Ruthenium dyes polypyridyl

The ruthenium(II) polypyridyl complexes are also popular but the brightnesses do not exceed 15,000 and thermal quenching is rather significant. This property can be utilized to design temperature-sensitive probes providing that the dyes are effectively shielded from oxygen (e.g., in polyacrylonitrile beads). Despite often very high emission quantum yields the visible absorption of cyclometallated complexes of iridium(III) and platinum(II) is usually poor (e < 10,000 M-1cm-1), thus,... 

Many PSPs are composed of probe dyes, such as polycyclic aromatic hydrocarbons (e.g., pyrene) and coordination compounds (e.g., platinum por-phryins and ruthenium(II) polypyridyl complexes) immobilized in various gas permeable polymer films such as silicon polymer, organic glassy polymers (e.g., poly(methylmethacrylate), polystyrene), fluorinated polymers, or cellulose derivatives such as ethyl cellulose [9,10]. As probe molecules interact with polymer matrices directly, the properties of PSPs strongly depend on the properties of polymer matrices. The oxygen permeability of polymer matrix is an especially important factor for highly sensitive PSP. 

The sensor for the measurement of high levels of CO2 in gas phase was developed, as well90. It was based on fluorescence resonance energy transfer between 0 long-lifetime ruthenium polypyridyl complex and the pH-active disazo dye Sudan III. The donor luminophore and the acceptor dye were both immobilized in a hydrophobic silica sol-gel/ethyl cellulose hybrid matrix. The sensor exhibited a fast and reversible response to carbon dioxide over a wide range of concentrations. 

Figure 6.11 Illustration of the photophysical processes expected for a TiCVbound ruthenium polypyridyl dye...

Durrant and co-workers have compared the electron injection and recombination processes of 28 or Zn-28 with that of N3 (a famous ruthenium polypyridyl complex with very high IPCE). Their experiments revealed that the electron injection and recombination kinetic for these three dyes on the surface of Ti02 are almost identical. The high IPCE for N3 dye probably originates from the electron transfer from the iodide redox couple to the dye cations. It is also possible that the lower efficiency of porphyrin sensitizers was caused by the annihilation of the excited states between the neighboring porphyrin molecules because of the closed proximity [70],... 

Both phthalocyanines and porhyrins are very promising sensitizers for wide band gap semiconductors. DSSCs fabricated from these kind of sensitizers present overall power conversion efficiency as high as 7%, which is still smaller than that achieved by the ruthenium polypyridyl complexes though, but higher than most of other dyes. The multiplicity on the molecular structure modification of these compounds provides a great potential for further promotion on their sensitization properties. The research in this field is still far from systematic and comprehensive and quantitatively much less than the researches on polypyridyl ruthenium complexes. But... 

Cosensitization of ruthenium—polypyridyl dyes with organic dyes in dye-sensitized solar cells 13CL1328. 

Another chromophore-catalyst assembly supported onto an electrode was reported by Meyer and coworkers.A ruthenium polypyridyl dye was covalently linked both to a single site ruthenium OEC and to the Ti02 electrode. Initial transient laser and photocurrent measurements on the nanosecond timescale reveal that excitation of the photosensitizer leads to a rapid electron injection to the Ti02 followed by an intramolecular electron transfer from the ruthenium center of the catalyst to the ruthenium center of the dye, in a sub-ns timescale. However, injection from the chromophore attached to Ti02 remains inefficient (< 10 %), so this assembly needs further improvement to provide a key material for photoanode fabrication. 

Since a few years, ruthenium- and iridium-based polypyridyl complexes are privileged photocatalysts in visible light photocatalysis. However, organic dyes should constitute a valuable alternative not only due to their relatively lower cost and wider availability but also by giving access to new transformations. The direct arylation of heteroarenes (e.g., furan, thiophene, and pyrrole)... 

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