Preparation and photocoagulation in chloroform of Au nanoparticles capped with azobenzene-derivatized alkanesulfides

Azobenzene-derivatized alkanesulfides di[10-(4-ethoxyphenylazo)-2-methyl-phenoxydecanyl]sulfide (2AM10)2S, and di[10-(4-octylphenylazo)-2-methyl-phenoxypentyl]sulfide (8AM5)2S, were synthesized and used to prepare capped Au nanoparticles. The conversion of photoisomerization (trans to cis) of these sulfides on Au nanoparticles dispersed in chloroform was 70–80%. Au nanoparticles capped with cis-(2AM10)2S were found to coagulate in chloroform, while those capped with trans-(2AM10)2S dispersed in chloroform. However, Au nanoparticles capped with (8AM5)2S always formed a dispersion in chloroform regardless of whether (8AM5)2S was in the trans or cis conformation.