Fabrication and fluorescence properties of perylene bisimide dye aggregates bound to gold surfaces and nanopatterns

Perylene bisimide dyes with two different imide substituents have been synthesized by sequential imidization reactions to give the disulfide 8 bearing two perylene bisimide dyes. Aggregation properties of this bis-perylene dye were studied by UV/Vis absorption and steady-state polarization-dependent as well as time-resolved fluorescence spectroscopy and the results were compared to those of the symmetrical perylene bisimide dye 4. In both cases, aggregation is expressed in a strong bathochromic shift of the excitation and the emission spectra and increasing concentration results in an increase in lifetime from 5 to 8 ns. By means of the thiol linker, self-assembly of 8 on gold surfaces was accomplished leading to surface-bound dye aggregates. Intense fluorescence from these dye aggregates was observed on surfaces decorated with hexagonal gold patterns, whereas the fluorescence is only weak on plain gold substrates.