By using density functional theory calculations, it is found that the most negative MEP inside the gold cage occurs at the center of the sphere. The largest regions with the most negative MEP outside the sphere are localized in the neighborhood of the bridge sites and the vertex regions of the five-coordinated are more positive. The absolute values of the most negative potentials in both the inner and outer cages as well as the vertex regions of the five-coordinated of Au-32 structure are much larger than those of Au-42, which means Au-32 is preferable for electrophilic attack or nucleophilic processes. (c) 2008 Elsevier B. V. All rights reserved.