Kinetically controlled self-assembly of atom-precise gold nanoclusters into multicolor emissive supramolecular...

Establishing self-assembly chemistry based on metal nanoclusters (NCs) holds great potential for promoting performance improvement and enriching functional diversity. Herein, by a well-designed liquid reaction strategy, the individual atomic-precise Au₅ NCs self-assembled into a highly regular and ordered nanofiber supramolecular structure with improved photoluminescence (PL). The kinetically controlled structural growth mechanism was unraveled through time-dependent in situ multi-spectral monitoring of the self-assembly process. The self-assembly experienced three structural evolution stages involving disordered aggregation, lateral arrangement and longitudinal stacking, which were driven by multiple driving forces involving aurophilic interaction, dipolar attraction and π-π stacking. By establishing dynamic structure-property relationship, the assembly-induced PL enhancement mechanism was illustrated. The enhanced aurophilic Au(I)-Au(I) interactions promoted the excited state relaxation dynamics via a radiative pathway, and the structures with enhanced rigidity reduced the level of nonradiative relaxation of excited states, which collectively contributed to the increase in PL intensity. The assembly-promoted average Au(I)-Au(I) distance decreased, causing a red shift in the PL wavelength. Inspired by the assembly-induced PL enhancement of Au₅ NCs, a series of multicolor emissive nanofibers were successfully obtained by the self-assembly of various atomically precise Au NCs. The multicolor nanofibers comprising independent and homogeneous chromophores exhibited phosphorescence emissions, with the PL wavelengths spanning the whole visible-light range. They were well employed as multicolor luminescent inks, showing broad prospects for optical property-related potential applications.