Porous Metal−Organic Frameworks Containing Alkali-Bridged Two-Fold Interpenetration: Synthesis, Gas Adsorption, and Fluorescence Properties

Solvothermal reactions of Zn(NO3)2·6H2O and alkali (Na, K) chloride with the trigonal-planar ligand benzene-1,3,5-tribenzoic acid (H3BTB) gave rise to two new crystalline porous metal−organic frameworks (MOFs), [Zn3Na2O(BTB)2(DMF)2](DMF)(H2O) and [Zn2K3(BTB)2(HCOO)(DMF)3](DMF)3(H2O)2, respectively. Both phases have Zn3Na2(μ4-O) and Zn2K2(HCOO) clusters as molecular building block nodes, and they form similar alkali-bridged 2-fold interpenetrated, (3,6)-connected nets with the mineral rtl-c topology. The alkali-bridged interpenetration reduces the flexibility of their interpenetrated nets, affording permanent porosity and high thermal stability. These two MOFs also exhibit high capacities of hydrogen uptake and strong solid fluorescent emissions.