Paper NS-TuP29
Surface Structure of Metal-Organic Framework Revealed by High-Resolution AFM

Tuesday, November 10, 2009, 6:00 pm, Room Hall 3

Metal-organic frameworks (MOFs) which consist of organic ligands linked together by metal ions belong to a relatively new class of porous materials.¹ Due to their potential applications in storage, separation, and heterogeneous catalysis, MOFs have attracted increasing attention. So far MOF research has been mainly focused on bulk structure of the material prepared in the form of a powder. Only very recently a new, and radically different, approach was undertaken by exploring the possibilities of MOF growth on surfaces in the form of thin films.^2,3 An important issue for further progress in optimizing growth of MOF crystals, and particularly MOF thin films, is control of their surface structure. Therefore, high-resolution imaging of MOF surfaces is of key importance, as has been previously recognized for zeolites which are analogous to MOFs.

The talk focuses on the AFM study of a MOF single crystal surface.⁴ By performing analysis both in air and under ultra high vacuum conditions the high-resolution AFM imaging of a MOF surface is demonstrated. The surface structure of a MOF crystal grown directly on the functionalized substrate is revealed and, moreover, this information is further utilized to optimize growth conditions. Finally, our study clearly demonstrates a much higher structural quality of MOF crystals grown on the substrate in comparison to the conventional powder growth method.

References

[1] O. M. Yaghi et al. 2003, Nature, 423, 705

[2] O. Shekah et al. 2007 J. Am. Chem. Soc. 129, 15118

[3] E. Biemmi et al. 2007 J. Am. Chem. Soc. 129, 8054

[4] K. Szelagowska-Kunstman et al. 2008 J. Am. Chem. Soc. 130, 14446