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 t he analysis of complex metal-organic frameworks (MOFs). We illustrate its a pplicability to rationalizing MOF crystal structures by analysis of nine ne w MOFs which have been characterized by single-crystal X-ray diffraction. T etrahedral 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 linke d into diamond networks, while those of Ni-2(ATC)(H2O)(4)(.)(H2O)(4) (MOF-3 4) have the structure of the Al network in SrAl2. Frameworks constructed fr om less symmetric tetrahedral SBUs have the Ga network of CaGa2O4 as illust rated by Zn-2(ATC)(.)(C2H5OH)(2)(H2O)(2) (MOF-35) structure. Squares and te trahedral 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 as sembly 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 octahed ral shapes, namely, the boron network in CaB6. New structure types for link ing triangular and trigonal prismatic SBUs are found in Zn3O(BTC)(2)(.)(HTE A)(2) (MOF-38) and Zn3O(HBTB)(2)(H2O)(.)(DMF)(0.5)(H2O)(3) (MOF-39). The sy nthesis, crystal structure, and structure analysis using the SBU approach a re presented for each MOF.