Boosting X-Ray Imaging with a Highly Emissive Steroidal Gold Cluster Featuring Aggregation-Induced Circularly Polarized Luminescence.

X-ray imaging is essential for safety inspections, disease diagnosis, and treatment. High-performance X-ray scintillators require high luminous efficiency and excellent contrast enhancement. Circularly polarized luminescence (CPL) materials effectively suppress crosstalk and enhance image contrast. Herein, a novel hexanuclear chiral gold cluster (Cluster-ETH) with steroidal ethisterone frameworks is presented. The rigidity-engineered AIE cluster achieves high quantum yield (84.9%) and an intense CPL signal with a glum value of -5.3 × 10-3 in the aggregated state. Crystal analysis and TD-DFT calculations show that helical packing via hydrogen bonding interactions and aurophilic interactions drives efficient triplet harvesting. Cluster-ETH enables the first chiral gold cluster scintillator for X-ray imaging, demonstrating a low-detection-limit (118 nGy s-1). Cluster-ETH establishes the novel application of chiral gold clusters in advanced imaging technologies, providing a paradigm for the development of efficient X-ray scintillators.