Solvent/Temperature and Dipyridyl Ligands Induced Diverse Coordination Polymers Based on 3‑(2′,5′-Dicarboxylphenyl)pyridine

Eleven new multidimensional transition coordination polymers, [Cd₂(dcpy)₂(H₂O)] (<b>1</b>), [Cd­(dcpy)]­·H₂O (<b>2</b>), [Cd­(dcpy)­(H₂O)_1.5]­·2H₂O (<b>3</b>), [Cd­(dcpy)­(bipy)_0.5(H₂O)]­·5H₂O (<b>4</b>), [Cd₂(dcpy)₂­(bipy)­(H₂O)₃]­·2.5H₂O (<b>5</b>), [Cd₂(dcpy)₂­(bipy)]­·4H₂O (<b>6</b>), [Cd­(dcpy)­(bpa)_0.5]­·2H₂O (<b>7</b>), [Ni­(dcpy)­(H₂O)₂] (<b>8</b>), [Ni­(dcpy)­(bpe)_0.5(H₂O)]­·3H₂O (<b>9</b>), [Ni­(dcpy)­(bpe)_0.5­(H₂O)]­·0.5H₂O (<b>10</b>), and [Ni­(dcpy)­(bpa)_0.5­(H₂O)₂]­·H₂O (<b>11</b>), have been synthesized by using a tritopic ligand 3-(2′,5′-dicarboxylphenyl)­pyridine acid (H₂dcpy) and three different N-donor ancillary ligands (bipy = 4,4′-bipyridine, bpe = 1,2-bi­(4-pyridyl)­ethene, and bpa = 1,2-bi­(4-pyridyl)­ethane) in different solvents and temperatures. <b>1</b> is a four-connected three-dimensional (3D) framework based on two kinds of Cd–O–Cd and Cd–(COO)–Cd chains. <b>2</b> shows also a four-connected 3D framework with one-dimensional (1D) channels formed by double left- and right-handed helical chains. <b>3</b> displays a 3D microporous framework composed of Cd₂O₃ as a secondary building unit (SBU) with a (4,6)-connected net. <b>4</b> is a two-dimensional (2D) layer based on Cd₂O₂ SBU and further stacks to generate a 3D supramolecular framework with open channels. <b>5</b> is a rare 3D homochiral microporous framework with left-handed helical chains. <b>6</b> presents the first (3,4,6)-connected 3D self-penetrating framework based on 1D metal–organic nanotubes (MONTs). <b>7</b> is a (3,4)-connected 3D microporous pillar-layer framework with 1D square channels filled by left- or right-handed helical water clusters chains. <b>8</b> is a 2D (3,6)-connected net based on Ni₂ dimers. <b>9</b> shows a wavelike 2D stacked layer framework possessing two types of open channels. <b>10</b> is a structural isomer of <b>9</b>, showing an intriguing (3,4)-connected self-penetrating network, while <b>11</b> exhibits a 2D (3,4)-connected layer. The effects of solvents, temperatures, metal cations, and the lengths and rigidness/flexibility of the dipyridyl ligand on the crystal architectures are discussed. The solid-state photoluminescence for <b>1</b>–<b>7</b> and the magnetic properties for <b>8</b> were also investigated. Gas adsorption studies for <b>9</b> shows a high selective adsorption of CO₂ over N<sub>2