Investigation and Enhancement of the Stability and Performance of Water Reduction Systems based on Cyclometalated Iridium(III) Complexes. Issue 1 (12th November 2012)

• Record Type: Journal Article
• Authors: Hansen, Sven; Pohl, Marga‐Martina; Klahn, Marcus; Spannenberg, Anke; Beweries, Torsten
• Is Part Of: ChemSusChem. Volume 6:Issue 1(2013:Jan.)
• Page Start: 92
• Page End: 101
• Publication Date: 2012-11-12
• Subjects: Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201200617
• Languages: English
• ISSNs: 1864-5631

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Water reduction systems that use a bis‐cyclometalated Ir^III photosensitiser (PS) along with homogeneous Pd complexes as a source of in‐situ‐formed colloidal Pd as the water reducing complex (WRC) and triethylamine (TEA) as the sacrificial electron donor were tested and characterised with respect to their photocatalytic H₂ production performance. It was confirmed that substitution of the 2‐(pyridin‐2‐yl)benzen‐1‐ide (pyb) ligand in the well‐known system [Ir(pyb)₂(bpy)]⁺ (bpy=2, 2′‐bipyridine) by the fluorinated cyclometalating ligand 5‐fluoro‐2‐(5‐methylpyridin‐2‐yl)benzen‐1‐ide (Fmpyb) tremendously enhanced the H₂ production rate. Moreover, variation of the bidentate N^N ligand bpy by alkyl substitution in the 4, 4′‐position resulted in an increase in the H₂ production yield by a factor of three. The incident‐photon‐to‐hydrogen‐efficiency could be enhanced from 2.6 to 12.3 %. Furthermore, a new dinuclear Co complex was used as a reduction catalyst and showed up to 760 turnovers after 20 h. A detailed study of the concentration impact of all components in the photoredox system was performed. DFT calculations were used to aid the explanation of the findings.</p> </abstract>