2013/05/14 by Zhichang Liu, Marco Frasconi, Juying Lei +11 · 1 citation
Engineering · Chemistry · #Extraction and Separation Processes #Enhanced Oil Recovery Techniques #Metal-Organic Frameworks: Synthesis and Applications
paper · pdf · doi:10.1038/ncomms2891
openalex publication_date 2013/05/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Gold recovery using environmentally benign chemistry is imperative from an environmental perspective. Here we report the spontaneous assembly of a one-dimensional supramolecular complex with an extended [K(OH2)6][AuBr4] (α-cyclodextrin)2n chain superstructure formed during the rapid co-precipitation of α-cyclodextrin and KAuBr4 in water. This phase change is selective for this gold salt, even in the presence of other square-planar palladium and platinum complexes. From single-crystal X-ray analyses of six inclusion complexes between α-, β- and γ-cyclodextrins with KAuBr4 and KAuCl4, we hypothesize that a perfect match in molecular recognition between α-cyclodextrin and [AuBr4]− leads to a near-axial orientation of the ion with respect to the α-cyclodextrin channel, which facilitates a highly specific second-sphere coordination involving [AuBr4]− and [K(OH2)6]+ and drives the co-precipitation of the 1:2 adduct. This discovery heralds a green host–guest procedure for gold recovery from gold-bearing raw materials making use of α-cyclodextrin—an inexpensive and environmentally benign carbohydrate. Currently, gold recovery from waste materials requires inorganic cyanides and more environmentally benign methods are required. Here, the authors report that host–guest interactions between α-cyclodextrin and gold lead to the precipitation of one-dimensional superstructures, offering a selective and green alternative.