title: Photoliquefiable ionic crystals: a phase crossover approach for photon energy storage materials with functional multiplicity.
abstract: Ionic crystals (ICs) of the azobenzene derivatives show photoinduced IC-ionic liquid (IL) phase transition (photoliquefaction) upon UV-irradiation, and the resulting cis-azobenzene ILs are reversibly photocrystallized by illumination with visible light. The photoliquefaction of ICs is accompanied by a significant increase in ionic conductivity at ambient temperature. The photoliquefaction also brings the azobenzene ICs further significance as photon energy storage materials. The cis-IL shows thermally induced crystallization to the trans-IC phase. This transition is accompanied by exothermic peaks with a total ΔH of 97.1 kJ mol(-1) , which is almost double the conformational energy stored in cis-azobenzene chromophores. Thus, the integration of photoresponsive ILs and self-assembly pushes the limit of solar thermal batteries.
authors.affiliation: Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, 744 Moto-oka Nishi-ku, Fukuoka 819-0395 (Japan).
authors.forename: Keita
authors.initials: K
authors.lastname: Ishiba
authors.forename: Masa-Aki
authors.initials: MA
authors.lastname: Morikawa
authors.forename: Chie
authors.initials: C
authors.lastname: Chikara
authors.forename: Teppei
authors.initials: T
authors.lastname: Yamada
authors.forename: Katsunori
authors.initials: K
authors.lastname: Iwase
authors.forename: Mika
authors.initials: M
authors.lastname: Kawakita
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kimizuka
keywords: energy storage; ionic liquids; phase transitions; photochemistry; self-assembly