A Family of Porous Lonsdaleite‑e Networks Obtained through Pillaring of Decorated Kagomé Lattice Sheets

A new and versatile class of metal–organic materials (MOMs) with augmented lonsdaleite-e (<b>lon-e</b>-a) topology is presented herein. This family of <b>lon-e</b> nets are built by pillaring of hexagonal two-dimensional kagomé (<b>kag</b>) lattices constructed from well-known [Zn₂(CO₂R)₄] paddlewheel molecular building blocks (MBBs) connected by 1,3-benzenedicarboxylate (bdc^2–) linkers. The pillars are [Cr₃(μ₃-O)­(RCO₂)]₆ trigonal prismatic primary MBBs decorated by six pyridyl moieties (tp-PMBB-1). The three-fold symmetry (<i>D</i>_3<i>h</i>) of tp-PMBB-1 is complementary with the alternating orientation of the axial sites of the paddlewheel MBBs and enables triple cross-linking of the <b>kag</b> layers by each pillar. These MOMs represent the first examples of axial-to-axial pillared undulating <b>kag</b> layers, and they are readily fine-tuned because the bdc^2– moieties can be varied at their 5-position without changing the overall structure. This <b>lon-e</b> platform possesses functionalized hexagonal channels since the <b>kag</b> lattices are necessarily eclipsed. The effects of the substituent at the 5-positions of the bdc^2– linkers upon gas adsorption, particularly the heats of adsorption of carbon dioxide and methane, were studied