Photoisomerisation and ligand-controlled reversible aggregation of azobenzene-functionalised gold nanoparticles†
The photochemical behaviour of functionalised gold nanoparticles (AuNPs) carrying azobenzenethiolate–alkylthiolate monolayers was investigated. Repeated trans–cis and cis–trans isomerisation cycles could be performed in all cases with high efficiency. Reversible photoinduced aggregation was observed when azothiolates with long alkyl spacers (≥C7) were combined with short (C5) alkylthiolate coligands. The choice of a coligand thus offers control over the aggregation properties of the nanoparticles.