Multifunctional Cobalt(II) Coordination Polymers Tuned by Flexible Bis(pyridylamide) Ligands with Different Spacers and Polycarboxylates

Ten multifunctional cobalt­(II) coordination polymers with the formulas of [Co­(<b>L</b>^<b>1</b>)_0.5(5-AIP)]­·H₂O (<b>1</b>), [Co­(<b>L</b>^<b>2</b>)­(5-AIP)­(H₂O)₂] (<b>2</b>), [Co­(<b>L</b>^<b>3</b>)_0.5­(5-AIP)] (<b>3</b>), [Co­(<b>L</b>^<b>4</b>)_0.5­(5-AIP)­(H₂O)]­·2H₂O (<b>4</b>), [Co­(<b>L</b>^<b>5</b>)­(5-AIP)] (<b>5</b>), [Co­(HBTC)­(<b>L</b>^<b>3</b>)]­·H₂O (<b>6</b>), [Co­(HBTC)­(<b>L</b>^<b>6</b>)­(H₂O)]­·3H₂O (<b>7</b>), [Co­(<b>L</b>^<b>2</b>)­(1,3-BDC)­(H₂O)₂] (<b>8</b>), [Co₂(<b>L</b>^<b>3</b>)₂­(1,3-BDC)₂]­·4H₂O (<b>9</b>), and [Co₂(<b>L</b>^<b>4</b>)_1.5­(1,2-BDC)­(μ₂-OH)­(μ₃-OH)­(H₂O)]­·H₂O (<b>10</b>) have been prepared by a hydrothermal technique employing six flexible bis­(pyridylamide) ligands with different spacers (<b>L</b>^<b>1</b> = <i>N</i>,<i>N</i>′-bis­(3-pyridyl)­oxamide, <b>L</b>^<b>2</b> = <i>N</i>,<i>N</i>′-bis­(3-pyridyl)­malonamide, <b>L</b>^<b>3</b> = <i>N</i>,<i>N</i>′-di­(3-pyridyl)­succinamide, <b>L</b>^<b>4</b> = <i>N</i>,<i>N</i>′-bis­(3-pyridyl)­adipamide, <b>L</b>^<b>5</b> = <i>N</i>,<i>N</i>′-bis­(3-pyridyl)­heptandiamide, <b>L</b>^<b>6</b> = <i><i>N</i></i>,<i>N</i>′-bis­(3-pyridyl)­sebacicdiamide) and four aromatic polycarboxylic acids mixed ligands (5-H₂AIP = 5-aminoisophthalic acid, H₃BTC = 1,3,5-benzenetricarboxylic acid, 1,3-H₂BDC = 1,3-benzenedicarboxylic acid, and 1,2-H₂BDC = 1,2-benzenedicarboxylic acid). Compound <b>1</b> exhibits a two-dimensional (2D) double-layer network. Compounds <b>2</b> and <b>8</b> are isostructural and possess one-dimensional (1D) circle-connecting-circle chain structures derived from 1D [Co­(<b>L</b>^<b>2</b>)]_<i>n</i> “Ω”-like chain and 1D [Co­(5-AIP)]<i>_n</i>­/[Co­(1,3-BDC)]<i>_n</i> wavelike chain. Compound <b>3</b> possesses a 3,8-connected three-dimensional (3D) coordination framework with {4².6}₂­{4⁴.6¹⁰.7⁹.8⁵} topology. Compound <b>4</b> is a 2D network containing a ladder-like chain. Compound <b>5</b> reveals a novel 3-fold interpenetrating CdSO₄-like framework. Compound <b>6</b> is a double-layer coordination network with a (3,5)-connected {4²·6⁷·8}­{4²·6} topology. Complex <b>7</b> shows a 2D (4,4) grid layer. Compound <b>9</b> features a 2-fold interpenetrating 3D α-Po-related topological framework. Compound <b>10</b> is a 6-connected 3D coordination polymer with a {4¹².6³} topology. The spacer length of the bis­(pyridylamide) ligands, as well as the substituent group and carboxyl group number of polycarboxylates, shows a significant effect on the ultimate architectures of various cobalt­(II) compounds <b>1</b>–<b>10</b>. The electrochemical behaviors of carbon paste electrodes (CPEs) bulk-modified by compounds <b>1</b>–<b>10</b> and the electrocatalytic activities of <b>1</b>-, <b>6</b>-, <b>9</b>-, <b>10</b>-CPEs have been investigated. The photocatalytic properties of compounds <b>1</b>–<b>10</b> toward the degradation of methylene blue (MB) in visible light irradiation have been investigated. The variable temperature magnetic susceptibilities for compounds <b>3</b>, <b>5</b>, <b>9</b>, and <b>10</b> indicate the existence of antiferromagnetic exchange interactions