Synthesis, Crystal Structure, and Luminescence of Zn/Cd Coordination Polymers with a New Fuctionalized Terpyridyl Carboxylate Ligand

Eight new coordination polymers, [Zn­(L)­Cl]_<i>n</i> (<b>1</b>), [Zn₂(L)₄]_<i>n</i>·2<i>n</i>H₂O (<b>2</b>), [Zn₂(L)₂(1,3-bdc)]_<i>n</i> (<b>3</b>), [Zn₂(L)­(1,3-bdc)­(OH)]_<i>n</i>·0.5<i>n</i>H₂O (<b>4</b>), [Zn₉(L)₄(1,3-bdc)₆(OH)₂]_<i>n</i>·3<i>n</i>H₂O (<b>5</b>), [Zn₂(L)₂(1,4-bdc)]_<i>n</i>·<i>n</i>H₂O (<b>6</b>), [Cd₂(L)₄]_<i>n</i>·<i>n</i>H₂O (<b>7</b>), and [Cd₃(L)₂(1,3-bdc)₂]_<i>n</i>·<i>n</i>H₂O (<b>8</b>) [HL = 4′-(2-carboxyphenyl)-4,2′:6′,4″-terpyridine, H₂(1,3-bdc) = benzene-1,3-dicarboxylic acid, H₂(1,4-bdc) = benzene-1,4-dicarboxylic acid] have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, and single crystal X-ray diffraction. Complexes <b>1</b>, <b>2</b>, and <b>7</b> display a two-dimensional (2D) layer structure. Complex <b>3</b> presents a complicated 2D layer structure with paddle-wheel units, which exhibits an interesting (3,4,6)-connected 3-nodal new topological net with the point symbol of (3·4·5·6²·7)₂(3·6·7)₂(3²·4²·5²·6²·7⁶·8). Complex <b>4</b> is a 2-nodal (3,5)-connected 2D bilayer structure with the <b>gek1</b> topological net and the point symbol of (3·4·5)­(3²·4·5·6²·7⁴). Complex <b>5</b> shows a self-penetrating three-dimensional (3D) framework based on pentanuclear clusters, which features an intriguing (3,3,4,4,12)-connected 5-nodal new topological net with the point symbol of (4·6²)₂(4²·6⁴)₄(4³)₂(4⁸·6³⁴·8²²·10²). Complex <b>6</b> features a 2-fold interpenetrating (3,4)-connected 3D framework with the <b>ins</b> topological net and the point symbol of (6³)­(6⁵·8). Complex <b>8</b> is a new (4,4,5,6)-connected 3D network built up by a linear Cd₃(COO)₆ trinuclear cluster with the point symbol of (4²·6³·8)₂(4³·6³)₂(4⁴·6⁴·8²)₂(4⁸·6⁶·8). The diverse structures indicate that rational adjustment of the second ligand, the pH value, and counteranion are good methods to further design metal–organic compounds with new structures and properties. In addition, the thermal stabilities and photoluminescence properties of <b>1</b>–<b>8</b> were also studied