ORGANIC INORGANIC LANGMUIR-BLODGETT-FILMS BASED ON METAL PHOSPHONATES- 3 - AN AZOBENZENE-DERIVATIZED PHOSPHONIC ACID FORMS CONTINUOUS LATTICE LAYERS WITH DIVALENT, TRIVALENT, AND TETRAVALENT METAL-IONS/

Metal phosphonate Langmuir-Blodgett (LB) films of an azobenzene-functi onalized phosphonic acid amphiphile, tetradecyloxyphenyldiazenyl)pheny l)butylphosphonic acid (A4), have been prepared with Zr4+, La3+, Gd3+, Ba2+, Mn2+, and Cd2+. Film formation and quality are characterized wi th optical spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The azobenzene chromophores are str ongly H-aggregated in all of the metal phosphonate LB films. With diva lent and trivalent ions, the in-plane metal phosphonate structure obse rved in the LB films is the same as that found in analogous solid-stat e layered phosphonates and depends on the identity of the metal ion. F ilms of A4 with the lanthanide ions La3+ and Gd3+ form with stoichiome try MH(O3PR)(2). When Ba2+ is incorporated into the films, the M(HO3PR )(2) structure-type is adopted, while Mn2+ and Cd2+ give rise to films of A4 with the stoichiometry M(O3PR). H2O. In each of these cases, th e inorganic continuous lattice crystallizes in the hydrophilic portion of the film formed by the A4 amphiphiles during deposition. Films inc orporating Zr4+ were prepared with a previously described three-step p rocedure which exploits the strong oxophilicity of the Zr4+ ion. The f ilms form with stoichiometry Zr(O3PR)(2), the same as that observed in solid-state zirconium phosphonate materials. Film transfer is shown t o be facile when the spacing of the inorganic network and the packing of the organic chromophores is commensurate, while a mismatch in these preferred spacings affects the deposition process. The results demons trate that the metal phosphonate continuous inorganic network can be f ormed in LB films of amphiphiles other than alkylphosphonic acids, inc luding those with larger organic groups.