A Series of Four-Connected Entangled Metal–Organic Frameworks Assembled from Pamoic Acid and Pyridine-Containing Ligands: Interpenetrating, Self-Penetrating, and Supramolecular Isomerism
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Abstract
Five novel compounds, {[Ni(PA)(bpe)(H<sub>2</sub>O)<sub>2</sub>]·DMF}<sub><i>n</i></sub> (<b>1</b>), {[Zn(PA)(bpe)]·DMF}<sub><i>n</i></sub> (<b>2</b>), {[Zn(PA)(bpe)]·2DMF·CH<sub>3</sub>OH}<sub><i>n</i></sub> (<b>3</b>), {[Cd<sub>2</sub>(PA)<sub>2</sub>(bpe)<sub>2</sub>(H<sub>2</sub>O)]·3.5H<sub>2</sub>O}<sub><i>n</i></sub> (<b>4</b>), {[Ni<sub>2</sub>(PA)<sub>2</sub>(bpp)<sub>2</sub>(H<sub>2</sub>O)<sub>3</sub>]·2DMF}<sub><i>n</i></sub> (<b>5</b>), based on pamoic acid (H<sub>2</sub>PA) (bpe = 1,2-bi(4-pyridyl)ethane, bpp = 1,3-bi(4-pyridyl)propane) have been synthesized. In such a system, both the PA<sup>2–</sup> anion ligand and dipyridyl ligands act as bipodal linkers, connecting the metal centers in square or tetrahedral geometries into 4-connected topologies with different entangled modes: 3-fold interpenetrating CdSO<sub>4</sub> net (6<sup>5</sup>.8) (<b>1</b>), roto-translational [2 + 2] interpenetrating diamond pseudosupramolecular isomers (<b>2</b> and <b>3</b>), 3-fold interpenetrating (6.7<sup>4</sup>.8)(6<sup>4</sup>.7.8) (<b>4</b>) and (6.8<sup>5</sup>)(6<sup>4</sup>.8<sup>2</sup>) net with both 2-fold interpenetrating and self-penetrating characters (<b>5</b>), respectively. The formation of unique penetrating frameworks was investigated in detail. Gas adsorption and photoluminescent properties of the compounds have also been explored
