title: Photoswitching of a thermally unswitchable molecular magnet Cu(hfac)₂L(i-Pr) evidenced by steady-state and time-resolved electron paramagnetic resonance.
abstract: Most photoswitchable molecular magnets exhibit thermally induced switching, as is typical of spin crossover (SCO), valence tautomerism and SCO-like phenomena. We report a rare case of a copper-nitroxide based molecular magnet Cu(hfac)2L(i-Pr) that does not exhibit quantitative SCO-like behavior in the temperature range of its chemical stability (2-350 K); however, it can be switched to a metastable thermally inaccessible spin state via visible/near-IR light at cryogenic temperatures. By means of photogeneration, unique information on this otherwise unobservable spin state has been obtained using steady-state Q-band (34 GHz) and time-resolved W-band (94 GHz) electron paramagnetic resonance (EPR) spectroscopy. In particular, we have found that the electronic structure and relaxation properties of the photoinduced state in Cu(hfac)2L(i-Pr) are very similar to those in its sister compound Cu(hfac)2L(n-Pr) that is thermally switchable and has been exhaustively characterized by many analytical methods, previously. The first observation of photoswitchable behavior in a thermally unswitchable copper-nitroxide based molecular magnet Cu(hfac)2L(i-Pr) paves the way for photoswitching applications of this and similar compounds in the remarkably broad temperature range of 2-350 K.
authors: International Tomography Center SB RAS , Institutskaya str. 3a, 630090 Novosibirsk, Russia.
authors: Irina Yu
authors: IY
authors: Barskaya
authors: Evgeny V
authors: EV
authors: Tretyakov
authors: Renad Z
authors: RZ
authors: Sagdeev
authors: Victor I
authors: VI
authors: Ovcharenko
authors: Elena G
authors: EG
authors: Bagryanskaya
authors: Kseniya Yu
authors: KY
authors: Maryunina
authors: Takeji
authors: T
authors: Takui
authors: Kazunobu
authors: K
authors: Sato
authors: Matvey V
authors: MV
authors: Fedin