Eckvahl Hannah J, Copley Graeme, Young Ryan M, Krzyaniak Matthew D, Wasielewski Michael R
Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States.
Center for Molecular Quantum Transduction, Northwestern University, Evanston, Illinois 60208-3113, United States.
J Am Chem Soc. 2024 Aug 28;146(34):24125-24132. doi: 10.1021/jacs.4c08706. Epub 2024 Aug 16.
Chirality-induced spin selectivity (CISS) has the potential to control the spin dynamics of chiral molecules for applications in quantum information science. Here we investigate the effect of CISS on the spin dynamics of radical pair formation following photodriven hole transfer in a pair of donor-chiral bridge-acceptor (D-Bχ-A) enantiomers, where D = 2,2,6,6-tetramethyl[1,3]-dioxolo[4,5-][1,3]benzodioxole, Bχ = ()- or ()-2,2'-dimethoxy-4,4'-diphenyl-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthalene, and A = naphthalene-(1,4:5,8)-bis(dicarboximide). The results are compared to those obtained on the corresponding achiral D-B-A reference molecule in which B = 2″,3',5',6″-tetramethyl-1,1':4',1″:4″,1‴-quaterphenyl. Photoexcitation of A in a randomly oriented sample of D-Bχ-A in glassy butyronitrile at 85 K results in subnanosecond two-step hole transfer from *A to D to form D-Bχ-A, which was characterized using time-resolved electron paramagnetic resonance (TREPR) spectroscopy at X (9.6 GHz), Q (34 GHz), and W (94 GHz) bands. The spectra show line shape changes that are characteristic of a ∼38% contribution of CISS to the spin dynamics of D-Bχ-A formation. The line shape changes resulting from CISS are particularly apparent in the TREPR spectra at -band as predicted by recent theory. These results show that (1) CISS has a significant influence on radical pair dynamics initiated by photodriven hole transfer, which is complementary to our recent electron transfer results, and (2) CISS can be detected using TREPR on radical pairs that are randomly oriented relative to an external magnetic field.
手性诱导自旋选择性（CISS）有潜力控制手性分子的自旋动力学，以应用于量子信息科学。在此，我们研究了CISS对一对供体-手性桥-受体（D-Bχ-A）对映体中光驱动空穴转移后自由基对形成的自旋动力学的影响，其中D = 2,2,6,6-四甲基[1,3]-二氧杂环戊并[4,5-][1,3]苯并二恶唑，Bχ =（）-或（）-2,2'-二甲氧基-4,4'-二苯基-5,5',6,6',7,7',8,8'-八氢-1,1'-联萘，且A =萘-（1,4:5,8）-双（二甲酰亚胺）。将结果与在相应的非手性D-B-A参考分子上获得的结果进行比较，其中B = 2″,3',5',6″-四甲基-1,1':4',1″:4″,1‴-四联苯。在85 K下，在玻璃态丁腈中对D-Bχ-A的随机取向样品中的A进行光激发，会导致亚纳秒级的两步空穴从*A转移到D，形成D-Bχ-A，这是使用X（9.6 GHz）、Q（34 GHz）和W（94 GHz）波段的时间分辨电子顺磁共振（TREPR）光谱进行表征的。光谱显示出线形变化，这是CISS对D-Bχ-A形成的自旋动力学贡献约38%的特征。如最近的理论所预测，由CISS引起的线形变化在-波段的TREPR光谱中尤为明显。这些结果表明：（1）CISS对光驱动空穴转移引发的自由基对动力学有显著影响，这与我们最近的电子转移结果互补；（2）可以使用TREPR在相对于外部磁场随机取向的自由基对上检测到CISS。
