Fluorescent gold nanoparticles: synthesis of composite materials of two-component disulfide gels and gold nanoparticles.

Pseudoenantiomeric ethynylhelicene oligomers containing a disulfide group formed two-component gels, which showed different solvent properties from gels without the disulfide group. The disulfide gels reacted with gold nanoparticles, and the resulting organic-inorganic composite materials exhibited fluorescence emission between 600-800 nm, along with emission from the oligomers at 450 nm. The disulfide gels and isolated gold nanoparticles loaded with the oligomers did not show the former emission. The 600-800 nm emission reversibly disappeared upon sol formation with heating, which was accompanied by an enhancement of the emission at 450 nm. The novel emission was also observed in the solid state.