Molecular aggregation to obtain conformer specific enhanced emissions from a triple emissive ESIPT dye

Abstract

Most of the excited state proton transfer exhibiting molecules show a dual emission. These emissions appear from two different conformers which equilibrate in the ground state. In the present work, we demonstrate an excited state intramolecular proton transfer exhibiting molecule which exhibits triple emission from different excited state species. The highly Stokes shifted normal emission is obtained by photoinduced planarization, and the keto-tautomer emission generates due to the phtotoinduced proton transfer. In the excited state, the tautomer undergoes torsional rotation induced isomerization to generate one more keto emission. The different ground state conformers of the molecule are separated from each other, and are exploited to produce aggregation induced emission enhancement with different emission colors. Thus, a single molecule is represented as a dual color emitting molecule.