Small aromatic thiol molecules HS-C6H4-X, where X = OH, COOH, NH2, and CH3, have been used to stabilize gold nanosized clusters. The physical properties of the surfactant-coated nanoparticles, both in solution and as thin films, were found to be dependent upon the nature of the functional group X. In particular it was found that particles bearing COOH and NH2 functionalities were prone to significant aggregation through hydrogen bond formation.