Water Oxidation by Mononuclear Ruthenium Complexes with TPA-Based Ligands

Abstract

The synthesis, characterization, and water oxidation activity of mononuclear ruthenium complexes with tris(2-pyridylmethyl)amine (TPA), tris(6-methyl-2-pyridylmethyl)amine (Me(3)TPA), and a new pentadentate ligand N,N-bis(2-pyridinylmethyl)-2,2'-bipyridine-6-methanamine (DPA-Bpy) have been described. The electrochemical properties of these mononuclear Ru complexes have been investigated by both experimental and computational methods. Using Ce(IV) as oxidant, stoichiometric oxidation of water by [Ru(TPA)(H(2)O)(2)](2+) was observed, while Ru(Me(3)TPA)(H(2)O)(2)](2+) has much less activity for water oxidation. Compared to [Ru(TPA)(H(2)O)(2)](2+) and [Ru(Me(3)TPA)(H(2)O)(2)](2+), [Ru(DPA-Bpy)(H(2)O)](2+) exhibited 20 times higher activity for water oxidation. This study demonstrates a new type of ligand scaffold to support water oxidation by mononuclear Ru complexes.

Solid-Phase Synthesis as a Platform for the Discovery of New Ruthenium Complexes for Efficient Release of Photocaged Ligands with Visible Light

“…The ligands DPAbpy, 72 N4Py 73 and TQA 71 were synthesized using literature procedures. Treating each ligand with one equiv of cis -[Ru(DMSO) 4 Cl 2 ] in MeOH at 80 °C led to rapid formation of the corresponding metal complex.…”

Role of ligands in catalytic water oxidation by mononuclear ruthenium complexes

“…As catalysts, metal complexes with the TPA ligand are attractive because their stable high oxidation states can be accessed through a PCET process both experimentally and by theoretical investigations [ 55 , 56 , 57 ]. Bearing these advantages in mind, Zhao and co-workers prepared a series of mononuclear Ru complexes with TPA-based ligands and reported their activity for water oxidation (Chart 7, 28-31) [58,59]. A descending trend of catalytic activity and stability for water oxidation by these complexes has been reported: 28 > 29 ≈ 30 ≈ 31.…”

Intramolecular Proton Transfer Boosts Water Oxidation Catalyzed by a Ru Complex

“…1,2,3,4,5,6 Efficient functionality for fast and oxidatively rugged 7,8 performance at neutral pH can provide durability for sufficiently long times as necessary for practical applications. 9,10 Here, we introduce and characterize a new family of Ru complexes, including compound [Ru IV (OH)(tda-κ-N 3 O)(py) 2 ] + with tda 2-=[2,2':6',2''-terpyridine]-6,6''-dicarboxylate, found to be an impressive water oxidation catalyst both under neutral and alkaline conditions.…”