The experimental conditions in the two-phase synthesis of hexanethiolate gold monolayer-protected clusters (C6-Au) have been investigated by varying the thiolation and reduction times to give particles with an average core diameter of 1.66 sun and a capacitance of 0.54-0.59 aF. These clusters were further functionalised with anthraquinone by reaction between the diazonium derivative of 1-amino anthraquinone and electrochemically or chemically charged nanoparticles. Cyclic voltammetry and differential pulse voltammetry measurements demonstrate functionalisation by the redox couple and the presence of quantised double layer (QDL) charging events at the gold core. The feasibility of using a dispersion of charged nanoparticles as reagents for driving a diazotisation reaction to attach redox ligands is demonstrated.