Axial Chirality Induction in Ferrocene-Amino Acid Hybrids - toward Chiral Redox-Active Building Blocks

In this paper, we report the construction of chiral ferrocene-containing (Fc) supramolecular platforms with high symmetry and well-defined geometry via dynamic covalent chemistry. Starting from amino acid hydrazides and ferrocene aldehydes, we obtained respective Fc-acylhydrazones with well-defined conformations, that display intense circular dichroism (CD) signals in the visible region associated with ferrocene-centered electronic transitions. CD and UV–vis spectroscopy, supported by computational analysis, reveal efficient transfer of chirality from the remote stereogenic centers to the Fc unit and a correlation between amino acid configuration, Fc helicity, and CD sign (l-amino acid → (P)-Fc → (−)CD at 470 nm). Exploiting the dynamic character of the acylhydrazone linker, amino acid trihydrazide l-2 was further assembled with ferrocene dialdehyde into D3-symmetric double-decker trigonal platform Fc3(l-2)2 with high synthetic efficiency (>90%). Under these conditions, narcissistic chiral self-sorting occurs via dynamic covalent exchange, which results in the formation of homochiral platforms from racemic precursors. The combination of conformationally locked axial chirality, reversible covalent connectivity, and inherent redox activity establishes new amino acid–based motifs as promising modules for constructing chiral Fc-containing porous architectures such as molecular cages, MOFs, and COFs, with potential for asymmetric electrochemical applications.