Orientation controlment of disperse red 1 molecules in matrix of zeolite crystals

Polarized absorption spectra for disperse red 1 (DR1) molecules solved in ethanol (DR1@ethanol) and DR1 incorporated in channels of AlPO4-5 crystals (DR1@ AlPO₄-5) have been investigated. The results show that the predominant structure of DR1 molecules in AlPO4-5 matrix is trans configuration. Its absorption band is centred at 520 nm, which shows strongly anisotropic polarizability. The absorption band for cis-configuration is centred at 470nm, which does not depend on polarization angle. The experimental energy difference between cis and trans configurations is 0.25 eV. Temperature dependent absorption spectra have also been investgated for DR1@ AlPO₄-5. The absorption band shifts to long wavelength with increasing temperature, which may be due to the bond expansion in DR1 molecules.