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The preconcentration of metal ions present at low concentration levels in aqueous systems and the selective removal of potentially toxic metals are important applications of adsorption processes. In this study, a heptadentate dinucleating ligand was anchored to chitosan for use in adsorption studies on Zn(II), Cu(II) and Ni(II) ions. The novel adsorbent was characterized by 13 C NMR and FT-IR spectroscopy, TGA and BET surface area analysis. The degree of substitution of the ligand in chitosan, obtained from CHN analysis, was 0.73. The adsorption kinetics followed a pseudo-second-order model. The rate constants and the adsorption capacities for multicomponent systems decreased in the order Cu(II) >> Ni(II) ∼ Zn(II), indicating the preferential adsorption of Cu(II). For Cu(II) ions, the Langmuir model provided the best fitting to the experimental data, and the monolayer Cu(II) adsorption capacity was 0.404 mmol g -1 , while the linear isotherm described Zn(II) and Ni(II) ion adsorption., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The synthesis, physico-chemical characterization and cytotoxicity of four new ligands and their respective copper(II) complexes toward two human leukemia cell lines (THP-1 and U937) are reported (i.e. [(HL1)Cu(μ-Cl)2Cu(HL1)]Cl2·H2O (1), [(H2L2)Cu(μ-Cl)2Cu(H2L2)]Cl2·5H2O (2), [(HL3)Cu(μ-Cl)2Cu(HL3)]Cl2·4H2O (3), [(H2L4)Cu(μ-Cl)2Cu(H2L4)]Cl2·6H2O (4)). Ligands HL1 and HL3 contain two pyridines, amine and alcohol moieties with a naphthyl pendant unit yielding a N3O coordination metal environment. Ligands H2L2 and H2L4 have pyridine, phenol, amine and alcohol groups with a naphthyl pendant unit providing a N2O2 coordination metal environment. These compounds are likely to be dinuclear in the solid state but form mononuclear species in solution. The complexes have an antiproliferative effect against both leukemia cell lines; complex (2) exhibits higher activity than cisplatin against U937 (8.20 vs 16.25μmoldm(-3)) and a comparable one against THP-1. These human neoplastic cells are also more susceptible than peripheral blood mononuclear cells (PBMCs) toward the tested compounds. Using C57BL/6 mice an LD50 of 55mgkg(-1) was determined for complex (2), suggesting that this compound is almost four times less toxic than cisplatin (LD50=14.5mgkg(-1)). The mechanism of cell death promoted by ligand H2L2 and by complexes (2) and (4) was investigated by a range of techniques demonstrating that the apoptosis signal triggered at least by complex (2) starts from an extrinsic pathway involving the activation of caspases 4 and 8. This signal is amplified by mitochondria with the concomitant release of cytochrome c and the activation of caspase 9., (Copyright © 2015 Elsevier Inc. All rights reserved.)