Gold nanoparticles stabilized using a fluorescent propargylic ester terminal alkyne at room temperature

Stabilized gold nanoparticles are attracting more and more the interest of the scientific community, and this is mostly due to their versatility. We present the synthesis and characterization of gold nanoparticles of a mean diameter of 5.6 ± 0.4 nm stabilized using a terminal alkyne derivative of pyrene, a fluorophore able to act as a spectrofluorimetric probe. This capping moiety, including a propargylic ester, was designed to present a good tendency to interact with the gold surface possibly forming carbenoid intermediates. Its behaviour has been compared with the one of a linear terminal alkyne, also derivatized with a pyrene moiety. The changes in the photophysical properties of pyrene unambiguously show the formation of gold nanoparticles only using the species able to perform a rearrangement, clearly indicating that this ability is crucial for binding on the nanoparticles, the rather poorly stabilizing terminal alkynes.