title: Collective In-Plane Molecular Rotator Based on Dibromoiodomesitylene π-Stacks.
abstract: Interest in artificial solid-state molecular rotator systems is growing as they enable systems to be designed for achieving specific physical functions. The phase transition behavior of four halomesitylene crystals indicated dynamic in-plane molecular rotator characteristics in dibromoiodomesitylene, tribromomesitylene, and dibromomesitylene crystals. Such molecular rotation in diiodomesitylene crystals was suppressed by effective I···I intermolecular interactions. The in-plane molecular rotation accompanied by a change in dipole moment resulted in dielectric phase transitions in polar dibromoiodomesitylene and dibromomesitylene crystals. No dielectric anomaly was observed for the in-plane molecular rotation of tribromomesitylene in the absence of this dipole moment change. Typical antiferroelectric-paraelectric phase transitions were observed in the dibromomesitylene crystal, whereas the dielectric anomaly of dibromoiodomesitylene crystals was associated with the collective in-plane molecular rotation of polar π-molecules in the π-stack. We found that the single-rope-like collective in-plane molecular rotator was dominated by intermolecular I···I interactions along the π-stacking column of polar dibromoiodomesitylene.
authors.affiliation: Graduate School of Engineering, Tohoku University , Sendai 980-8579, Japan.
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Ichikawa
authors.affiliation: Graduate School of Engineering, Tohoku University , Sendai 980-8579, Japan.|Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University , 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Norihisa
authors.initials: N
authors.lastname: Hoshino
authors.affiliation: Graduate School of Engineering, Tohoku University , Sendai 980-8579, Japan.|Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University , 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Takeda
authors.affiliation: Graduate School of Engineering, Tohoku University , Sendai 980-8579, Japan.|Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University , 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Akutagawa
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry*; D003461:Crystallography; D015394:Molecular Structure
chemical_list: D001555:Benzene Derivatives; C010219:mesitylene