A Computational Protocol to Predict Anti-Kasha Emissions: The Case of Azulene Derivatives

In this contribution we present a computational protocol to predict anti-Kasha photoluminescence. The herein developed protocol is based on state-of-the-art quantum chemical calculations and excited state decay rate theories (i.e., thermal vibration correlation function formalism), along with appropriate kinetic models which include all relevant electronic states. This protocol is validated for a series of azulene derivatives. For this series, we have computed absorption and emission spectra for both their first and second excited states, their radiative and non-radiative rates as well as fluorescence yields from the two different excited states. All the studied azulene derivatives are predicted to exclusively display anomalous anti-Kasha S₂ emission. A quantitative agreement for the herein computed excited state spectra, lifetimes and fluorescence quantum yieldsis obtained with respect to the experimental values. Given the increasing interest on anti-Kasha emitters, we foresee that the herein developed computational protocol can be used to pre-screen dyes with the desired aforementioned anomalous photoluminescence properties.