Novel Binding of Beryllium to Dicarboxyimidazole-Based Model Compounds and Polymers

The ligand 4,5-dicarboxyimidazole (H₂DCI) and its methyl derivative 1-methyl-4,5-dicarboxyimidazole (H₂MDCI) have been shown to bind to Be(II) forming a zwitterionic species that has been structurally characterized. A new dicarboxyimidazole-based polymer has been prepared and its Be-binding properties have been studied using NMR (¹H and ⁹Be) and fluorescence spectroscopy; it represents a rare example of beryllium binding to a polymer. Models of the mononuclear and polymeric Be(II)-binding sites have been studied using density functional theory (DFT), and the ⁹Be NMR chemical shifts of these model materials have been calculated for the purpose of direct comparison to experimentally observed values. Differences in the binding modes of the mononuclear and polymeric species are discussed.