Synthetic Chemical Systems Involving Self-Catalytic Reactions of Helicene Oligomer Foldamers.

Self-catalysis is defined as catalysis by a product of a chemical reaction, that causes a significant increase in reaction rate in terms of the progress of the reaction. When a self-catalytic reaction is involved in a reversible nonequilibrium-to-equilibrium chemical reaction, notable kinetic phenomena appear including sigmoidal kinetics, the seeding effect, thermal hysteresis, and chiral symmetry breaking. The nature of self-catalytic reactions is characterized by microscopic mechanisms involving pathways of molecular structural changes and by macroscopic mechanisms involving molecular flux. Reversible self-catalytic reactions, which exhibit notably high sensitivity to environmental changes, are also observed. In this Review, reversible self-catalytic reactions of helicene oligomer foldamers during formation of homo- and hetero-double-helices are discussed, which exhibit the properties outlined above.