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Abstract: The `photometric selection' approach as a high throughput, sample tolerant, low cost and highly automatable method of carrying out serial crystallography is presented. Crystalline samples are loaded and distributed onto a simple transparent substrate and an in-line camera identifies crystals using image recognition algorithms from the computer vision project OpenCV. In contrast to established serial techniques, which generally require that crystal samples be refined with narrow size distributions and defined habits, the sample requirements when using photometric selection are shown to be minimal. We demonstrate how broadly effective photometric selection can be by collecting high-quality datasets from three exemplar systems: a small-mol­ecule organometallic, a small-mol­ecule organic and a metal–organic framework system. In contrast to previously established grid-scanning techniques, data collection using photometric selection can be up to six times faster.

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Abstract: The construction of discrete coordination cages using s-block metal ions is challenging due to the weak and electrostatic nature of their coordination bonds, which can lead to the formation of mixtures of products that include intractable coordination polymers, rather than well-defined structures. The alkali and alkaline earth elements are also weaker templates for imines, as they are more oxophilic than transition metals. Here we describe a strategy to overcome these challenges by employing a chelating tris(pyridyl)aldehyde subcomponent to define the vertices of magnesium-templated cages. This subcomponent constrains the flexible coordination sphere of magnesium, enabling the assembly of three distinct coordination cage structure types: edge-bridged and face-capped tetrahedra, and a heteroleptic trigonal prism. These hosts displayed diverse binding properties for a range of guests. The two magnesium-based tetrahedral cages also luminesce upon illumination, a feature absent in their transition-metal counterparts. Our work thus provides a general strategy for accessing discrete s-block coordination cages and introduces magnesium coordination cages as a new class of luminescent supramolecular materials.

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Abstract: The incorporation of lanthanides into polyoxometalates (POMs) is a fascinating area of research due to their unique chemical and physical properties, as well as their potential applications. Polyoxopalladate (POP) clusters feature flexible central cavities and coordination geometries dictated by their central metal ion templates and external capping groups. Two primary structure types have been reported: {Pd12} cubes and {Pd15} stars, which can accommodate various central metal ions, ranging from common transition metals in the +2 oxidation state to less conventional lanthanides in the +3 oxidation state. This work explores POP clusters containing cerium ions, leading to the discovery of two new structure types: [CePd13O9 (SeO3)9(H2O)]6- (1) and [Ce3Pd22O16(SeO3)16]8- (2). Cluster 1 adopts a fused “star-cube” structure, combining half {Pd15} star and half {Pd12} cube with Ce4+ as the central template. 2 exhibits a twisted dumbbell-shaped structure (D2d symmetry), where two Ce4+-centred {CePd11} cubes are bridged by a third Ce4+ ion at the cluster core. Parallel experiments with other lanthanides yielded two propeller-like chiral POPs [LnPd12O7(SeO3)8Cl(H2O)2]4- (Ln = Eu3+ 3; Ln = Gd3+ 4), both displaying C3 symmetry. Notably, this represents one of the rare instances in POP chemistry where a capping ligand (SeO32-) directly coordinates to the central lanthanide ions (Eu3+ and Gd3+). The twisted coordination of this capping ligand induces a uniform tilt in a set of {PdO4} planes, resulting in the clusters’ propeller-like chirality. In contrast, similar reaction conditions for Tb3+ produced [TbPd12O8(SeO3)8]5- (5), a normal cubic structure.

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Abstract: Positional isomerism in pyridyl naphthalene diimide formic acid co-crystals controls crystal symmetry, yielding centrosymmetric (I2/a) and polar (Pc) structures from 4- and 2-pyridyl isomers respectively. Both materials function as reversible photochromic switches upon UV irradiation via a proton-coupled electron transfer type mechanism, generating NDI radical anions, as confirmed by UV-Vis and ATR-FTIR spectroscopy.

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Abstract: A tetramine subcomponent featuring 1,5-naphthylene arms was designed to exhibit extensive secondary interactions when assembled around stereochemically flexible tetracoordinate CuI ions. Using 6-methyl-2-formylpyridine, a [CuI12L6]12+ pseudo-hexagonal prismatic cage formed, stabilized by 29–32 C─H···π interactions and 12 arene stacking interactions. Replacing the aldehyde component with 3-methyl-2-formylpyridine introduced steric clashes that partially prevented these interactions, leading instead to the formation of a [CuI8L4]8+ rectangular open prism. The system exhibited structural interconversion: adding 6-methyl-2-formylpyridine to the [CuI8L4]8+ cage transformed it into the [CuI12L6]12+ structure through selective displacement of 8 out of 24 aldehyde residues per cage, matching the number of sterically-hindered positions predicted from structural analysis. This work demonstrates rational control over cage architecture through fine-tuning of steric factors and intermolecular interactions, providing design principles for generating diverse structures from identical building blocks.