Synthesis of Cu (II) Schiff base complex as a recyclable and highly efficient catalyst for one pot three component synthesis of tetrahydro-4H-chromenes

Schiff base ligands can bind to metal ions as chelating ligands and form metal complexes with interesting properties. These Schiff bases normally bind to metal ions via the azomethine nitrogen. [1] Schiff base complexes especially Copper (II) complexes have shown excellent catalytic activity in different reactions. [2] A tridentate Schiff base ligand, 4-bromo-2-((quinolin-8-ylimino) methyl) phenol (HL), and its Cu (II) complex [Cu(L)(NO3)], have been synthesized and characterized by elemental analyses, FT-IR, molar conductivity, UV–Vis spectroscopy. The structure of catalyst has been accomplished by single crystal X-ray diffraction. The coordination geometry around the copper (II) ion in the mononuclear species is four coordinated square planar with one oxygen and two nitrogen atom from the tridentate ligand. The prepared compound was also screened for catalytic activities. the catalytic activities of this complex have been investigated on the electrophilic reaction of malononitrile along with aldehydes, ethyl acetoacetate and dimedone in ethanol solution in order to tetrahydro-4H-chromenes, respectively. [3]