Dicarboxylate Ligands Modulated Structural Diversity in the Construction of Cd(II) Coordination Polymers Built from N-Heterocyclic Ligand: Synthesis, Structures, and Luminescent Sensing

Six Cd(II) coordination polymers (CPs) {[Cd(mbbt)(1,2-bdc)(H2O)]center dot H2O}(n) (1), [Cd(mbbt)(1,3-bdc)](n) (2), [Cd(mbbt)2(1,4-bdc)](n) (3), [Cd( mbbt)(1,4-ndc)](n) (4), [Cd(mbbt)(1,3-adc)](n) (5), and {[Cd(mbbt)(1,3-ada)(H2O)]center dot H2O}(n) (6) were constructed by selecting dicarboxylate ligands in the system Cd(II)/ mbbt (mbbt = 1-(2-methylbenzimidazol-1ylmethyl)benzotriazole, 1,2-H(2)bdc = 1,2-benzenedicarboxylic acid, 1,3- H(2)bdc = 1,3-benzenedicarboxylic acid, 1,4-H(2)bdc = 1,4-benzenedicarboxylic acid, 1,4-H(2)ndc = 1,4-naphthalenedicarboxylic acid, 1,3-H(2)adc = 1,3-adamantanedicarboxylic acid, 1,3-H(2)ada = 1,3-adamantanediacetic acid). Structural analyses indicate that CP 1 manifests a three-dimensional (3D) 66-dia framework. CP 2 displays a 3D 412.63 network based on dinuclear units Cd-2(COO)(2). CP 3 shows a one-dimensional (1D) zigzag chain structure. CP 4 presents a 65.8 framework with paddle-wheel-like Cd-2(COO)(4) secondary building units. CPs 5 and 6 show a 1D double-chain structure and a 1D linear chain structure, respectively. The structural discrepancy of CPs 1-6 demonstrates that dicarboxylate ligands have a major impact on the structures of CPs. Furthermore, CP 4 shows remarkable sensing performance for Fe3+ ions and pesticides with luminescent quenching, which can function as a luminescent sensor for Fe3+ ions and pesticides.