- Macrocyclic complexes of [Ru(N-N)2]2+ units [N-N = 1,10 phenanthroline or 4-(p-anisyl)-1,10-phenanthroline]: Synthesis and photochemical expulsion studies
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Two ruthenium complexes [Ru(phen)2(m-36)]2+ and [Ru(aphen)2(m-36)]2+, indicated as 1 and 2 respectively, which contain a 36-membered macrocycle incorporating a sterically hindered bipyridine (m-36), and two 1,10-phenanthroline (phen) or 4-(p-anisyl)-1,10-phenanthroline (aphen) ligands, have been synthesised. Under light irradiation, as seen from the metal-to-ligand-charge-transfer (MLCT) bands of the visible spectral region, the [Ru(phen)]22+ core of 1 and 2 is selectively expelled from the macrocycle to give the corresponding bis-acetonitrile derivative. This photochemical process was found to be notably less efficient than that observed in a simpler related complex [Ru(phen)2dmbp]2+ (dmbp = 6,6′dimethyl-2,2′-bipyridine), that lacks the macrocyclic motif. In the case of 1 thermal back reaction takes place quantitatively affording a completely reversible system. The isolation, by chromatographic techniques, of the axial-axial cis-[(a,a)Ru(aphen)2Cl2] isomer, where the two aphen ligands bear two p-anisyl groups disposed trans to one another enabled the preparation of 2. This type of complex undergoes a more complicated photochemical process, in fact, following the expected photolabilisation of the [Ru(aphen)2]2+ unit, photoisomerisation of the primary photo-product occurs and gives a statistical mixture of the three geometrical isomers: cis-[(a,a)Ru(aphen)2(CH3CN)2] (PF6)2, cis-[(a,e)Ru(aphen)2(CH3CN)2] (PF6)2 and cis-[(e,e)Ru(aphen)2(CH3CN)2] (PF6)2. This side-reaction precludes its use as rotaxane precursor suggesting that, for this purpose, a bis-phenanthroline ligand stabilising the ruthenium core is needed. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Laemmel, Anne-Chantal,Collin, Jean-Paul,Sauvage, Jean-Pierre,Accorsi, Gianluca,Armaroli, Nicola
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- Luminescent Metal Complexes. Part 5. Luminescence Properties of Ring-substituted 1,10-Phenanthroline Tris-complexes of Ruthenium(II)
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The absorption characteristics, emission spectra, luminescent quantum yields, and lifetimes are reported for 24 ruthenium(II) tris-1,10-phenanthroline complexes in EtOH-MeOH solution.Quantum yields fall between 0.019 and 0.403, the highest values being re
- Alford, Peter C.,Cook, Michael J.,Lewis, Anthony P.,McAuliffe, Glenn S. G.,Skarda, Vladimir,et al.
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p. 705 - 710
(2007/10/02)
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