瑞士洛桑联邦理工学院 Oppermann, Malte团队报道了Fe(II)配合物自旋交叉动力学的手性控制。相关研究成果发表在2022年5月26日出版的国际学术期刊《自然化学》。

铁基自旋交叉配合物作为分子器件中的多功能开关具有巨大的应用前景。然而，现实世界的技术应用要求激发的高自旋态具有动力学稳定性，这一特性只有在低温下才能实现。

该文中，研究人员通过控制溶液中典型铁（II）三（4,4′-二甲基-2,2′-联吡啶）的手性构型来证明高自旋态捕获，与三三(3,4,5,6-四氯苯-1,2-diolato- kb 2o1,O2)磷(V) (P(O2C6Cl4)3 -或TRISPHAT)阴离子的对映体纯Δ或∧对映体进行立体控制。研究人员利用深紫外宽带超快圆二色光谱结合瞬态吸收和各向异性测量表征了高自旋态弛豫。

研究发现，高自旋态衰变伴随着其光学活性的超快变化，反映出与通常假设的情况相反的对称破缺扭-扭模式的耦合。非对映选择性离子对抑制了已识别反应坐标的振动布居，从而实现了高自旋态寿命的四倍增长。更普遍地说，研究结果激发了对铁（II）配合物扭转模式的综合控制，作为操纵其自旋交叉动力学的补充途径。

 附：英文原文

Title: Chiral control of spin-crossover dynamics in Fe(II) complexes

Author: Oppermann, Malte, Zinna, Francesco, Lacour, Jrme, Chergui, Majed

Issue&Volume: 2022-05-26

Abstract: Iron-based spin-crossover complexes hold tremendous promise as multifunctional switches in molecular devices. However, real-world technological applications require the excited high-spin state to be kinetically stable—a feature that has been achieved only at cryogenic temperatures. Here we demonstrate high-spin-state trapping by controlling the chiral configuration of the prototypical iron(II)tris(4,4′-dimethyl-2,2′-bipyridine) in solution, associated for stereocontrol with the enantiopure Δ- or Λ-enantiomer of tris(3,4,5,6-tetrachlorobenzene-1,2-diolato-κ2O1,O2)phosphorus(V) (P(O2C6Cl4)3– or TRISPHAT) anions. We characterize the high-spin-state relaxation using broadband ultrafast circular dichroism spectroscopy in the deep ultraviolet in combination with transient absorption and anisotropy measurements. We find that the high-spin-state decay is accompanied by ultrafast changes of its optical activity, reflecting the coupling to a symmetry-breaking torsional twisting mode, contrary to the commonly assumed picture. The diastereoselective ion pairing suppresses the vibrational population of the identified reaction coordinate, thereby achieving a fourfold increase of the high-spin-state lifetime. More generally, our results motivate the synthetic control of the torsional modes of iron(II) complexes as a complementary route to manipulate their spin-crossover dynamics.

DOI: 10.1038/s41557-022-00933-0

Source: https://www.nature.com/articles/s41557-022-00933-0