Poly(p‐benzamide) having isopropyl‐substituted chiral tri(ethylene glycol) side Chain: Synthesis and helical conformation

Abstract

Isopropyl-substituted tri(ethylene glycol) is used as a chiral side chain of N-substituted poly(p-benzamide) in order to increase the difference of stability between the right-and lefthanded helical structures of the polymer. The target polymer is synthesized by the chain-growth condensation polymerization of the corresponding monomer with an initiator using lithium 1,1,1,3,3,3-hexamethyldisilazide as a base. A circular dichroism (CD) study of the polymer reveals that the CD signal is due to an excess of a thermodynamically controlled right-handed helical structure of the polymer, and that the replacement of the methyl group with a bulkier isopropyl group at the side chain of poly(p-benzamide) increases the abundance of right-handed helical structure in chloroform.

Transformation of Step-Growth Polymerization into Living Chain-Growth Polymerization

“…This is probably due to the increased difference of stability between the right-and lefthanded helical structures of the polymer (Scheme 8). 55 ). Indeed, the polymerization of 7 with Ni(dppp)Cl 2 (dppp = 1,3-bis(diphenylphosphino)propane) at room temperature proceeded in a chain polymerization manner.…”