Redox characteristics of Schiff base manganese and cobalt complexes related to water-oxidizing complex of photosynthesis


Hotchandani S., Ozdemir Ü., Nasr C., Allakhverdiev S., Karacan N., Klimov V., ...More

BIOELECTROCHEMISTRY AND BIOENERGETICS, vol.48, no.1, pp.53-59, 1999 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 48 Issue: 1
  • Publication Date: 1999
  • Doi Number: 10.1016/s0302-4598(98)00235-9
  • Journal Name: BIOELECTROCHEMISTRY AND BIOENERGETICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.53-59
  • Keywords: water-oxidizing complex (WOC), photosystem II (PS II), cyclic voltammetry, manganese complex, cobalt complex, PHOTOSYSTEM-II MEMBRANES, OXYGEN-EVOLVING COMPLEX, CRYSTAL-STRUCTURE, MONONUCLEAR MANGANESE(IV), LACTOBACILLUS-PLANTARUM, BIOLOGICAL RELEVANCE, OXIDATION COFACTOR, ACTIVE-SITE, LIGANDS, DIMERS
  • Gazi University Affiliated: Yes

Abstract

In an effort to obtain synthetic analogues of water-oxidizing complex (WOC) of photosystem II (PS II) of plant photosynthesis, a Schiff base manganese and a cobalt complex, employing Niten, a SALEN type ligand, have been prepared. Cyclic and square wave voltammetric measurements have been performed to assess their redox characteristics. Both complexes undergo several reduction processes in cathodic negative potential region at more or less similar potentials. In view of these reductions being independent of the nature of the metal, they are thought to be ligand-localized. Although similar in negative region, a marked difference in the behavior of the complexes is observed in anodic region. While the cobalt complex is electrochemically inactive in the positive potentials up to +1.0 V vs. Ag/AgCl, the manganese complex displays two oxidation waves at +0.25 and +0.5 V vs. Ag/AgCl. The presence of oxidation wave in manganese complex at +0.5 V vs. Ag/AgCl or +0.7 V vs. NHE suggests that this complex can catalyze the oxidation of water and can, thus, simulate the WOC of PS II. (C) 1999 Elsevier Science S.A. All rights reserved.