Three isomeric copper(II) coordination polymers based on a bis-triazole-bis-amide ligand: Assembly, structures, and luminescent properties

Three copper(II) isomers, [Cu(dtcd)(DNBA)2]n (1–3) (HDNBA = 3,5-dinitrobenzoic acid, dtcd = N,N-di(4H-1,2,4-triazole)cyclohexane-1,4-dicarboxamide), were synthesized in a one-pot reaction, and structurally characterized. Polymer 1 shows a 1-D single chain in which dtcd connect adjacent Cu2+ ions, while DNBA− is monodentate. In 2, every two Cu2+ ions are linked by carboxylate of a DNBA− in a chelate-bridging mode into a binuclear unit, which is further connected by dtcd ligands into a 1-D double chain. In 3, dtcd connect Cu2+ ions via triazole nitrogens to generate 1-D single chains, which are further extended into a 2-D network by the amide oxygens of a dtcb from an adjacent chain. The pH plays an important role in product distribution of 1–3. The coordination behaviors of dtcd and DNBA− also influence the final structures. Luminescent properties of 1–3 have been investigated.