Polarized Electronic and IR Spectra of Hybrid Materials of Chiral Mn(II) Complexes and Different Types of Photochromic Dyes Showing Photoisomerization or Weigert Effect

A series of organic/inorganic hybrid materials containing two kinds of chiral Schiff base Mn(II) complexes, 1 and 2, with the photochromic compounds stilbene (ST) or 1,3,3-trimethylindolino-6'-nitrobenzopyrylospiran (SP) cast into polymethyl methacrylate (PMMA) films were prepared. To understand the efficiency of increasing optical anisotropy of ST or SP resulting from polarized UV light irradiation, we investigated the molecular alignment based on Weigert effect (only polarized UV light irradiation) and photoisomerization (alternate irradiations with polarized UV and visible light) for 1-ST-PMMA, 2-ST-PMMA, 1-SP-PMMA, and 2-SP-PMMA. Polarized electronic spectra and polarized IR spectra of the hybrid materials demonstrated gradually increasing anisotropy of both photochromic compounds and Mn(II) complexes and only Mn(II) complexes, respectively. These features suggest that interactions of ST are valid for both Weigert effects and photoisomerization, while those of SP are valid for photoisomerization mainly, and intermolecular interaction of 2 between photochromic compounds and Mn(II) complexes in PMMA cast films is weaker than that of 1.