September 29, 2026 by National Institutes of Natural Sciences edited by Sadie Harley, reviewed by Andrew Zinin Scientific Editor Chief Editor This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: fact-checked peer-reviewed publication trusted source proofread Chiral metal clusters that emit circularly polarized light often face a trade-off between photoluminescence efficiency and luminescence dissymmetry. A study published in the journal Advanced Optical Materials tested whether highly luminescent racemic carbon-centered gold(I)-silver(I) clusters could be converted into bright CPL emitters by enantioresolution with chiral donor ligands. Researchers have shown that treating highly luminescent but racemic carbon-centered gold(I)-silver(I) clusters with chiral oxygen-donor ligands can separate them into mirror-image forms (enantiomers) that retain strong photoluminescence while gaining the ability to emit circularly polarized light. A phosphate-protected enantiomer pair achieved a photoluminescence quantum yield of 0.92/0.93 and the largest luminescence dissymmetry factor (|glum| = 0.008) among the clusters tested. Incorporating the cluster into a composite device with a cholesteric liquid crystal raised the measured device-level |glum| to 1.25. Materials that emit circularly polarized luminescence (CPL)-light whose electric field rotates in a preferred direction-are of interest for optical applications. But such materials generally must combine two properties that are difficult to achieve together: a high photoluminescence quantum yield (PLQY, the fraction of absorbed photons re-emitted as light) and a high luminescence dissymmetry factor (|glum|), which quantifies how strongly the emitted light is circularly polarized. Chiral metal clusters are one candidate platform, but conventional bottom-up asymmetric synthesis has struggled to deliver both properties simultaneously. Earlier work produced racemic (mixed mirror-image) carbon-centered Au6Ag6 and Au6Ag5 clusters with near-unity PLQYs of up to 0.92, but the clusters showed no CPL because they were racemic. It had remained unclear whether using chiral oxygen-donor ligands to separate a racemic mixture into its two mirror-image forms (enantioresolution), rather than building chirality in from the start, could preserve the strong emission and produce a sizable |glum|. The researchers synthesized carbon-centered Au6Ag6 and Au6Ag5 clusters by combining a gold-phosphine precursor with silver ions and chiral or achiral carboxylic, phosphinic, phosphoric or sulfonic acids. They characterized the resulting enantiopure clusters using single-crystal X-ray diffraction, mass spectrometry, NMR, and solution and solid-state photoluminescence, circular dichroism (CD) and CPL spectroscopy, supported by TD-DFT computational modeling. They also built proof-of-concept devices combining cluster-doped polymer films with cholesteric liquid crystals to test whether the CPL signal could be amplified. In dichloromethane solution, the phosphate-protected cluster pair (R/S-5) reached the highest PLQY (0.92/0.93) and highest |glum| (0.008) of the three ligand types. The carboxylate-protected pair (R/S-3) had a PLQY of 0.37/0.36 and |glum| of 0.003, while the sulfonate-protected pair (R/S-7) had a PLQY of 0.21/0.21 and |glum| of 0.002. Measured decay rate constants showed higher radiative rates for the fully protected Au6Ag6 clusters than for the Au6Ag5 clusters, and progressively lower nonradiative rates from carboxylate to phosphinate to phosphate ligand, consistent with the observed PLQY trend. Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. Sign up for our free newsletter and get updates on breakthroughs, innovations, and research that matter-daily or weekly. In all three enantiomer pairs, solid-state |glum| (0.002-0.003) was substantially lower than in solution or in polymer (PMMA) film, indicating that the surrounding environment strongly affects the degree of circular polarization achieved. CD spectra showed mirror-image signals between R and S enantiomers in solution and film, confirming chirality transfer from ligand to cluster, though solid-state CD signals were faint, especially for the sulfonate pair. DFT calculations found a smaller HOMO-LUMO energy gap for R-7 (3.33 eV) than for R-3 (3.71 eV) or R-5 (3.88 eV), attributed to an elevated highest occupied molecular orbital energy. Time-dependent DFT modeling further attributed R-5's strong CPL to a low-energy electronic transition with a large calculated rotatory strength localized on the chiral metal core rather than the ligand. Combining the phosphate-protected cluster with a cholesteric liquid crystal in a composite device raised the measured |glum| to 1.25, compared with 0.89 for an achiral cluster analog in the same device architecture and more than 150 times the value for the cluster film alone. Taken together, these results show that enantioresolution of highly luminescent Au-Ag clusters is a straightforward route to bright CPL-active emitters. The phosphate-protected pair highlights oxygen-donor ligands as a practical way to tune emission efficiency and chiroptical response. Integration with cholesteric liquid crystals further amplified CPL at the device level and enabled polarization-dependent information display. Further optimization of ligand, cluster and device design could extend this approach toward advanced photonic, display and information-security technologies. Wen‐Ting Liu et al, Enantioresolution of Well‐Defined Au-Ag Clusters With Near‐Unity Phosphorescent Quantum Yields for Brilliant Circularly Polarized Luminescence, Advanced Optical Materials (2026). DOI: 10.1002/adom.71553 Journal information: Advanced Optical Materials Provided by National Institutes of Natural Sciences BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries.

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