Crystal Engineering of a Permanently Porous Network Sustained Exclusively by Charge-Assisted Hydrogen Bonds

A permanently porous crystalline solid is reported that is sustained exclusively by charge-assisted H-bonds. The single-crystal X-ray structure of a layered H-bonded solid, compound 1, {[Ni(tame)₂]₁(PES)₂}_∞ (tame = 1,1,1-tris(aminomethyl)ethane, PES = 2-phenylethynesulfonate), is reported which shows a hexagonal H-bonding motif between divalent metal complexes and sulfonate anions. This targeted motif, which orients pendant groups such that porosity could be generated, is obtained after two stages of design modification. Compound 1 is not porous as pendant groups interdigitate. Employing a disulfonate anion, the pillared layered solid {[Ni(tame)₂]₁(BSEB)₁}_∞ (BSEB = 4,4‘-bis(sulfoethynyl)biphenyl), 2e, is obtained. This is a highly robust solid for which a likely structure was extracted from powder X-ray diffraction data by analogy to 1. Unit cell indexing and Pawley refinement give parameters which correlate exceptionally well for the desired structure. Reversible CO₂ and N₂ sorption isotherms show that compound 2e retains permanent porosity.