Solid phase extraction of Pb(II), Cu(II), Cd(II) and Cr(III) with syringe technique using novel silica-supported bis(diazoimine) ligands

Novel multidentate silica-supported bis(diazoimine) ligands were synthesized and characterized by elemental analysis, solid phase NMR (29Si and 13C CP MAS), FT-IR, TG/DTA, SEM and EDX techniques. In the synthesis, diazotized electrophiles of 1,4-diaminobenzene and 1,3-diaminobenzene coupled with 2,4-dihydroxybenzaldehyde to give bis(diazocarbonyl) compounds; (A1: 5,5′-(1,4-phenylenebis(diazene-2,1-diyl))bis(2,4-dihydroxybenzaldehyde and A2: 5,5′-1,3-phenylenebis(diazene-2,1-diyl))bis(2,4-dihydroxybenzaldehyde)) which were chemically supported with amino-modified silica-gel (L1 and L2). The electrochemical properties of bis(diazocarbonyl) compounds (A1 and A2) were investigated by cyclic voltammetry. Optimum solid phase extraction parameters of the synthesized sorbents for syringe and batch techniques were determined by using ICP-OES. At optimum conditions, the recoveries of Pb(II), Cu(II), Cd(II) and Cr(III) were 95–99% ± 2–3%. All the multifunctional multidentate silica-supported ligands showed highly effective solid phase extraction properties.

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► Synthesis of novel bis(diazoaldehyde)s and silica-supported bis(diazoimine) ligands.
► Characterization and electrochemical properties of the novel compounds.
► Multidentate bis(diazoimine) ligands exhibit highly efficient solid phase extraction properties.