title: Cooperativity of dynamics of 18-crown-6 molecule forming one-dimensional chain in Cs2(18-crown-6)3[Ni(dmit)2]2.
abstract: Heat capacity of Cs2(18-crown-6)3[Ni(dmit)2]2 was measured by adiabatic calorimetry. A broad thermal anomaly was observed around 225 K. The entropy gain (about 52 J K(-1) mol(-1)) is much larger than that expected for twofold disordering of 18-crown-6 assumed in the previous structure analysis. The shape of thermal anomaly was qualitatively explained by a linear Ising model developed for cooperative disordering in polymers. The 18-crown-6 molecules forming a one-dimensional chain in the crystal are orientationally disordered with moderate cooperativity.
authors.affiliation: Research Center for Molecular Thermodynamics, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Satoaki
authors.initials: S
authors.lastname: Ikeuchi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Sadamu
authors.initials: S
authors.lastname: Takeda
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Akutagawa
authors.forename: Sadafumi
authors.initials: S
authors.lastname: Nishihara
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Nakamura
authors.forename: Kazuya
authors.initials: K
authors.lastname: Saito