of dicyclic polymeric topological isomers with y and manacle constructions were formed through the metathesis clip process using an H-shaped precursor with allyloxy end groups at each chain end (Scheme 10). 21 The selective construction of a dicyclic, manacle-shaped polymer topology was achieved through the click coupling of a bifunctional linear telechelic precursor containing azide groups with a cyclic polymer precursor bearing an alkyne group obtainable through the ESA-CF protocol (Scheme 10).…”