CHEMISTRY: Golden Glow

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Science  30 Jul 2004:
Vol. 305, Issue 5684, pp. 575d-577d
DOI: 10.1126/science.305.5684.575d

The performance of organic display materials in a variety of applications can benefit from the inclusion of luminescent compounds that have long emission lifetimes at visible wavelengths, and metal complexes containing small clusters of gold atoms can display these optical properties. Wang et al. now report on a set of isostructural complexes containing a tetrahedral core of three gold atoms and one silver atom; these complexes allow the relation of structure to emission to be explored in more detail.

In these compounds, the tripod of gold atoms is capped on one side by the silver atom and on the other side by an oxygen, sulfur, or selenium atom. The three gold-silver edges are bridged by diphenylphosphine-2-pyridine ligands. X-ray crystallography reveals that dimers form in the solid state through an aurophilic bridge between the exposed gold-gold edges. The emission is blue for the oxygen capping ligand, yellow or green for sulfur (which was also prepared as the diphenylphosphine-4-methylpyridine complex), and red for selenium. The authors assign the emission, based on the relative energy of the lone pair orbitals of these capping ligands, to a ligand-to-metal-metal charge-transfer process. — PDS

J. Am. Chem. Soc.10.1021/ja048091d (2004).

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