Simple Production of Single-Molecule White-Light Fluorophores via One-Photon Photoproduction

In this work, we present a novel white-light single-molecule fluorophore produced from the photoreaction of simple amines and iodine-containing naphthalene derivatives. Ultrafast one-photon photodissociation of iodine from the naphthalene derivative results in a reaction between this ion and the amine molecule to generate the photoproduct in observable quantities visible to the naked eye, within a time frame of minutes. The resulting photoproduct demonstrates broad fluorescence from 300 to 700 nm with a quantum yield of ∼0.38. We postulate that the broad fluorescence and relatively high quantum yield result from a number of triplet–singlet interactions in the excited state of the fluorophore, enhanced by the high orthogonality in the structure of the fluorophore, resulting in single-donor, dual acceptor electronic charge-transfer excited states identified through computational studies herein. This is further supported by observations of the solid-state photoproduct, which demonstrates the hallmarks of thermally activated delayed fluorescence, with fluorescence occurring between 600 and 700 nm with triexponential fluorescence lifetimes of 5.6, 32, and 640 ns. We conclude that these findings represent an exciting new development in single-molecule fluorophores that warrants significant further study.