Divergent luminescence behaviour from differential interactions in dinuclear Pt, Au, and mixed Pt-Au complexes built on a xanthene scaffold

A diethynylxanthene unit is used to tether cyclometallated Pt(II) and Au(III) complexes in a geometry that favours interfacial interactions. This leads to protection from non-radiative decay pathways in the Au-2 dimer and to low-energy 'aggregate-like' emission in a closely related Pt-2 dimer, whilst rapid Au-to-Pt energy transfer occurs in the heterodimer.