Copper(II) complexes of novel N-alkylated derivatives of cis,cis-1,3,5-triaminocyclohexane. 2. Metal-promoted phosphate diester hydrolysis.

Academic Article


  • Aqueous copper(II) N,N',N' '-trimethyl-cis,cis-1,3,5-triaminocyclohexane (Cu(tach-Me(3))(2+)(aq)) promotes the hydrolysis of activated phosphate diesters in aqueous medium at pH 7.2. This complex is selective for cleavage of the phosphate diester sodium bis(p-nitrophenyl) phosphate (BNPP), the rate of hydrolysis of the monoester disodium p-nitrophenyl phosphate being 1000 times slower. The observed rate acceleration of BNPP hydrolysis is slightly greater than that observed for other Cu(II) complexes, such as [Cu([9]aneN(3))Cl(2)] ([9]aneN(3) identical with 1,4,7-triazacyclononane). The rate of hydrolysis is first-order in phosphate ester at low ester concentration and second-order in [Cu(tach-Me(3))](2+)(aq), suggesting the involvement of two metal complexes in the mechanism of substrate hydrolysis. The reaction exhibits saturation kinetics with respect to BNPP concentration according to a modified Michaelis-Menten mechanism: 2CuL + S <==> LCu-S-CuL --> 2CuL + products (K(M) = 12.3 +/- 1.8 mM(2), k(cat) = (4.0 +/- 0.4) x 10(-)(4) s(-1), 50 degrees C) where CuL (triple bond) [Cu(tach-Me(3))](2+), S (triple bond) BNPP, and LCu-S-CuL is a substrate-bridged dinuclear complex. EPR data indicate that the dicopper complex is formed only in the presence of BNPP; the active LCu-S-CuL intermediate species then slowly decays to products, regenerating monomeric CuL.
  • Authors

  • Deal, KA
  • Park, G
  • Shao, J
  • Chasteen, ND
  • Brechbiel, MW
  • Planalp, Roy
  • Status

    Publication Date

  • August 13, 2001
  • Keywords

  • Copper
  • Cyclohexylamines
  • Electron Spin Resonance Spectroscopy
  • Hydrogen-Ion Concentration
  • Kinetics
  • Digital Object Identifier (doi)

    Pubmed Id

  • 11487320
  • Start Page

  • 4176
  • End Page

  • 4182
  • Volume

  • 40
  • Issue

  • 17