Synthesis, characterization and solid-phase extraction properties of novel bis(diazo-azomethine) ligands supported on mesoporous silica

The novel mesoporous silica-supported bis(diazo-azomethine) compounds have been synthesized and characterized successively. In the first step, 1,3-phenylenedimethanamine and 4,4-diaminodiphenylmethane were diazotized, and the obtained bis(diazonium) cations were coupled with 2,4-dihydroxybenzaldehyde. The synthesized bis(diazo-carbonyl) compounds, 5,5-((1,3-phenylenebis(methylene))bis(diazene-2,1-diyl))bis(2,4-dihydroxybenzaldehyde) (A1) and 5,5-((methylenebis(4,1-phenylene))bis(diazene-2,1-diyl))bis(2,4-dihydroxybenzaldehyde) (A2) were chemically supported on amino-modified silica-gel (as L1 and L2). Elemental analysis, liquid chromatography-mass spectroscopy, liquid-phase NMR (H-1 and C-13) and solid-phase NMR (CP-MAS Si-29 and C-13), FT-IR, TG/DTA, scanning electron microscopy and energy-dispersive X-ray spectroscopy techniques were used for characterizations of all the synthesized compounds. The syringe and batch techniques were applied for the solid-phase extraction properties of Pb(II), Cu(II), Cd(II) and Cr(III) ions using an inductively coupled plasma-atomic emission spectroscopy instrument. The recoveries of Pb(II), Cu(II), Cd(II) and Cr(III) ions have been achieved to 95-99% with the (RSDs) of +/- 2-3% in optimum conditions.