Triggered Ligand Release Coupled to Framework Rearrangement: Generating Crystalline Porous Coordination Materials

A robust 3-D porous structure of formula [Ln2(PDC)3(DMF)2]∞ has
been constructed from lanthanide cations (Ln = Er3+ or Y3+) and
the non-linear anionic bridging ligand, pyridine-3,5-dicarboxylate
(PDC2-) in dimethylformamide (DMF). The solvated framework
polymers {[M2(PDC)3(DMF)2]·n(solv)}∞ (M = Er, Y) undergo a
solid-state, crystal-to-crystal reaction upon heating and are
converted via loss of both sorbed and coordinated solvent and
rearrangement of the framework core to give a desolvated and
porous form with retention of structural integrity. This structural
transfer is the first crystallographically characterized system with
lanthanide metal ions. These porous products are shown to be
effective absorbants for H2, N2, and benzene.