80907-59-1Relevant academic research and scientific papers
Reductive electron transfer quenching of MLCT excited states bound to nanostructured metal oxide thin films
Bergeron, Bryan V.,Meyer, Gerald J.
, p. 245 - 254 (2003)
The ruthenium compounds Ru(deeb)(bpz)2(PF6)2, Ru(deeb)2(bpz)(PF6)2, and Ru(deeb)2(dpp)(PF6)2, where deeb is 4,4a?2-(CO2CH2CH3)2-2,2a?2-b ipyridine, bpz is 2,2a?2-bipyrazine, and dpp is 2,3-bis(2-pyridyl)pyrazine, have been prepared, characterized, and anchored to mesoporous nanoparticle thin films comprised of the wide band gap semiconductor TiO2 or the insulator ZrO2. The metal-to-ligand charge-transfer (MLCT) excited states of these compounds are potent photooxidants (Eo(RuII*/+) > +1.0 V vs SCE) with long lifetimes (?? > 1 ??s) that efficiently oxidize iodide and phenothiazine with rate constants that approach the diffusion limit in acetonitrile. Photogalvanic cells based on the sensitized TiO2 materials yield photocurrent action spectra that agree well with the Ru(II) absorptance spectra. The photocurrent efficiency was very low, ?? -4. Transient absorption data show that neither the excited nor the reduced state of the ruthenium compounds efficiently inject electrons into the TiO2 particles. The cage escape yields following excited-state electron transfer are approximately 2/3 lower in the mesoporous thin films than in fluid solution. Intermolecular energy transfer across the nanoparticle surfaces is manifest in a second-order component to the excited-state relaxation kinetics.
Physical, spectroscopic, and biological properties of ruthenium and osmium photosensitizers bearing diversely substituted 4,4′-di(styryl)-2,2′-bipyridine ligands
Cariou, Kevin,Gasser, Gilles,Karges, Johannes,Tharaud, Micka?l,Vinck, Robin
, p. 14629 - 14639 (2021/11/03)
Capitalising on the previous identification of a distyryl coordinated Ru(ii) polypyridine complex as a promising photosensitizer for photodynamic therapy, eight new complexes were synthesized by modifications of the ligands or by changing the metal coordinated. We report in this work the effects of these modifications on the physical, spectroscopic, and biological properties of the synthesized complexes. Subtle structural modifications of the distyryl ligand only had a moderate effect on the corresponding complexes' visible light absorption and singlet oxygen quantum yield. These modifications however had a significant effect on the lipophilicity, the cellular uptake and the phototoxicity of the complexes. Although the lipophilicity of the complexes had a somewhat expected effect on their cellular uptake, this last parameter could not be directly correlated to their phototoxicity, revealing other underlying phenomena. Overall, this work allowed identification of two promising ruthenium complexes as photosensitisers for photodynamic therapy and provides some guidance on how to design better photosensitizers. This journal is
Photosubstitution in tris chelate complexes of ruthenium(II) containing the ligands 2,2′-bipyrazine, 2,2′-bipyrimidine, 2,2′-bipyridine, and 4,4′-dimethyl-2,2′-bipyridine: Energy gap control
Ross, Helen B.,Boldaji, Massoud,Rillema, D. Paul,Blanton, Charles B.,White, Russell P.
, p. 1013 - 1021 (2008/10/08)
Photosubstitution was studied for a series of ruthenium(II) complexes containing the ligands 2,2′-bipyridine (bpy), 2,2′-bipyrimidine (bpm), 2,2′-bipyrazine (bpz), 4,4′-dimethyl-2,2′-bipyridine ((CH3)2bpy), pyridine (py), CH3CN, and Cl-. For the study, a number of new complexes were synthesized that include [Ru(bpz)2(bpm)]2+, [Ru((CH3)2bpy)2(py)2]2+, [Ru(bpm)2(py)2]2+, [Ru(bpz)2-(py)2]2+, [Ru(bpz)(bpy)(py)2]2+, [Ru(bpm)2(bpz)]2+, [Ru(bpz)(bpm)(bpy)]2+, [Ru(bpm)2(CH3CN)Cl]+, and Ru(bpm)2Cl2 and their absorption, emission, and electrochemical properties were determined. The newly synthesized complexes exhibited MLCT transitions that ranged from 439 nm for [Ru((CH3)2bpy)2(py)2]2+ to 571 nm for Ru(bpm)2Cl2, corrected emission maxima that ranged from 615 nm for [Ru((CH3)2bpy)2(py)2]2+ to 788 nm for [Ru(bpm)2(CH3CN)Cl]+, Ru(III/II) metal-centered redox potentials that varied from 0.58 V for Ru(bpm)2Cl2 to 1.87 V vs SSCE for [Ru(bpz)2(bpm)]2+, ligand-centered reductions, the first of which varied from -0.75 V for [Ru(bpz)2(bpm)]2+ to -1.46 V vs SSCE for [Ru((CH3)2bpy)2(py)2]2+, and radiative quantum yields that ranged from 0.04 for [Ru(bpz)2(bpm)]2+ to 1.8 × 10-5 for [Ru(bpm)2(CH3CN)Cl]+. Photosubstitution quantum yields of the complexes [Ru(bpz)2(bpm)]2+, [Ru(bpm)2(bpz)]2+, [Ru(bpz)(bpm)(bpy)]2+, [Ru(bpm)2(CH3CN)Cl]+, [Ru(bpz)2-(CH3CN)Cl]+, and [Ru(L-L)2(py)2]2+ (L-L = (CH3)2bpy, bpy, bpm, bpz), and Ru(bpy)n(L′-L′)3-n(n = 0-3; L′-L′ = bpz, bpm) were studied in acetonitrile containing 1 mM Cl- at room temperature (25 ± 0.1°C). The substitution quantum yields ranged from 0.35 for [Ru(bpz)3]2+ to 1.7 × 10-4 for [Ru(bpy)2(bpz)]2+. The logarithm of the observed photochemical substitution quantum yield was found to correlate linearly with ΔE1/2, where ΔE1/2 is the difference in redox potential between the first oxidation and first reduction of the ruthenium complexes. The correlation of In φp(obs) with ΔE1/2 occurred in two series: one with complexes containing bpm and bpz ligands and the other with complexes containing only bpy-type ligands. Under a set of limiting conditions, the correlation of In φp(obs) with ΔE1/2 was shown to relate to the energy gap law.
Comparative chemistry of bipyrazyl and bipyridyl metal complexes: Spectroscopy, electrochemistry, and photoanation
Crutchley,Lever
, p. 2276 - 2282 (2008/10/08)
The photoanation of the bipyrazyl complex Ru(bpz)3(PF6)2, in acetonitrile containing chloride ion, leads to the formation of cis-Ru(bpz)2(CH3CN)Cl+ (maximum quantum yield 0.37), cis-Ru(bpz)2Cl2 (maximum quantum yield 0.001), and an unidentified mono(bipyrazyl)ruthenium(II) derivative. The mechanism of this reaction is discussed. Reaction of M(CO)6 (M = W, Mo) with bipyrazyl yields M(CO)4bpz. The electronic, vibrational, and 1H NMR spectra and electrochemistry of these products were compared with those of their bipyridyl analogues. It is concluded that bipyrazyl is no better a π acceptor than bipyridyl because of weaker σ bonding leaving the metal ion more positvely charged.
