Three-Dimensional Ordering of Molecules: p-Nitroaniline in Aligned ZSM-5 Single Crystals

Single-crystal zeolites can be aligned in silicon grooves with a surface coverage of more than 50%. The crystals are fixed to the substrate with tetramethoxysilane. Access to the microporous system is checked with N 2 adsorption measurements. Two different types of ZSM-5 zeolites are used to realize a three-dimensional ordering of p -nitroaniline (PNA). Coupled thermogravimetry/FTIR reveals a loading of PNA in ZSM-5 of 8 wt %, which amounts to almost four molecules/unit cell. FTIR spectra of PNA adsorbed into ZSM-5 zeolites best resemble single-crystal PNA. Polarization dependent photoluminescence experiments at 4.5 K reveal a high degree of orientation of the molecules. Slight differences in the synthesis condition of the two types are responsible for the different peaks at 522 and 560 nm in the emission spectrum.