Time-Correlated Single-Photon Counting Investigations of the Effects of Temperature, Solvent, and Excitation Energy on the Fluorescence Lifetime of Adamantyl Diazirine
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Date
1995
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Ohio State University
Abstract
Diazirines exhibit complex photochemistry. They serve as precursors for carbenes (via extrusion of $N_{2}$), which can subsequently undergo intramolecular rearrangements (e.g., 1, 2-hydrogen migration to form alkenes) or react in an intermolecular fashion (e.g., with solvents). It is often difficult to determine whether these products are formed via the carbene or directly from the diazirine. Owing to its highly strained geometry, adamantyl diazirine possesses a significant barrier to intramolecular rearrangement. As a consequence, other photochemical pathways are enhanced in admantyl diazirine relative to other dialkyldiazirines. Recently, we have confirmed that the excited state of adamantyl diazirine can also decay via fluorescence. [FIGURE] We have obtained time-correlated singlephoton counting fluorescence decays for adamantyl diazirine in a variety of solvents, over a wide range of temperatures (77 K-320 K), across the diazirine absorption band (320 nm-400 nm). The lifetime of the primary decay component is on the order of 250 ps. These data and the results of complementary steady-state measurements will be presented, along with a preliminary interpretation of their significance. [FIGURE]
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