フェノチアジン誘導体のキラル対称性の破れを伴う単結晶構造転移と円偏光発光特性の発現

抄録

  We report a new category of molecular-level spontaneous chiral symmetry breaking (CSB): complete CSB within a single crystal. A racemic compound (space group Pna2₁) of a phenothiazine derivative with dynamic chirality at the nitrogen center, undergoes a single-crystal-to-single-crystal (SC–SC) structural transition to a chiral conglomerate (space group P2₁) upon heating. This transition was characterized by differential scanning calorimetry, variable-temperature powder X-ray diffraction, and polarized optical microscopy. When the chiral seed crystal was placed in contact with the racemic compound, the resulting chirality after transition matched that of the seed with over 95% probability. The post-transition chiral crystals exhibited circularly polarized luminescence with g_lum = 8.9 × 10⁻⁴, functioning as a thermally stimulus-responsive, turn-on CPL material. These discoveries provide the simplest model system for molecular-level CSB occurring entirely within a single component without solvent involvement.