Bis-terpyridine Os(Ⅱ) Complex Sensitized [FeFe] Hydrogenase Mimic Systems: Synthesis and Photophysical Study

Abstract

Fe 0 at -1.77 eV, which shifts 180 mV more negative than the corresponding reduction potential of compound 2. Excitation of the MLCT absorption of compound 1b leads to a strong luminescence at 740 nm with lifetime of 105 ns in CH 3 CN. However, the luminescence of dyad 1a was significantly quenched with efficiency of 92%. Under the same condition, the luminescence of 1b was slightly quenched by one equivalent of compound 2. The quenching efficiency of 1b was changed from 4% to 65% when the concentration of 2 was increased from 1 to 10 equivalents. According to Rehm-Weller equation, the photoinduced electron transfer from the excited osmium complex to Fe 2 S 2 moiety neither in intramolecular dyad 1a nor in intermolecular (1b＋2) system is feasible for the uphill free energy change. Consequently, the luminescence quenching in intramolecular dyad 1a and intermolecular (1b＋2) system was tentatively attributed to energy transfer from 3 MLCT of osmium complex to Fe 2 S 2 cluster.

Photocatalytic Hydrogen Production Based on a Serial Metal‐Salen Complexes and the Reaction Mechanism

“…Inspired by natural photosynthesis, a colorful array of iron, nickel and cobalt complexes have been crafted for hydrogen evolving catalysts, many of which show outstanding turnover frequencies and catalytic lifetimes . However, for molecular systems, the majority still employ noble or rear metals used in photosensitizer (PS) such as Pt, Ru, Ir, Os, Re etc. Especially, in order to thoroughly excavate catalysts’ catalytic ability, PS containing noble metals are usually used several times’ scale over catalysts in a multi‐components system, which greatly increases the cost of hydrogen production systems.…”