Long-lived photoluminescence of unnatural quinine analogues

Cinchona alkaloids have played an important part in the history of fluorescence studies and the recent discovery of their long-lived emission makes them a useful tool for exploring new applications in labelling and tagging. Furthermore, they are excellent model systems for exploring the fundamental nature of charge transfer due to the through-space charge transfer between the nitrogen atom on the cage and the quinoline aryl group. However, the synthetic routes and pathways to modification are cumbersome and new synthetic routes are required. Here we demonstrate new synthetic pathways to create a wide range of unnatural quinine analogues giving control over the chromophore point of attachment and N-aryl distance. Furthermore the molecules demonstrate long-lived emission confirming that we are capturing some of the novel photophysical properties of their natural analogues.