Centrochirality induces exceptionally high CISS by the sergeant-and-soldier effect: achiral poly(amino acid)s as transducers of chiral information

Chiral materials can induce spin selectivity (CISS) in electron transport, creating spin-polarization without the need of external magnetic fields. This effect has received attention in chiral soft matter, where symmetries like centrochirality, axial chirality and helical chirality are accessible by molecular design and transform into the specific spin polarization of electrons in interaction with solid matter. We here have designed achiral helices as transducer of chirality to induce a CISS effect over ~ 6 nm, linked to a centrochiral molecule distant to the surface, transmitting the CISS only via the so induced helical chirality. Based on a 310-helix built from the achiral amino acid, α-aminoisobutyric acid (Aib), dynamic helices are generated in their oligomeric forms A*-(Aib)n– S (n=10 – 20, A*: chiral head group; S : sulphur)), enhanced by the chirality of only one centrochiral molecule (A*) attached as head group. When bound to a gold surface a self-assembled monolayer of ~ 6 nm height is formed, further probing the CISS effect of the respective R- and S-forms and the induced left-handed M- or right-handed P-helices. By conductive atomic force microscopy (c-AFM) measurements, we demonstrate that it is possible to transfer the effect of chirality of a centrochiral molecule via an achiral transmitting-block to induce CISS effects of high efficiency, now spatially separated from the source of chirality. The exceptional electron-transporting abilities and the unique folding into a 310-helix are made responsible to reach the here observed outstanding spin polarisation of over 99%, hitherto unprecedented for the currently known peptides.