Solvent dependent formation of metallogels and single-crystal MOFs by La(III) and Ce(III) connectors and 3,5-pyridinedicarboxylate

Formation of new metallogels containing La(III) (G1) and Ce(III) ions (G2) coordinating with conformationally rigid pyridine-3,5-dicarboxylate (3,5-PDC) in dimethylacetamide (DMA) solvent is reported. Single crystals of the corresponding metal-organic frameworks of La(III) and Ce(III), [Ln(III)(3,5-PDC)_1.5(DMF)]_n.DMF, (Ln = La (1), Ce (2)) have been prepared as well by crystallizing the metallo-organic materials in dimethylformamide (DMF) solvent. The metallogels formed have been characterized using environmental scanning electron microscopy (ESEM), scanning electron microscopy (SEM), tube inversion test, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), rheological studies, and FT-IR spectroscopy. The PXRD patterns indicate that the gel materials are amorphous in nature. The FT-IR spectra of the gels and single crystals reveal comparable fingerprints suggesting similar structural behavior in the two phases. The isomorphous crystal structures of the MOF materials reveal channeled architectures with molecules of the crystallization solvent trapped within them.