Synthesis, characterization, and antioxidant activity of Zn2+ and Cu2+ coordinated polyhydroxychalcone complexes

Four new metal complexes [Cu(ISO)(2)], [Cu(BUT)(2)] and [Zn(ISO)(2)], [Zn(BUT)(2)] of the polyhydroxychalcones (isoliquiritigenin and butein) are synthesized, structurally characterized and their antioxidant activity is investigated. The formation of the complexes [Cu(ISO)(2)] and [Zn(ISO)(2)] is followed by Job's plot using NMR titration. The resulting compounds are characterized by mass spectrometry, IR spectroscopy, and elemental analysis. Studies on the radical scavenging activity are performed using DPPH as substrate. The results showed that the antioxidant activities of isoliquiritigenin and butein are enhanced after binding to copper or zinc.