Structure and properties of the composite zeolite silica-ZSM-12/para-nitroaniline

The pure silica form of zeolite ZSM-12 was loaded with hyper-polarizable para-nitroaniline (pNA) molecules to form a composite material pNA/silica-ZSM-12. 7.6 wt.% of pNA is occluded in the straight non-intersecting channels (free diameter � 6 � of the host material. The composite was characterized by optical microscopy, thermal analysis, NMR- and FTIR-spectroscopy, second harmonic generation (SHG) experiments, molecular modelling and X-ray powder diffraction. The pNA molecules are perfectly aligned with their long axis parallel to the channel direction. The molecules have specific docking sites in the channel, and each molecule uses the channel length of two unit cells. However, the overall symmetry of the composite is centrosymmetric. As indicated by FTIR spectroscopy and thermal analysis, the hydrogen bonds between the sorbate molecules inside the host lattice of silica-ZSM-12 (one-dimensional hydrogen bond system) are weaker as compared to pure pNA crystals (three-dimensional hydrogen bond system). The color of the composite material is yellow. The crystals are dichroitic and change their color in polarized light from colorless to bright yellow. pNA/silica-ZSM-12 shows hardly any SHG. This is in contrast to the composite pNA/AlPO4-5 which contains the highly polarizable pNA molecules in a non-centrosymmetric arrangement yielding, therefore, strong SHG activity. 2002 Elsevier Science Inc. All rights reserved.

[1]  L. Ernst,et al.  13C-NMR- Spektroskopie , 1980 .

[2]  C. Baerlocher.  The X-ray Rietveld system XRS-84 , 1984 .

[3]  J. Caro,et al.  On the anisotropy of the optical properties of zeolites loaded with organic molecules , 1992 .

[4]  J. Caro,et al.  Dipole Chains in Zeolite Pores: The Effects of Symmetry Breaking , 1996 .

[5]  B. Limburg,et al.  Zeolite-dye microlasers , 1998, physics/9811008.

[6]  Ordered and disordered pNA molecules in mesoporous MCM-41 , 1997 .

[7]  J. L. Schlenker,et al.  The framework topology of ZSM-12: A high-silica zeolite , 1985 .

[8]  J. Caro,et al.  PYROELECTRIC EFFECTS ON MOLECULAR SIEVE CRYSTALS LOADED WITH DIPOLE MOLECULES , 1994 .

[9]  G. Calzaferri,et al.  Time- and Space-Resolved Luminescence of a Photonic Dye-Zeolite Antenna. , 2001, Angewandte Chemie.

[10]  K. Trueblood,et al.  A three-dimensional refinement of the crystal structure of 4-nitroaniline , 1961 .

[11]  Frank Marlow,et al.  Structure of Dipole Chains in an MFI Type Molecular Sieve , 1996 .

[12]  H. Gies,et al.  Crystal structure of silica-ZSM-12 by the combined use of high-resolution solid-state MAS NMR spectroscopy and synchrotron x-ray powder diffraction , 1990 .

[13]  Hans Bebie,et al.  Polarity of Organic Supramolecular Materials: A Tunable Crystal Property , 2000 .

[14]  Jürgen Caro,et al.  Optical second harmonic generation (SHG) on p-nitroaniline in large cyrstals of AIPO4-5 and ZSM-5 , 1992 .

[15]  G. Stucky,et al.  Polarized IR Spectra of p-Nitroaniline-Loaded AlP04-5 Single Crystals , 1995 .

[16]  C. P. Nicolaides,et al.  A catalytic method for the quantitative evaluation of crystallinites of ZSM-5 zeolite preparations , 1992 .

[17]  R. C. Weast.  Handbook of chemistry and physics , 1973 .

[18]  H. van Koningsveld,et al.  Preparation and structure of crystals of zeolite H-ZSM-5 loaded with p-nitroaniline , 1997 .