“…[13,22,25,26] Tw oclasses of MOFs,which both are based on secondary building units (SBUs) comprising dinuclear tetracarboxylate clusters [M 2 (O 2 CR) 4 ]h aving the so-called paddle-wheel symmetry,h ave been successfully deposited in the form of highly defined SURMOFs.F irst, the cubic HKUST-1 MOF (Cu 3 btc 2 ;b tc = benzene-1,3,5-tricarboxylate) and its derivatives, [13,27] and second, the tetragonal, layered MOFs of the general formula [M 2 L 2 P],w here M = Cu 2+ or Zn 2+ ,L = a rigid, linear dicarboxylate linker,and P = an optional diamine pillar. [22,26,28,29] While the first class of MOFs can be formed very reliably and thus has turned out to be avery robust test system, the pillared-layer system shows al arger structural variability,and thus abroader range of potential applications, because of the basically independent choice of Land P. Aset of rules has been developed to predict the surface growth of these MOFs.W hile for the cubic HKUST-1 systems mostly the density of coordinating groups at the surface seems to determine the SURMOFs orientation, [30] in the tetragonal pillared-layer system the nature of the surface-exposed ligands is of major importance.Thus,monodentate functional groups (e.g. -OH or pyridyl), which coordinate at the apical position of the paddle-wheel SBUs, usually induce SURMOF growth in the [001] direction, while bidentate ones (typically -COO À )p romote ag rowth in either the [100] or the [010] direction, depending on the exact symmetry of the MOF system.…”