Thioether sulfur oxygenation from O2 or H2O2 reactivity of copper complexes with tridentate N2Sthioether ligands.
To model thioether-copper coordination chemistry including oxidative reactivity, such as occurs in the copper monooxygenases peptidylglycine -hydroxylating monooxygenase (PHM) and dopamine beta-hydroxylase (DbetaH), we have synthesized new tridentate N2S ligands LSEP and LSBz [LSEP = methyl(2-phenethylsulfanylpropyl)(2-pyridin-2-ylethyl)amine; LSBz = (2-benzylsulfanylpropyl)methyl(2-pyridin-2-ylethyl)amine)]. Both copper(I) and copper(II) complexes have been prepared, and their respective O2 and H2O2 chemistry has been studied. Under mild conditions, oxygenation of [(LSEP)CuI]+ (1a) and [(LSBz)CuI]+ (2a) leads to ligand sulfoxidation, thus exhibiting copper monooxygenase activity. A copper(II) complex of this sulfoxide ligand product, [(LSOEP)CuII(CH3OH)(OClO3)2], has been structurally characterized, demonstrating Cu-Osulfoxide ligation. The X-ray structure of [(LSEP)CuII(H2O)(OClO3)]+ (1b) and its solution UV-visible spectral properties [S-CuII LMCT band at 365 nm (MeCN solvent); epsilon = 4285 M-1 cm-1] indicate the thioether sulfur atom is bound to the cupric ion in both the solid (CuII-S distance: 2.31 A) and solution states. Reaction of 1b with H2O2 leads to sulfonation via the sulfoxide; excess hydrogen peroxide gives mostly sulfone product. These results may provide some insight into recent reports concerning protein methionine oxidation, showing the potential importance of copper-mediated oxidation processes in certain biological settings.
Lee
Yunho
Y
Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Lee
Dong-Heon
DH
Sarjeant
Amy A Narducci
AA
Zakharov
Lev N
LN
Rheingold
Arnold L
AL
Karlin
Kenneth D
KD
D003300:Copper / Q000737:chemistry*; D004299:Dopamine beta-Hydroxylase / Q000737:chemistry / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry*; D008024:Ligands; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000378:metabolism; D015394:Molecular Structure; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D012451:Safrole / Q000031:analogs & derivatives / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry*
D008024:Ligands; D009097:Multienzyme Complexes; D009942:Organometallic Compounds; D013440:Sulfides; D013455:Sulfur; D003300:Copper; D006861:Hydrogen Peroxide; D006899:Mixed Function Oxygenases; D004299:Dopamine beta-Hydroxylase; C035189:peptidylglycine monooxygenase; D012451:Safrole; D010100:Oxygen; C005746:sulfoxide