Enhancing Spectral Resolution for Detecting Chirality-Induced Spin Selectivity in DNA Hairpins Using Photogenerated...

Recent findings have highlighted molecular chirality as a tool for controlling electron spin states through the chirality-induced spin selectivity (CISS) effect. In CISS, the transmission of an electron or hole through a chiral molecule or material results in electron spin polarization. We have investigated a series of donor-chiral bridge-acceptor (D-Bχ-A) molecules, where Bχ is a B-form DNA helix consisting of 4-6 base pairs, D is naphthalene-1,8:4,5-bis(dicarboximide) (NDI), which serves as the hairpin linker chromophore and hole donor, and perylene-d₁₁ (Per-d₁₁) serves as the terminal hole acceptor. Photoexcitation of NDI results in rapid hole transfer through the DNA and trapping of the hole on Per-d₁₁ to produce the NDI^•--Per-d₁₁^•+ spin-correlated radical pair (SCRP) in which the narrow line width of Per-d₁₁^•+ and the g-factor difference between NDI^•- and Per-d₁₁^•+ allow for a more accurate evaluation of the CISS contribution to SCRP formation. Simulations of the time-resolved electron paramagnetic resonance spectra of the SCRPs at X- and Q-bands require the inclusion of a 34-62% CISS contribution to the initial SCRP state. Harnessing the chirality of DNA to manipulate electron spin states presents a promising avenue for future quantum information technologies.