Sensing of the Induced Helical Chirality by the Chiroptical Response of the Ferrocene Chromophore

The experimental (infrared, nuclear magnetic resonance, circular dichroism) and computational (density functional theory) methods allowed us to demonstrate the potential of the ferrocene chromophore to translate chiral information stored at N-terminally attached l-Ala, and transmitted through achiral (Aib)(n) sequence (n=1 to 3), into a characteristic signal in circular dichroism spectra near 470 nm. The sufficiently long tetrapeptide forms a robust and highly organized 3(10) helices capable of perturbing the environment of the highly symmetric ferrocene chromophore in an asymmetric manner. The origin of the sign in the circular dichroism spectra of the ferrocene chromophore (near the 470 nm) strongly correlates with the sign of the dihedral angle chi, accounting for a rotation of a substituent attached to the cyclopentadienyl ring that depends on the helicity of peptide sequence. These observations may help us in the design of future ferrocene-based probes for the assignment of the screw-sense preference of short peptides.

Automated summary

The study demonstrates the potential of the ferrocene chromophore to translate chiral information stored in l-Ala and transmitted through an achiral sequence into a characteristic signal in circular dichroism spectra. The findings suggest the possibility of designing ferrocene-based probes to determine the screw-sense preference of short peptides.