Purely organic room-temperature phosphorescence endowing very fast intersystem crossing from through-space systems has not been well investigated. Here we report three space-confined bridged phosphors, where phenothiazine is linked with dibenzothiophene, dibenzofuran, and carbazole by a 9,9-dimethylxanthene bridge. Nearly pure phosphorescence is observed in the crystals at room temperature. Interestingly, phosphorescence comes solely from the phenothiazine segment. Experimental results indicate that bridged counterparts of dibenzothiophene, dibenzofuran, and carbazole contribute as close-lying triplet states with locally excited (LE) character. The through-space spin–orbit coupling principle is proposed in these bridged systems, as their ¹LE and ³LE states have intrinsic spatial overlap, degenerate energy levels, and tilting face-to-face alignment. The resulting effective through-space spin–orbit coupling leads to efficient intersystem crossing a with rate constant as high as 10⁹ s^–1 and an overwhelming triplet decay channel of the singlet excited state.

中文翻译：

---

纯有机室温磷光通过空间自旋-轨道耦合实现快速系统间交叉

纯有机室温磷光赋予空间系统非常快的系统间交叉尚未得到很好的研究。在这里，我们报告了三种空间受限的桥接磷光体，其中吩噻嗪通过 9,9-二甲基呫吨桥与二苯并噻吩、二苯并呋喃和咔唑连接。在室温下在晶体中观察到几乎纯的磷光。有趣的是，磷光仅来自吩噻嗪片段。实验结果表明，二苯并噻吩、二苯并呋喃和咔唑的桥连对应物作为具有局部激发 (LE) 特性的紧密三线态做出贡献。在这些桥接系统中提出了空间自旋轨道耦合原理，因为它们的¹ LE 和³LE 状态具有内在的空间重叠、退化的能级和倾斜的面对面对齐。由此产生的有效通过空间自旋轨道耦合导致有效的系统间交叉，速率常数高达 10 ⁹ s ^–1和单线激发态的压倒性三线态衰减通道。