Synthesis and functional analysis of deferriferrichrysin derivatives: Application to colorimetric pH indicators

Use of a Compact Tripodal Tris(bipyridine) Ligand to Stabilize a Single-Metal-Centered Chirality: Stereoselective Coordination of Iron(II) and Ruthenium(II) on a Semirigid Hexapeptide Macrocycle

Fe(II)-coordinating hexapeptides containing three 2,2'-bipyridine moieties as side chains were designed and synthesized. A cyclic hexapeptide having three [(2,2'-bipyridin)-5-yl]-d-alanine (d-Bpa5) residues, in which d-Bpa5 and Gly are alternately arranged with 3-fold rotational symmetry, coordinated with Fe(II) to form a 1:1 octahedral Fe(II)-peptide complex with a single facial-Λ configuration of the metal-centered chirality. NMR spectroscopy and molecular dynamics simulations revealed that the Fe(II)-peptide complex has an apparent C₃-symmetric conformations on the NMR time scale, while the peptide backbone is subject to dynamic conformational exchange between three asymmetric β/γ conformations and one C₃-symmetric γ/γ/γ conformation. The semirigid cyclic hexapeptide preferentially arranged these conformations of the small octahedral Fe(II)-bipyridine complex, as well as the Ru(II) congener, to underpin the single configuration of the metal-centered chirality.

Fe(ii)-Complexation of tripodal hexapeptide ligands with three bidentate triazolylpyridines: induction of metal-centred chirality by peptide macrocyclization

Cyclic and open-chain hexapeptides with three common triazolyl-pyridine residues afforded two Fe(ii) complexes with distinct metal-centred chirality.