title: Molecular thermal hysteresis in helix-dimer formation of sulfonamidohelicene oligomers in solution.
abstract: Sulfonamidohelicene oligomers up to the nonamer level were synthesized by the repeated coupling reactions of a building block. A tetramer formed a helix dimer in 1,3-difluorobenzene, which unfolded to a random coil with heating. This structural change exhibited thermal hysteresis in which different thermal responses were observed in the course of temperature increase and decrease. The feature of the hysteresis was examined under different heating/cooling modes, and the mechanisms are discussed on the basis of the population change and the presence of an induction period. A proposal regarding the use of thermal hysteresis for sensing a temperature increase/decrease is also given.
authors.affiliation: Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aoba, Sendai 980-8578, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Shigeno
authors.forename: Yo
authors.initials: Y
authors.lastname: Kushida
authors.forename: Masahiko
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D005464:Fluorobenzenes / Q000737:chemistry; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D013449:Sulfonamides / Q000138:chemical synthesis / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D005464:Fluorobenzenes; D011108:Polymers; D013449:Sulfonamides; C079487:1,3-difluorobenzene
keywords: dimerization; helical structures; oligomers; sulfonamides; thermodynamics