β-Diketone: Mg2+ ground and excited state interaction

► β-diketone is good Mg2+ binder in the ground state. ► Their excited state is more loosely bound compared to the ground state. ► Mg2+ form both ground and excited state isosbestic with all the four different diketones. ► Stabilisation of the diketone/Mg(II) complexes are the determining factor for this interaction. ► β-diketones themselves have ICT which is further enhanced due to the addition of Mg2+.