Long-range hydrogen-bond relay catalyses the excited-state proton transfer reaction.

Solvent (, water)-catalyzed proton transfer (SCPT) the relay of hydrogen (H)-bonds plays a key role in proton migration. In this study, a new class of 1-pyrrolo[3,2-]quinolines (PyrQs) and their derivatives were synthesized, with sufficient separation of the pyrrolic proton donating and pyridinic proton accepting sites to probe excited-state SCPT. There was dual fluorescence for all PyrQs in methanol, , normal (PyrQ) and tautomer 8-pyrrolo[3,2]quinoline (8H-PyrQ) emissions.