Red-light-driven photocatalytic hydrogen evolution using a ruthenium quaterpyridine complex

Abstract

A high-temperature, microwave synthesis of [Ru(qpy)3](2+) (qpy = 4,4':2',2'':4'',4'''-quaterpyridine) affords the photosensitiser in quantitative yield. The complex produces H2 photocatalytically in a range extending from the UV region of the spectrum to the red with greater efficiency when compared to [Ru(bpy)3](2+).

Hydrogen Photoevolution from a Green‐Absorbing Iridium(III)–Cobalt­(III) Dyad

“…The low quantum yield of [Ir‐Py] + could be related to the fact that this photoinduced electron‐transfer rate is slower than that of [Ir(ppy) 2 (bpy)] + (the low homogeneous activity of the Ir–Co assembly could also characterize directional electron transfer through the pyridylterpyridine to cobaloxime19). The pendant pyridine ring of [Ir‐Py] + could act as an electron relay from the PS to the catalyst, as it links both entities9d and is the coordination site for cobaloxime. Coordination of cobaloxime to the PS appears to be a crucial factor for the efficiency and stability of the system 9…”

A Bisamide Ruthenium Polypyridyl Complex as a Robust and Efficient Photosensitizer for Hydrogen Production

“…For an efficient photocatalytic system, the PS and the catalyst must be in close proximity for efficient electron transfer; many assemblies exist that are covalently linked or connected by pendant pyridine (py) on the PS, which coordinates the catalysts ,,. Indeed, the better the electron transfer, the lesser is the probability of PS decomposition induced by ligand dissociation; for example, the multi‐metallic center‐based supramolecular assembly Ru–Co 6 has better efficiency than the dissociated [Ru(bpy) 3 ] 2+ –[Co(dmgH) 2 ] + (dmgH=dimethylglyoxime) system . Charge‐separated states and electronic transfer rates were also investigated through hydrogen‐bonding or hydrophobic‐interaction studies .…”

“…TEOA is used as a sacrificial electron donor (SED). As we recently reported for a Ru–Co 6 system, the photocatalytic activity and decomposition pathways of the reagents and catalysts depend on the wavelengths of irradiation …”

Near‐Infrared Light‐Driven Hydrogen Evolution from Water Using a Polypyridyl Triruthenium Photosensitizer

“…[9] However,the integrated photon flux can be almost doubled if the 280-800 nm domain (39.6 %ofthe total solar irradiance) could be fully used by the PS when driving H 2 evolution. In this context, Hanan et al employed qpy (4,4':2,2'':4'',4'''-quarterpyridine) instead of bpy,and showed that [Ru(qpy) 3 ] 2+ (see Figure 1A)i sc apable of absorbing longer wavelength light and can actually drive photochemical H 2 evolution even by irradiation at 630 nm, [10] corresponding to the tail of its metal-to-ligand charge transfer ( 1 MLCT) absorption band. Thel imits of their system were shown by the fact that no measurable H 2 evolves under the near-infrared light (733 nm) irradiation, clearly due to the negligible absorptivity at this wavelength.…”

“…Oxidative and reductive quenchingp athwaysf or H 2 evolution driven by molecular photosystems where *d enotesi ts triplet state. by irradiation at 630 nm, [10] corresponding to the tail of its metal-to-ligand charge transfer ( 1 MLCT) absorption band. Thel imits of their system were shown by the fact that no measurable H 2 evolves under the near-infrared light (733 nm) irradiation, clearly due to the negligible absorptivity at this wavelength.…”