Preparation of an anion dye intercalated into layered double hydroxides and its controllable luminescence properties

The inorganic–organic composites have been prepared by intercalation of ammonium 1-anilinonaphthalene-8-sulfonate (ANS) into ZnAl and MgAl layered double hydroxide (LDH) with the molar ratio (M2+/M3+) of 2:1 and 3:1, respectively. The powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) confirm the intercalation of ANS into the galleries of LDH. Fluorescence polarization method was applied to investigate the preferential orientation of the interlayer ANS molecule, and the results show that ANS anions are accommodated between the sheets of Zn2Al-LDH, Zn3Al-LDH, Mg2Al-LDH and Mg3Al-LDH with an orientation angle Ψ (defined as the angle between the transition moment of ANS molecule with respect to the normal to the LDH layer) of 58°, 57°, 55° and 52°, respectively. TG–DTA results reveal that the thermal stability of ANS was markedly enhanced upon intercalation. Fluorescence spectra demonstrate that the Zn3Al-ANS-LDH sample exhibits the optimal luminous intensity among the four ANS-LDH composites. It was also found that the luminescence behavior of ANS can be modulated via changing the two parameters: the type and ratio of cation species in LDH matrix due to host–guest interactions. Therefore, the ANS-LDH composites can be used as good candidates for solid photoluminescence materials.