title: Tuning the geometry and biomimetic catalytic activity of manganese(III)-tetrabromocatecholate based robust platforms by introducing substitution at pyridine.
abstract: The present report describes synthesis, characterization, crystal structures and catecholase activity of a series of five new manganese(III) complexes (1-5) derived from redox-noninnocent tetrabromocatecholate ligand in combination with different substituted pyridines. X-ray crystallography reveals that the geometry of manganese(III) centers in 1 and 2 is square pyramidal and they are pseudo-dimeric in the solid state resulting from the weak bonding of manganese(III) with a catecholate oxygen atom from the adjacent manganese(III) unit together with other weak interactions like hydrogen bonding and π⋯π stacking interactions. On the other hand, complexes 3-5 are discrete octahedral structures. All the complexes exhibit strong catecholase activity and their diverse catalytic activity can nicely be explained by the nature of substitution at pyridine ring - better electron donor inhibits the reduction of the metal center thereby lowering catecholase activity and vice versa (1 and 2 vs. 3-5). Besides the donor property of ancillary ligands, the structural distortion has also significant role in the biomimetic catalytic activity (1 vs. 2).
authors.affiliation: Department of Chemistry, Panskura Banamali College, Panskura RS, WB 721152, India.
authors.forename: Narayan Ch
authors.initials: NCh
authors.lastname: Jana
authors.affiliation: Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal; CICECO, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Brandão
authors.affiliation: Department of Chemistry, Panskura Banamali College, Panskura RS, WB 721152, India. Electronic address: ampanja@yahoo.co.in.
authors.forename: Anangamohan
authors.initials: A
authors.lastname: Panja
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D004156:Catechol Oxidase / Q000737:chemistry*; D002396:Catechols / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006842:Hydrocarbons, Brominated / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*
chemical_list: D002396:Catechols; D006842:Hydrocarbons, Brominated; D011725:Pyridines; D008345:Manganese; D004156:Catechol Oxidase; C023666:pyridine
keywords: Catecholase activity; Crystal structure; Geometrical preferences; Manganese-catecholate complex