Unequivocal Experimental Evidence of the Relationship between Emission Energies and Aurophilic Interactions

In this paper, we describe experimental evidence of a change in the emission energy as a function of the Au−Au distance. We have employed a luminescent complex exhibiting an aurophilic interaction, which is weak enough to allow its length to be modified by external pressure but rigid enough to confer structural stability on the complex. By determining the crystal structures and emission characteristics over a range of pressures, we have identified an exponential relationship between the energy of the emitted light and the metal−metal distances under pressure. This result can be indirectly related to the repulsive branch of the fitted function representing the energy of the system in the ground state at different Au−Au distances. The relativistic nature of gold appears to play an important role in the behavior of this complex.