Spectroscopy of jet-cooled polar complexes of aminophthalimides

The spectroscopy and excited-state lifetimes of 3- and 4-aminophthalimides (3AP, 4AP), N-methyl-4AP (NM4AP) and some complexes with polar molecules have been explored under supersonic jet conditions. Spectroscopic data, MM2-level structure calculations and rotational coherence spectroscopy show that a single water molecule attaches to 3AP by accepting a hydrogen bond from the imide > NH group. Whereas 3AP/H2O is present as a single species, the case of 4AP is complicated by the presence of two isomers, having significantly different fluorescence decay times and radiative lifetimes. This observation, which is repeated for methanol complexation, is evidence for the sensitivity of the electronic structure of 4AP to a site-specific interaction.