Dibenzothiophene-5-oxide (DBTO) cleanly produces dibenzothiophene (DBT) on direct photolysis, but with very low quantum yield. A proposed mechanism involves scission of the S−O bond which is coupled to an intersystem crossing step, thus producing the sulfide and O(3P) via a unimolecular pathway. To test this hypothesis, heavy atom substituted DBTOs were prepared and photolyzed. Iodo-, bromo-, and chloro-substituted
二苯并噻吩-5-氧化物(DBTO)在直接光解过程中干净地产生了
二苯并噻吩(DBT),但量子产率很低。拟议的机制涉及切断与系统间交叉步骤耦合的S-O键,从而通过单分子途径产生
硫化物和O(3 P)。为了验证该假设,制备了重原子取代的DBTO并进行了光解。与母体分子相比,
碘,
溴和
氯取代的DBTO显示出更高的脱氧量子产率,其顺序与系统间穿越相关的重原子效应一致。
2-碘二苯并噻吩也经历光
化学脱
碘。
磷光数据与重原子辅助的系统间交叉相一致。