title: Mesophases and ionic conductivities of simple organic salts of M(m-iodobenzoate) (M = Li(+), Na(+), K(+), Rb(+), and Cs(+)).
abstract: Simple organic salts such as (Li(+))(m-IBA) (1), (Na(+))(m-IBA) (2), (K(+))(m-IBA) (3), (Rb(+))(m-IBA) (4), and (Cs(+))(m-IBA) (5) (m-IBA = m-iodobenzoate) were shown to form a mesophase before crystal melting or decomposition. The crystals were obtained in the hydrated form, e.g., 1·(H2O), 2·(H2O), 3·0.5(H2O), 4·(H2O), and 5·(H2O); they were then converted into dehydrated forms by increasing the temperature to ∼450 K. Optically anisotropic-layered mesophases were observed in unhydrated crystals 2, 3, 4, and 5, whereas an optically isotropic mesophase (e.g., rotator phase) was found for crystal 1. The single-crystal X-ray structural analysis of the hydrated crystals revealed an inorganic-organic alternate layer structure, which is consistent with the average molecular orientation in the layered mesophase. The m-IBA anions formed a π-stacking columnar structure in the hydrated crystals, while one- or two-dimensional M(+)∼O networks were observed in the inorganic layers. Our results showed that the M(+)∼O interactions and their connectivity are strongly influenced by the size of the cations. The reconstruction of the M(+)∼O networks by removing H2O molecules was crucial for the formation of the mesophases. A strong response of both the real and imaginary parts of the dielectric constant was observed around the solid-mesophase phase-transition temperatures of crystals 1-5, with the ionic conductions playing a critical role.
authors.affiliation: Graduate School of Engineering, Tohoku University , Sendai 980-8579, Japan.
authors.forename: Manami
authors.initials: M
authors.lastname: Endo
authors.forename: Yuta
authors.initials: Y
authors.lastname: Nakane
authors.forename: Kiyonori
authors.initials: K
authors.lastname: Takahashi
authors.forename: Norihisa
authors.initials: N
authors.lastname: Hoshino
authors.forename: Takashi
authors.initials: T
authors.lastname: Takeda
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Noro
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Nakamura
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Akutagawa