Metallacrowns as products of the aqueous medium self-assembly of histidinehydroxamic acid-containing polypeptides

Self-assembly is a widely studied, spontaneous, and reversible phenomenon leading to the formation of the ordered structures by non-covalent specific interactions among starting molecules. In this work, a new template for the self-assembly of polypeptides based on peptides containing the C-terminal histidinehydroxamic acid moiety and Cu²⁺ ions is characterized. Two peptide (tripeptide and pentadecapeptide) hydroxamic acid systems were synthesized and their interactions with Cu²⁺ ions were investigated, revealing a high stability of the supramolecular assemblies formed. The supramolecular metallacrown-based L₄Cu₅ complexes exist at physiological pH in the presence of Cu²⁺ ions as is evidenced from the spectroscopic methods, ESI mass spectrometry, and physicochemical techniques.