Accumulation of mono-reduced [Ir(piq)2(LL)]+ photosensitizers relevant for solar fuels productions

Details

Supervisors

Elias, Benjamin ; Troian-Gautier, Ludovic

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

A series of nine [Ir(piq)2(LL)] .PF6 photosensitizers were developed and investigated for excited-state electron transfer with sacrificial electron donors that included triethanolamine (TEOA), triethylamine (TEA), and 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH) in acetonitrile. The photosensitizers were obtained in 57-82% yield starting from the common [Ir(piq)2Cl]2 precursor and were all characterized by UV-Vis absorption as well as by steady-state, time-resolved spectroscopies, and electrochemistry. The excited-state lifetimes ranged from 250 to 3350 ns and were also shown, in some cases, to be strongly influenced by dissolved oxygen. Excited-state electron transfer quenching rate constants in the 10 M–1s–1 range were obtained when BIH was used as electron donor. These quenching rate constants were three orders of magnitude higher than when TEA or TEOA is used. Steady-state photolysis in the presence of BIH showed that the stable and reversible accumulation of mono-reduced photosensitizers was possible, highlighting the potential use of these Ir-based photosensitizers in photocatalytic reactions relevant for solar fuels production.