title: Nonequilibrium Molecular Switching of Chiral Helicene Oligomers in Double-Helix Formation.
abstract: Molecular switching is the phenomenon in which a molecular structural change occurs reversibly in response to an external stimulus or energy. It plays an important role in biology, in which it is used for sensing environmental changes. In contrast to well-studied equilibrium molecular switching involving thermodynamically stable states, nonequilibrium molecular switching involving a metastable state is a notable chemical phenomenon and is the theme of this study. Sulfonamido- and aminomethylenehelicene oligomers show a reversible structural change from a double helix to a random coil in dilute solution. A metastable state consisting of random coils can be generated by heating, which shows various nonequilibrium thermodynamic properties. Molecular phenomena including molecular thermal hysteresis, molecular memory effect, and one-directional three-state molecular structural change occur, none of which is observed in an equilibrium molecular switching system. They can be applied to sensing environmental changes such as temperature increases/decreases, temperature change rates, and concentration increases, and for counting the numbers 1 and 2.
authors.affiliation: Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University.
authors.forename: Masanori
authors.initials: M
authors.lastname: Shigeno
mesh_terms: D002119:Calcium Carbonate; D002951:Citrates; D004338:Drug Combinations; D018257:Helix-Loop-Helix Motifs; D008277:Magnesium Oxide; D015394:Molecular Structure; D011083:Polycyclic Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature; D013816:Thermodynamics
chemical_list: D002951:Citrates; D004338:Drug Combinations; D011083:Polycyclic Compounds; C050615:Suby's G solution; C031660:helicenes; D008277:Magnesium Oxide; D002119:Calcium Carbonate