Highly Conductive Topologically Chiral Molecular Knots as Efficient Spin Filters

Knot-like structures
were found to have interesting magnetic properties
in condensed matter physics. Herein, we report on topologically chiral
molecular knots as efficient spintronic chiral material. The discovery
of the chiral-induced spin selectivity (CISS) effect opens the possibility
of manipulating the spin orientation with soft materials at room temperature
and eliminating the need for a ferromagnetic electrode. In the chiral
molecular trefoil knot, there are no stereogenic carbon atoms, and
chirality results from the spatial arrangements of crossings in the
trefoil knot structures. The molecules show a very high spin polarization
of nearly 90%, a conductivity that is higher by about 2 orders of
magnitude compared with that of other chiral small molecules, and
enhanced thermal stability. A plausible explanation for these special
properties is provided, combined with model calculations, that supports
the role of electron–electron interaction in these systems.