A chain of photoinduced transformations of a photosensitively labeled crown ether (p-azido-benzo-18-crown-6) is studied in organic solvent and water to estimate the radiation dozes needed for optimum binding of photolabel. Transient absorption spectra of p-azido-benzo-18-crown-6 are measured with picosecond time resolution. The well-known photoinduced dynamics of phenylazide is compared to the dynamics of p-azido-benzo-18-crown-6. (c) 2005 Elsevier B.V. All rights reserved.