Construction of a 2D rectangular grid and 3D diamondoid interpenetrated frameworks and their functionalities by changing the second spacers

Abstract

Three new metal–organic Zn^II frameworks, {[Zn(bipy)(1,4‐ndc)(H₂O)₂]·2H₂O} (1), {[Zn(bpe)(1,4‐ndc)]₂·2DMF} (2), {[Zn(bpee)(1,4‐ndc)]₂·2DMF} (3) [bipy = 4,4′‐bipyridyl, 1,4‐ndc = 1,4‐naphthalenedicarboxylate, bpe = 1,2‐bis(4‐pyridyl)ethane, bpee = 1,2‐bis(4‐pyridyl)ethylene], have been synthesized by using mixed‐ligand systems under solvothermal conditions and characterized structurally by single‐crystal X‐ray diffraction. Compound 1 has a 2D structure with 4⁴‐sql net topology, whereas 2 and 3 have a 3D diamondoid structure with interesting fourfold interpenetrated topology. Topological analyses of the diamondoid nets in compounds 2 and 3 reveal a 4‐connected net with 66 topology. Thermogravimetric experiments suggest that the solvent‐free compounds 1–3 are stable up to 370, 330, and 280 °C, respectively. The grids of 1 stack in –ABCD– fashion without any regular channel structure. Desolvated compound 2 (2′) selectively adsorbs CO₂ over N₂, and such discrimination is regulated by the restricted window dimension of the channels. Solvent vapor (H₂O, MeOH, and EtOH) adsorption studies with 2′ suggest a hydrophobic nature of the pore surface. Gas and vapor adsorption studies with 3′ reveal no uptake, which can be correlated to a smaller pore size relative to the kinetic diameter of the respective adsorbates.