Chiral molecules to transmit electron spin

Understanding how electrons move through molecules and carry energy with them has been crucial for the development of multiple technologies, including photovoltaic cells and light-emitting diodes. The standard theory (1) establishes that electron transfer (ET) can be understood by considering energy conservation and the movement of electrons and nuclei. However, this view of ET has been challenged with the observation of chirality-induced spin selectivity (CISS), whereby electrons with one spin move differently through a material than do electrons of the other spin (2, 3). On page 197 of this issue, Eckvahl et al. (4) report a CISS signal for an isolated chiral molecular system in a liquid crystal environment, after excitation with light. These results suggest that the standard ET theory should be modified to include both energy and total (orbital plus spin) angular momentum conservation, thereby opening the door to new CISS applications, including “green” hydrogen generation.