Photoinduced processes in dyads and triads containing a ruthenium(II)-bis(terpyridine) photosensitizer covalently linked to electron donor and acceptor groups. [Ru(ttp) sub 2 sup 2+ where ttp=4 prime -p-tolyl-2,2 prime :6 prime ,2 double prime -terpyridine]

Journal Article · Wed Oct 30 00:00:00 EST 1991 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00022a026· OSTI ID:7163206

Collin, J P; Guillerez, S; Sauvage, J P ^[1]; Barigelletti, F; Flamigni, L ^[2]; De Cola, L; Balzani, V ^[3]

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1. Univ. Louis Pasteur, Strasbourg (France)
2. Inst. FRAE-CNR, Bologna (Italy)
3. Univ. di Bologna (Italy)

Five supramolecular systems containing the Ru(ttp){sub 2}{sup 2+} photosensitizer (P) covalently linked to an electron acceptor (A), MV{sup 2+}, and/or an electron donor (D), PTZ or DPAA, have been synthesized; ttp is 4{prime}-p-tolyl-2,2{prime}:6{prime},2{double prime}-terpyridine, MV{sup 2+} is methyl viologen, PTZ is phenotiazine, and DPAA is di-p-anisylamine. In the D-P-A triads the electron donor and acceptor groups are linked in opposite positions with respect to the photosensitizer. The spectroscopic properties (room-temperature absorption spectra, emission spectra and lifetimes in the 90-200 K temperature range, and transient absorption spectra and lifetimes at 150 K) and the (room-temperature) electrochemical behavior of the supramolecular systems and of their components have been investigated. At 90 K, where the solvent is frozen, no quenching of the photosensitizer luminescence is observed for all the supramolecular systems. At 150 K, where the solvent is fluid, the results obtained were as follows. In the PTZ-Ru(ttp){sub 2}{sup 2+} dyad, neither quenching of the photosensitizer luminescence nor formation of oxidized donor are observed. In the DPAA-Ru(ttp){sub 2}{sup 2+} dyad, luminescence quenching and transient formation of the oxidized donor take place. For the Ru(ttp){sub 2}{sup 2+}-MV{sup 2+} dyad, transient formation of the reduced acceptor is observed, but the lifetime of the photosensitizer luminescence increases, indicating that charge recombination leads back to the excited photosensitizer. The PTZ-Ru(ttp){sub 2}{sup 2+}-MV{sup 2+} triad behaves as the Ru(ttp){sub 2}{sup 2+}-MV{sup 2+} dyad. For the DPAA-Ru(ttp){sub 2}{sup 2+}-MV{sup 2+} triad, strong luminescence quenching is observed, and transient absorption spectroscopy shows that charge separation is followed by a very fast charge recombination reaction ({tau}<100 ns). Thermodynamic and kinetic aspects of the photoinduced electron-transfer processes are discussed.

• OSTI ID: 7163206
• Journal Information: Inorganic Chemistry; (United States), Vol. 30:22; ISSN 0020-1669
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
RUTHENIUM COMPLEXES
CHEMICAL PREPARATION
ELECTROCHEMISTRY
PHOTOCHEMISTRY
ABSORPTION SPECTRA
ABSORPTION SPECTROSCOPY
AMBIENT TEMPERATURE
AMINES
BINDING ENERGY
BIPYRIDINES
ELECTRONS
EMISSION SPECTRA
LASER RADIATION
LIGANDS
LUMINESCENCE
NMR SPECTRA
PHENOTHIAZINES
PHOTOLYSIS
PHOTOSENSITIVITY
PYRIDINES
VALENCE
AZINES
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ENERGY
FERMIONS
HETEROCYCLIC COMPOUNDS
LEPTONS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHOTOCHEMICAL REACTIONS
RADIATIONS
SENSITIVITY
SPECTRA
SPECTROSCOPY
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
400500* - Photochemistry
400400 - Electrochemistry
400201 - Chemical &amp; Physicochemical Properties