Our latest article with the title ‘Full-Dimensional Photodynamics of Bistable Proton Transfer Switches’ just got accepted for publication in Zeitschrift für Physikalische Chemie!
Abstract: Excited-state intramolecular proton transfers (ESIPT) are one of the fastest reactions in chemistry (<100 fs) which – among other features like high photostability – makes them an important reaction class for molecular switches. ESIPTs can be coupled with double bond rotation/isomerization, so that molecules can act as “molecular cranes”, facilitating long-range proton transfer. A versatile model system is 7-hydroxy-4-methylquinoline-8-carbaldehyde (HMQCA): it features two proton-accepting sites, two stable ground-state isomers and should allow for easy derivatization. There is also experimental and theoretical reference data available, however, only for static properties, e.g., ground-state IR spectra or potential energy surface scans. In this contribution we show the results of full-dimensional surface- hopping molecular dynamics (MD) of HMQCA after photo-excitation, employing semiempirical quantum mechanics coupled to floating-occupation configuration interaction. The results support the potential of HMQCA as prototype system for directed proton transport by ESIPT.
UPDATE: The article is now available online: https://doi.org/10.1515/zpch-2019-1587