مشخصات پژوهش

Two new chromogenic receptors 1,2‐[1‐(3‐imino‐4‐hydroxophenylazobenzene)]‐4‐chlorobenzene (1 a) and 1,2‐[1‐(3‐imino‐4‐hydroxophenylazo‐4‐nitrobenzene)]‐4‐chlorobenzene (1 b) have been designed and chearcterized for detection of some transition metal ions in DMSO solution by UV/Vis spectroscopy. Upon addition of Cd2+, Zn2+ and Cu2+ ions to 1 a in DMSO, the peak at 460 nm increases in intensity, while the band at 352 nm decreases in intensity and approximately disappears. n→π* transition of azo groups of 1 a decreases in intensity after adding Hg2+ ions and does not change after adding Ni2+ ions. This indicates high tendency of 1 a towards Cd2+, Zn2+ and Cu2+ against Ni2+ and Hg2+ions. Compound 1 b shows some color changes after addition of metal ions. Upon addition of all metal ions to 1 b in DMSO, the band at 560 nm increases in intensity with the hypsochromic shift for Cu2+, Zn2+, Co2+ and Ni2+. But the largest blue shift (‐67 nm) is seen after adding Cu2+ ion with remarkable color change from violet‐green to orange. Benesi‐ Hildebrand plot and Job′s method are used for determination of binding constant (Ka) and stoichiometry of formed complexes with 1 b. Then, complex Cu(II) with 1 b is synthezied for recognition of binding sites of ligand. The results indicate that 1 b behaves as one tetradentate ligand with N and O donor atoms when bound to Cu(II). Moreover, the study of antioxidant properties of 1 a and 1 b with DPPH method reveals good and significant activity.