Synthesis, characterization and biological activity of Cu(II), Ni(II) and Zn(II) complexes of biopolymeric Schiff bases of salicylaldehydes and chitosan

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• 作者：Eliene Leandro de Araú ; jo^a ; Hellen Franciane Gonç ; alves Barbosa^a ; Edward Ralph Dockal^b ; É ; der Tadeu Gomes Cavalheiro^a ; ^{cavalheiro@iqsc.usp.br}
• 关键词：Schiff bases ; Chitosan ; Biological activity
• 刊名：International Journal of Biological Macromolecules
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：95
• 期：Complete
• 页码：168-176
• 全文大小：2100 K
• 卷排序：95

文摘

Schiff bases have been prepared from biopolymer chitosan and salicylaldehyde, 5-methoxysalicylaldehyde, and 5-nitrosalicylaldehyde. Ligands were synthesized in a 1:1.5 mol ratio, and their Cu(II), Ni(II) and Zn(II) complexes in a 1:1 mol ratio (ligand:metal). Ligands were characterized by 1H NMR and FTIR, resulting in degrees of substitution from 43.7 to 78.7%. Complexes were characterized using FTIR, electronic spectra, XPRD. The compounds were confirmed by the presence of an imine bond stretching in the 1630–1640 cm−1 and νMetal-N and νMetal-O at <600 cm−1. Electronic spectra revealed that both Cu(II) and Ni(II) complexes present a square plane geometry. The crystallinity values were investigated by X-ray powder diffraction. Thermal behavior of all compounds was evaluated by TGA/DTG and DTA curves with mass losses related to dehydration and decomposition, with characteristic events for ligand and complexes. Schiff base complexes presented lower thermal stability and crystallinity than the starting chitosan. Residues were the metallic oxides as confirmed by XPRD, whose amounts were used in the calculation of the percentage of complexed metal ions. Surface morphologies were analyzed with SEM-EDAX. Preliminary cytotoxicity tests were performed using MTT assay with HeLa cells. Despite the differences in solubility, the free bases presented relatively low toxicity.