Synthesis, characterization and photoluminescence properties of copper(II)–azido/thiocyanato complexes with thiazolylazo dye and1,2-bis(diphenylphosphino)ethane

A series of copper(II) complexes of the formula [Cu(L)(dppe)(N3)2] (1a–3a) and [Cu(L)(dppe)(NCS)2] (1b–3b) (where L = 4-(2′-thiazolylazo)chlorobenzene (L1); 4-(2′-thiazolylazo)bromobenzene (L2) and 4-(2′-thiazolylazo)iodobenzene (L3); dppe = cis-1,2-bis(diphenylphosphino)ethane) has been prepared and characterized on the basis of their elemental analysis, molar conductance, magnetic moment, IR, UV–vis and 1H NMR spectral studies. The electrochemical behaviour of the complexes showed that the redox responses of copper(II) complexes shifted to more negative potential in order of decrease in electron withdrawing nature of the substituent on the azo ligands. All the complexes exhibit intraligand (π→π*) fluorescence in blue-green region with high quantum yield in DMF solution.