Synthesis, structure, catechol oxidase activity and antibacterial studies of MnIII complex with sterically constrained phenol-based N2O2 ligand

Department of Chemistry, Department of Botany,

Sidho-Kanho-Birsha University, Purulia-723 104, West Bengal, India

E-mail : deb_mandal@yahoo.co.in

Department of Biotechnology, The University of Burdwan, Golapbag, Burdwan-713 104,

West Bengal, India

Department of Organic Chemistry,Department of Inorganic Chemistry,

Indian Association for the Cultivation of Science, Kolkata-700 032, India

Manuscript received 15 July 2017, accepted 26 August 2017

Mn^III complex with sterically constrained phenol based tetradentate N₂O₂ ligand together with acetylacetone as ancillary ligand has been synthesized and characterized. Sterically constrained tetradentate ligand N,N'-dimethyl-N,N'-bis(2-hydroxy-3,5-dimethylbenzyl)-ethylenediamine (H₂L) has been used here to synthesize mononuclear octahedral mixed ligand complex [Mn^IIIL(acac)] 1. Characterization of this compound is carried out by various spectroscopic tools. Compound 1 crystallizes in orthorhombic space group Pna21 with a = 8.325 Å, b = 23.150 Å, c = 13.428 Å. The compound shows both antibacterial activity as well as catecholase activity. Antibacterial activity of complex 1 was performed by well plate technique. In the above experiment, V. harveyi, V. vulnificus, V. parahaemolyticus, A. hydrophila and E. coli were found sensitive to the mononuclear mixed ligand complex [Mn^IIIL(acac)] 1. At the same time, the mixed ligand Mn^III complex catalyses the oxidation of 3,5-di-tert-butylcatechol in methanol in the presence of molecular oxygen with first order reaction kinetics. The kinetic studies confirm that the turnover number is 1.2×10⁵ h ^–1 .