Chemical Scavenging Yields for Short-Lived Products from the Visible Light Photoionization of the Tris(bipyridine)ruthenium(II) Triplet Metal-to-Ligand Charge-Transfer Excited State

Abstract

The rate of visible light photoionization of the tris­(bipyridine)­ruthenium­(II) triplet metal-to-ligand charge-transfer excited state (3MLCT) is very strongly dependent on the acid concentration in aqueous solution, and the pattern of this dependence is similar to that reported for the photoionization of iodide. With 405 nm visible irradiation of 3MLCT, less than 15% of the photoionized products appear as free solvated electrons in bulk solution, while more than 75% of the photoproducts appear to be solvent-separated, (oxidized substrate)–electron ion pairs that efficiently recombine with the photo-oxidized complex in the absence of an electron scavenger. The quantum yield of free solvated electrons generated by these 405 nm irradiations is approximately 0.004, but the net quantum yield of scavengeable electrons is estimated to be about 0.04. A visible-region photoionization threshold energy for the 3MLCT is consistent with thermodynamic expectations, and similar behavior is expected for many redox-active complexes.

Understanding the Photocatalytic Reduction of CO2with Heterometallic Molybdenum(V) Phosphate Polyoxometalates in Aqueous Media

“…3 [Ru III (bpy) 2 (bpy •− )] 2+, * has been reported for wavelengths that range from the UV 48 to the violet 49 regions of the spectrum. Thus, it might be reasonable to think that the LSCT band that originates from the ground state of [Ru II (bpy) 2 (bpy •− )] + (which bears a lower positive charge) is red-shifted because of the higher-lying nature of the singly occupied molecular orbital (Figure S18), favoring the photogeneration of solvated electrons at our photocatalytic conditions (λ > 415 nm).…”

“…In the presence of CO 2 , solvated electrons tend to localize in an empty π* MO of CO 2 , resulting in a CO 2 •– radical anion with a bent structure , and importantly, accomplishing the first electron injection. The photoionization of 3 [Ru III (bpy) 2 (bpy •– )] 2+,* has been reported for wavelengths that range from the UV to the violet regions of the spectrum. Thus, it might be reasonable to think that the LSCT band that originates from the ground state of [Ru II (bpy) 2 (bpy •– )] + (which bears a lower positive charge) is red-shifted because of the higher-lying nature of the singly occupied molecular orbital (Figure S18), favoring the photogeneration of solvated electrons at our photocatalytic conditions (λ > 415 nm).…”

Kalium Permanganat: Termodinamika Mengenai Transport Ionik dalam Air

“…•ΔS yang meningkat Untuk merumuskan dua faktor di atas diperlukan besaran yang disebut : Energi Bebas (G) (146)(147)(148)(149)(150)(151)(152)(153) Rumus : ΔG = ΔH -T.ΔS…”

Controlling Spin‐Correlated Radical Pairs with Donor–Acceptor Dyads: A New Concept to Generate Reduced Metal Complexes for More Efficient Photocatalysis

“…The 3 MLCT lifetimed ecrease from~600 ns (Ru(bpy) 3 2 + )t õ 130 ps (dyad) indicates quantitative 3 MLCT quenching (99.98 %) in our dyad and based on our results, intramolecular TTET is the only quenching pathway.T herefore, it seems natural to assume at riplet anthracene formationq uantum yield of 100 %u pon visible excitation of Ru(bpy) 3 2 + -xy 1 -Ant, and we performed relative actinometry [70] with Ru(bpy) 3 2 + in water as widely used reference system, [29,71,72] following the methodology that we recently explained in detail. [57] Using 532 nm laser pulses for excitation,ad ouble determination of the molar absorptionc oefficient of Ru(bpy) 3 2 + -xy 1 -3 Ant gave av alue of 23 000(AE 500) m À1 cm À1 at the triplet anthracene absorption maximum, 427 nm.…”