A Picosecond Time-Resolved Spectroscopic Investigation of the Effect of pH on Morin Fluorescence.

In this work, we investigated for the first time morin in MeOH at different pH values by picosecond time-resolved fluorescence. We identified the two species responsible for the fluorescence at low and high pH. The solvated morin-solvent hydrogen-bonded complex has been experimentally observed for the first time. We give also the typical fluorescence spectra as well as the fluorescence lifetimes of the probable emitting species. In this work we put forward new insights concerning the contribution of free morin to the fluorescence. We hope that these new data improve the accuracy of the interpretation of the cation:morin complexes titration using fluorescence signal.