80907-58-0Relevant articles and documents
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.
