Mixed-matrix metal-organic framework membranes for molecular separations

A mixed-matrix membrane for molecular separation, the membrane comprising:

• a plurality of metal organic framework (MOF) nanosheets, the MOF comprising a square grid pillared by an inorganic building block, the square grid being Ni(pyrazine)2 and the inorganic building block selected from [NbOF5]2−, [AlF5(H2O)]2−, [FeF5(H2O)]2− and [GaF5(H2O]2−;
• and
• a polymer matrix,
• wherein the plurality of MOF nanosheets are incorporated into the polymer matrix and the incorporated nanosheets are in-plane aligned with one another such that 1D channels of the nanosheets are parallel with one another.

A method of making a mixed-matrix membrane for molecular separation, the method comprising:

• contacting a ligand and a pillar component at a ligand to pillar ratio between about 10 and about 120 to form a plurality of MOF nanosheets, and the MOF has the formula MaMbF5 (O/H2O)(pyrazine)2·x(solv), wherein Ma is Ni2+, Mb is Nb5+, Al3+, Fe3+, Fe5+ or Ga3+;
• x is from 0 to 10 and solv is one or more of H2O, CO2, DMF, EtOH, NMP, and MeOH;
• contacting the plurality of MOF nanosheets with a polymer matrix in a dispersion of solvent to form a solution in which the plurality of MOF nanosheets incorporate into the polymer matrix to form a mixed-matrix membrane;
• and
• evaporating the solvent at a rate sufficient to induce in-plane alignment of the incorporated nanosheets with one another in the mixed-matrix membrane such that 1D channels of the nanosheets are parallel with one another.