Structural Diversities and Fluorescent and Photocatalytic Properties of a Series of Cu^II Coordination Polymers Constructed from Flexible Bis-pyridyl-bis-amide Ligands with Different Spacer Lengths and Different Aromatic Carboxylates

Thirteen new Cu^II coordination polymers, namely, [Cu­(3-dppa)­(1,3,5-HBTC)] (<b>1</b>), [Cu­(3-dpha)­(1,3,5-HBTC)­(H₂O)]­·H₂O (<b>2</b>), [Cu₃(3-dpsea)­(1,3,5-BTC)₂­(H₂O)₅]·4H₂O (<b>3</b>), [Cu­(3-dpba)­(1,2-BDC)]­·H₂O (<b>4</b>), [Cu­(3-dpha)­(1,2-BDC)] (<b>5</b>), [Cu­(3-dpsea)­(1,2-BDC)]­·H₂O (<b>6</b>), [Cu₂(3-dpyp)­(1,3-BDC)₂­(H₂O)₄]­·3H₂O (<b>7</b>), [Cu­(3-dppa)­(1,3-BDC)­(H₂O)]­·2H₂O (<b>8</b>), [Cu­(3-dppia)­(1,3-BDC)­(H₂O)₂]­·2H₂O (<b>9</b>), [Cu₂(3-dpsea)₂­(1,3-BDC)₂­(H₂O)₂]­·7H₂O (<b>10</b>), [Cu­(3-dpba)­(1,4-NDC)]­·3H₂O (<b>11</b>), [Cu­(3-dpyh)­(1,4-NDC)­(H₂O)]­·3H₂O (<b>12</b>), [Cu­(3-dpyh)_0.5­(1,4-NDC)]­·H₂O (<b>13</b>), have been purposefully synthesized under hydrothermal conditions [3-dppa = <i>N</i>,<i>N</i>′-di­(3-pyridyl)­propanediamide, 3-dpba = <i>N</i>,<i>N</i>′-di­(3-pyridyl)­butanediamide, 3-dpha = <i>N</i>,<i>N</i>′-di­(3-pyridyl)­hexanedioicdiamide, 3-dppia = <i>N</i>,<i>N</i>′-di­(3-pyridyl)­pimelicdiamide, 3-dpsea = <i>N</i>,<i>N</i>′-di­(3-pyridyl)­sebacicdiamide, 3-dpyp = <i>N</i>,<i>N</i>′-di­(3-pyridine­carboxamide)-1,3-propane, 3-dpyh = <i>N</i>,<i>N</i>′-di­(3-pyridine­carboxamide)-1,6-hexane, 1,3,5-H₃BTC = 1,3,5-benzenetricarboxylic acid, 1,2-H₂BDC = 1,2-benzenedicarboxylic acid, 1,3-H₂BDC = 1,3-benzenedicarboxylic acid and 1,4-H₂NDC = 1,4-naphthalenedicarboxylic acid]. Complexes <b>1</b>–<b>3</b> based on the same auxiliary ligand show various structures. Complex <b>1</b> features a one-dimensional (1D) ∞-like double-chain structure, which consists of a [Cu-1,3,5-HBTC]_<i>n</i> chain and [Cu-3-dppa]_<i>n</i> <i>meso</i>-helical chain. Complex <b>2</b> possesses a (2,4) undulated honeycomb (hcb) net. Complex <b>3</b> is a 3-fold interpenetrating three-dimensional (3D) framework, which shows trinodal (2,3,3)-connected topology with the Schläfli symbol of (10·12²)₂(10³)₂(12). Complexes <b>4</b>–<b>6</b> with 1,2-BDC as secondary ligand exhibit different two-dimensional (2D) layer structures. Complex <b>4</b> exhibits a 2D (2,4)-connected (4·12⁴·14)­(4) net. Complexes <b>5</b> and <b>6</b> have similar structures and show 2D networks with undulated sql topology. For complexes <b>7</b>–<b>10</b> based on 1,3-BDC secondary ligand, complex <b>7</b> shows a 1D zigzag chain, while complexes <b>8</b>–<b>10</b> have similar wave-like 2D structures. When 1,4-NDC was used as the auxiliary ligand, complex <b>11</b> is a 2D puckered (4,4) network, complex <b>12</b> reveals a 4-connected topology with the point symbol of (4⁴·6²), while complex <b>13</b> exhibits a 3-fold interpenetrating 3D α-Po framework. The structural diversity indicates that the bis-pyridyl-bis-amide ligands with different spacers and the aromatic polycarboxylates play important roles in tuning the dimensionalities and structures of the title complexes. The fluorescent and photocatalytic properties for <b>1</b>–<b>13</b> have also been investigated in detail