Characterization of Ternary Copper(II) Complexes Containing Reduced PQQ (PQQH2) and Bipyridine or Terpyridine

Abstract The ternary copper(II) complex containing reduced coenzyme PQQ (PQQH2) and bipyridine or terpyridine was prepared and characterized by electronic absorption and electron paramagnetic resonance (EPR) spectroscopy. The structures of these complexes are quite similar to those of the corresponding ternary complexes containing PQQ (oxidized form), in which the binding of PQQ to Cu(II) through N(6) and COO−(7) groups has been proposed.