Engineering topics
Rowland, Casey A.
Publications and source records attributed to Rowland, Casey A..
Design and synthesis of aryl-functionalized carbazole-based porous coordination cages
A subset of coordination cages have garnered considerable recent attention for their potential permanent porosity in the solid state. Herein, we report a series of functionalized carbazole-based cages of the structure type M 12 (R-cdc) 12 (M = Cr, Cu, Mo) where the functional groups include a range of aromatic substituents. Single-crystal X-ray structure determinations reveal a variety of intercage interactions in these materials, largely governed by pi–pi stacking. Density functional theory for a subset of these cages was used to confirm that the nature of the increased stability of aryl-functionalized cages is a result of inter-cage ligand interactions.
Novel syntheses of carbazole-3,6-dicarboxylate ligands and their utilization for porous coordination cages
The molecular nature, and thus potential solubility, of coordination cages endows them with a number of advantages as compared to metal–organic frameworks and other extended network solids. However, their lack of three-dimensional connectivity typically limits their thermal stability as inter-cage interactions in these materials are relatively weak. This is particularly the case for carbazole-based coordination cages. Here, we report the design and synthesis of a benzyl-functionalized octahedral coordination cage that displays moderate surface area and increased thermal stability as compared to its unfunctionalized counterpart. Structural analysis suggests the increased thermal stability is a result of aryl–aryl interactions between ligand groups on adjacent cages. We have further adapted the ligand synthesis strategy to afford a novel, high-yielding preparatory route for the isolation of carbazole-3,6-dicarboxylic acid that does not rely on pyrophoric reagents or transition metal catalysts.