REACTIVITIES OF CHROMOPHORE-CONTAINING METHYL TRI-N-BUTYLAMMONIUM ORGANOBORATE SALTS AS FREE-RADICAL PHOTOINITIATORS - DEPENDENCE ON THE CHROMOPHORE AND BORATE COUNTERION

Several UV absorbing chromophores have been incorporated in ammonium t riphenylbutyl- and tetraphenylborates as light-harvesting groups, and the reactivity of the resulting salts as unimolecular free radical ini tiators has been studied. The results are compared with kinetic and th ermodynamic data calculated for the primary photochemical step leading to generation of the initiating species. The dependence of the initia tion reactivities on the structure of both the chromophore and the bor ate counteranion is discussed.