Highly Crystalline Nanofilm by Layering of Porphyrin Metal−Organic Framework Sheets

Layer-structured metal−organic framework (MOF) nanofilms (NAFS-2) consisting of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (H2TCPP) molecules and copper ion metal linkers were assembled on a gold or a silicon surface by applying a solution-based layer-by-layer growth technique coupled with the Langmuir−Blodgett method. Synchrotron X-ray diffraction measurements showed that NAFS-2 exhibits highly crystalline order in both the in-plane and out-of-plane orientations. Each MOF sheet (monolayer) adheres without pillaring units, and the nanofilm maintains its highly crystalline order above 200 °C. The results provide an excellent demonstration of how to exercise in a facile way fine control of the assembly of molecule-based hybrid objects and their thermal stability, which is a key issue for the future use of MOFs in potential applications in nanodevices.