HYDROGEN-BONDED COMPLEXES IN THE GROUND AND EXCITED-STATES BETWEEN INDOLE AND TROPANE DERIVATIVES

In nonpolar media the indole fluorescence is quenched by tropane alkaloids mainly due to the formation of a hydrogen bonded complex in the ground and excited states. The results obtained indicate the existence of only two species at equilibrium, in the concentration range used. The parameters involved in the static and dynamic quenching have been determined separately. From these parameters is apparent that the tropane alkaloids are efficient as quenchers a useful feature for their use in the study of the muscarinic receptors in the nanosecond range. In acetonitrile, an equilibrium in the excited state is attained between indole and its deprotonated phototransfer product.