Monolithic, Crystalline MOF Coating: An Excellent Patterning and Photoresist Material

Metal–organic frameworks, MOFs, are a class of crystalline porous metal–organic hybrid materials which have originally been developed for applications in gas storage and separation. Here, we demonstrate that due to the enormous chemical flexibility of these molecular materials, they also provide an excellent basis for the development of photoresist materials. In particular, we used an epitaxial process with automated systems to grow either homogeneous or patterned SURMOFs (surface-anchored MOFs) of the type [Zn2(N3BPDC)2(Dabco)] on different solid substrates. The huge flexibility of the MOF chemistry allowed for different variants of photolithography based on the post-synthesis modification (PSM) of the MOF materials. Here, two particular and popular PSM-strategies were employed, the azide–alkyne click reaction and thiol–yne click chemistry. The azide–alkyne click reaction was initiated by the photoreduction of CuII to the active CuI catalyst, whereas the thiol–yne click chemistry was induced directly by UV light. Furthermore, heteroepitaxial growth of multilayer systems (Cu-N3BPDC+Cu-BPDC+Cu-N3BPDC+Cu-BPDC+Cu-N3BPDC+Cu-BPDC) was also used to control the localization of subsequent PSM. The results demonstrated that the patterned functionalization of MOF thin film is not limited to the two dimensions of the mounting surface but is indeed possible in 3D.