Single‐Atom Tunning Visible‐Near‐Infrared CPL in Chiral Metal Clusters

ABSTRACT Circularly polarized luminescence (CPL)‐active nanoclusters hold great promise for advanced photonic applications, yet the improvement of the | g lum | has always been the core challenge in this field for a long time. Herein, we report the enantiomeric pairs of homometallic cationic ( R/S )‐[Ag 21 (S 2 PO 2 C 17 H 14 ) 12 ] + ( R/S ‐Ag 21 ) and heterometallic neutral ( R/S )‐[PtAg 20 (S 2 PO 2 C 17 H 14 ) 12 ] ( R/S ‐PtAg 20 ) clusters stabilized by a bis‐thiophosphinate spiro ligand and featuring eight free electrons. R/S ‐Ag 21 exhibits a single emission with a | g lum | value of 4.7 × 10 −4 , whereas R/S ‐PtAg 20 with only one atom changed exhibits visible‐near‐infrared (NIR) dual emission CPL behavior, with a visible‐light emission | g lum | value of 6.4 × 10 −4 and an NIR emission | g lum | value of 1.3 × 10 −2 —among the highest reported for metal clusters. Research has revealed that the luminescence of R/S ‐PtAg 20 originates from two independent triplet excited states: a core‐based charge transfer (CT) state and a ligand‐to‐core CT state, which are bridged by a direct CT process mediated by ligand vibrations. The high | g lum | value of R/S ‐PtAg 20 in the NIR region stems from the strong correlation between its electronic cloud and the peripheral chiral ligands. Furthermore, guest‐induced modulation of ligand rigidity enables tunable emission modes—visible‐only, NIR‐only, or dual‐visible‐NIR. This work presents a novel strategy for constructing DECPL‐active metal clusters, offering fundamental insights into the design principles governing CPL efficiency and paving the way for multifunctional photonic systems, such as optical encryption.