Chemistry

Controlling Cluster Color

See allHide authors and affiliations

Science  07 Oct 2011:
Vol. 334, Issue 6052, pp. 19
DOI: 10.1126/science.334.6052.19-a
CREDIT: PANCE NAUMOV AND JOSE MARIA LOPEZ DE LUZURIAGA

Strongly photoluminescent materials that respond to changes in their environment, such as mechanical stress or chemical solvation, are useful in sensing applications. Lasanta et al. synthesized gold-silver clusters by reacting gold bearing a halogenated phenyl ligand (2-C6F4I, RII) with silver trifluoroacetate [Ag(tfa)]. Crystallographic analysis revealed that the resulting anionic compound, [Au2Ag2(2-C6F4I)4(tfa)2]2−, forms through metallophilic interactions—the bridging silver atoms each bear a tfa ligand and coordinate to two gold atoms—and through halogen bonds between iodine and gold atoms. This compound has strong green luminescence, but the addition of a coordinating solvent such as acetonitrile initially creates a dimeric form of the compound through gold bridging interactions. In this yellow luminescent material, the silver atoms bear no coordinating solvent. After a few minutes, the final polymeric form, a red emitter, forms through additional gold bridges and coordinates acetonitrile at the silver atoms. The monomeric form could be recovered by aging for several hours or by grinding the polymer in excess tfa.

J. Am. Chem. Soc. 131, 10.1021/ja206845s (2011).

Navigate This Article