The first observation of photoinduced tuning of AC magnetization for organic–inorganic hybrid materials composed of Mn12-acetate and azobenzene

New organic–inorganic hybrid material composed of typical single-molecule magnet [Mn12(CH3COO)16(H2O)4O12]·2CH3COOH·4H2O (Mn12-acetate) and photochromic azobenzene in PMMA cast films was prepared to observe novel photomagnetic phenomenon. We characterized it by means of UV–visible absorption and IR spectra to confirm photoisomerization of azobenzene even at room temperature. We measured temperature and field dependence of DC susceptibility, and temperature and frequency dependence of AC susceptibility as comparing with bulk precipitates of Mn12-acetate. We found some differences in hysteresis loops for them. After alternate illumination of UV or visible light for 3 min at 3 K, we could observe reversible decrease or increase of in-phase AC susceptibility (and little changes of DC susceptibility) for the hybrid materials accompanying cis–trans photoisomerization of azobenzene.