Four new hybrid lead(II) halide perovskites, γ-(FA) 2 PbBr 4 , (FA) 1.5 (AA) 0.5 PbBr 4 , (PY)(GA)PbBr 4 and (PY)(TZ)PbBr 4 ((FA) = formamidinium, (AA) = acetamidinium, (PY) = pyrazolium, (GA) = guanidinium and (TZ) = 1,2,3-triazolium), adopt (110)-oriented layered perovskite structures. While (PY) is found to template the formation of 'conventional' (110)-oriented structure types (i. e. containing staggered [PbBr 4 ] 1 layers), (FA) is shown to facilitate formation of much less common variants based 3 : 1 ordering of the interlayer species or 3 × 2 step-like corrugation of the perovskite-like layers themselves.
A laboratory activity is described for senior high school or first year undergraduate level students that illustrates key concepts linked to extractive metallurgy. This experiment demonstrates preferential binding of a methoxyphenolic oxime ligand to Cu 2+ in the presence of other transition metal ions in aqueous solution. The students are tasked to investigate the importance of the spatial relationship between the oxime and phenol group of two potential ligands by performing a series of short and simple tests. The objective is achieved by identifying which methoxyphenolic oxime ligand selectively and rapidly forms an isolable precipitate with Cu 2+ ions. Only one of the potential ligands exhibits a clear preference for binding to Cu 2+ , and this can easily be identified visually (and confirmed by UV−visible spectroscopy if desired). The experiment has successfully been employed as part of an extracurricular laboratory course involving groups of 25−30 high school students.
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