Ultrafast Spintronics: Dynamics of the Photoisomerization-Induced Spin–Charge Excited-State (PISCES) Mechanism in Spirooxazine-Based Photomagnetic Materials

The optical control of spin state is of interest in the development of spintronic materials for data processing and storage technologies. Photomagnetic effects at the single-molecule level have recently been observed in the thin film state at 300 K in photochromic cobalt dioxolenes. Visible light excitation leads to ring-closure of a photochromic spirooxazine bound to a cobalt dioxolene, which leads to generation of a high magnetization state. Formation of the photomagnetic state occurs through a photoisomerization-induced spin-charge excited-state process and is dictated by the spirooxazine ligand dynamics. Here, we report a mechanistic investigation by ultrafast spectroscopy in the UV-vis region of the photochemical ring-closing process in the parent spirooxazine, azahomoadamantylphenanthroline spirooxazine, and the photomagnetic spirooxazine cobalt–dioxolene complex. The cobalt appears to stabilize a photomerocycanine transient intermediate, presumably the TCC isomer, formed along the ground-state pote...