Catalytic activities of novel silica-supported multifunctional Schiff base ligand & metal complexes under microwave irradiation

•Synthesis of novel silica-supported azo-containing Schiff base ligand and its four metal complexes are investigated.•Catalytic oxidation of cyclohexane under microwave power is discussed.•Those of novel catalysts in this paper show remarkable performance.

In this paper, a novel solid phase supported Schiff base ligand (L1: MDPMP) was prepared from 2-hydroxy-5-((2-methoxyphenyl)diazenyl) benzaldehyde (L: HMDB) and silica-gel, activated with 3-aminopropyltriethoxysilane (APTES). Cu (II), Co (II), Ni (II) and Mn (II) complexes of silica-supported ligand (L1: MDPMP) were obtained. The ligand and its four metal complexes were characterized by using NMR (1H and 13C), FT-MIR/FIR, elemental analysis, ICP-OES, TGA and Scanning Electron Microscope (SEM). Their catalytic performances in catalytic oxidation of cyclohexane were investigated for the selective oxidation of cyclohexane under microwave power. Silica-supported L1–Cu (II) complex was observed well selective catalytic properties for the oxidation of cyclohexane to cyclohexanol and cyclohexanone.

Graphical abstractThe graphical abstract shows the synthesized silica-supported ligand and coordination mode of metal ions to ligand “L1”. Addition, there are four proposed metal-complex moieties illustrated (Cu (II), Mn (II), Co (II), and Ni (II)).Figure optionsDownload full-size imageDownload as PowerPoint slide