The structures of the red polymorph (space group P1) and the black polymorph (space group P2₁/c) of 4,4′‐dimethyl‐6,6′‐dichlorothioindigo were solved from single‐crystal samples. For both polymorphs, the spatial stacking of the flat molecules is driven by π‐stacking and noncovalent interactions within the layers. Spectroscopic (UV–vis, IR and photoluminescence) and thermal properties of the red polymorph were investigated experimentally. The bandgap of this polymorph was estimated as 2.08 eV at room temperature. It is demonstrated that the electric conductivity of the red polymorph follows the hopping mechanism.

中文翻译：

---

4,4'-二甲基-6,6'-二氯硫靛蓝的晶体结构和介电性能（颜料红181）

从单晶样品中解析了4,4'-二甲基-6,6'-二氯硫靛蓝的红色多晶型物（空间群P 1）和黑色多晶型物（空间群P 2 ₁ / c）的结构。对于这两种多晶型物，平面分子的空间堆积是由层中的π堆积和非共价相互作用驱动的。通过实验研究了红色多晶型物的光谱（紫外可见，红外和光致发光）和热学性质。在室温下，该多晶型物的带隙估计为2.08 eV。结果表明，红色多晶型物的电导率遵循跳跃机制。