Figure-eight thermal hysteresis of aminomethylenehelicene oligomers with terminal C alkyl groups during hetero-double-helix formation

1 : 1 mixtures of aminomethylenehelicene ( P )-tetramer and ( M )-pentamer with terminal C 16 alkyl groups in fluorobenzene showed structural changes between hetero-double-helices B and C and random-coils 2 A . Figure-eight thermal hysteresis appeared when the solution was cooled and heated at a constant rate and involved the crossing of cooling and heating curves in Δ /temperature profiles. This unusual thermal hysteresis emerged in the intermediate state between counterclockwise and clockwise thermal hystereses. This phenomenon arose from the competition between self-catalytic reactions to form B and C from 2 A . Significant effects of terminal C 16 alkyl groups on the thermodynamic and kinetic phenomena are also described. 1 : 1 mixtures of aminomethylenehelicene ( P )-tetramer and ( M )-pentamer with terminal C 16 alkyl groups in fluorobenzene showed structural changes between hetero-double-helices B and C and random-coils 2 A .