Tuning the gate opening pressure of a flexible doubly interpenetrated metal-organic framework through ligand functionalization.
A functional doubly interpenetrated MOF [(Zn4O)2(MDCPB)6DMF]·3DMF·3H2O (JLU-Liu33F, H2MDCPB = 5-methyl-1,3-di(4-carboxyphenyl)benzene, DMF = N,N-dimethylformamide) with pcu topology has been solvothermally synthesized. JLU-Liu33F (F = functionalization) is the isostructural analogue of JLU-Liu33, which is constructed by -CH3 functional V-shaped ligand and a classical Zn4O cluster. Similar to the adsorption property of JLU-Liu33, JLU-Liu33F also exhibits breathing behavior upon N2 and CO2 adsorption at 77 and 195 K, respectively. However, due to the introduction of -CH3 functional groups, the interpenetration degree of JLU-Liu33F become closer to that of JLU-Liu33, which results in higher gate opening pressures for both N2 and CO2 adsorption. Moreover, the breathing behavior of JLU-Liu33F for C2H6 and C3H8 adsorption disappeares. Moreover, JLU-Liu33F also exhibits commendable selectivity for C2H2 over CH4.