An atomically precise silver nanocluster for artificial light-harvesting system through supramolecular functionalization

Designing an artificial light-harvesting system (LHS) with high energy transfer efficiency has been a challenging task. Herein, we report an atom-precise silver nanocluster (Ag NC) as a unique platform to fabricate the artificial LHS. A facile one-pot synthesis of [Cl@Ag16S(S-Adm)(8)(CF3COO)(5)(DMF)(3)(H2O)(2)]center dot DMF (Ag-16) NC by using a bulky adamantanethiolate ligand is portrayed here which, in turn, alleviates the issues related to the smaller NC core designed from a highly steric environment. The surface molecular motion of this NC extends the non-radiative relaxation rate which is strategically restricted by a recognition site-specific supramolecular adduct with beta-cyclodextrin (beta-CD) that results in the generation of a blue emission. This emission property is further controlled by the number of attached beta-CD which eventually imposes more rigidity. The higher emission quantum yield and the larger emission lifetime relative to the lesser numbered beta-CD conjugation signify Ag-16 boolean AND beta-CD2 as a good LHS donor component. In the presence of an organic dye (beta-carotene) as an energy acceptor, an LHS is fabricated here via the Forster resonance energy transfer pathway. The opposite charges on the surfaces and the matched electronic energy distribution result in a 93% energy transfer efficiency with a great antenna effect from the UV-to-visible region. Finally, the harvested energy is utilized successfully for efficient photocurrent generation with much-enhanced yields compared to the individual components. This fundamental investigation into highly-efficient energy transfer through atom-precise NC-based systems will inspire additional opportunities for designing new LHSs in the near future.