Porphyrinylphosphonate‐Based Metal–Organic Framework: Tuning Proton Conductivity by Ligand Design

Abstract A novel metal–organic framework [Zn3(Ni‐H2TPPP)(Ni‐H4TPPP)(Ni‐H5TPPP)⋅7(CH3)2NH2⋅DMF⋅7 H2O] (where Ni‐HxTPPP (x=2,4,5) are partially deprotonated [5,10,15,20‐tetrakis(3‐(phosphonatophenyl)‐porphyrinato(2‐))]nickel(II) species), IPCE‐2Ni, with outstanding proton conductivity (1.0×10−2 S cm−1 at 75 °C and 95 % relative humidity) has been obtained. The high concentration of free phosphonate groups and compensating dimethylammonium cations bound by hydrogen bonds in the unique crystal structure of IPCE‐2Ni is a key factor responsible for the observed high proton conductivity, which is one order of magnitude higher than for the corresponding MOF based on 5,10,15,20‐tetrakis(4‐(phosphonatophenyl)porphyrinato(2‐))]nickel(II) IPCE‐1Ni and comparable with that of leaders among MOFs.