Azo-hydrazone tautomerism by in situ CuII ion catalysis and complexation with the H2O2 oxidant of C.I. Disperse Yellow 79

A novel dinuclear copper(II) complex 2 bearing double μ2-oxo bridges has been obtained by in situ CuII ion catalysis and complexation with the H2O2 oxidant of C.I. Disperse Yellow 79 (1), where a new dianionic ligand is in situ formed having an additional phenolic group and it coordinates with the central CuII ion as a tridentate chelating ligand. Furthermore, both of the starting material 1 and the final neutral dye-metal product 2 have been structurally and spectrally characterized and compared, where azo-hydrazone tautomerism has been observed before and after metal-ion complexation. To the best of our knowledge, this is the first structural report about the heterocyclic dyes having quinoline-2,4-dione skeleton and the corresponding azo-hydrazone tautomerism between them.

A novel dinuclear copper(II) complex 2 has been obtained by in situ CuII ion catalysis and complexation with the H2O2 oxidant of C.I. Disperse Yellow 79 (1) Both 1 and 2 have been structurally and spectrally characterized and compared, where azo-hydrazone tautomerism has been observed before and after metal-ion complexation.Figure optionsDownload as PowerPoint slideHighlights
► Two heterocyclic dyes bearing quinoline-2,4-dione skeleton are structurally described.
► A dinuclear CuII complex is obtained by in situ CuII ion catalysis and complexation with the H2O2 oxidant of C.I. Disperse Yellow 79.
► Azo-hydrazone tautomerism has been observed before and after metal-ion complexation.