Single-phase synthesis of functionalized gold nanoparticles

A single-phase synthesis of thiolate monolayer-protected gold clusters (MPCs) is described. This method avoids the problem of persistent ionic contamination from residual phase-transfer catalyst while retaining the versatility associated with the commonly used two-phase Brust synthesis. MPCs having alkyl, diphenylacetylene, ether, amide, or ester functionalities were prepared by this single-phase synthesis and characterized via H-1 NMR, FT-IR, and UV-vis absorption spectroscopy, TGA, STM, and TEM. Comparisons of products synthesized by this method and by existing methods are made for a subset of MPCs. Results are considered in the context of using MPC thin films as chemically sensitive interface layers in chemiresistor vapor sensors.