Selective Recognition of Dicyanoaurate(I) by a Bambus[n]uril Macrocycle in Water


      Carola Rando, Julián Vázquez,^ Jan Sokolov, Zoran Kokan, Marek Nečas, Vladimír Šindelář
                                                 ^

 ^1Department of Chemistry and RECETOX, Faculty of Science, Masaryk University, Kamenice 5, 625 00
                                       Brno, Czech Republic

                                    e-mail: 503709@mail.muni.cz


Bambus[n]urils are powerful macrocycles that are able to bind anions in water.^1 Most of the
investigations on anion recognition deal with halides, carboxylates, and other biologically
relevant oxoanions such as: phosphate, sulfate, and nitrate. Herein, we decided to investigate, for
the first time in the Bambus[n]urils scenario, the complexation of metal transition anions. More
specifically, [Au(CN)[2]]^- has attracted our attention for its unique properties and its use in
the gold industry.^2 Among all Bambus[n]urils we decided to make use of the water soluble
properties of PEG-BU.^3 The formation of the complex was studied not only by means ^1H NMR and ITC
methods but also, through UV-Vis spectroscopy. The stability of the complex and the photochemical
properties of gold anion led to a novel and accurate assay. Furthermore, the outstanding
characteristics of this new complex make Bambus[n]urils ideal green candidates for the gold mining
industry.


Scheme 1 Schematic representation of Bambus[n]uril macrocycle derived with polyethylene glycol
chains (PEG-BU)





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2 Gold Ore Processing: Project Development and Operations; Adams, M. D., Ed.; Elsevier: Singapore,
2016

3 T. Fiala, K. Sleziakova, K. Marsalek, K. Salvadori and V. Sindelar, J. Org. Chem., 2018, 83,
1903–1912.