Disclosed herein are novel nanoparticles, particularly metal nanoparticles, such as gold nanoparticles. According to one embodiment of a method disclosed herein nanoparticles are functionalized via ligand exchange reactions. Also disclosed is a method for controlling nanoparticle spacing to produce nanoparticle arrays having defined spacing. Such nanoparticles and arrays thereof are particularly useful in nanoelectronics, nanophotonics, catalysis, sensors, and biotaggents.