Supramolecular assembly under the control of the chelating ligand for the MnII/bridging ligands/3-sulfobenzoate system and catalytic properties for the disproportionation of hydrogen peroxide

Abstract

Six Mn^II 3-sulfobenzoate complexes with neutral ligands, [Mn(4,4′-bipy)₂(H₂O)₄](3-sb)·3H₂O (1), {[Mn(3-sb)(bpe)_1.5(H₂O)₂](bpe)_0.5·H₂O}_n (2), [Mn(3-sb)(phen)(H₂O)₃](4,4′-bipy)·H₂O (3), [Mn₂(3-sb)₂(phen)₂ (4,4′-bipy)(H₂O)₄] (4), [Mn(3-sb)(phen)₂(H₂O)] (bpe)_0.5·4H₂O (5), and [Mn(3-sb)(phen)₂(H₂O)](bpe)_0.5·H₂O (6) [where 3-sb is 3-sulfobenzoate, 4,4′-bipy is 4,4′-bipyridine, bpe is 1,2-bis(4-pyridine)ethylene, and phen is 1,10-phenanthroline], were synthesized and characterized by several modern analytic methods. The molecular structures for the six complexes are monomers for complexes 3, 5, and 6, cation–anion species for complex 1, dimer for complex 4, and 1-D polymer for complex 2. The phen ligands in complexes 3 and 4 generate some effects on the hydrogen-bonding network, π–π interactions, and supramolecular assembly. TG analysis showed that desolvated complexes containing 4,4′-bipy are less stable than those of complexes containing bpe ligands. The emission strength order is 1 > 5 > 6 > 3 > 2 > 4, while the UV-vis absorption strengths are 4 > 3 > 1 for complexes containing 4,4′-bipy, and 5 > 6 > 2 for bpe metal complexes. The catalytic experiments showed that these six complexes are catalytically active for the disproportionation of H₂O₂ in the presence of imidazole and complex 3 has the best catalytic activity.