Spin filtering in self-assembled bowl-shaped aromatics

Abstract

Bowl-shaped aromatics can be chiral, so their columnar self-assembly can yield homochiral supramolecular structures. This valuable—but underexploited—property adds a novel twist to the disruptive applications of these materials, rendering them potentially useful in the burgeoning field of molecular spintronics. Herein, we demonstrate that columnar arrays based on chiral subphthalocyanine aromatics can efficiently function as spin filters via the chirality-induced spin selectivity (CISS) effect. To this end, we prepared enantiopure SubPcs engineered to establish head-to-tail intermolecular interactions with varying strengths, as reflected in their final self-assembled structures. Specifically, SubPcs equipped with peripheral arylamides and long paraffinic chains form fibers, whereas those endowed solely with aromatic moieties featuring paraffinic chains lead to the formation of nanorings. Using magnetic-conductive atomic force microscopy (mc-AFM), we observed that these supramolecular architectures display effective spin filtering, yielding spin polarization values between 35% and 45%. Overall, these findings open a new frontier in the application of columnar materials based on π-conjugated bowl-shaped derivatives.