Reversible Single-Crystal-to-Single-Crystal Phase Transition of Chiral Salicylidenephenylethylamine
Akifumi Takanabe,
Takuro Katsufuji,
Kohei Johmoto,
Hidehiro Uekusa,
Motoo Shiro,
Hideko Koshima,
Toru Asahi
Affiliations
Akifumi Takanabe
Department of Advanced Science and Engineering, Graduate School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
Takuro Katsufuji
Department of Advanced Science and Engineering, Graduate School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
Kohei Johmoto
Department of Chemistry and Materials Science, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
Hidehiro Uekusa
Department of Chemistry and Materials Science, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
Motoo Shiro
Researh Organization for Nano & Life Innovation, Waseda University, 513 Wasedatsurumaki-cho, Shinjuku-ku, Tokyo 162-0041, Japan
Hideko Koshima
Researh Organization for Nano & Life Innovation, Waseda University, 513 Wasedatsurumaki-cho, Shinjuku-ku, Tokyo 162-0041, Japan
Toru Asahi
Department of Advanced Science and Engineering, Graduate School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
The chiral crystal of enantiomeric (S)-N-3,5-di-tert-butylsalicylidene-1-phenylethylamine in the enol form [enol-(S)-1] undergoes a reversible single-crystal-to-single-crystal (SCSC) phase transition at Tc ≈ 3 °C from the room temperature α-form in orthorhombic space group P212121 (Z′ = 1) to the low temperature β-form in the monoclinic space group P21 (Z′ = 2) with a thermal hysteresis of approximately 1.7 °C. A detailed comparison of the crystal structures of the α- and β-forms revealed that the 5-tert-butyl group of one molecule in the asymmetric unit of the β-form rotated by ca. 60°, and the dihedral angle between the phenyl and salicyl planes increased slightly in the β-form crystal. However, the changes in the molecular conformation and packing arrangement are small, which leads to the reversible SCSC phase transition with no destruction of the crystal lattice. The dielectric constant along the b-axis was small, probably due to the weak intermolecular interactions in the crystals.
