The chiral-induced spin selectivity (CISS) effect relates to the spin-selective electron transport through chiral molecules; therefore, the chiral molecules act as spin filters. In past studies, correlation was found between the magnitude of the spin filtering and the intensity of the circular dichroism (CD) spectrum (the first Compton peak) of the molecules. Since the intensity of the CD peak relates to both the magnitude of the electric and magnetic dipole transitions, it was not clear which of these properties correlate with the CISS effect. This work aims at addressing this question. By studying the spin-dependent conduction and the CD spectra of the thiol-functionalized enantiopure binaphthalene (BINAP) and ternaphthalene (TERNAP), we found that both BINAP and TERNAP exhibit a similar spin polarization of 50%, despite the first Compton peak in TERNAP being almost twice as intense as the peak in BINAP. These results can be explained by the similar values of their anisotropy (or dissymmetry) factor, gabs, which is proportional to the magnetic transition dipole moment. Hence, we concluded that the CISS effect is proportional to the transition dipole moment in chiral molecules, namely, to the dissymmetry factor.
Bibliographical noteFunding Information:
RN acknowledges support by a research grant from Jay and Sharon Levy, the Sassoon and Marjorie Peress Philanthropic Fund, and the Estate of Hermine Miller and from the US Department of Energy Grant ER46430. OG acknowledges European Union's Horizon 2020 research and innovation program (grant agreement no. 850836, ERC Starting Grant “PolyHelix”).
© 2023 The Authors. Chirality published by Wiley Periodicals LLC.
- circular dichroism
- electron transfer
- optical activity