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

Abstract

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 Cu(2+) ions is characterized. Two peptide (tripeptide and pentadecapeptide) hydroxamic acid systems were synthesized and their interactions with Cu(2+) 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 Cu(2+) ions as is evidenced from the spectroscopic methods, ESI mass spectrometry, and physicochemical techniques.

Diversity in the Interaction of Amino Acid- and Peptide-Based Hydroxamic Acids with Some Platinum Group Metals in Solution

“…As it is seen in Scheme 1, in addition to the hydroxamate-type (O,O) chelate (structure I), even if the parent amino acid does not have a side-chain donor, primary derivatives of α-, β-and γ-amino acids are capable of forming 5-, 6-, and 7-membered (N,N)-type chelates (structure II), respectively, via the amino-N and deprotonated hydroxamate or doubly deprotonated hydroximate-N atoms [13,34]. The versatility of the coordination modes can be even higher with amino acids containing side chain donors [34][35][36], or with peptide derivatives (structure III) [37][38][39][40][41].…”

“…The most interesting binding modes, however, can occur with borderline metal ions, with which the formation of both types of chelates is likely, and this, in many cases, results in the formation of exciting polynuclear coordination complexes with high structural and functional diversity. In particular, metallacrowns (MCs, incorporating metal-heteroatom coordination units, (-[M-N-O]-) n ), in a cyclic arrangement) have been attracting considerable attention due to their fascinating molecular architecture and diverse applicability, such as molecular magnets, catalysts, sensors, and recognition reagents for cations, anions, or molecules [40][41][42][43][44][45][46][47][48][49]. Although, among the ligands, amino acid-based hydroxamates are frequently used for producing metallacrowns, there are examples for the existence of MCs with other types of ligands, including peptide-based hydroxamic acids as well [40,41].…”

“…In particular, metallacrowns (MCs, incorporating metal-heteroatom coordination units, (-[M-N-O]-) n ), in a cyclic arrangement) have been attracting considerable attention due to their fascinating molecular architecture and diverse applicability, such as molecular magnets, catalysts, sensors, and recognition reagents for cations, anions, or molecules [40][41][42][43][44][45][46][47][48][49]. Although, among the ligands, amino acid-based hydroxamates are frequently used for producing metallacrowns, there are examples for the existence of MCs with other types of ligands, including peptide-based hydroxamic acids as well [40,41]. Most of the published homometallic metallacrowns incorporate 3d metal ions, while heterometallic ones commonly contain a 3d metal ion in the ring and a 4f ion as a core metal, but, rarely, some metallacrowns with other types of metal ions have also been synthesized [43,44].…”