The influence of core size on electronic coupling in shell–core nanoparticles: gold clusters capped with pyrenoxylalkylthiolate

Abstract

The mean size of the metallic core of monolayer-protected gold clusters densely capped with 9-(1-pyrenoxyl)octane-1-thiol or 1-dodecanethiol can be adjusted by controlling the thiol/HAuCl₄ ratio during synthesis. Upon reduction of tetrachloroaurate by NaBH₄, lower mean metal core diameters were attained in those composites prepared from mixtures with higher thiol/Au ratios. The efficiency of electronic coupling between the core metal cluster and pyrenyl groups appended as an outer shell in this size-graded family was studied by absorption and fluorescence spectroscopy. The observed emission intensity from the bound fluorophores is independent of the gold core size.