Sarkar Sujan K, Gatlin DeVonna M, Das Anushree, Loftin Breyinn, Krause Jeanette A, Abe Manabu, Gudmundsdottir Anna D
Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221, USA.
Org Biomol Chem. 2017 Sep 13;15(35):7380-7386. doi: 10.1039/c7ob01731f.
Irradiation of nanocrystals of azide 1 results in a solid-to-solid reaction that forms imine 2 in high chemical yield. In contrast, solution photolysis of azide 1 yields a mixture of products, with 7 as the major one. Laser flash photolysis (LFP) of a nanocrystalline suspension of azide 1 in water shows selective formation of benzoyl radical 4 (λ ∼ 400 nm), which is short-lived (τ = 833 ns) as it intersystem crosses to form imine 2. In comparison, LFP of azide 1 in methanol reveals the formation of triplet alkylnitrene 10 (λ ∼ 340 nm). The selectivity observed in the solid-state is related to stabilization of the triplet ketone with (n,π*) configuration by the crystal lattice, which results in α-cleavage being favored over triplet energy transfer to the azido chromophore. Both the solid-state and solution reaction mechanisms are further supported by density functional theory calculations. Thus, laser flash photolysis has been used to effectively elucidate the medium dependent reaction mechanisms of azide 1.
叠氮化物1的纳米晶体经辐照会引发固-固反应，以高化学产率生成亚胺2。相比之下，叠氮化物1的溶液光解会产生产物混合物，其中7是主要产物。叠氮化物1在水中的纳米晶体悬浮液的激光闪光光解（LFP）显示选择性形成苯甲酰基自由基4（λ ∼ 400 nm），其寿命较短（τ = 833 ns），因为它会通过系间窜越形成亚胺2。相比之下，叠氮化物1在甲醇中的LFP揭示了三重态烷基氮烯10（λ ∼ 340 nm）的形成。在固态中观察到的选择性与晶格对具有（n,π*）构型的三重态酮的稳定作用有关，这导致α-裂解比三重态能量转移到叠氮发色团更受青睐。密度泛函理论计算进一步支持了固态和溶液反应机理。因此，激光闪光光解已被用于有效阐明叠氮化物1的介质依赖性反应机理。
