Florian has contributed to a computational study on proton transfer induced excited-state aromaticity gain for chromophores with maximal Stokes shifts led by Felix Plasser at Loughborough University. The study has now been published in Chemical Science. Congratulations to Felix and first author Dong!
Excited state aromaticity (ESA) offers a fascinating route for driving photophysical and photochemical processes but is challenging to harness fully due to its inherent association with unstable antiaromatic ground states. We propose to circumvent this problem via the introduction of a new class of photophysical processes, the generation of ESA via an excited-state intramolecular proton transfer. We selected twelve candidate molecules based on the cyclobutadiene and pentalene scaffolds and investigated their ground and excited state properties using computation. The study highlights the feasibility of proton transfer induced ESA gain and shows that it gives rise to pronounced excited-state relaxation producing Stokes shifts in excess of 2 eV. The underlying electronic structure properties were analysed in terms of the orbitals involved as well as aromaticity descriptors illustrating the pronounced changes these molecules undergo upon both excitation and proton transfer. In summary, we believe that the present work will pave the way toward a new class of chromophores with maximal Stokes shifts and excited-state relaxation.
D. Xing, F. Glöcklhofer, F. Plasser, Proton transfer induced excited-state aromaticity gain for chromophores with maximal Stokes shifts, Chem. Sci. 2024, 15, 17918-17926. [Link, open access]
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