title: Thermally Induced Intra-Carboxyl Proton Shuttle in a Molecular Rack-and-Pinion Cascade Achieving Macroscopic Crystal Deformation.
abstract: Proton transport via dynamic molecules is ubiquitous in chemistry and biology. However, its use as a switching mechanism for properties in functional molecular assemblies is far less common. In this study, we demonstrate how an intra-carboxyl proton shuttle can be generated in a molecular assembly akin to a rack-and-pinion cascade via a thermally induced single-crystal-to-single-crystal phase transition. In a triply interpenetrated supramolecular organic framework (SOF), a 4,4'-azopyridine (azpy) molecule connects to two biphenyl-3,3',5,5'-tetracarboxylic acid (H4BPTC) molecules to form a functional molecular system with switchable mechanical properties. A temperature change reversibly triggers a molecular movement akin to a rack-and-pinion cascade, which mainly involves 1) an intra-carboxyl proton shuttle coupled with tilting of the azo molecules and azo pedal motion and 2) H4BPTC translation. Moreover, both the molecular motions are collective, and being propagated across the entire framework, leading to a macroscopic crystal expansion and contraction.
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.|World Premier International (WPI) Center for Materials Nanoarchitectonics (MANA), Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan.
authors.forename: You-Gui
authors.initials: YG
authors.lastname: Huang
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Shiota
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
authors.forename: Sheng-Qun
authors.initials: SQ
authors.lastname: Su
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
authors.forename: Shu-Qi
authors.initials: SQ
authors.lastname: Wu
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
authors.forename: Zi-Shuo
authors.initials: ZS
authors.lastname: Yao
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
authors.forename: Guo-Ling
authors.initials: GL
authors.lastname: Li
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Kanegawa
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
authors.forename: Soonchul
authors.initials: S
authors.lastname: Kang
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kamachi
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Yoshizawa
authors.affiliation: World Premier International (WPI) Center for Materials Nanoarchitectonics (MANA), Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Ariga
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Sato
keywords: crystal deformation; molecular machine; phase transitions; proton shuttle