Regensburg 2007 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 15: Poster Session

DS 15.10: Poster

Dienstag, 27. März 2007, 15:00–17:00, Poster B

Layer-by-layer growth of Metal-Organic Open Frameworks on a Functionalized Organic Surface — •Osama Shekhah, Hui Wang, Thomas Strunskus, and Christof Woell — Ruhr University Bochum, Lehrstuh fur Physikalshe Chemie 1, Universitatsstr 150, 44780 Bochum

Using a novel layer-by-layer approach, Metal-Organic Open Frameworks (MOFs) based on benzenetricarboxylic acid (BTC) ligand and Zn(II)-ions were deposited on a COOH-terminated organic surface. The deposited layers were characterized using XPS, IRS, NEXAFS and AFM. AFM data showed the selective deposition of a BTC layer with a height of about 1.6 nm. XPS and IRS data showed the same increase in thickness per layer up to 8 layers. Considering AFM data and the fact that NEXAFS data reveal an orientation of the BTC-units which is mainly perpendicular to the surface, allowed to put a model, yielding a structure of almost vertical layers of the authentic Zn(II)-BTC MOFs which are interconnected as in the bulk structure by water molecules. Attempts to obtain a powder XRD pattern for MOFs with a thickness of up to 8 layers were unsuccessful, as expected for organic adlayers of small thickness. We could, however, successfully demonstrate the gas-loading properties of a 8-layer MOF by an exchange experiment where the water in the BTC-layer is repeatedly and reversibly exchanged by Ammonia. This layer-by-layer deposition of MOFs on organic surfaces opens up the possibility to synthesize completely new types of MOFs with compositions and structures not accessible by bulk synthesis routes.