Synthesis and characterization of a six-coordinate monomeric Mn(III) complex with SOD-like activity

• The complex [Mn-III(HL)(L)(py)(CH3OH)](CH3OH)-C-. (H2L=2-ortho-hydroxyphenylbenzimidazole, py pyridine), 1, has been characterized spectroscopically and by X-ray crystallography. The complex is triclinic, space group P-1(-) with a = 10.396(2), b = 10.7340(10), c = 15.193(2) angstrom, alpha = 73.193(4)degrees, beta = 76.283(8)degrees, gamma = 61.400(40)degrees, V = 1415.1(4)angstrom(3), Z = 2, D-c = 1.445 Mg m(-3), M-r = 615.56, mu = 0.515 mm(-1), F(000) = 640, R = 0.0631, wR = 0.1525. Manganese is six-coordinate in an N3O3 ligand sphere created by two bidentate H2L ligands and solvent molecules with a slightly distorted, axially elongated octahedral geometry. Electronic absorption spectra show pi-pi* and Ligand Metal Charge Transfer (LMCT) transitions in the UV region and d-d transitions in the visible region. Solvent molecules coordinated to the Mn(III) ion in the crystal are thought to retain their coordination in solution. It is shown that 1 has reaction activity with the superoxide ion, as indicated by inhibition of pyrogallol autoxidation and by spin trapping electron paramagnetic resonance (EPR) spectroscopy. The N3O3 ligand set in 1 is similar to that in native MnSOD (superoxide dismutatase) in the substrate-bound state. The correlation between the ligand set in 1 and its reaction with the superoxide ion is discussed.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

2-dimethyl-3

4-dihydro-2H-pyrrole-1-oxide

spin trap

pyrogallol

autoxidation

2

superoxide ion reactivity

superoxide dismutase

structure

X-ray

pyridine

Manganese(III)

2-o-hydroxyphenylbenzimidazole

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