Abstract
1 : 1 mixtures of aminomethylenehelicene (P)-tetramer and (M)-pentamer with terminal C16 alkyl groups in fluorobenzene showed structural changes between hetero-double-helices B and C and random-coils 2A. 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 Δε/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 2A. Significant effects of terminal C16 alkyl groups on the thermodynamic and kinetic phenomena are also described.
Highlights
Hysteresis is the dependence of a state on its history and, alternatively, the time delay between an input and an output, and it appears broadly in nature, materials, environments, biological phenomena, and societies.[1,2] Magnetic hysteresis is derived from external magnetic eld strength and magnetization.[3]
Physics-based models and phenomenological models have been suggested, and the classi cation of hysteretic phenomena has been attempted: (1) rate-dependent hysteresis is de ned by the disappearance of hysteresis with a decreasing input rate, whereas rateindependent hysteresis is not affected by the input rate.[12,13] (2) The shapes of hysteresis loops are classi ed into six types: leaf, crescent, classical, tilted classical, double loop, and bat.[14] (3) Four types of loops of hysteresis curves are described by the IUPAC in the adsorption and desorption of gases as a function of pressure.[15] (4) We propose symmetric and asymmetric types of hysteresis, both of which result from the nature of the input
We have reported that thermal hysteresis can appear in reversible noncovalent chemical reactions of molecules dispersed in solution, which involve different macroscopic mechanisms during cooling and heating
Summary
Hysteresis is the dependence of a state on its history and, alternatively, the time delay between an input and an output, and it appears broadly in nature, materials, environments, biological phenomena, and societies.[1,2] Magnetic hysteresis is derived from external magnetic eld strength (input) and magnetization (output).[3]. Hysteresis occurs in biological phenomena, which are based on reversible
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