Study of the introduction of gold(I) on the luminescence of organometallic complexes

Abstract

In recent years, the interest in luminescent gold(I) complexes has increased significantly, due to the effect of this metal centre on modulating the light emission properties of the ligands attached to it. This is mainly due to two factors: relativistic effects and supramolecular interactions. In this project, new bis(phosphane) gold(I) complexes have been prepared, aiming to study how the introduction of gold affects the luminescence of the ligands. The work involved the synthesis of the phosphanes with expected intrinsic luminescent properties, their corresponding gold(I) complexes, and the optimisation of these syntheses to obtain satisfactory yields. To evidence the correct formation of the target compounds, a variety of characterisation techniques were used (NMR, IR and HRESI-MS). A basic photophysical characterisation was carried out using UV-vis and emission spectroscopies, quantum yields and lifetimes. These studies showed a significant increase in fluorescence emission and a redshift (ca. 10 nm) in every gold complex compared to their corresponding free ligand. However, no phosphorescence was observed, even under nitrogen-saturated conditions. This suggests that either the energy gap between the first excited state and the triplet state is too large for the intersystem crossing to occur; that phosphorescence emission is only detectable at low temperatures or that there are other competitive mechanisms that compete with phosphorescence emission after population of the triplet excited state. To gain a deeper understanding of the observed phenomena, additional studies such as variable-temperature emission experiments and computational studies should be performed. The obtained results suggest the potential of these gold(I) complexes use in optoelectronic devices such as light-emitting electrochemical cells (LECs). Understanding the correlation between structural aspects and photophysical properties in these systems could contribute to the development of next generation luminescent materials