Synthesis of silica-stabilized Ag44 clusters aided by a designed mercaptosilane ligand

Abstract

The novel and precise design of both a microscopic ligand and macroscopic structure has been demonstrated to improve the stability and potential optical applications of Ag₄₄ clusters. The ligand with designed silane substituents on its thiophenol enabled the synthesized [Ag₄₄(SPhSi(OEt)₃)₃₀](PPh₄)₄ clusters to maintain UV-vis absorption for 13 h when heated at 60 °C in air and be readily coated with silica shells via a one-pot reverse microemulsion method. This composite structure overcomes the issue that non-luminescent Ag₄₄ clusters cannot be applied in photothermal and photoacoustic imaging due to their instability.