Synthesis of mixed ligand and pillared paddlewheel MOFs using waste polyethylene terephthalate material as sustainable ligand source

A series of five isostructural pillared-paddlewheel MOFs, [M₂(BDC)₂(DABCO)] (1-5), (where M = Fe(II) (1), Co(II) (2), Ni(II) (3), Cu(II) (4) and Zn(II) (5); BDC = benzene-1,4-dicarboxylate; and DABCO = 1,4-diazabicyclo[2.2.2]octane) have been synthesized by using waste polyethylene terephthalate (PET) material as a direct BDC source. The optimal reaction condition has been achieved for all the MOFs with 100% depolymerization of waste PET material in the reaction. The synthesized MOFs have been characterized using powder X-ray diffraction, scanning electron microscopy, thermal gravimetric analyses, and N₂ gas sorption measurements. Results showed that the porous MOFs have similar properties of their corresponding literature reports.