Interaction of size-selected Gold nanoclusters with Dopamine

We present density functional theory based results on the interaction of size-selected gold nanoclusters, Au-10 and Au-20, with dopamine molecule. The gold clusters interact strongly with the nitrogen site of dopamine, thereby forming stable gold-dopamine complexes. Our calculations further show that there is no site specificity on the planar Au-10 cluster with all the edge gold atoms equally preferred. On the other hand, in the pyramidal Au-20 cluster, the vertex metal atom is the most active site. As the size increased from Au-10 to Au-20, the interaction strength has shown a declining trend. The effect of aqueous environment on the interaction strengths were also studied by solvation model. It is found that the presence of solvent water stabilizes the interaction between the metal cluster and dopamine molecule, even though for Au-10 cluster the energy ordering of the isomers changed from that of the gas-phase.