Heterogeneous water oxidation by bidentate Schiff base manganese complexes in the presence of cerium(IV) ammonium nitrate

Abstract

Oxygen evolution was observed upon mixing solid manganese(III) bidentate Schiff base complexes with aqueous solutions of cerium(IV) ammonium nitrate. However, oxygen evolution was not observed upon mixing solutions of the complexes (in acetonitrile) with Ce(IV). Electron-withdrawing substituents on the Schiff base ligands (NO 2 , Br) enhanced the reactivity of the manganese complexes toward oxygen evolution. Oxygen evolution was also affected by R groups on the ligands, in the order Me [ Et ) Bz.Electronic supplementary material The online version of this article (

From manganese complexes to nano-sized manganese oxides as water-oxidizing catalysts for artificial photosynthetic systems: Insights from the Zanjan team

“…We reported on Mn(II), MnO 4 À and insoluble Mn products which show weak absorption bands characteristic of an {Mn 2 O 2 } core in the region of 600e700 cm À1 [13]. Using ESI(þ)eMS/MS at pH~4.5 we also showed that the mononuclear complex [Mn(tptz)(CH 3 COO)(OH 2 ) 2 ]NO 3 is not fully preserved and is in equilibrium with some cationic species [15].…”

“…Previously, we reported on an oxygen-evolution reaction upon mixing solid Mn(III) bidentate Schiff base complexes with aqueous solutions of Ce(IV) [13]. We reported on Mn(II), MnO 4 À and insoluble Mn products which show weak absorption bands characteristic of an {Mn 2 O 2 } core in the region of 600e700 cm À1 [13].…”

Manganese Compounds as Water Oxidizing Catalysts in Artificial Photosynthesis

“…Oxygen evolution was also observed upon mixing solid manganese(III) bidentate Schiff base complexes with aqueous solutions of (NH 4 ) 2 [(Ce(NO 3 ) 6 ] (Najafpour & Boghaei, 2009). However, oxygen evolution was not observed upon mixing solutions of the complexes (in acetonitrile) with Ce(IV).…”

“…Electron-withdrawing substituents on the Schiff base ligands (NO 2 , Br) enhanced the reactivity of the manganese complexes toward oxygen evolution. Oxygen evolution was also affected by R groups on the ligands, in the order Me>Et > Bz (Najafpour & Boghaei, 2009). (Fig.…”

Amorphous Manganese-Calcium Oxides as a Possible Evolutionary Origin for the CaMn4 Cluster in Photosystem II

“…The cell was charged with Ce(IV). Cerium(IV) ammonium nitrate (0.01 M) was dissolved in 25 ml water magnetically stirred at 25.0 0 C. Ce(IV) was stable in this condition and oxygen evolution was not observed (Yagi and Narita 2004;Najafpour and Boghaei 2009). After deaeration of Ce(IV) with nitrogen, the compounds as solid suspensions were added and oxygen evolution was recorded with the oxygen meter under stirring (Scheme 2).…”