Catherine Hemmert

Preparation, characterization and crystal structures of manganese(II), iron(III) and copper(II) complexes of the bis[di-1,1-(2-pyridyl)ethyl]amine (BDPEA) ligand; evaluation of their DNA cleavage activities

Abstract. The synthesis of a new tetrapyridyl ligand, bis[di-1,1-(2-pyridyl)ethyl]amine (BDPEA), is described. Complexation of this ligand with manganese(II), iron(III) or copper(II) chlorides afforded mononuclear complexes: Mn(BDPEA)Cl2 (1) [Fe(BDPEA)Cl2]Cl (2) and [Cu(BDPEA)Cl]Cl (3). In all cases, BDPEA is coordinated to the metal center by three pyridine nitrogen atoms and the secondary amine. The geometrical environments around the metals in Mn(BDPEA)Cl2 and [Fe(BDPEA)Cl2]Cl are best described as distorted octahedrals and in [Cu(BDPEA)Cl]Cl as a slightly distorted square pyramid. The DNA cleavage activities of manganese(II), iron(III) or copper(II) complexes of both BDPEA and another tetrapyridyl ligand, bis[di(2-pyridyl)methyl]amine (BDPMA), in the presence of an oxidant (H2O2) or a reducing agent (ascorbate) with air, are reported. The iron(III) complexes exhibited significantly enhanced efficiencies, compared to copper(II) complexes. [Fe(BDPEA)Cl2]Cl is found to be the most active DNA cleaver, in agreement with a better stability of BDPEA in oxidizing conditions.

Preparation and Crystal Structures of Manganese, Iron, and Cobalt Complexes of the Bis[di(2-pyridyl)methyl]amine (bdpma) Ligand and Its Oxidative Degradation Product 1,3,3-Tris(2-pyridyl)-3H-imidazo[1,5-a]pyridin-4-ium (tpip); Origin of the bdpma Fragility

The fragility of the benzylic C−H bonds of bis[di(2-pyridyl)methyl]amine (bdpma) has been demonstrated by a detailed crystallographic study of the wide variety of compounds obtained with the tetrapyridyl ligand and manganese, iron, and cobalt salts (figure).

Oxidative degradation of chlorinated phenols catalyzed by a non-heme iron(III) complex

A new symmetric pentadentate ligand containing four pyridine groups, bis(di-2-pyridylmethyl)amine (BDPMA), has been synthesized in a good yield. The corresponding non-heme iron(III) complex, [Fe(BDPMA)](NO3)3, with potassium monopersulfate as oxidant, catalyzed the oxidative degradation of aromatic pollutants chlorinated phenols to yield the corresponding benzoquinones.

Synthesis of Bis[di(2-pyridyl)methyl]amine (BDPMA) by a Novel One-Pot Multi-Step Reductive Amination with Molecular Sieves and Zn/iPrOH

Bis[di(2-pyridyl)methyl]amine (BDPMA) has been syn-thesized by refluxing di-2-pyridyl ketone and di-(2-pyridyl)methylamine in isopropanol in the presence of molecular sieves and acetic acid and subsequent reduction with zinc dust. The established methods for reductive amination, i.e. NaBH3CN, NaBH(OAc)3 and NaBH4, failed in the synthesis of BDPMA due to a disfavored equilibrium towards the imine formation and therefore long reaction times were required, involving side reactions. The presented method can be used on large-scales and tolerates aromatic heterocycles as functional groups.

Unprecedented amido-bridged dinuclear mixed-valence cobalt complexes: first structure of a dinuclear μ-OMe Co(II)/Co(III) complex

The complexation of the pentadentate ligand bis[1,1-di(2-pyridyl)ethyl]amine (BDPEA), n by cobalt(II) salts leads to novel Co(II)/Co(III) mixed-valence complexes: the n secondary amine of the starting BDPEA is deprotonated, leading to a dinucleating bridging amido ligand.

Isolation and characterization of an oxidative degradation product of a polypyridine ligand

The origin of the fragility of a polypyridine ligand under oxidizing conditions is discussed.

Second generation of a polypyridine ligand to mimic enzymes containing non-heme iron centers

Abstract A new tetrapyridyl ligand (BDPEA) and the corresponding di-iron(III) μ-oxo complex were synthesized. The iron complex structure, determined by X-ray crystallography, exhibited the dinuclear core [Fe2III(BDPEA)2(μ-O)(NO3)2](NO3)2 (1). With monopersulfate as oxidant, this complex catalyzed the conversion of 2,4,6-trichlorophenol and catechol, with a better activity and an enhanced life-time compared to the previously reported complex [FeIII(BDPMA)](NO3)3 (2) (BDPMA: bis[di(2-pyridyl)methyl]amine) which contained two fragile benzylic C–H bonds on the tetrapyridyl ligand.