Ultrafast Study of <i>p</i>-Biphenylyldiazomethane and <i>p</i>-Biphenylylcarbene
作者:Jin Wang、Gotard Burdzinski、Terry L. Gustafson、Matthew S. Platz
DOI:10.1021/jo061029+
日期:2006.8.1
p-Biphenylyldiazomethane was excited by femtosecond pulses of UV light in acetonitrile, in cyclohexane, and in methanol. Ultrafast photolysis produces a singlet excited state of p-biphenylyldiazomethane with λmax = 490 nm, and lifetimes of less than 300 fs in acetonitrile, in cyclohexane, and in methanol. The decay of the excited state is accompanied by the growth of transient absorption with λmax
p -Biphenylyldiazomethane通过在乙腈UV光的飞秒脉冲,在环己烷中激发,并在甲醇中。超快光解产生的单重激发态p -biphenylyldiazomethane与λ最大= 490纳米,小于300个飞秒的乙腈溶液,在环己烷中的寿命,并在甲醇中。激发态的衰减伴随着λmax = 360 nm的瞬态吸收的增长。这种瞬态吸收的载体归因于单重态p-联苯基卡宾,这一结果与TD-DFT计算的预测相一致。在乙腈和环己烷中,单线态卡宾的寿命分别为200 ps和77 ps,并通过跨系统转换为低能三线态来控制。由于丁腈的形成,瞬态吸收不会衰减到乙腈的基线。单线态和三线态对联苯基卡宾的平衡混合物与乙腈反应形成腈基内酰胺(λmax = 370 nm),并在激光脉冲后1-20 ns通过CH插入与环己烷反应生成环己烷。由于与溶剂的快速反应,在甲醇中单线态卡宾的寿命仅为7.9 ps。与溶剂反应部分生成对