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Updated: Aug 5, 2025

Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
Time-resolved photoelectron spectroscopy of 4-(dimethylamino)benzethyne - an experimental and computational study
Kevin Issler1, Floriane Sturm1, Jens Petersen1
1Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany. ingo.fischer@uni-wuerzburg.de.
Abstract:
We investigated the excited-state dynamics of 4-(dimethylamino)benzethyne (4-DMABE) in a combined theoretical and experimental study using surface-hopping simulations and time-resolved ionisation experiments. The simulations predict a decay of the initially excited S2 state into the S1 state in only a few femtoseconds, inducing a subsequent partial twist of the dimethylamino group within ∼100 fs. This leads to drastically reduced Franck-Condon factors for the ionisation transition to the cationic ground state, thus inhibiting the effective ionisation of the molecule, which leads to a vanishing photoelectron signal on a similar timescale as observed in our time-resolved photoelectron spectra. From the phototoelectron spectra, an adiabatic ionisation energy of 7.17 ± 0.02 eV was determined. The experimental decays match the theoretical predictions very well and the combination of both reveals the electronic characteristics of the molecule, namely the role of intramolecular charge transfer (ICT) states in the deactivation pathway of electronically excited 4-DMABE.
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