Various Polycarboxylate-Directed Cd(II) Coordination Polymers Based on a Semirigid Bis-pyridyl-bis-amide Ligand: Construction and Fluorescent and Photocatalytic Properties

Nine new Cd­(II) coordination polymers (CPs) including [Cd₃(4-bmbpd)₄­Cl₆(H₂O)₂] (<b>1</b>), [Cd­(4-bmbpd)­(2,2′-BDC)­(H₂O)] (<b>2</b>), [Cd­(4-bmbpd)­(OBA)]­·H₂O (<b>3</b>), [Cd­(4-bmbpd)_0.5­(ADTZ)­(H₂O)]­·H₂O (<b>4</b>), [Cd₄(4-bmbpd)­(1,3-ATDC)₄­(H₂O)₆]­·2H₂O (<b>5</b>), [Cd­(4-bmbpd)­(3-NPH)­(H₂O)]­·H₂O (<b>6</b>), [Cd­(4-bmbpd)_0.5­(NIP)­(H₂O)] (<b>7</b>), [Cd­(4-bmbpd)_0.5­(HIP)]­·H₂O (<b>8</b>), and [Cd₃(4-bmbpd)₂­(1,3,5-BTC)­(H₂O)₄]­·4H₂O (<b>9</b>) (4-bmbpd = <i>N</i>,<i>N</i>′-bis­(4-methylenepyridin-4-yl)-1,4-benzenedicarboxamide, 2,2′-H₂BDC = 2,2′-biphenyldicarboxylic acid, H₂OBA = 4,4′-oxybis­(benzoic acid, H₂ADTZ = 2,5-(s-acetic acid)­dimercapto-1,3,4-thiadiazole, 1,3-H₂ATDC = 1,3-adamantanedicarboxylic acid, 3-H₂NPH = 3-nitrophthalic acid, H₂NIP = 5-nitroisophthalic acid, H₂HIP = 5-hydroxyisophthalic acid, and 1,3,5- H₃BTC = 1,3,5-benzenetricarboxylic acid), have been produced with a hydrothermal/solvothermal technique and structurally characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis, and infrared spectroscopy. Complex <b>1</b> exhibits a one-dimensional (1D) wave-like double chain constructed from [Cd₃(4-bmbpd)₂­Cl₆(H₂O)₂] subunits and μ₂-bridging 4-bmbpd ligands. <b>2</b> is a two-dimensional (2D) 4-connected layer consisting of 1D [Cd-4-bmbpd]_<i>n</i> zigzag chains and 1D [Cd-2,2′-BDC]_<i>n</i> single-strand helix chains. Complex <b>3</b> is also a 2D 4-connected network constituted of 1D [Cd-OBA]_<i>n</i> linear chains and [Cd­(4-bmbpd)]_<i>n</i> wave-like chains. Complex <b>4</b> has a (2,4,4)-connected 2D architecture based on [Cd₂(ADTZ)₂] rings and μ₄-bridging 4-bmbpd ligands with {4²·8²·10²}­{ 4²·8⁴}₂{4}₂ topology. Complex <b>5</b> exhibits an intriguing 1D chain constructed from [Cd₄(1,3-ATDC)₄] rings and μ₂/μ₄-bridging 4-bmbpd ligands. Complex <b>6</b> presents a 1D ladder-shaped chain. Complex <b>7</b> displays a 3D (4,4)-connected framework giving an interesting self-penetrating structure. Complex <b>8</b> is a 3D (4,5)-connected architecture with {4⁴·6²}­{4⁴·6⁶} topology. <b>9</b> shows a 3D (2,3,4,4)-connected framework, which contains [Cd-1,3,5-BTC]_<i>n</i> 1D double chains. The versatile structures reveal the impact of the carboxyl position and number, the flexibility, as well as the functional groups of polycarboxylate auxiliary ligands on the architectures. Furthermore, the effects of different organic solvents on the fluorescent behaviors of <b>1</b>–<b>4</b> and <b>7</b>–<b>9</b>, and the photocatalytic properties of <b>1</b>–<b>9</b> under UV irradiation, were studied