Synthesis and characterization of porphyrazines as novel extractants for the removal of Ag(I) and Hg(II) from aqueous solution

In this study, the synthesis and characterization of new metal-free and metallo-porphyrazines, peripherally and symmetrically derived from 1,3-alternate26,28-[34,37-dithia-29,32,40,43-tetraoxa-35-en]calix[4]arene-25,27-diol, were performed. Dicyano compound was prepared starting from cis-1,2-dicyano-1,2-ethylenedithiolate disodium salt and 1,3-alternate 26,28-bis[2-(2-iodoethoxy)ethoxy]calix[4]arene-25,27-diol, which was prepared by the conversion reaction of 26,28-bis[2-(2-chloroethoxy)ethoxy] calix[4]arene-25,27-diol with NaI. The demetalation of magnesium porphyrazine was achieved by the treatment with trifluoroacetic acid that resulted in the metal-free derivative. The solvent extraction of heavy metal cations such as Ag(I), Hg(II), Cu(II), Mn(II), Cr(III), Ni(II), Pb(II) and Zn(II) by the dicyano compounds and its derived metal-free and magnesium porphyrazines was investigated. From the results of two phase extraction studies on the novel compounds, one can conclude that the metal-free and metallo-porphyrazines show very high selectivity for silver and mercury ions when compared with other metal ions. The novel compounds were characterized using the techniques of UV–vis, 1H, 13C NMR, IR, MS and elemental analysis.

► Novel calix[4]arene substituted MgPz and H2Pz were prepared and characterized.
► The extraction abilities of dicyano and porphyrazine compounds were evaluated by using several heavy metal picrates.
► The extraction affinities of Pz’s for Ag+ and Hg2+ were found to be the highest in solvent extraction experiments.