Date of Award
Chemistry and Biochemistry
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Inorganic/organic hybrid perovskites have emerged as synthetic materials that exhibit light-harvesting properties. Although perovskites with alkylammonium cations have been previously reported, a perovskite family with phosphonium cations has not been investigated. Firstly, a library of phosphonium salts was made with the intention of further reaction with the group 14 halides towards creating a perovskite crystal. The composition of these salts were elucidated via NMR spectroscopy, and the crystal structures of three of the phosphonium salts were determined. The phosphonium iodide salts were then reacted with the lead, tin, and germanium iodides and bromides to discover if variant perovskitic structures are obtained. The reaction of lead(II) iodide with various phosphonium salts produced a charge-balanced network of PbI3- fragments connecting in a face-sharing octahedral motif. These phosphonium-templated iodoplumbates were found to possess semi-conducting properties, as suggested by the results of UV-Vis and their high thermal stability was confirmed by TGA experiments. Three novel crystal structures were isolated from reaction of phosphonium salts with tin(II) and tin(IV) iodide, each of them producing an iodostannate anion with a unique geometry. In a reaction with SnI4 an unpredictable oxidation of starting material produced a potentially Lewis acidic tin(IV) cation. Finally, the reaction of phosphonium salts with germanium(II) halides produced charge-balanced compounds with an ABX3 general formula that did not crystallize in a perovskitic manner. Germanium(IV) iodide formed a series of co-crystals when reacted with the phosphonium iodide salts. These species were found to form Ge-I‧‧‧‧I halogen-bonding interactions.
Omahen, Emily Helen, "Towards Putting the ‘P’ in Perovskite: Exploring the Reactivity of Phosphonium Salts with Group 14 Halides" (2018). Electronic Theses and Dissertations. 7552.