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 |gPL| 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 |gEL| = |gPL|. 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.