Folding Construction of Doubly Fused Tricyclic, β- and γ-Graph Polymer Topologies with kyklo-Telechelic Precursors Obtained through an Orthogonal Click/ESA-CF Protocol

Abstract

An alkyne–azide addition (click) reaction of a linear poly(tetrahydrofuran), poly(THF), precursor having an alkyne group at the center position and cyclic ammonium salt end groups has been applied with the complementary linear poly(THF) precursors having an azide group at single or both chain ends to produce asymmetric star- and H-shaped poly(THF) precursors having cyclic ammonium salt end groups. The subsequent electrostatic self-assembly and covalent fixation (ESA-CF) process after introducing dicarboxylate counteranions having an additional alkene or alkyne group could afford the designated kyklo-telechelic precursors, having either a tadpole form containing an alkyne group at the top-head and an alkene group at the tail-end positions or an isomeric manacle/theta form containing two alkene groups at the orthogonal positions. The further click coupling of the former with a linear telechelic precursor having azide groups followed by the metathesis folding (clip) process could produce effectively a doubly fused tricyclic polymer having β-graph topology. Moreover, the convergent folding by the clip reaction of the latter manacle/theta isomeric precursors could produce exclusively another doubly fused tricyclic polymer having γ-graph topology.