Structural insights into f-block heterobimetallic dicyanoaurate coordination polymers

Date created: 
Inorganic chemistry
Crystal engineering
3d printing

The first series of uranyl ([UO2]2+)-dicyanoaurate coordination polymers has been synthesized and characterized. The diversity of structures generated demonstrates the flexibility of uranyl and dicyanoaurate as building blocks. Small changes in solvent, reactions conditions, dicyanoaurate salt, and ancillary ligands lead to a wide range of structures, ranging from molecular compounds, to a series of one-dimensional chains (including a ladder with alternating aurophilic and peroxo rungs), to a two-dimensional network of aurophilic and hydrogen-bonds, and an unusual three-dimensional lattice of tetranuclear uranyl-oxo-nitrate clusters connected by dicyanoaurate linkers, with the rotation of the clusters providing the increased dimensionality. This final material undergoes a reversible single-crystal to single-crystal transformation on exposure to or removal from water vapour. The luminescence properties of these materials have been found to range from no detectable emission, to only the uranyl-based emission being detected, to both uranyl and either Au(I) or aurophilic emission being detected. Building on this f-block chemistry, a series of lanthanide-dicyanoaurate-2,2′-bipyridine dioxide (OOBipy) coordination polymers has been created with the formula Ln(OOBipy)2(H2O)x(Au(CN2)3)·yEtOH·zH2O, where x and y = 0–2, and z = 0–4. It is possible to convert between these coordination polymers by the addition of heat or water vapour. The coordination polymers containing Sm, Eu, and Tb were found to be emissive, and those with only Eu or Tb were found to have excellent quantum yields. Attempts to create blended materials of Eu and Tb lead to the quenching of Tb’s emission, and blending of Sm and Tb produced lackluster quantum yields. A procedure to export ellipsoidal crystallographic data to 3D printing file formats was documented. This method gives the ability to export structures from the CCDC’s Mercury to 3D printing file formats, allowing 3D ellipsoidal models to be printed quickly and easily. This has been demonstrated using the uranyl-peroxo coordination polymer mentioned above. Additionally, a method of 3D printing complex or challenging structures by breaking them into parts with connectors, printing each part separately, and then assembling the structure post-printing was developed. This has advantages such as multicoloured printing, framework optimization and reduction, print time reduction, and can be used to bypass print size limitations.

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This thesis may be printed or downloaded for non-commercial research and scholarly purposes. Copyright remains with the author.
Daniel B. Leznoff
Science: Department of Chemistry
Thesis type: 
(Thesis) Ph.D.