The intermetallic synergy plays a critical role in exploring the chemical-physical properties of metal nanoclusters. However, the controlled doping or layer-by-layer alloying of atom-precise metal nanoclusters (NCs) has long been a challenging pursuit. In this work, two novel alloy nanoclusters [PPh₄]₄[Ag₃₂Cu₁₈(PFBT)₃₆] ((AgCu)₅₀) and [PPh₄]₄[Au₁₂Ag₂₀Cu₁₈(PFBT)₃₆] (Au₁₂(AgCu)₃₈), where PFBT is pentafluorobenzenethiolate, with shell-by-shell configuration of M₁₂@Ag₂₀@Cu₁₈(PFBT)₃₆ (M = Ag/Au) were synthesized by a facile one-pot co-reduction method. Notably, a fingerprint library of [Ag_50−xCu_x(PFBT)₃₆]⁴⁻ (x = 0 to 50) from Ag₅₀ to Cu₅₀ has been successfully established as revealed by electrospray ionization mass spectrometry. Single-crystal X-ray diffraction analysis of trimetallic Au₁₂(AgCu)₃₈ confirmed the layer-by-layer alloying under reducing conditions. What is more, (AgCu)₅₀ and Au₁₂(AgCu)₃₈ both show broad photoluminescence (PL) peak in the second near-infrared (NIR-II) window, and the Au doping in the innermost shell considerably enhances the photoluminescence intensity. This work not only offers an insight in the process of metal cluster alloying but also provides a platform to study the doping-directed PL properties in the multimetallic cluster system.

Herein, we prepared two novel pairs of enantiomeric gold cluster complexes, Au₄PL₄/Au₄PD₄ and (Au₄L₄)_n/(Au₄D₄)_n with atomic precision. In Au₄PL₄/Au₄PD₄, the discrete chiral Au₄-based aggregation-induced emission (AIE) luminogens are separated by bulky substitutes. The corresponding aggregates are cyan-emitting with a photoluminescence quantum yield (PLQY) of 14.4%. Upon decreasing the size of the substituents, these chiral Au₄ clusters are strung together by inter-cluster Au-Au interactions, which cause a low-energy green emission from the aggregated (Au₄L₄)_n/(Au₄D₄)_n with a much higher PLQY of 41.4% and more intense circularly polarised photoluminescence (CPL) with a dissymmetry factor |g_PL| of 7.0 × 10^-3. Using (Au₄L₄)_n/(Au₄D₄)_n, circularly polarised organic light-emitting diodes (CP-OLEDs) were for the first time fabricated with |g_EL| = |g_PL|. These findings signify that inter-cluster metallophilic interactions are a new and important type of driving force for AIE and crystallization-induced emission (CIE), suggesting great potential of CPL-active metal clusters in CP-OLEDs.