Multiple Anti-Kasha Emissions in Transition Metal Complexes

11 July 2019, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


In this manuscript we present a from-first-principlesevidence that several higher-lying excited states are responsible for the emission spectrum of [M(CO)4(bpy)] (M = Cr, Mo, W and bpy=2,2’-bipyrimidine) complexes. These results highlight the violation of Kasha’s rule, which states that after irradiation molecules emit light with appreciable yield only from its lowest energy excited state. Furthermore, in [W(CO)4(bpy)] and [Mo(CO)4(bpy)], the breaking of Kasha’s rule is two-fold, because at least two different excited states besides T1are involved in emission. To our knowledge, these are the first transition metal complexes unambiguously demonstrated to display simultaneous equilibrated and non-equilibrated anti-Kasha emissions. This work also highlights the complexity of the emissive processes of tetracarbonyl-diimine transition metal complexes, which are controlledviaa subtle interplay of electronic and geometrical effects along the excited state deactivation dynamics.


Kasha rule
computational photochemistry
inorganic photo physics

Supplementary materials

SI Escudero


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