Ln-MOFs using a compartmental ligand with a unique combination of hard-soft terminals and their magnetic, gas adsorption and luminescence properties

The present work is part of our ongoing quest for developing multifunctional lanthanide-organic hybrid materials using non-conventional soft N-rich pyridyl-pyrazole-based ligands. Accordingly, we have embarked on an interesting venture of generating lanthanide-metal-organic frameworks (MOFs) using a new N-rich compartmental type ligand. It is imperative to note that compartmental ligands are seldom used in MOF synthesis, let alone lanthanide-MOFs. The terminals of the newly designed titular ligand comprise two contrasting functional moieties, a hard carboxylic group and a soft chelating pyridyl-pyrazole moiety. Their contrasting coordination behaviours are manifested in two isostructural lanthanide-based MOFs (Ln = Gd (1), Dy (2)). Single crystal X-ray analyses reveal archetypal graphite-like framework formation containing substantial pores inside the network with a corresponding moderately high surface area and N-2 and CO2 gas sorption properties. Another important aspect of lanthanide-MOFs is magnetism and the results of the present work are highly encouraging. The occurrence of the magnetocaloric effect (MCE) of mononuclear Gd-based MOF-1 further boasts the notion of generating magnetic materials. Dy-based MOF-2, on the other hand, features single ion magnet (SIM) behavior, as further confirmed by ac susceptibility measurements.