Synthesis and coordination of a tert-butyl functionalized facially coordinating 2-histidine-1-carboxylate model ligand

Herein, we report a bulky variant of a bis-benzimidazole carboxylate ligand. The five-position of the benzimidazole groups were substituted with tertiary butyl groups with the intention of preventing bis-ligation and oligomerization, as was observed in other studies using similar ligands. Unfortunately, even with the bulkier substituents, the new ligand still formed a bis-ligated structure. Although the new ligand did not afford the desired mono-ligated species under the conditions studied here, the preparation of the new ligand and coordination compounds provides an added design principle in the ongoing efforts of preparing structurally faithful 2-histidine-1-carboxylate model ligands in biomimetic chemistry.