For structures formed by smaller amines with short alkyl chains or small cyclic structures, such as in SU-102, SU-107, SU-108 and SU-111, the OSDAs tend to fit into pockets formed at the junctions between the metal and ligands. Apart from tetramethylammonium in SU-111, these are more peripheral amines with a higher degree of polarization and seemingly tend to form 3D frameworks where the nitrogen atom of the ammonium cation occupies the corners of the pore windows . In the structure of SU-107, the small size of the DABCO cations allow them to perfectly occupy pocket sites at the corners of the larger pore (Fig. ). In SU-108, in which two crystallographically unique OSDAs are present, one of the amines fits in the corners of the pores, while another one occupies the interlayer space. A similar mechanism can be observed in SU-104 and SU-110, where hindered and bulky tertiary ammonium cations with long carbon chains of six or eight carbon atoms, respectively, yield layered structures. As shown in Fig. , two of the carbon chains from one OSDA in SU-104 align parallel to the layers, occupying the interlayer voids and stabilizing the layered structure. The third chain, however, tends to extend into the pore. For SU-109 with the shorter alkyl chains in tributylammonium the resulting MOF is instead a 3D framework.