The photochemistry of 2-naphthylsulfonyl azide (2-NpSO 2N 3) was studied by femtosecond time-resolved infrared (TR-IR) spectroscopy and with quantum chemical calculations. Photolysis of 2-NpSO 2N 3 with 330 nm light promotes 2-NpSO 2N 3 to its S 1 state. The S 1 excited state has a prominent azide vibrational band. This is the first direct observation of the S 1 state of a sulfonyl azide, and this vibrational feature allows a mechanistic study of its decay processes. The S 1 state decays to produce the singlet nitrene. Evidence for the formation of the pseudo-Curtius rearrangement product (2-NpNSO 2) was inconclusive. The singlet sulfonylnitrene 1(2-NpSO 2N) is a short-lived species (τ ≈ 700 ± 300 ps in CCl 4) that decays to the lower-energy and longer-lived triplet nitrene 3(2-NpSO 2N). Internal conversion of the S 1 excited state to the ground state S 0 is an efficient deactivation process. Intersystem crossing of the S 1 excited state to the azide triplet state contributes only modestly to deactivation of the S 1 state of 2-NpSO 2N 3.
ASJC Scopus subject areas
- Colloid and Surface Chemistry