Intercluster aurophilicity-driven aggregation lighting circularly polarized luminescence of chiral gold clusters

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.