The first observation of azo-hydrazone and cis–trans tautomerisms for disperse yellow dyes and their nickel(ii) and copper(ii) complexes

Azo-hydrazone and cis-trans tautomerisms have been firstly observed between two disperse yellow dyes (cis/trans-HL(1) and cis-HL(2)) and three neutral dye-metal complexes (one mononuclear Ni(II) complex 3 and two Cu(II) coordination polymers 4 and 5 formulated as [Ni(trans-L(1))(2)(CH(3)OH)(2)].2H(2)O, [Cu(cis-L(1))(2)](n) and [Cu(L(3))(H(2)O)](n)).