Electrostatically Tuning the Photodissociation of the Irgacure 2959 Photoinitiator in the Gas Phase by Cation Binding

Our paper reports a combined experimental and computational investigation of the electrostatic tuning of Irgacure 2959, a Norrish-type I photoinitiator, in the presence of bound cations (H⁺ , Li⁺ , Na⁺ , K⁺ , Zn²⁺ , Ca²⁺ and Mg2+). Laser photodissociation action spectroscopy is deployed to acquire photodissociation spectra of mass- selected cation complexes. Quantum chemical calculations (TD-DFT and SCS-CC2) reveal that the cations are acting as point charges such that shifts of the key ππ* and nπ* states can be modelled as perturbations by an oriented electric field (OEF). The model agrees with the experimental photodissociation action spectra.