Route to a Family of Robust, Non-interpenetrated Metal-Organic Frameworks with pto-like Topology

A combination of topological rules and quantum chemical calculations has facilitated the development of a rational metal-organic framework (MOF) synthetic strategy using the tritopic benzene-1,3,5-tribenzoate (btb) linker and a neutral cross-linker 4,4'-bipyridine (bipy). A series of new compounds, namely [M-2(bipy)](3)(btb)(4) (DUT-23(M), M=Zn, Co, Cu, Ni), [Cu-2(bisqui)(0.5)](3)(btb)(4) (DUT-24, bisqui=diethyl (R,S)-4,4'-biquinoline-3,3'-dicarboxylate), [Cu-2(py)(1.5)-(H2O)(0.5)](3)(btb) 4 (DUT-33, py=pyridine), and [Cu-2(H2O)(2)](3)(btb)(4) (DUT-34), with high specific surface areas and pore volumes (up to 2.03 m(3) g(-1) for DUT-23(Co)) were synthesized. For DUT-23(Co), excess storage capacities were determined for methane (268 mg g(-1) at 100 bar and 298 K), hydrogen (74 mg g(-1) at 40 bar and 77 K), and n-butane (99 mg g(-1) at 293 K). DUT-34 is a non-cross-linked version of DUT-23 (non-interpenetrated pendant to MOF-14) that possesses open metal sites and can therefore be used as a catalyst. The accessibility of the pores in DUT-34 to potential substrate molecules was proven by liquid phase adsorption. By exchanging the N,N donor 4,4'-bipyridine with a substituted racemic biquinoline, DUT-24 was obtained. This opens a route to the synthesis of a chiral compound, which could be interesting for enantioselective separation.