Control over Catenation in Pillared Paddlewheel Metal-Organic Framework Materials via Solvent-Assisted Linker Exchange

Control over catenation in a pillared paddlewheel metal-organic framework was achieved via solvent-assisted linker exchange. The linker exchange was demonstrated on the noncatenated structure of DO-MOF, by using 4,4'-bipyridine (L4) and 4,4'-azobis(pyridine) (L5) as linkers, leading to noncatenated materials SALEM-3 and SALEM-4. The de novo synthesized analogues of SALEM-3 and SALEM-4 can only be obtained as 2-fold interpenetrated frameworks. The reaction progress of the linker exchange was monitored by NMR spectroscopy, and structure and framework catenation were characterized by powder X-ray diffraction and thermogravimetric methods.