Assembly of metal-organic frameworks from large organic and inorganic secondary building units: New examples and simplifying principles for complex structures

The secondary building unit (SBU) has been identified as a useful tool in the analysis of complex metal-organic frameworks (MOFs). We illustrate its applicability to rationalizing MOF crystal structures by analysis of nine new MOFs which have been characterized by single-crystal X-ray diffraction. Tetrahedral SBUs in Zn(ADC)(2)(.)(HTEA)(2) (MOF-31), Cd(ATC)(.)[Cd(H2O)(6)](H2O)(5) (MOF-32), and Zn-2(ATB)(H2O)(.) (H2O)(3)(DMF)(3) (MOF-33) are linked into diamond networks, while those of Ni-2(ATC)(H2O)(4)(.)(H2O)(4) (MOF-34) have the structure of the Al network in SrAl2. Frameworks constructed from less symmetric tetrahedral SBUs have the Ga network of CaGa2O4 as illustrated by Zn-2(ATC)(.)(C2H5OH)(2)(H2O)(2) (MOF-35) structure. Squares and tetrahedral SBUs in Zn-2(MTB)(H2O)(2)(.)(DMF)(6)(H2O)(5) (MOF-36) are linked into the PtS network, which is the simplest structure type known for the assembly of these shapes. The octahedral SBUs found in Zn-2(NDC)(3)(.)[(HTEA)(DEF)(ClBz)](2) (MOF-37) form the most common structure for linking octahedral shapes, namely, the boron network in CaB6. New structure types for linking triangular and trigonal prismatic SBUs are found in Zn3O(BTC)(2)(.)(HTEA)(2) (MOF-38) and Zn3O(HBTB)(2)(H2O)(.)(DMF)(0.5)(H2O)(3) (MOF-39). The synthesis, crystal structure, and structure analysis using the SBU approach are presented for each MOF.