ARYL AZIDES AS PHOTOAFFINITY LABELS. A PHOTOCHEMICAL STUDY OF SOME 4-SUBSTITUTED ARYL AZIDES

Abstract

Abstract— The photochemistry of a series of aryl azides used in, or closely related to some of those used in photoaffinity labeling studies, has been investigated by flash photolysis, continuous irradiation and low-temperature irradiation with IR and UV spectroscopic analysis. Results indicate that labeling preferentially takes place via singlet species. The reactive intermediates appear to be cycloazaheptatetraenes and/or the corresponding benzazirines. The reactive intermediates have τ½ of the order of milliseconds or shorter and oxygen may act as a quencher, thereby interfering with the affinity labeling.