Blue copper protein analogue: synthesis and characterization of copper complexes of the N sub(2)S sub(2) macrocycle 1,8-dithia-4,11-diazacyclotetradecane

To improve understanding of copper at the active site of Type 1 copper proteins, Cu super(I) and Cu super(II) complexes of 1,8-dithia-4,11-diazacyclotetradecane, shown in Fig. 1, have been successfully isolated and structurally characterized by X-ray crystallography. In these compounds, both Cu super(I) and Cu super(II) are centered in the plane of the macrocycle containing two sulphur and two nitrogen heteroatoms comprising the distorted tetrahedral/square planar coordination geometry. The UV/VIS spectra, electrochemistry and EPR properties have been obtained for the Cu super(II) complex 2. Three absorption bands at 295 nm, 354 nm, and 545 nm are observed in aqueous solution at a pH of 5. These bands have been assigned to the N arrow right Cu super(II) and S arrow right Cu super(II) charge transfer bands and the d-d transitions respectively. The Cu super(I/II) redox midpoint potential of complex 2 in CH sub(3)CN is +403 mV versus NHE.