Gold cluster

Gold clusters in cluster chemistry are gold-derived materials that can either be discrete molecules or larger colloidal particles. Both types are describes as nanoparticles, with diameters of less than one micrometer.

Discrete gold clusters
Well-defined, molecular clusters are known, invariably containing organic ligands on their exteriors. Two examples are   [Au6CP(C6H5)3)6]2+ and [Au9(P(C6H5)3)8]3+.

Colloidal clusters
Gold clusters can be obtained in colloid form. Such colloids often occur with a surface coating of alkanethiols or proteins. Such clusters can be used in immunohistochemical staining. Evidence has been presented for the existence of hollow golden cages with the partial formula Aun- with n = 16 to 18. These cluster compounds with diameter of 5.5 angstrom are observed in the gas-phase after they have been generated by laser vaporization and can only be observed in the gas phase by photoelectron spectroscopy.

gold metal nanoparticles (NPs) are characterized by an intense absorption in the visible region, which enhances the utility of these species for the development of completely optical devices. The wavelength of this surface plasmon resonance (SPR) band depends on the size and shape of the nanoparticles as well as their interactions with the surrounding medium. The presence of this band enhances the utility of gold nanoparticle as building blocks for devices for data storage, ultrafast switching, and gas sensors.