Chirality, a fundamental characteristic of biological systems, is abundantly manifested in nature. A profound exploration into the origins of chirality within chiral clusters at the atomic level has significance for the domains of chiral chemistry and cluster chemistry. Notably, a mere 7.8% of chiral crystalline compounds encompass chiral metal clusters, predominantly prevalent in precious metals, rare earth metals, and transition metals.
In a study published in Journal of the American Chemical Society, Prof. ZHANG Jian and Prof. FANG Weihui from Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences have pioneered the fabrication of the chiral aluminum oxide clusters (cAlOCs) via synergistic coordination synthesis strategy, harnessing its utility in circularly polarized luminescence (CPL).
The researchers found that the cAlOCs-Al5 cluster system was adeptly constructed through the synergistic coordination synthesis strategy using chiral amino acid ligand bridging and auxiliary pyridine-2,6-dicarboxylic acid chelation. The cAlOCs-Al5 clusters integrate the chirality intrinsic to cluster molecules, DNA-like chiral double helices, and the chiral hydrogen bond qtz topology. Based on the hydrogen bonding between clusters, chirality transfer and amplification between clusters were achieved, and a new method using four-connected clusters as nodes was provided for assembling chiral topology.
The researchers also found that this synergistic coordination synthesis strategy possesses universality by extending its applicability to isomorphic ligands and diverse counter ions. These cAlOCs materials are amenable to synthesis on the gram scale and have good stability and high Brunauer-Emmett-Teller (BET) surface area.
Furthermore, the researchers harnessed cAlOCs materials in chiral optics by imbuing organic dye molecules into the nano-sized helical channels of the cluster-based hydrogen bonding framework. Extensive characterization corroborated the efficacious doping and uniform distribution of dye molecules, with theoretical calculations elucidating the interactions between dye anions and Al5 clusters.
Chirality transfer between chiral helical channels and fluorescent dye anions culminated in a conspicuous CPL with the signal intensity rivaling that of certain chiral noble metal clusters. These cAlOCs materials can be prepared into flexible, transparent, and inexpensive films, demonstrating potential practical applications.
This study offers a cost-effective method for synthesizing chiral aluminum oxo clusters, and opens up possibilities for low-cost CPL material synthesis.
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